Optimizing the electrical excitation of an atmospheric pressure plasma advanced oxidation process

The impact of pulse-modulated generation of atmospheric pressure plasma on the efficiency of organic dye degradation has been investigated. Aqueous samples of methyl orange were exposed to low temperature air plasma and the degradation efficiency was determined by absorbance spectroscopy. The plasma was driven at a constant frequency of 35kHz with a duty cycle of 25%, 50%, 75% and 100%. Relative concentrations of dissolved nitrogen oxides, pH, conductivity and the time evolution of gas phase ozone were measured to identify key parameters responsible for the changes observed in degradation efficiency. The results indicate that pulse modulation significantly improved dye degradation efficiency, with a plasma pulsed at 25% duty showing a two-fold enhancement. Additionally, pulse modulation led to a reduction in the amount of nitrate contamination added to the solution by the plasma. The results clearly demonstrate that optimization of the electrical excitation of the plasma can enhance both degradation efficiency and the final water quality.

TEM characterization of dislocations in TiB2 particles after hypervelocity impact

Characteristic of dislocations in TiB2 particles associated with hypervelocity impact craters in 65 vol.% TiB2/Al composite were investigated by transmission electron microscopy (TEM). Two kinds of dislocation networks in as-impacted TiB2 particles were identified. One is hexagonal dislocation networks including 1/3〈1̄21̄0〉, 〈0001〉, 1/3〈1̄21̄3〉 type dislocations on {0001}, {101̄0}, and {123̄0} planes. Another one is the hexagonal dislocation networks including 1/3〈112̄0〉, 〈0001〉, and 1/3〈112̄3〉 type dislocations on {0001}, {101̄0}, and {11̄00} planes. Formation of dislocation network should be contributed to the parallel sets of "a" type dislocations (1/3〈112̄0〉 or 1/3〈1̄21̄0〉 type dislocations) reacting with parallel sets of "b" type dislocations (〈0001〉 type dislocations) to form "c" type dislocations (1/3〈112̄3〉 or 1/3〈1̄21̄3〉 type dislocations). Moreover, dislocations reaction processes do not result in an energy reduction, and are called quasi-equilibrium configurations. Formation of dislocations may result from high temperature or pressure generated by hypervelocity impact. During the cooling from high temperature and unloading from high pressure, dislocations in TiB2 particles rearranged and transformed to dislocation networks to lower the defect energy.

Polymorphysims of CYP17-I Gene in the Exons Were Associated with the Reproductive Endocrine of Japanese Flounder (Paralichthys olivaceus)

The cytochrome P450c17-I (CYP17-I) is one of the enzymes critical to gonadal development and the synthesis of androgens. Two single nucleotide polymorphisms (SNPs) were detected within the coding region of the CYP17-I gene in a population of 75 male Japanese flounder (Paralichthys olivaceus). They were SNP1 (c.C445T) located in exon2 and SNP2 (c.T980C (p.Phe307Leu)) located in exon5. Four physiological indices, which were serum testosterone (T), serum 17β-estradiol (E₂), Hepatosomatic index (HSI), and Gonadosomatic index (GSI), were studied to examine the effect of the two SNPs on the reproductive endocrines of Japanese flounder. Multiple comparisons revealed that CT genotype of SNP1 had a much lower T level than CC genotype (p<0.05) and the GSI of individuals with CC genotype of SNP2 was higher than those with TT genotype (p<0.05). Four diplotypes were constructed based on the two SNPs and the diplotype D3 had a significantly lower T level and GSI. In conclusion, the two SNPs were significantly associated with reproductive traits of Japanese flounder.

Effects of curcumin on hippocampal expression of NgR and axonal regeneration in Aβ-induced cognitive disorder rats

Curcumin has been widely used for the prevention and treatment of Alzheimer's disease (AD), but its mechanism is still not clear. Inhibitory factors of axonal regeneration have been shown to cause a series of pathophysiological changes in the early period of AD. In this study, the co-receptor (Nogo receptor; NgR) of three axonal growth-inhibitory proteins was examined, and effects of curcumin on spatial learning and memory abilities and hippocampal axonal growth were investigated in amyloid β-protein (Aβ)1-40-induced AD rats. Results showed that the expression of NgR in the AD group significantly increased and the number of axonal protein-positive fibers significantly reduced. The spatial learning and memory abilities of AD rats were significantly improved in the curcumin group. Furthermore, hippocampal expressions of NgR mRNA and protein decreased, and the expression of axonal protein significantly increased. There was a negative correlation between the expression of NgR and axonal growth. Together, these results suggested that curcumin could improve the spatial learning and memory abilities of AD rats. The mechanism might be related with its lowering of hippocampal NgR expression and promoting axonal regeneration.

Superposed pulse amplitude modulation for visible light communication

We propose and experimentally demonstrate a novel modulation scheme called superposed pulse amplitude modulation (SPAM) which is low-cost, insensitive to non-linearity of light emitting diode (LED). Multiple optical pulses transmit parallelly from different spatial position in the LED array and overlap linearly in free space to realize SPAM. With LED arrangement, the experimental results show that using the modulation we proposed the data rate of 120 Mbit/s with BER 1 × 10(-3) can be achieved with an optical blue filter and RC post-equalization.

Determination of amantadine and rimantadine using a sensitive fluorescent probe

Amantadine hydrochloride (AMA) and rimantadine hydrochloride (RIM) are non-fluorescent in aqueous solutions. This property makes their determination through direct fluorescent method difficult. The competing reactions and the supramolecular interaction mechanisms between the two drugs and coptisine (COP) as they fight for occupancy of the cucurbit[7]uril (CB[7]) cavity, were studied using spectrofluorimetry, (1)H NMR, and molecular modeling calculations. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescent probe method of high sensitivity and selectivity was developed to determine AMA or RIM in their pharmaceutical dosage forms and in urine samples with good precision and accuracy. The linear range of the method was from 0.0040 to 1.0 μg mL(-1) with a detection limit ranging from 0.0012 to 0.0013 μg mL(-1). This shows that the proposed method has promising potential for therapeutic monitoring and pharmacokinetics and for clinical application.

Cloning and bioinformatic analysis of an acidophilic beta-mannanase gene, Anman5A, from Aspergillus niger LW-1

Using 3' and 5' rapid amplification of cDNA ends (RACE) techniques, the full-length cDNA sequence of the AnmanSA, a gene that encodes an acidophilic beta-mannanase of Aspergillus niger LW-1 (abbreviated to AnMan5A), was identified from the total RNA. The cDNA sequence was 1417 bp in length, harboring 5'- and 3'-untranslated regions, as well as an open reading frame (ORF) which encodes a 21-aa signal peptide, a 17-aa propeptide and a 345-aa mature peptide. Based on the topology of the phylogenetic tree of beta3-mannanases from glycoside hydrolase (GH) family 5, the AnMan5A belongs to the subfamily 7 of the GH family 5. Its 3D structure was modeled by the bitemplate-based method using both MODELLER 9.9 and SALIGN programs, based on the known beta-mannanase crystal structures of Trichoderma reesei (1QNO) and Lycopersicon esculentum (1RH9) from the GH family 5. In addition, the complete DNA sequence of the Anman5A was amplified from the genomic DNA using the pUCm-T vector-mediated PCR and conventional PCR methods. The DNA sequence was 1825 bp in length, containing a 5'-flanking regulatory region, 2 introns and 3 exons when compared with the full-length cDNA.

Cloning and sequence analysis of complete gene encoding an alkaline lipase from Penicillium cyclopium

The complete gene (PG37 lipI) encoding an alkaline lipase (PG37 LipI) was cloned from the genomic DNA of Penicillium cyclopium PG37. The cloned PG37 lipI is 2020 bp in length, consisting of 632 bp of the 5' flanking promoter region and 1388 bp of the downstream fragment that contains 6 exons and 5 short introns. The promoter region harbors putative TATA box, CAAT box and several transcription factor binding sites. The open reading frame (ORF) encodes a PG37 LipI of 285 amino acid residues, which was predicted to contain a 20-aa signal peptide, a 7-aa propeptide and a 258-aa mature peptide with a conserved motif Gly-X-Ser-X-Gly. However, PG37 LipI shows only 32%, 30%, 28% and 26% identity with lipases of Aspergillus parasiticus, Penicillium camembertii, Thermomyces lanuginosus and Rhizomucor miehei, respectively. It was predicted that the main secondary structures of PG37 LipI are alpha-helix and random coil. Three amino acid residues, Ser132-Asp188-His241, compose the enzymatic active center in the tertiary structure.

Molecular cloning, functional characterization and phylogenetic analysis of TRAIL in Japanese pufferfish Takifugu rubripes

In this study, the complementary DNA (cDNA) of Japanese pufferfish Takifugu rubripes tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) was cloned by reverse-transcription PCR. The open reading frame of the TRAIL consisted of 870 bases. The deduced amino-acid sequence of the TRAIL showed a high homology with the sequences of other teleosts. Recombinant soluble TRAIL was fused with a small ubiquitin-related modifier gene to enhance the soluble expression level in Escherichia coli BL21 (DE3). In vitro, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide (MTT) assay indicated that the purified soluble TRAIL was able to induce apoptosis of Jurkat and HeLa cells in a dose-dependent manner.

Regenerated host axons form synapses with neurons derived from neural stem cells transplanted into peripheral nerves

It is reported that neural stem cells (NSC) can arrest denervated muscle atrophy and promote nerve regeneration when transplanted into injured peripheral nerves, and that regenerated host axons can form synapses with transplanted and differentiated NSC. In this study, F344 rat nerve segments and F344 rat NSC were transplanted into host green fluorescence protein (GFP) transgenic F344 rats. This allowed transplanted F344 rat tissue to be used as a nonluminous background for the clear visualization of regenerated host GFP axons. Regenerated host axons grew into the transplanted F344 nerve segment 2 weeks after nerve anastomosis. Immunohistochemical staining and confocal microscope analysis revealed that regenerated host axons formed synapses with NSC-derived neurons. The findings confirmed that regenerated peripheral axons form synapses with neurons in peripheral nerves, possibly forming the basis for clinical application in peripheral nerve injury.

Study on the interaction of morphine chloride with deoxyribonucleic acid by fluorescence method

The mode and mechanism of the interaction of morphine chloride, an important alkaloid compound to calf thymus deoxyribonucleic acid (ct DNA) was investigated from absorption and fluorescence titration techniques. Hypochromic effect was founded in the absorption spectra of morphine when concentration of DNA increased. The decreased fluorescence study revealed non-cooperative binding of the morphine to DNA with an affinity of 3.94x10(3)M(-1), and the stoichiometry of binding was characterized to be about one morphine molecule per nucleotide. Stern-Volmer plots at different temperatures proved that the quenching mechanism was static. Ferrocyanide quenching study showed that the magnitude of K(SV) of the bound morphine was lower than that of the free one. In addition, it was found that ionic strength could affect the binding of morphine and DNA. Fluorescence polarization and denatured DNA studies also applied strong evidences that morphine molecule was partially intercalated between every alternate base pairs of ct DNA. As observed from above experiments, intercalation was well supported as the binding mode of morphine and ct DNA.

Simultaneous nitrification-denitrification achieved by an innovative internal-loop airlift MBR: comparative study

This study assessed the performance of different single-stage continuous aerated submerged membrane bioreactors (MBR) for nitrogen removal. Almost complete nitrification was achieved in each MBR irrespective of operating mode and biomass system. Denitrification was found to be the rate-limiting step for total nitrogen (T-N) removal. The MBR with internal-loop airlift reactor (ALR) configuration performed better as regards T-N removal compared with continuous stirred-tank reactor (CSTR). It was demonstrated that simultaneous nitrification and denitrification (SND) is the mechanism leading to nitrogen removal and the contribution of microenvironment on SND is more remarkable for the MBRs with hybrid biomass. Macroenvironment analyses showed that gradient distribution of dissolved oxygen (DO) level in airlift MBRs imposed a significant effect on SND. Higher mixed liquor suspended solid (MLSS) concentration led to the improvement in T-N removal by enhancing anoxic microenvironment. Apparent nitrite accumulation coupled with higher nitrogen reduction was accomplished at MLSS concentration exceeded 12.6 g/L.

Study on the fluorescence properties of a new intramolecular charge transfer compound 1,5-diphenyl-3-(N-ethylcarbazole-3-yl)-2-pyrazoline

The fluorescence properties of a newly synthesized compound, 1,5-diphenyl-3-(N-ethylcarbazole-3-yl)-2-pyrazoline (DEP) have been studied. On excitation at 352 nm, the fluorescence spectrum exhibits a large red shift with an increase in the polarity of solvents. The intensity of the band is different in different solvents as well. The change in the dipole moment in various solvents at room temperature has been characterized by the absorption and steady state fluorescence techniques and calculated based on the Lippert-Mataga equation. DEP has an increase of dipole moment of 2.83 D units on excitation to the lowest singlet state. It is concluded that photo-induced charge transfer from N (1) to C (3) actually exists in the excited state of the pyrazoline moiety. Its fluorescence property is relative to viscosity and temperature of solvents. The phi(f) of DEP in neutral medium or basic medium is higher than acidic medium. In addition, when the concentration of DEP is higher than 10(-3) M, its fluorescence is quenched by the collision of each molecule. The red shift of the maximum emission of DEP attributes to the formation of aggregates and the conjugate system is strengthened.

Second amorphous-to-crystalline phase transformation in Cu(60)Ti(20)Zr(20) bulk metallic glass

The second amorphous-to-crystalline phase transformation in Cu(60)Ti(20)Zr(20) bulk metallic glass was investigated by differential scanning calorimetry and x-ray diffractometry. The difference of the Gibbs free energies between the amorphous phase and the crystalline products during the transformation is estimated to be about 2.46 kJ mol(-1) at 753 K, much smaller than the 61 kJ mol(-1) obtained assuming that it is a polymorphic transformation. It was revealed that the phase transformation occurs through a eutectic crystallization of Cu(51)Zr(14) and Cu(2)TiZr, having an effective activation energy of the order of 400 kJ mol(-1). The average Avrami exponent n is about 2.0, indicating that the crystallization is diffusion controlled.

Sphingosine kinase 1 participates in insulin signalling and regulates glucose metabolism and homeostasis in KK/Ay diabetic mice

AIMS/HYPOTHESIS

The aim of this study was to determine the potential role of sphingosine kinase 1 (SPHK1), a key sphingolipid metabolic enzyme, in glucose metabolism and homeostasis.

METHODS

SMMC-7721 hepatoma cells and C2C12 myotube cells were used to explore the role of SPHK1 in glucose uptake in vitro. KK/Ay type 2 diabetic mice, which were transfected with adenovirus harbouring the human SPHK1 gene by i.v. injection, were used to investigate the glucose-lowering effects of SPHK1 in vivo.

RESULTS

The basal glucose uptake and the insulin-stimulated glucose uptake in both 7721 cells and C2C12 cells were markedly enhanced when SPHK1 was overexpressed by adenovirus-mediated gene transfer, whereas they were substantially reduced when the expression of SPHK1 was inhibited or the activity of SPHK1 was blocked. Insulin could activate SPHK1 of both cell lines in a dose-dependent manner. SPHK1 gene delivery significantly reduced the blood glucose level of KK/Ay diabetic mice, but had no effect on that of normal animals. It also attenuated elevated levels of plasma insulin, NEFA, triacylglycerol, cholesterol and LDL, significantly ameliorated hyperglycaemia-induced injury of liver, heart and kidney, and enhanced phosphorylation of insulin-signalling kinases such as Akt and glycogen synthase kinase 3beta in livers of the diabetic animals.

CONCLUSIONS/INTERPRETATION

SPHK1 is involved in insulin signalling and plays an important role in the regulation of glucose and fat metabolism; adenovirus-mediated SPHK1 gene transfer might provide a novel strategy in the treatment of type 2 diabetes mellitus.

Self-assembled pattern formation of block copolymers on the surface of the sphere using self-consistent field theory

The spherical surface is spatially discretized with triangular lattices to numerically calculate the Laplace-Beltrami operator contained in the self-consistent field theory (SCFT) equations using a finite volume method. Based on this method we have developed a spherical alternating-direction implicit (ADI) scheme for the first time to help extend real-space implementation of SCFT in 2D flat space to the surface of the sphere. By using this method, we simulate the equilibrium microphase separation morphology of block copolymers including AB diblocks, ABC linear triblocks and ABC star triblock copolymers occurred on the spherical surface. In general, two classes of microphase separation morphologies such as striped patterns for compositionally symmetric block copolymers and spotted patterns for asymmetric compositions have been found. In contrast to microphase separation morphology in 2D flat space, the geometrical characteristics of a sphere has a large influence on the self-assembled morphology. For striped patterns, several of spiral-form and ring-form patterns are found by changing the ratio of the radius of a sphere to the averaging width of the stripes. The specific pattern such as the striped and spotted pattern with intrinsic dislocations or defects stems from formed periodic patterns due to microphase separation of block copolymers arranged on the curved surface.

Cloning of novel laccase isozyme genes from Trametes sp. AH28-2 and analyses of their differential expression

Three novel laccase isozyme genes, lacA, lacB, and lacC, have been identified from basidiomycete Trametes sp. AH28-2. These genes display a high similarity with other basidiomycete laccases at the amino acid level. An inferred TATA box and several putative CAAT, MRE, XRE, and CreA consensus sequences were identified in the lacA, lacB, and lacC promoter regions. Different from the TATA boxes of lacA and lacB at about -100, the TATA box of lacC is located at -172. For all the isozymes, copper ion is essential for laccase synthesis in Trametes sp. AH28-2. More interestingly, different aromatic compounds can selectively induce the production of distinct laccase isozymes, with o-toluidine inducing the expression of laccase A (LacA) while 3,5-dihydroxytoluene mainly stimulating the production of laccase B (LacB). Quantitative reverse transcriptase-polymerase chain reaction showed that the accumulation of laccase messenger RNA transcripts is accompanied by the increase of corresponding enzyme activity in cultures. The glucose-repression effect on laccase expression in Trametes sp. AH28-2 was also observed. Furthermore, lower Cu2+ concentration (lower than 0.5 mM) can induce LacA and a novel laccase (LacC), and the latter will disappear when Cu2+ concentration is increased up to 1-2 mM. Upon induction by 3,5-dihydroxytoluene, the ratio of LacA to LacB decreased in the later phase of induction.

Conformal miniaturization of domains with low domain-wall energy: monoclinic ferroelectric states near the morphotropic phase boundaries

A theory is developed for intermediate monoclinic (FE(m)) phases near morphotropic phase boundaries in ferroelectrics of complex oxides. It is based on the conformal miniaturization of stress-accommodating tetragonal domains under the condition of low domain-wall energy density. The microdomain-averaged lattice parameters are determined and attributed to the parameters of an adaptive monoclinic phase. The theory is applied to the temperature, electric field, and compositional dependent FE(m) lattice parameters. The predictions of the theory are rigidly obeyed over the entire FE(m) stability range.

Characterization of capsid genes, expressed in the baculovirus system, of three new genetically distinct strains of "Norwalk-like viruses"

"Norwalk-like viruses" (NLVs), members of a newly defined genus of the family Caliciviridae, are the most common agents of outbreaks of gastroenteritis in the United States. Two features of NLVs have hindered the development of simple methods for detection and determination of serotype: their genetic diversity and their inability to grow in cell culture. To assess the immune responses of patients involved in outbreaks of gastroenteritis resulting from infection with NLVs, we previously used recombinant-expressed capsid antigens representing four different genetic clusters, but this panel proved insufficient for detection of an immune response in many patients. To extend and further refine this panel, we expressed in baculovirus the capsid genes of three additional genetically distinct viruses, Burwash Landing virus (BLV), White River virus (WRV), and Florida virus. All three expressed proteins assembled into virus-like particles (VLPs) that contained a full-length 64-kDa protein, but both the BLV and WRV VLPs also contained a 58-kDa protein that resulted from deletion of 39 amino acids at the amino terminus. The purified VLPs were used to measure the immune responses in 403 patients involved in 37 outbreaks of acute gastroenteritis. A majority of patients demonstrated a fourfold rise in the titer of immunoglobulin G to the antigen homologous to the outbreak strain, but most seroconverted in response to other genetically distinct antigens as well, suggesting no clear pattern of type-specific immune response. Further study of the antigenicity of the NLVs by use of VLPs should allow us to design new detection systems with either broader reactivity or better specificity and to define the optimum panel of antigens required for routine screening of patient sera.

"Norwalk-like viruses". Public health consequences and outbreak management

"Norwalk-like viruses" (NLVs) cause outbreaks of gastroenteritis and are spread frequently through contaminated food or water. Molecular diagnostics now enables detecting viruses in clinical and environmental specimens, linking of NLV strains causing outbreaks in multiple geographic locations, and tracing them to their sources in contaminated food or water. This report reviews recent advances in NLV detection and provides guidelines and recommendations for investigating NLV-related outbreaks, including specimen collection and disease prevention and control. This report also updates information provided in CDC's previously published, Viral Agents of Gastroenteritis: Public Health Importance and Outbreak Management (MMWR 1990;39 [No. RR-5]: 1-24). These CDC recommendations are intended for public health professionals who investigate outbreaks of acute gastroenteritis but could be useful in academic and research settings as well.

Hydrogen peroxide induces apoptosis in human hepatoma cells and alters cell redox status

Direct exposure of human hepatoma cell line SMMC-7721 to hydrogen peroxide (H2O2) can induce apoptosis. Apoptosis induced by H2O2 was inhibited by cycloheximide, actinomycin D, 3-aminobenzamide, EGTA or Zn2+. H2O2 can increase the level of intracellular Ca2+, downregulate GSH levels, slightly induce lipid peroxidation, and lead to change in the ratio of reduced ion components to oxidized ion components of cells. Analysis of flow cytometry indicates that H2O2 decreases the level of Bcl-2. The data indicate that H2O2-induced apoptosis requires new mRNA and protein syntheses; H2O2 can activate Ca2+/Mg2+-dependent endonuclease leading to internucleosomal DNA fragmentation and activation of poly (ADP-ribose) polymerase interfering with the energy metabolism of the cell. The H2O2 downregulation of GSH may be more important for apoptosis than H2O2 induction of lipid peroxidation, and the H2O2 induced changes in redox status of the cell may be among the original events which lead up to other biochemical changes.

A laser scanning confocal microscopy method. Simultaneous detection of intracellular Ca2+ and apoptosis using Fluo-3 and Hoechst 33342

OBJECTIVE

To develop a simple and direct method to simultaneously determine apoptotic cells from a treated population of cells and detect the changes of intracellular Ca2+ in these apoptotic cells, in particular single ones, by confocal microscopy.

STUDY DESIGN

MGC-803 cells treated with As2O3 were used as the double-staining cell model with Hoechst 33342 as a DNA probe and Fluo-3AM as a Ca2+ indicator. MGC-803 cell apoptosis induced by As2O3 was first demonstrated by DNA ladder in gel electrophoresis. Based on the difference in DNA stainability with Hoechst 33342 and corresponding fluorescence intensity between live and apoptotic cells, apoptotic cells and the changes in intracellular Ca2+ were detected at the same time by confocal microscopy. No necrotic cells in the group treated with As2O3 were found by the trypan blue exclusion test.

RESULTS

The results from confocal microscope detection showed that intact and apoptotic cells were successfully recognized and the changes of intracellular Ca2+ in apoptotic and intact cells were simultaneously detected in the same sample.

CONCLUSION

We provided a useful method to exactly detect changes in intracellular Ca2+ in apoptotic cells, especially in single ones, by confocal microscopy and to exclude the artifact effect of necrotic and intact cells.

Induction of apoptosis and inhibition of human gastric cancer MGC-803 cell growth by arsenic trioxide

Arsenic trioxide (As2O3), used to treat human diseases for centuries in traditional Chinese medicine, has been identified as a very effective antileukaemic agent, but its effect on solid tumours which could be more suitable for clinical treatment with arsenic compounds is still unknown. In this study, we investigated the in vitro effect of As2O3 at concentrations of 0.01-1 microM against six human malignant cell lines, MGC-803, HIC, MCF-7, HeLa, BEL-7402 and A549 cells. As2O3 inhibited growth and induced apoptosis in these malignant cells at varying degrees, in a time dose-dependent manner. The most marked effects were seen in the gastric cancer cell line, MGC-803. In contrast, minimal growth inhibition and induction of apoptosis occurred in human embryonic pulmonary cells following treatment with As2O3 found at the same concentrations. Changes in intracellular Ca2+, following As2O3 treatment were measured by Ca2+ sensitive fluorescent probe Indo-1/AM in flow cytometric assays. The increase in intracellular Ca2+ correlated with the sensitivity of these cells to As2O3, possibly indicating that a critical intracellular Ca2+ signal transduction pathway could be involved in As2O3-mediated cell-death and its selectivity. The marked sensitivity of MGC-803 cells in vitro suggests that As2O3 may be a potential antigastric cancer agent.