[Impact of catalytic ozonation with ferric hydroxide on HAAs formation potential of a filtered surface water]

Formation potential of five haloacetic acids (HAA5FP) of a filtered surface water was studied after ozonation alone and catalytic ozonation with a ferric hydroxide (FeOOH). Factors studied were oxidation time, bromide, pH, bicarbonate alkalinity, and ozone dosages. The haloacetic acids detected were dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), and dibromoacetic acid (DBAA) when bromide existed. The catalytic ozonation caused a reduction of HAA5FP of the non-bromide containing water for 9.5% - 18.3% compared to that of ozonation in 5-20 minutes. Incremental addition of bromide led to a much lower HAA5FP after catalytic ozonation than that after ozonation. HAA5FP of the water at neutral pH was higher than that at acidic and basic conditions. Catalytic ozonation showed a most advantageous potential in controlling HAA5FP over ozonation at neutral pH. The HAA5FP decreased as bicarbonate concentration increased, and the disparity between ozonation and catalytic ozonation was also reduced. The HAA5FP after catalytic ozonation was 11.2% to 28.0% lower than that after ozonation while the ratio of O3/TOC ranging from 0.45 to 1.43. The effect of catalytic ozonation on HAA5FP of the water is closely related to its enhanced generation of hydroxyl radicals in catalytic process.

Suspended aggregates as an immobilization mode for high-density perfusion culture of HEK 293 cells in a stirred tank bioreactor

Cells of the human embryonic kidney cell line (HEK 293) grown in repeated suspension and perfusion systems were characterized and described. Cell aggregates that formed immediately after the HEK 293 cells were inoculated in stirred vessels in serum-containing Dulbecco's modified Eagle's medium (D-MEM)/F-12 medium. The mean diameter of the cell aggregates reflecting the aggregate size increased with culture time, shifting from 63 to 239 mum after 1 and 8 days of culture in spinner flasks, respectively. No significant differences in cell performance were observed between HEK 293 cell populations grown as suspended aggregates and those grown as anchored monolayers. Replacing the D-MEM/F-12 with CD 293 medium caused the compact spherical cell aggregates to dissociate into single cells and small irregular aggregates without any apparent effect on cell performance. Moreover, the spherical cell aggregates could reform from individual cells and small aggregates when exposed to the serum-containing D-MEM/F-12 dominant medium. Perfusion culture of HEK 293 cells grown as suspended aggregates in a 7.5-l stirred tank bioreactor for 17 days resulted in a maximum viable cell density of 1.2 x 10(7) cells ml(-1). These results demonstrate the feasibility and proof-of-concept for using aggregates as an immobilization system in large-scale stirred bioreactors because a small-scale culture can be used as easily as the inoculum for larger bioreactors.

Transient electrostatic fields and related energetic proton generation with a plasma fiber

We observe a hollow structure and a fine ring in the proton images from a petawatt scale laser interaction with a "cone-fiber" target. The protons related to the hollow structure are accelerated from the cone-tip surface and deflected later by a radial electric field surrounding the fiber. Those associated with the fine ring are accelerated from the fiber surface by this radial electric field. This field is found to decay exponentially within 3 ps from about 5 x 10(12) V/m. Two-dimensional particle-in-cell simulations produce similar proton angular distributions.

Demonstration of bulk acceleration of ions in ultraintense laser interactions with low-density foams

Ion acceleration inside low-density foams irradiated by ultraintense laser pulses has been studied experimentally and theoretically. It is found that the ion generation is closely correlated with the suppressed hot electron transport inside the foams. Particle-in-cell simulations suggest that localized electrostatic fields with multi peaks around the surfaces of lamellar layers inside the foams are induced. These fields inhibit hot electron transport and meanwhile accelerate ions inside the foams, forming a bulk acceleration in contrast to the surface acceleration at the front and rear sides of a thin solid target.

[Effect of organic acids adsorption on catalytic ozonation with metal oxides]

The effectiveness of ozonation, adsorption and catalytic ozonation with ferric hydroxide (FeOOH) and cerium dioxide (CeO2) as catalysts on removal of several organic acids were investigated. The organic acids selected were benzoic acid (BA), phthalic acid (PA), commercial humic acid (CHA), and humic acid of Songhua River water (SHA) concentrated with reverse osmosis (RO). FeOOH was active in catalytic ozonation of the non-adsorbable BA, with 45% of BA removal higher than ozonation alone. It was inactive in case of ozonation of PA, the adsorption of which on FeOOH caused 5% reduction of its concentration. CeO2 enhanced ozonation of PA that was strongly adsorbed, but not for the non-adsorbed BA. Oxalate ions as product of oxidation of PA were also removed by CeO2 catalytic ozonation. As adsorption of humic acids on CeO2 is stronger than that on FeOOH, its catalytic removal by CeO2 was more than by FeOOH. The activity of catalytic ozonation of humic acids was scavenged in case of competition for adsorption sites on the catalysts by inorganic anions.

Engineering and functional evaluation of a single-chain antibody against HIV-1 external glycoprotein gp120

The HIV-1 envelope glycoprotein surface subunit gp120 is an attractive target for molecular intervention. This is because anti-HIV-1 gp120 neutralizing antibodies display the potential ability to inhibit HIV-1 infection. The present investigation describes the construction of a genetically engineered single chain antibody (scFv102) against HIV-1 gp120, its expression and functional evaluation. The parental hybridoma cell line (102) produces an immunoglobulin directed against the conserved CD4-binding region of gp120. cDNAs encoding the variable regions of the heavy (V(H)) and light (V(L)) chains were prepared by reverse transcription PCR and linked together with an oligonucleotide encoding a linker peptide (Gly(4)Ser)(3) to produce a single chain antibody gene. The resulting DNA construct was cloned into a prokaryotic expression vector (pET28) and recombinant scFv102 was expressed in Eserichia coli as an insoluble protein. The denatured scFv102 was refolded and purified by immobilized metal ion affinity chromatography. Purified scFv102 had the same specificity as the intact IgG in immuno-blotting assays and immuno-fluorescence (IF) detection, but ELISA analyses demonstrated the affinity of scFv102 to be 5-fold lower than that of the parental monoclonal antibody. In neutralization assays, scFv102 at concentrations lower than 40 microg/ml exhibited efficient interference with viral replication and inhibition of viral infection (90%) across a range of primary isolates of subtype B HIV-1. These results suggest that the constructed anti-HIV-1 gp120 scFv102 has good biological activity and can potentially be used for in vitro diagnostic and in vivo therapeutic applications.

Enhancement of energetic electrons and protons by cone guiding of laser light

Energetic electrons and protons are observed when a target consisting of a reentrant cone with a disk at the tip is irradiated by a petawatt (PW) laser at an intensity of approximately 10(19) W cm(-2). The angular distribution of the electrons and protons, dependent on the open angle of the reentrant cone, is found to differ from that in the case when a target with planar geometry is used. Two jet beams are observed, in directions parallel to the cone axis and normal to the cone-shaped wall. The number and cutoff energies of the generated protons are also related to the open angle of the cone. The efficiency of the generation of energetic electrons from the cone target is 2-3 times higher than that from a simple plane target. These results indicate a guiding of the PW laser beam in the cone geometry.

Plasma devices to guide and collimate a high density of MeV electrons

The development of ultra-intense lasers has facilitated new studies in laboratory astrophysics and high-density nuclear science, including laser fusion. Such research relies on the efficient generation of enormous numbers of high-energy charged particles. For example, laser-matter interactions at petawatt (10(15) W) power levels can create pulses of MeV electrons with current densities as large as 10(12) A cm(-2). However, the divergence of these particle beams usually reduces the current density to a few times 10(6) A cm(-2) at distances of the order of centimetres from the source. The invention of devices that can direct such intense, pulsed energetic beams will revolutionize their applications. Here we report high-conductivity devices consisting of transient plasmas that increase the energy density of MeV electrons generated in laser-matter interactions by more than one order of magnitude. A plasma fibre created on a hollow-cone target guides and collimates electrons in a manner akin to the control of light by an optical fibre and collimator. Such plasma devices hold promise for applications using high energy-density particles and should trigger growth in charged particle optics.

Algal degradation of a known endocrine disrupting insecticide, alpha-endosulfan, and its metabolite, endosulfan sulfate, in liquid medium and soil

The role of algae in the persistence, transformation, and bioremediation of two endocrine disrupting chemicals, alpha-endosulfan (a cyclodiene insecticide) and its oxidation product endosulfan sulfate, in soil (incubated under light or in darkness) and a liquid medium was examined. Incubation of soil under light dramatically decreased the persistence of alpha-endosulfan and enhanced its transformation to endosulfan sulfate, over that of dark-incubated soil samples, under both nonflooded and flooded conditions. This enhanced degradation of soil-applied alpha-endosulfan was associated with profuse growth of indigenous phototrophic organisms such as algae in soil incubated under light. Inoculation of soil with green algae, Chlorococcum sp. or Scenedesmus sp., further enhanced the degradation of alpha-endosulfan. The role of algae in alpha-endosulfan degradation was convincingly demonstrated when these algae degraded alpha-endosulfan to endosulfan sulfate, the major metabolite, and endosulfan ether, a minor metabolite, in a defined liquid medium. When a high density of the algal inoculum was used, both metabolites appeared to undergo further degradation as evident from their accumulation only in small amounts and the appearance of an endosulfan-derived aldehyde. Interestingly, beta-endosulfan was detected during degradation of alpha-endosulfan by high density algal cultures. These algae were also capable of degrading endosulfan sulfate but to a lesser extent than alpha-endosulfan. Evidence suggested that both alpha-endosulfan and endosulfan sulfate were immediately sorbed by the algae from the medium, which then effected their degradation. Biosorption, coupled with their biotransformation ability, especially at a high inoculum density, makes algae effective candidates for remediation of alpha-endosulfan-polluted environments.

Inhibition of type A GABA receptors by L-type calcium channel blockers

Modulation of type A GABA receptors (GABAA) by L-type Ca++ channel blockers was investigated. The dihydropyridines nifedipine and nitrendipine, and the phenylalkylamine verapamil inhibited recombinant rat alpha1beta2gamma2 receptors recorded from human embryonic kidney (HEK) 293 cells; nifedipine at low concentrations also elicited modest stimulatory effects on GABA-gated current. The IC50 for GABA current inhibition was lowest for nitrendipine (17.3 +/- 1.3 microM), so subsequent studies were focused on further exploring its mechanism and possible site of action. When co-applied with GABA, nitrendipine had minimal effects on initial current amplitude, but significantly enhanced current decay rate. Nitrendipine-mediated inhibition was subunit-selective, as its IC50 was 10-fold lower in alpha1beta2 receptors. Nitrendipine's effect in recombinant human alpha1beta2gamma2 receptors was similar (IC50=23.0 +/- 1.3 microM) to that observed in rat receptors of the same configuration, indicating the site of action is conserved in the two species. The inhibitory effects were dependent on channel gating, were independent of transmembrane voltage, and were also observed in GABAA receptors recorded from hypothalamic brain slices. The pharmacologic mechanism of inhibition by nitrendipine was non-competitive, indicating it does not act at the GABA binding site. Nitrendipine block was retained in the presence of the benzodiazepine antagonist flumazenil, indicating it does not interact at the benzodiazepine site. The actions of nitrendipine were not affected by a mutation (beta2T246F) that confers resistance to the channel blocker picrotoxin, and they were not altered in the presence of the picrotoxin site antagonist alpha-isopropyl-alpha-methyl-gamma-butyrolactone, demonstrating nitrendipine does not act at the picrotoxin site of the GABAA receptor. Possible interaction of nitrendipine with the Zn++ site was also eliminated, as mutation of beta2 H267 to A, which confers resistance to Zn++, had no effect on nitrendipine-mediated inhibition. Our data suggest some of the central effects of dihydropyridines may be due to actions at GABAA receptors. Moreover, the effects may be mediated through interaction with a novel modulatory site on the GABAA receptor.

High-energy electrons produced in subpicosecond laser-plasma interactions from subrelativistic laser intensities to relativistic intensities

The characteristics of the forward hot electrons produced by subpicosecond laser-plasma interactions are studied for different laser polarizations at laser intensities from subrelativistic to relativistic. The peak of the hot electron beam produced by p-polarized laser beam shifts to the laser propagation direction from the target normal direction as the laser intensity reaches the relativistic. For s-polarized laser pulse, hot electrons are mainly directed to the laser axis direction. The temperature and the maximum energy of hot electrons are much higher than that expected by the empirical scaling law. The energy spectra of the hot electrons evolve to be a single-temperature structure at relativistic laser intensities from the two-temperature structure at subrelativistic intensities. For relativistic laser intensities, the forward hot electrons are less dependent on the laser polarization under the laser conditions. The existing of a preplasma formed by the laser amplified spontaneous emission pedestal plays an important role in the interaction. One-dimensional particle-in-cell simulations reproduce the most characteristics observed in the experiment.

Energetic electrons emitted from ethanol droplets irradiated by femtosecond laser pulses

We investigate the angular distribution and the energy spectrum of hot electrons emitted from ethanol droplets irradiated by linearly polarized 150-fs laser pulses at an intensity of 10(16) W/cm(2). Two hot electron jets symmetrically with respect to the laser propagation direction are observed within the polarization plane. This is due to the spherical geometry of droplets in the intense laser field. The maximum energy of the hot electrons is found to be more than 600 keV. Particle-in-cell simulations suggest that the resonance absorption is the main mechanism for hot electron generation.

Laminin chain expression suggests that laminin-10 is a major isoform in the mouse hippocampus and is degraded by the tissue plasminogen activator/plasmin protease cascade during excitotoxic injury

Laminins are important components of the extracellular matrix, and participate in neuronal development, survival and regeneration. The tissue plasminogen activator/plasmin extracellular protease cascade and downstream laminin degradation are implicated in excitotoxin-induced neuronal degeneration. To determine which specific laminin chains are involved, we investigated the expression of laminins in the hippocampus, and the cell types expressing them. Reverse transcription-PCR demonstrated that the messenger RNAs for all laminin chains could be detected in the hippocampus. To determine the localization of laminin chain expression, immunostaining was used. This method showed that alpha5, beta1 and gamma1 are most highly expressed in the neuronal cell layers. Immunoblotting confirmed the hippocampal expression of the chains alpha5, beta1 and gamma1, and RNA in situ hybridization showed a neuronal expression pattern of alpha5, beta1 and gamma1. At early time points following intrahippocampal injection of kainate, alpha5, beta1 and gamma1 chain immunoreactivities were lost. In addition, tissue plasminogen activator-deficient mice, which are resistant to kainate-induced neuronal death, show no significant change in laminins alpha5, beta1 and gamma1 after intrahippocampal kainate injection. Taken together, these results suggest that laminin-10 (alpha5-beta1-gamma1) comprises a major neuronal laminin in the mouse hippocampus, and is degraded before neuronal death during excitotoxic injury by the tissue plasminogen activator/plasmin protease cascade. By identifying a neuronal laminin (laminin-10) that participates in neuronal degeneration after excitotoxic injury, this study clarifies the molecular definition of the extracellular matrix in the hippocampus and further defines a pathway for mechanisms of neuronal death.

Propagation of hot electrons through high-density plasmas

Propagation of hot electrons through high-density plasmas generated by femtosecond laser pulses is investigated using three types of target configurations: Al-coated glass, Al and glass separated by a vacuum gap, and Al foil alone. Collimated ionization tracks lasting for 60 ps and extending 150-300 microm in length and 8 microm in cross section are observed via optical probing. For the Al-foil-alone target, a narrow plasma jet is formed at the rear surface in line with the laser. The collimation of the hot electrons may be attributed to a strong self-generated magnetic field in the target.

Third-order harmonic generation by self-guided femtosecond pulses in air

Strong third-order harmonic (TH) emission is observed with a conversion efficiency higher than 10(-3) from a plasma channel formed by self-guided femtosecond laser pulses propagating in air. The main characteristics of TH emission in various conditions and the phase-matching condition between the fundamental and the TH wave are investigated. An optimized condition is found, under which the TH conversion efficiency is maximized. Our experimental results show that radiation of the emission in ultraviolet wavelength range makes a major attribution to TH emission, whereas the effects of self-phase modulation are not important when intense laser pulses interact with gaseous media.

Jasplakinolide reversibly disrupts actin filaments in suspension-cultured tobacco BY-2 cells

Jasplakinolide is potentially a useful pharmacological tool for the study of actin organization and dynamics in living cells, since it induces actin polymerization in vitro and, unlike phalloidin, is membrane permeative. In the present work, the effect of jasplakinolide on the actin cytoskeleton of living suspension-cultured Nicotiana tabacum 'Bright Yellow 2' cells was investigated. Actin filaments in the living cells were disrupted by jasplakinolide. The effect of jasplakionlide on the actin cytoskeleton was concentration and time dependent. When cells were treated with a moderate concentration (150 nM) of jasplakinolide, cortical actin filaments were disrupted preferentially, whereas actin aggregated at the perinuclear region. With concentrations higher than 400 nM and exposure times longer than 30 min, actin filaments in the cell disappeared completely. The effect of jasplakinolide on the actin cytoskeleton was reversible even at high concentration. Actin bundles appeared first in the perinuclear region within 5 min, and the cortical actin array was reestablished in 15 min, suggesting that actin filaments might be organized at this region.

A new multiflorane triterpenoid ester from Momordica cochinchinensis Spreng

A new triterpenoid ester 3,29-di-O-(p-methoxy)benzoylmultiflora-8-ene-3 alpha,29-diol-7-one from the seeds of Momordica cochinchinensis Spreng has been isolated. Its structure was elucidated by spectroscopic evidence and confirmed by X-ray crystallography.

Crystallization and preliminary crystallographic studies of antibacterial polypeptide LCI expressed in Escherichia coli

LCI is a type of novel antibacterial polypeptide secreted by a Bacillus subtilis strain. It consists of 47 residues with a molecular weight of 5468 Da. Using bioengineering, LCI was expressed in Escherichia coli DH5alpha with recombinant plasmid pBVAB16. It was crystallized using PEG 4000 as a precipitant. The crystal belongs to space group P6(2)22 or P6(4)22, with unit-cell parameters a = b = 29.30, c = 187.09 A, and diffracts to 2.44 A. A set of diffraction data to 2.8 A was collected.

Pharmacokinetics of sarafloxacin in pigs and broilers following intravenous, intramuscular, and oral single-dose applications

Pharmacokinetics of sarafloxacin, a fluoroquinolone antibiotic, was determined in pigs and broilers after intravenous (i.v.), intramuscular (i.m.), or oral (p.o.) administration at a single dose of 5 (pigs) or 10 mg/kg (broilers). Plasma concentration profiles were analysed by a noncompartmental pharmacokinetic method. Following i.v., i.m. and p.o. doses, the elimination half-lives (t1/2beta) were 3.37 +/- 0.46, 4.66 +/- 1.34, 7.20 +/- 1.92 (pigs) and 2.53 +/- 0.82, 6.81 +/- 2.04, 3.89 +/- 1.19 h (broilers), respectively. After i.m. and p.o. doses, bioavailabilities (F) were 81.8 +/- 9.8 and 42.6 +/- 8.2% (pigs) and 72.1 +/- 8.1 and 59.6 +/- 13.8% (broilers), respectively. Steady-state distribution volumes (Vd(ss)) of 1.92 +/- 0.27 and 3.40 +/- 1.26 L/kg and total body clearances (ClB) of 0.51 +/- 0.03 and 1.20 +/- 0.20 L/kg/h were determined in pigs and broilers, respectively. Areas under the curve (AUC), mean residence times (MRT), and mean absorption times (MAT) were also determined. Sarafloxacin was demonstrated to be more rapidly absorbed, more extensively distributed, and more quickly eliminated in broilers than in pigs. Based on the single-dose pharmacokinetic parameters determined, multiple dosage regimens were recommended as: a dosage of 10 mg/kg given intramuscularly every 12 h in pigs, or administered orally every 8 h in broilers, can maintain effective plasma concentrations with bacteria infections, in which MIC90 are <0.25 microg/mL.

Hot electrons in the interaction of femtosecond laser pulses with foil targets at a moderate laser intensity

Characteristics of hot electrons produced in the interaction of femtosecond laser pulses with foil targets were investigated at a moderate laser intensity. Both outgoing and ingoing hot electrons from the femtosecond laser plasma were studied. A collimated jet of outgoing hot electrons was observed in the target normal direction. An ingoing energetic hot-electron beam was found in the laser propagation direction, while the low-energy ingoing electrons spread into wider cone angle due to the collisional effects in the plasma and target material. These observations were supported by three-dimensional Monte Carlo simulations. The hot-electron temperature obtained from electron spectra and absorption experiments implies that resonance absorption is partially responsible for the generation of hot electrons.

[The labeling of procollagen gene probe by PCR and the detection of procollagen gene expression in hepatic stellate cells]

AIM

To establish a new method for labeling of procollagen gene probe and the detection of procollagen mRNA expression in HSC.

METHODS

According to gene sequences from NCBI Gene Bank, the primers for the amplification of type I, III and IV procollagen genes were designed by OLIGO software, the procollagen genes were amplified by RT-PCR and were labeled by PCR and DIG-dUTP, and the probes were applied to detect procollagen mRNA expression in cultured hepatic stellate cells by in situ hybridization.

RESULTS

The procollagen genes were successfully amplified by the Primers and RT-PCR and were labeled by DIG-dUTP and PCR, the procollagen mRNA expression in cultured hepatic stellate cells was detected by the probes.

CONCLUSIONS

A new simplified method for labeling of procollagen genes is successfully found and it can be used for other gene amplification and labeling.

[The tissue culture of medicinal plant Trichosanthes kirilowii and its protein analysis]

We reported preliminary results of rapid propagation, callus induction and regeneration of Trichosanthes Kirilowii, and its protein analysis. Pre-existing meristerms regenerate shoots very rapidly when grown on MS medium containing 0.5 or 1.0 mg/L 6-BA; calli could be induced from leaf sections when put on MS medium containing 4.0 mg/L 6-BA + 0.2 mg/L IAA; shoots regenerated successfully 30 days after calli induction and the differentiation ratio was one shoot out of every four leaf sections; and all shoots gave rise to roots after removing onto MS medium containing 0.1 mg/L NAA and 100% survived when transplanted into soil. Very excitingly, these plants produced small tubers in one month, where satisfactory expression of TCS protein was detected by Western blot analysis.

Pharmacokinetics of lactosaminated recombinant human growth hormone in mice

AIM

To study the pharmacokinetic characteristics of lactosaminated recombinant human growth hormone (hGH-L) in mice.

METHODS

The biodistribution was studied with in vivo radioactive tracer technique. The pharmacokinetics was investigated by radioimmunoassay (RIA) method of hGH-L. The results were compared with that of recombinant human growth hormone (hGH).

RESULTS

125I-hGH-L has remarkable livertaxis. The area under drug concentration-time curve (32686.9 microg . min . L-1) in blood and serum mean residence time (21.4 min) of hGH-L are less than that of hGH (36913.1 microg . min . L-1 and 24.9 min) (P < 0.05). In target organ liver, hGH-L distribution half life (1.8 min) and elimination half life (11.1 min) are shorter than that of hGH (2.1 min and 27.7 min) (P < 0.05). The area under drug concentration-time curve (17621.9 microg . min . L-1) of hGH-L is bigger than that of hGH(12148.2 microg . min . L-1) (P < 0.05) in liver.

CONCLUSION

The pharmacokinetic parameters of hGH-L has obvious advantage over that of hGH.

Reactive oxygen species involved in trichosanthin-induced apoptosis of human choriocarcinoma cells

The type-I ribosome-inactivating protein trichosanthin (TCS) has a broad spectrum of biological and pharmacological activities, including abortifacient, anti-tumour and anti-HIV activities. We have found for the first time that TCS stimulated the production of reactive oxygen species (ROS) in JAR cells (a human choriocarcinoma cell line) in a time- and concentration-dependent manner by using the fluorescent probe 2',7'-dichlorofluorescein diacetate with confocal laser scanning microscopy. ESR spectral studies and the inhibition of ROS formation by the superoxide radical anion (O(2)(-.)) scavenger superoxide dismutase, the H(2)O(2) scavenger catalase and the hydroxyl radical (OH(.)) scavenger mannitol suggested the involvement of O(2)(-.), H(2)O(2) and OH(.). TCS-induced ROS formation was shown to be dependent on the presence of both extracellular and intracellular Ca(2+); moreover, ROS production paralleled the intracellular Ca(2+) elevation induced by TCS, suggesting that ROS production might be a consequence of Ca(2+) signalling. TCS-induced activation of caspase-3 was initiated within 2 h; however, TCS-induced production of ROS was initiated within 5 min, suggesting that the production of ROS preceded the activation of caspase-3. Simultaneous observation of the nuclear morphological changes via two-photon laser scanning microscopy and ROS production via confocal laser scanning microscopy revealed that ROS is involved in the apoptosis of JAR cells. The involvement of ROS was also confirmed by the inhibition of TCS-induced cell death by the antioxidant Trolox and the ROS scavengers catalase and mannitol. Diethylenetriaminepenta-acetic acid, an inhibitor of metal-facilitated OH(.) formation, markedly inhibited TCS-induced cell death, suggesting that TCS induced OH(.) formation via the Fenton reaction. The finding that ROS is involved in the TCS-induced apoptosis of JAR cells might provide new insight into the anti-tumour and anti-HIV mechanism of TCS.