Inhibition of DLX4 promotes apoptosis in choriocarcinoma cell lines

Homeodomain (HDM) proteins encoded by homeobox (HBX) genes represent a large family of transcriptional factors that control differentiation and development in certain cell types. DLX4 is a member of Distal-less (DLX) family of HBX genes. Recent studies have demonstrated that abnormal expression of DLX4 is present in several types of human tumors, such as breast cancer, leukemia and colon cancer. In the present study, we investigated DLX4 mRNA and protein expression in both normal placental tissues and human choriocarcinoma cell lines. Also, using RNA interference (RNAi) technique, we knocked down the expression of DLX4 and examined apoptosis in JEG-3 cells. Our studies demonstrated that DLX4 RNAi inhibited DLX4 mRNA expression and decreased DLX4 protein mass specifically and effectively, potentially enhancing apoptosis. Moreover, we examined expression of caspase-3 and caspase-8, and found that both caspases were increased after DLX4 knockdown. However, DLX4 RNAi did not influence Bax expression in JEG-3 cells. In conclusion, this study suggests that DLX4 may be involved in the survival of human choriocarcinoma cells, which may be mediated by the inhibition of apoptosis. The detailed mechanism needs further investigation.

Evidence of hemoglobin binding to arsenic as a basis for the accumulation of arsenic in rat blood

Four trivalent arsenic species, inorganic arsenite (iAs(III)), monomethylarsonous acid (MMA(III)), dimethylarsinous acid (DMA(III)), and phenylarsine oxide (PhAs(III)O), have shown increasing binding affinity with the hemoglobin (Hb) of rats and humans. The binding stoichiometry was consistent with the number of reactive cysteine residues in the alpha and beta chains of Hb. Comparing the binding affinity of rat Hb and human Hb for the same trivalent arsenic species, rat Hb was 3-16 times stronger than human Hb as demonstrated by their apparent binding constants. Comparative experiments involving incubation of human and rat red blood cells (RBC) with iAs(III), MMA(III), and DMA(III) showed that 15-30-fold more arsenic species were bound to the Hb of rat RBC than that of human RBC. In vivo experiments using rats fed with an arsenic-supplemented diet showed that arsenic in RBC of the rats was predominantly found in the protein-bound form. Further characterization by nanoelectrospray mass spectrometry of the arsenic species in the RBC of these rats confirmed that most arsenic was bound to the alpha chain of Hb. Taken together, these results suggest that the stronger binding affinity of these arsenic species to rat Hb is responsible for the accumulation of arsenic in rat blood. The results provide a chemical basis to explain the previously observed intriguing difference in the retention of arsenic in the human and the rat. The techniques and approaches described can be applied to the studies of arsenic interactions with other functional proteins.

Increased hyperalgesia after tissue injury and faster recovery of allodynia after nerve injury in the GalR1 knockout mice

Evidence suggests that galanin and its receptors including GalR1 are involved in the modulation of nociception. To understand the contributions of this galanin receptor subtype to the analgesic effect of galanin, we systematically examined the nociception phenotype of the GalR1 knockout (KO) mice. (1) Baseline thresholds: Thermal escape latencies and tactile thresholds of the hind paws were not different between the GalR1 KO and wild type (WT) mice. (2) Thermal injury evoked hyperalgesia: Thermal injury (52 degrees C, 45 s) to one hind paw resulted in a reduction in the thermal escape latency as compared to the uninjured paw. The right/left difference score was significantly greater in the KO (5.9 +/- 0.8 s) than for the WT (2.8 +/- 0.7 s) indicating a greater hyperalgesia. (3) Formalin-induced flinching: Formalin paw injection (2.5%/20 microl) produced a two-phase flinching in both GalR1 KO and WT groups, that was detected by an automated flinching sensor device. Phase II flinching of KO (1510 +/- 90) was slightly greater than that observed for WT (1290 +/- 126), but the difference is not statistically significant. (4) Nerve injury evoked allodynia: Tactile thresholds were assessed prior to and at intervals up to 21 days after left L5 spinal nerve ligation and transection. In both GalR1 KO and WT mice, nerve injury caused thresholds to fall to 0.2-0.3g though 11 days. On days 14-21, GalR1 KO animals showed a significant recovery as compared to WT. In summary, GalR1 KO mice showed no difference from WT with respect to acute nociception, but showed a modest tendency towards increased hyperalgesia after tissue injury and inflammation. These results are consistent with a regulatory effect of galanin at GalR1 receptors on nociceptive processing.

Peripheral genotype-phenotype correlations in Asian Indians with type 2 diabetes mellitus

OBJECTIVE

A genome-wide scan of gene expression in leucocytes in Asian Indians with type 2 diabetes was performed and correlated with their known phenotype.

METHODS

Microarray gene profiling of 13,474 sequence-verified, non-redundant human cDNAs was done to study leukocyte gene expression in Asian Indians with type 2 diabetes (DM: n=3) and matched controls (n=3).

RESULTS

Significant differential expression (fold change <0.3 or >3) was noted for 897 genes in DM vs. controls. The 147 known genes in this category belonged to following broad functional groups (%): enzyme (32), nucleic acid binding (22), ligand binding or carrier (10), signal transducer (9), transporter (7), structural protein (6), cell adhesion (3), tumor suppressor (3), transcription factor binding (2), enzyme inhibitor (2), chaperone (2), cell cycle regulator (1), and defense/immunity protein (1). The 20 genes with at least a 3-fold change, annotated with known phenotypic associations in the current gene databank (phenotype association, fold change) were aspartoacylase (Canavan disease, 9.96), growth hormone receptor (Laron dwarfism, idiopathic short stature, 8.25), lipoprotein lipase (familial chylomicronemia syndrome, lipoprotein lipase deficiency, 8.00), vitamin D (1,25- dihydroxyvitamin D3) receptor (involutional osteoporosis, vitamin D resistant rickets, 7.94), intercellular adhesion molecule 1 human rhinovirus receptor (cerebral malaria susceptibility, 7.16), peroxisomal membrane protein 3 35-kDa (Refsum disease, infantile form, Zellweger syndrome-3, 6.00), Bardet-Biedl syndrome 2 (Bardet-Biedl syndrome, 5.87), ribosomal protein S19 (Diamond Blackfan anemia, 5.85), apolipoprotein C-III (hypertriglyceridemia, 5.44), argininosuccinate lyase (argininosuccinicaciduria, 5.22), myosin VA (Griscelli syndrome-type pigmentary dilution with mental retardation, 4.92), lysozyme (renal amyloidosis, 4.17), SAM domain, SH3 domain and nuclear localisation signals 1 (Cherubism, 4.12 ), von Hippel-Lindau syndrome (hemangioblastoma, cerebellar, somatic, von Hippel-Lindau syndrome, 3.94), early-onset breast cancer 1 (BRCA1, papillary serous carcinoma of the peritoneum, 3.73), UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (inclusion body myopathy, autosomal recessive, sialuria, 3.53), apolipoprotein A-I (amyloidosis, 3 or more types, hypoalphalipoproteinemia, 3.29), midline 1 Opitz/BBB syndrome (Opitz G syndrome, type I, 3.28), ATPase, Na+/K+ transporting, alpha 2 (+) polypeptide (familial hemiplegic migraine, 3.05). Canavan disease, Zellweger syndrome, infantile Refsum disease, Griscelli syndrome, cherubism, breast cancer, peritoneal papillary serous carcinoma, Opitz G/BBB syndrome, and familial hemiplegic migraine (FHM) are phenotypes not previously reported in association with type 2 DM, but whose underlying genes were up-regulated in this peripheral genome scan of Asian Indians.

CONCLUSION

Rare and/or previously unknown phenotypes linked to known genes with significant differential expression in type 2 DM are reported. Further testing of heterogeneity in diabetes phenotype syndromes may reveal common pathogenic mechanisms and potential candidate genes responsible for type 2 DM.

Molecular networks perturbed in a developmental animal model of brain injury

Methylazoxymethanol (MAM) is widely used as a developmental neurotoxin and exposure to its glucoside (i.e., cycasin) is associated with the prototypical neurological disorder western Pacific ALS/PDC. However, the specific molecular targets that play a key role in MAM-induced brain injury remain unclear. To reveal potential molecular networks targeted by MAM in the developing nervous system, we examined characteristic phenotypic changes (DNA damage, cytoarchitecture) induced by MAM and their correlation with gene expression differences using microarray assays (27,648 genes). Three day-old postnatal C57BL/6 mice (PND3) received a single injection of MAM and the cerebellum and cerebral cortex of PND4, 8, 15, and 22 mice were analyzed. DNA damage was detected in both the cerebellum (N7-mGua, TUNEL labeling) and cerebral cortex (N7-mGua) of PND4 mice, but progressive disruption of the cytoarchitecture was restricted to the cerebellum. A majority (>75%) of the genes affected (cerebellum 636 genes, cortex 1080 genes) by MAM were developmentally regulated, with a predominant response early (PND4) in the cerebellum and delayed (PND8 and 15) in the cerebral cortex. The genes and pathways (e.g., proteasome) affected by MAM in the cerebellum are distinct from cortex. The genes perturbed in the cerebellum reflect critical cellular processes such as development (17%), cell cycle (7%), protein metabolism (12%), and transcriptional regulation (9%) that could contribute to the observed cytoarchitectural disruption of the cerebellum. This study demonstrates for the first time that specific genes and molecular networks are affected by MAM during CNS development. Further investigation of these targets will help to understand how disruption of these developmental programs could contribute to chronic brain injury or neurodegenerative disease.

Development of a global stochastic model relating the distribution of individual cell and population physiological states

Our ability to predict the lag (lambda) prior to growth of foodborne pathogens is limited by our lack of understanding of the physiological changes taking place in the individual cell during the adaptation process. Theoretical models have been developed to describe the stochastic nature of individual cells, and probability distributions have been used to assign hypothetical values of the physiological state to individual cells (p(i)). The aim of this study is to develop a polynomial model which will link distributions of p(i) values to the physiological state of the population (h(0)), and thus to the lambda. Risk analysis software was used to simulate values of p(i) for populations of cells drawn from lognormal distributions with parameters alpha and beta, and growth curves were simulated using a modified continuous-discrete-continuous (CDC) model. Values for h(0) were then obtained for each growth curve by fitting with the heterogeneous population model (HPM). Multiple regression analysis was used to develop a polynomial function which described the subsequent h(0) value as a function of alpha and beta (R(2)=0.9957). Outputs from simulations using the polynomial model agree well with results from related stochastic models, and suggest that distributions can accurately describe the physiological state of cell populations.

Developmental consequences of in utero sodium arsenate exposure in mice with folate transport deficiencies

Previous studies have demonstrated that mice lacking a functional folate binding protein 2 gene (Folbp2-/-) were significantly more sensitive to in utero arsenic exposure than were the wild-type mice similarly exposed. When these mice were fed a folate-deficient diet, the embryotoxic effect of arsenate was further exacerbated. Contrary to expectations, studies on 24-h urinary speciation of sodium arsenate did not demonstrate any significant difference in arsenic biotransformation between Folbp2-/- and Folbp2+/+ mice. To better understand the influence of folate pathway genes on arsenic embryotoxicity, the present investigation utilized transgenic mice with disrupted folate binding protein 1 (Folbp1) and reduced folate carrier (RFC) genes. Because complete inactivation of Folbp1 and RFC genes results in embryonic lethality, we used heterozygous animals. Overall, no RFC genotype-related differences in embryonic susceptibility to arsenic exposure were observed. Embryonic lethality and neural tube defect (NTD) frequency in Folbp1 mice was dose-dependent and differed from the RFC mice; however, no genotype-related differences were observed. The RFC heterozygotes tended to have higher plasma levels of S-adenosylhomocysteine (SAH) than did the wild-type controls, although this effect was not robust. It is concluded that genetic modifications at the Folbp1 and RFC loci confers no particular sensitivity to arsenic toxicity compared to wild-type controls, thus disproving the working hypothesis that decreased methylating capacity of the genetically modified mice would put them at increased risk for arsenic-induced reproductive toxicity.

Thomson scattering measurements of heat flux from ion-acoustic waves in laser-produced aluminum plasmas

Thomson scattering (TS) measurements are performed at different locations in a laser-produced aluminum plasma. Variations of the separation, wavelength shift, and asymmetric distribution of the two ion-acoustic waves are investigated from their spectral-time-resolved TS images. Detailed information on the space-time evolution of the plasma parameters is obtained. Electron distribution and variation of the heat flux in the plasma are also obtained for a steep temperature gradient.

Age-dependence of urinary normal and modified nucleosides in childhood as determined by reversed-phase high-performance liquid chromatography

Modified nucleosides have been characterized as tumor markers for a number of malignant diseases. In order to use these markers in children, the age-dependence of the nucleoside levels in healthy children has to be established and taken into account in diagnostic decisions. In this study, the levels of 12 normal and modified nucleosides in urine of 166 healthy children and adolescents with an age between 1 day and 19 years are determined by reversed-phase HPLC, and age-dependent reference ranges are defined. The urinary nucleoside concentrations are related to the creatinine concentrations, which allows the use of randomly collected urine samples. All nucleoside levels in urine of children decrease with age, most pronounced during the first 4 years of life, and the age-dependence of the reference values of the individual nucleosides can be approximated by a mathematical function y = b(0) + b(1) (1/x) with the regression coefficients b(0) and b(1,) the nucleoside levels y and the age x between 1 year and 19 years. In the very young children, the shifts in the nucleoside concentrations are more differentiated. Starting with low levels on the first day of life, the concentrations of all studied nucleosides rise up to an age of 1-2 months, when they reach their absolute maximum for all age periods, and then decrease.

Effects of dietary folate intake and folate binding protein-2 (Folbp2) on urinary speciation of sodium arsenate in mice

Folate binding protein-2 (Folbp2(-/-)) knockout mice have been previously shown to be highly susceptible to the teratogenic effects of arsenic. Arsenic biotransformation is achieved primarily by biomethylation. Given the potential close relationship between folate biochemistry and arsenic biotransformation, the aims of our study were to: (1) test whether Folbp2(-/-) mice have altered arsenic biotransformation which would suggest a potential mechanism for their enhanced susceptibility; (2) examine whether dietary folate deficiency alters arsenic biotransformation. Folbp2(-/-) mice were found to have slightly lower plasma folate levels than wildtype mice. No genotype-specific effects were observed in arsenic speciation thereby negating altered biotransformation of arsenic as the mechanism of the enhanced teratogenicity seen in Folbp2(-/-) mice. Reduction in excretion of organic arsenicals was observed during folate deficiency, suggesting an important role for folic acid homeostasis in arsenic biotransformation.

Application of a virological tracer method for the assessment of pathogen removal by physicochemical treatment and chemical disinfection

Coxsackie B3 (CoxB3) virus was used as a virological tracer for an assessment of the efficiency of pathogen removal by several typical physicochemical treatment and chemical disinfection processes, such as coagulation-filtration, ultra-filtration, and disinfection using chlorine and ozone, with regard to the pathogenic quality of the treated domestic wastewater for reuse purposes. The CoxB3 virus was seeded to sterilized secondary effluent to make a raw water of known pathogenic level. After applying the raw water to each treatment or disinfection process, the residual virus in the finished water was concentrated, and virus assay was carried out by the Tissue Culture Infectious Dose technique. TCID50 was used as an indicative parameter of CoxB3 virus in the raw and treated water. Parallel experiments were also conducted to evaluate the effectiveness of each process for the removal of coliform bacteria. It was noticed from the experiment that both coagulation-filtration and ultrafiltration could achieve substantial removal of TCID50 at about the same level (2-log removal). However, the effect of the two processes on the removal of coliform bacteria was much different: 2-log removal by coagulation-filtration and 4 to 5-log removal by ultrafiltration. The TCID50 removal correlates more closely with the removal of turbidity than that of coliform bacteria. Chlorine was found to be effective in coliform removal but almost had no effect on TCID50. As ozone was applied, a high removal of both coliform bacteria and TCID50 could be obtained.

Patterns of seizures, hippocampal injury and neurogenesis in three models of status epilepticus in galanin receptor type 1 (GalR1) knockout mice

The neuropeptide galanin exhibits anticonvulsant effects in experimental epilepsy. Two galanin receptor subtypes, GalR1 and GalR2, are present in the brain. We examined the role of GalR1 in seizures by studying the susceptibility of GalR1 knockout (KO) mice to status epilepticus (SE) and accompanying neuronal injury. SE was induced in GalR1 KO and wild type (WT) mice by Li-pilocarpine, 60 min electrical perforant path stimulation (PPS), or systemic kainic acid (KA). Seizures were analyzed using Harmonie software. Cell injury was examined by FluoroJade B- and terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end labeling; neurogenesis was studied using bromodeoxyuridine labeling. Compared with WT littermates, GalR1 KO showed more severe seizures, more profound injury to the CA1 pyramidal cell layer, as well as injury to hilar interneurons and dentate granule cells upon Li-pilocarpine administration. PPS led to more severe seizures in KO, as compared with WT mice. No difference in the extent of neuronal degeneration was observed between the mice of two genotypes in CA1 pyramidal cell layer; however, in contrast to WT, GalR1 KO developed mild injury to hilar interneurons on the side of PPS. KA-induced seizures did not differ between GalR1 KO and WT animals, and led to no injury to the hippocampus in either of experimental group. No differences were found between KO and WT mice in both basal and seizure-induced neuronal progenitor proliferation in all seizure types. Li-pilocarpine led to more extensive glia proliferation in GalR1 KO than in WT, and in both mouse types in two other SE models. In conclusion, GalR1 mediate galanin protection from seizures and seizure-induced hippocampal injury in Li-pilocarpine and PPS models of limbic SE, but not under conditions of KA-induced seizures. The results justify the development and use of GalR1 agonists in the treatment of certain forms of epilepsy.

The novel molecule porcine OSR1 up-regulated expression on porcine endothelial cell by human peripheral blood mononuclear cell activation

INTRODUCTION

Clinical xenotransplantation is being considered to overcome the shortage of human organ donors. In our previous studies, using human-anti-porcine xenogeneic mixed mononuclear cell-endothelial cell cultures with the suppression subtractive hybridization method, we obtained a subtracted cDNA library that included about 300 clones corresponding to up-regulated genes. One porcine sequence showed 81% identity with the human oxidative-stress responsive 1 (OSR1) molecule. The objective of this study was to confirm the gene up-regulation and obtain the full-length sequences.

METHODS

The full-length gene was cloned through the technique of rapid amplification of cDNA ends (RACE). The other methods included bioinformatics analysis and RT-PCR.

RESULTS

RT-PCR confirmed that the gene was up-regulated upon the interactions of human peripheral blood mononuclear cells (PBMCs) and porcine endothelial cells. By SMART RACE technique, we obtained the full-length cDNA of porcine OSR1. The gene is 4333 bp. The open-read frame of 1590 bp encodes 529 amino acid residues. GenBank accession number is AY271356. The gene shows 92.8% nucleotide identity and 95.5% amino acid identity with human OSR1.

CONCLUSION

We obtained the full-length cDNA of porcine OSR1. It was up-regulated on porcine endothelial cells following activation by human PBMCs. We succeeded in constructing a pcDNA-pOSR1 recombinant eukaryotic cell expression vector, the function of which is the subject as our ongoing work.

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.

Nitric oxide is significantly reduced in ex vivo porcine arteries during reverse flow because of increased superoxide production

Oscillatory and negative flows occur normally in the cardiovascular system, which predispose those regions to atherosclerosis. Nitric oxide (NO) production increases in proportion to the magnitude of flow and is known to be athero-protective. What is not known, however, is the effect of flow reversal on NO concentration ([NO]). The hypothesis of the present study is that [NO] is reduced in reverse flow. An additional hypothesis is that the reduction in [NO] is mediated through an increase in superoxide production during flow reversal. These hypotheses were tested in an ex vivo preparation of porcine elastic and muscular arteries. The flow of a physiological solution through the vessels was regulated in the forward and reverse direction and the effluent was assayed for nitrite levels using a combination of a diazo coupling method and high performance liquid chromatography. Our results show that [NO] is significantly reduced during reverse flow. Furthermore, addition of tempol (superoxide dismutase-mimetic) which is a superoxide scavenger returns the [NO] during reverse flow to mirror those of forward flow. These results have important implications since the action of superoxide is implicated in many cardiovascular diseases, and the present finding suggests that flow reversal should be added to the list.

Prolongation of skin allograft survival by combined feeding of donor spleen cells and cyclosporine in mice

BACKGROUND

Oral immune tolerance is a method for inducing donor-specific immunotolerance and prolonging graft survival.

OBJECTIVES

We studied the effect of feeding donor spleen cells in combination with cyclosporine (CsA) on skin allograft survival in mice.

METHODS

Tail skins from BALB/c (H-2d) female mice were transplanted onto C57BL/6 (H-2b) female mice. The animals were divided into four groups, each with eight mice: group I, untreated controls; group II, treated with spleen cells; group III, treated with CsA; and group IV, treated with spleen cells and CsA. All grafts were inspected daily. Rejection was diagnosed when the graft loss was >80% to 90%. The immune responses of C57BL/6 toward donor mice were examined by delayed-type hypersensitivity (DTH).

RESULTS

Survival times of allogeneic skin grafts in groups I, II, III, and IV were 9.9 +/- 0.6, 13.1 +/- 0.6, 14.7 +/- 0.9, and 20.0 +/- 0.7 days, respectively. When compared with group I, the survival times of groups II, III, and IV were prolonged significantly (P < .01). The survival time for group IV was prolonged significantly compared with groups II and III (P < .01). The DTH responses of group IV were decreased significantly in contrast to groups II and III (P < .01).

CONCLUSIONS

Feeding donor spleen cells prolonged the survival of skin allografts in mice; combination with CsA led to further prolongation of skin allograft survival.

Arsenic on the hands of children after playing in playgrounds

Increasing concerns over the use of wood treated with chromated copper arsenate (CCA) in playground structures arise from potential exposure to arsenic of children playing in these playgrounds. Limited data from previous studies analyzing arsenic levels in sand samples collected from CCA playgrounds are inconsistent and cannot be directly translated to the amount of children's exposure to arsenic. The objective of this study was to determine the quantitative amounts of arsenic on the hands of children in contact with CCA-treated wood structures or sand in playgrounds. We compared arsenic levels on the hands of 66 children playing in eight CCA playgrounds with levels of arsenic found on the hands of 64 children playing in another eight playgrounds not constructed with CCA-treated wood. The children's age and duration of playtime were recorded at each playground. After play, children's hands were washed in a bag containing 150 mL of deionized water. Arsenic levels in the hand-washing water were quantified by inductively coupled plasma mass spectrometry. Our results show that the ages of the children sampled and the duration of play in the playgrounds were similar between the groups of CCA and non-CCA playgrounds. The mean amount of water-soluble arsenic on children's hands from CCA playgrounds was 0.50 microg (range, 0.0078-3.5 microg). This was significantly higher (p < 0.001) than the mean amount of water-soluble arsenic on children's hands from non-CCA playgrounds, which was 0.095 microg (range, 0.011-0.41 microg). There was no significant difference in the amount of sand on the children's hands and the concentration of arsenic in the sand between the CCA and non-CCA groups. The higher values of arsenic on the hands of children playing in the CCA playgrounds are probably due to direct contact with CCA-treated wood. Washing hands after play would reduce the levels of potential exposure because most of the arsenic on children's hands was washed off with water. The maximum amount of arsenic on children's hands from the entire group of study participants was < 4 microg, which is lower than the average daily intake of arsenic from water and food.

Arsenic speciation in urine from acute promyelocytic leukemia patients undergoing arsenic trioxide treatment

Arsenic has been used successfully in clinical trials for treating acute promyelocytic leukemia (APL). Although sublethal doses of inorganic arsenic are used, little is known about the pharmacokinetics and metabolism of the high levels of arsenic in APL patients. To fill this important gap, this study describes the speciation of arsenic in urine from four APL patients treated with arsenic. Each patient was injected daily with an arsenite (As(III)) solution that contained 10 mg of As(2)O(3) precursor. Speciation analysis of the patient urine samples collected consecutively for 48 h, encompassing two intravenous injections of arsenic, revealed the presence of monomethylarsonous acid (MMA(III)), dimethylarsinous acid (DMA(III)), monomethylarsonic acid (MMA(V)), and dimethylarsinic acid (DMA(V)). The intermediate methyl arsenic metabolites, MMA(III) and DMA(III), were detected in most urine samples from all of the patients when a preservative, diethyldithiocarbomate, was added to the urine samples to stabilize these trivalent arsenic species. The major arsenic species detected in the urine samples from the patients were As(III), MMA(V), and DMA(V), accounting for >95% of the total arsenic excreted. The relative proportions of As(III), As(V), MMA(V), and DMA(V) in urine samples collected 24 h after the injections of As(III) were 27.6 +/- 6.1, 2.8 +/- 2.0, 22.8 +/- 8.1, and 43.7 +/- 13.3%, respectively. The relatively lower fraction of the methylated arsenic species in these APL patients under arsenic treatment as compared with that from the general population exposed to much lower levels of arsenic suggests that the high levels of As(III) inhibit the methylation of arsenic (inhibits the formation of methyl arsenic metabolites). The arsenic species excreted into the urine accounted for 32-65% of the total arsenic injected. These results suggest that other pathways of excretion, such as through the bile, may play an important role in eliminating (removing) arsenic from the human body when challenged by high levels of As(III).

Modeling cellular processes with variational Bayesian cooperative vector quantizer

Gene expression of a cell is controlled by sophisticated cellular processes. The capability of inferring the states of these cellular processes would provide insight into the mechanism of gene expression control system. In this paper, we propose and investigate the cooperative vector quantizer (CVQ) model for analysis of microarray data. The CVQ model could be capable of decomposing observed microarray data into many different regulatory subprocesses. To make the CVQ analysis tractable we develop and apply variational approximations. Bayesian model selection is employed in the model, so that the optimal number processes is determined purely from observed micro-array data. We test the model and algorithms on two datasets: (1) simulated gene-expression data and (2) real-world yeast cell-cycle microarray data. The results illustrate the ability of the CVQ approach to recover and characterize regulatory gene expression subprocesses, indicating a potential for advanced gene expression data analysis.