http://www.mdpi.com/section/molecular_toxicology Related Special Issues in other IJMS Sections: Special Issue: Mycotoxins: Mechanisms of Toxicological Activity - Treatment and Prevention Links to Special Issues published in other MDPI journals: Toxins special issue of Molecules Marine Toxins special issue of Marine Drugs http://www.mdpi.com/1422-0067/11/3/896/ A bacterial strain EMS with the capability of degrading microcystins (MCs) was isolated from Lake Taihu, China. The bacterium was tentatively identified as a Stenotrophomonas sp. The bacterium could completely consume MC-LR and MC-RR within 24 hours at a concentration of 0.7 µg/mL and 1.7 µg/mL, respectively. The degradation of MC-LR and MC-RR by EMS occurred preferentially in an alkaline environment. In addition, mlrA gene involved in the degradation of MC-LR and MC-RR was detected in EMS. Due to the limited literature this gene has rare homologues. Sequencing analysis of the translated protein from mlrA suggested that MlrA might be a transmembrane protein, which suggests a possible new protease family having unique function. http://www.mdpi.com/1422-0067/11/3/896/ Tue, 02 Mar 2010 00:00:00 CET International Journal of Molecular Sciences 2010-03-02 11 3 Article 896 911 1422-0067 Degradation of Microcystin-LR and RR by a Stenotrophomonas sp. Strain EMS Isolated from Lake Taihu, China 2010-03-02 doi: 10.3390/ijms11030896 Jian Chen Liang Bin Hu Wei Zhou Shao Hua Yan Jing Dong Yang Yan Feng Xue Zhi Qi Shi http://www.mdpi.com/1422-0067/11/2/779/ A series of phthalimide derivatives planned as drugs candidates to treat the symptoms of sickle cell anemia were evaluated in a mutagenicity test using strains of Salmonella typhimurium TA100 and TA102, without and with addition of S9 mixture, with the aim to identify the best structural requirements for a drug candidate without genotoxic activity. The compounds (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl nitrate (1); (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethyl nitrate (2); 3-(1,3-dioxo-1,3-dihydro-2H-iso-indol-2-yl)benzyl nitrate (3); 4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N-hydroxy-benzenesulfonamide (4); 4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)benzyl nitrate (5) and 2-[4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)phenyl]ethyl nitrate (6) presented mutagenic potency ranging between 0-4,803 revertants/μmol. These results allowed us to propose that a methyl spacer linked to a nitrate ester subunit associated to meta aromatic substitution decreases mutagenicity. http://www.mdpi.com/1422-0067/11/2/779/ Thu, 25 Feb 2010 00:00:00 CET International Journal of Molecular Sciences 2010-02-25 11 2 Communication 779 788 1422-0067 Mutagenicity of New Lead Compounds to Treat Sickle Cell Disease Symptoms in a Salmonella/Microsome Assay 2010-02-25 doi: 10.3390/ijms11020779 Jean Leandro dos Santos Eliana A. Varanda Lídia Moreira Lima Chung Man Chin http://www.mdpi.com/1422-0067/11/2/647/ Drywall from China has been reported to release sulfur producing products which are corrosive to metals, result in noxious odors, and represent a significant health risk. It has been reported that these emissions produce medical symptoms such as respiratory or asthma type problems, sinusitis, gastrointestinal disorders, and vision problems in home owners and their household pets. We report here a method of identifying a causative agent for these emissions by sampling affected gypsum wallboard and subjecting those samples to Real Time Polymerase Chain Reaction [RT-PCR] studies. Specific DNA probes and primers have been designed and patented that detect a specific iron and sulfur reducing bacterium (i.e., Thiobacillus ferrooxidans). One hundred percent of affected drywall samples obtained from homes located in the southeastern United States tested positive for the presence of T. ferrooxidans. All negative controls consisting of unaffected wallboard and internal controls, Geotrichum sp., tested negative within our limits of detection. http://www.mdpi.com/1422-0067/11/2/647/ Fri, 05 Feb 2010 00:00:00 CET International Journal of Molecular Sciences 2010-02-05 11 2 Article 647 655 1422-0067 Isolation of Sulfur Reducing and Oxidizing Bacteria Found in Contaminated Drywall 2010-02-05 doi: 10.3390/ijms11020647 Dennis G. Hooper John Shane David C. Straus Kaye H. Kilburn Vincent Bolton John S. Sutton Frederick T. Guilford http://www.mdpi.com/1422-0067/11/1/268/ Microcystins (MC) are potent hepatotoxins produced by the cyanobacteria of the genera Planktothrix, Microcystis, Aphanizomenon, Nostoc and Anabaena. These cyclic heptapeptides have strong affinity to serine/threonine protein phosphatases (PPs) thereby acting as an inhibitor of this group of enzymes. Through this interaction a cascade of events responsible for the MC cytotoxic and genotoxic effects in animal cells may take place. Moreover MC induces oxidative stress in animal cells and together with the inhibition of PPs, this pathway is considered to be one of the main mechanisms of MC toxicity. In recent years new insights on the key enzymes involved in the signal-transduction and toxicity have been reported demonstrating the complexity of the interaction of these toxins with animal cells. Key proteins involved in MC up-take, biotransformation and excretion have been identified, demonstrating the ability of aquatic animals to metabolize and excrete the toxin. MC have shown to interact with the mitochondria. The consequences are the dysfunction of the organelle, induction of reactive oxygen species (ROS) and cell apoptosis. MC activity leads to the differential expression/activity of transcriptional factors and protein kinases involved in the pathways of cellular differentiation, proliferation and tumor promotion activity. This activity may result from the direct inhibition of the protein phosphatases PP1 and PP2A. This review aims to summarize the increasing data regarding the molecular mechanisms of MC toxicity in animal systems, reporting for direct MC interacting proteins and key enzymes in the process of toxicity biotransformation/excretion of these cyclic peptides. http://www.mdpi.com/1422-0067/11/1/268/ Thu, 21 Jan 2010 00:00:00 CET International Journal of Molecular Sciences 2010-01-21 11 1 Review 268 287 1422-0067 Molecular Mechanisms of Microcystin Toxicity in Animal Cells 2010-01-21 doi: 10.3390/ijms11010268 Alexandre Campos Vitor Vasconcelos http://www.mdpi.com/1422-0067/10/7/3065/ Seven new oxime-based acetylcholinesterase reactivators were compared with three currently available ones (obidoxime, trimedoxime, HI-6) for their ability to lessen cholinesterase inhibition in blood and brain of cyclosarin-treated rats. Oximes were given at doses of 5% their LD50 along with 21 mg/kg atropine five min before the LD50 of cyclosarin (120 ug/kg) was administered. Blood and brain samples were collected 30 minutes later. The greatest difference between acetylcholinesterase inhibition in blood of cyclosarin-treated rats was found after administration of HI-6 (40%), compared to 22% for trimedoxime and 6% for obidoxime. Only two of the seven newly synthesized oximes had any effect (K203 at 7%, K156 at 5%). Effective oximes against cyclosarin-inhibited plasma butyrylcholinesterase were HI-6 (42%), trimedoxime (11%), and K156 (4%). The oximes were less effective in brain than in blood, with reactivation values for HI-6 30% against acetylcholinesterase and 10% against butyrylcholinesterase. Values for newly synthesized oximes were less than 10% for K206, K269 and K203. http://www.mdpi.com/1422-0067/10/7/3065/ Tue, 07 Jul 2009 00:00:00 CEST International Journal of Molecular Sciences 2009-07-07 10 7 Article 3065 3075 1422-0067 Effect of Seven Newly Synthesized and Currently Available Oxime Cholinesterase Reactivators on Cyclosarin-Intoxicated Rats 2009-07-07 doi: 10.3390/ijms10073065 Jana Zdarova Karasova Jiri Kassa Kamil Musilek Miroslav Pohanka Ladislav Novotny Kamil Kuca http://www.mdpi.com/1422-0067/9/11/2243/ The therapeutical efficacies of eleven oxime-based acetylcholinesterase reactivators were compared in an in vivo (rat model) study of treatment of intoxication caused by tabun. In this group there were some currently available oximes (obidoxime, trimedoxime and HI-6) and the rest were newly synthesized compounds. The best reactivation efficacy for acetylcholinesterase in blood (expressed as percent of reactivation) among the currently available oximes was observed after administration of trimedoxime (16%) and of the newly synthesized K127 (22432) (25%). The reactivation of butyrylcholinesterase in plasma was also studied; the best reactivators were trimedoxime, K117 (22435), and K127 (22432), with overall reactivation efficacies of approximately 30%. Partial protection of brain ChE against tabun inhibition was observed after administration of trimedoxime (acetylcholinesterase 20%; butyrylcholinesterase 30%) and obidoxime (acetylcholinesterase 12%; butyrylcholinesterase 16%). http://www.mdpi.com/1422-0067/9/11/2243/ Fri, 14 Nov 2008 00:00:00 CET International Journal of Molecular Sciences 2008-11-14 9 11 Article 2243 2252 1422-0067 Effect of Several New and Currently Available Oxime Cholinesterase Reactivators on Tabun-intoxicated Rats 2008-11-14 doi: 10.3390/ijms9112243 Jana Zdarova Karasova Jiri Kassa Young-Sik Jung Kamil Musilek Miroslav Pohanka Kamil Kuca http://www.mdpi.com/1422-0067/4/2/45/ Endogenous estrogens have significant immunomodulatory effects characterized as suppression of cell mediated immunity and stimulation of humoral immunity. Xenoestrogens are environmental estrogens that have endocrine impact, acting as estrogen agonists and antagonists but whose immune effects are not well characterized. Using CD4+ Jurkat T cells as a model, the effects of representative xenoestrogens on T proliferation, cell cycle, and apoptosis were examined. Coumestrol (CM), a phytoestrogen, and tetrachlorodioxin (TCDD) in concentrations of 10-4 to 10-6M significantly inhibited Jurkat T cell lymphoproliferation, whereas bisphenol A (BPA) and DDT had minimal effect, but did antagonize 17-β-estrtadiol induced effects. Xenoestrogens, especially CM, produced accumulation of Jurkat T cells in G2/M phase, and subsequently induced apoptosis, particularly CM (% apoptotic cells = 30 ± 12 vs. control = 5 ± 2). These changes were associated with DNA fragmentation. BPA and DDT also induced DNA fragmentation but not significant DNA hypoploidy. Xenoestrogen – CM, BPA, DDT, and TCDD - exposure suppressed bcl-2 protein and mRNA transcript levels but augmented p53 protein and mRNA transcripts. Human purified peripheral blood lymphocytes responded with similar significant cell cycle changes (G0/G1 exodus and G2/M accumulation) for CM, BPA, and DDT exposure. These preliminary data, taken together, suggest that xenoestrogens have direct, compound-specific T lymphocyte effects that enhance our understanding of environmental modulation of immune and autoimmune responses. http://www.mdpi.com/1422-0067/4/2/45/ Fri, 31 Jan 2003 00:00:00 CET International Journal of Molecular Sciences 2003-01-31 4 2 Article 45 61 1422-0067 Effects of Xenoestrogens on T Lymphocytes: Modulation of bcl-2, p53, and Apoptosis 2003-01-31 doi: 10.3390/i4020045 Kenneth Ndebele Paul B. Tchounwou Robert W. McMurray http://www.mdpi.com/1422-0067/4/2/34/ Ion transport enzymes may play an important role in T cell activation. This study investigates the role of turmeric and its individual components, turmerin-and curcumin-on Ca2+ and Na/K+ adenosine triphosphatases (ATPase) in the course of T cell activation. Concanavalin A (Con A) stimulated human blood mononuclear T cell proliferation paradigm was investigated for 3, 5 and 7 day periods with different concentrations of turmeric, curcumin and turmerin. Con A-stimulated cells treated with turmeric (250, 50, 5 μg/ml) for 3 and 5 days inhibited ATPase levels when compared to base levels obtained by cells in media alone. At day 7, there was a 3-fold increase for Ca2+ATPase levels and a 2-fold increase for Na/K+ATPase. Curcumin (250, 50, 5 μg/ml) showed the same pattern for ATPase activity as turmeric at 3 and 5 days with a 2-fold increase at day 7. Turmerin (2500, 1250, 250, 25 ng/ml) for Na/K+ ATPase activity showed an increase at day 3, a decrease on day 5, and a 2-fold increase on day 7. Ca2+ ATPase activity in the presence of turmerin showed an increase in ATPase levels at day 3 (except at 2500ng/ml where it decreased) and a decrease in day 5 (except at 25 ng/ml where it increased). Turmeric and curcumin generally inhibited Ca2+ATPase and Na/K+ATPases in early (day 3) and intermediate (day 5) stages of mitogen stimulation. However, the effect after 7 days incubation for turmeric, curcumin and turmerin showed a marked increase up to three fold. http://www.mdpi.com/1422-0067/4/2/34/ Fri, 31 Jan 2003 00:00:00 CET International Journal of Molecular Sciences 2003-01-31 4 2 Article 34 44 1422-0067 Effect of Turmeric, Turmerin and Curcumin on Ca2+, Na/K+ Atpases in Concanavalin A-Stimulated Human Blood Mononuclear Cells 2003-01-31 doi: 10.3390/i4020034 Hari H. P. Cohly Maheshwara-Rajeswara Rao Vijaya K. Kanji Babu Patlolla Anelle Taylor Melanie T. Wilson Michael F. Angel Suman K. Das http://www.mdpi.com/1422-0067/4/2/22/ Oxidative stress is implicated in HIV-infection. It has been suggested that plant antioxidants may offer protection from viral replication and cell death associated with oxidative stress in patients with HIV/AIDS. Because of inherent antioxidant properties of turmeric (T) and its derivatives, water-soluble extract turmerin (Tm) and lipid soluble curcumin (Cu), their potential efficacy as anti-HIV drugs were examined. Cell viability and p-24 antigen release by CEMss-T cells (1 x 105 cells/ml) infected with HIV-IIIB strain, used as an acute model of infection, were tested in the presence of 3’azido-3’deoxythmidine (AZT). Proliferative responses of human mononuclear cells derived from HIV patients (chronic model) stimulated with phyohemagglutinin (PHA), concanavalin A (ConA), and pokeweed mitogen (PWM) were also examined in the presence of AZT and Tm. In the infection assay, T, Tm and Cu individually did not reduce p-24 antigen release or improve cell viability. AZT (5μM) + Tm (800 ng/ml) inhibited infection by 37 % and increased cell numbers by 30%; whereas, Tm (80 ng/ml) inhibited infection by 26% and increased cell number by 60%. In the proliferation assay, lymphocytes from HIV-infected patients showed better inhibition of mitogen responsiveness to Tm (800 ng/ml) when compared to AZT at 5 μM or Tm at 80 ng/ml. Turmerin inhibited HIV-infected T-cell proliferation and, in combination with AZT, decreased T-cell infection and increased cell viability. These data provide evidence suggesting that efficacious anti-HIV therapy may be possible using lower, less toxic doses of AZT in the presence of turmerin. http://www.mdpi.com/1422-0067/4/2/22/ Fri, 31 Jan 2003 00:00:00 CET International Journal of Molecular Sciences 2003-01-31 4 2 Article 22 33 1422-0067 Effect of Antioxidant (Turmeric, Turmerin and Curcumin) on Human Immunodeficiency Virus 2003-01-31 doi: 10.3390/i4020022 H. H. P. Cohly S. Asad S. K. Das M. F. Angel M. Rao http://www.mdpi.com/1422-0067/4/1/13/ Based on the hypothesis that arsenic exposure results in toxicity and mitogenecity, this study examined the dose-response of arsenic in established human cell lines of keratinocytes (HaCaT), melanocytes (1675), dendritic cells (THP-1/A23187), dermal fibroblasts (CRL1904), microvascular endothelial cells (HMEC), monocytes (THP-1), and T cells (Jurkat). Cytotoxicity was determined by incubating THP-1, THP-1+ A23187 and JKT cells in RPMI 1640, 1675 in Vitacell, HMEC in EBM, and dermal fibroblasts and HaCaT in DMEM with 10% fetal bovine serum, 1% streptomycin and penicillin for 72 hrs in 96-well microtiter plates, at 37oC in a 5% CO2 incubator with different concentrations of arsenic using fluorescein diacetate (FDA). Cell proliferation in 96-well plates was determined in cultured cells starved by prior incubation for 24 hrs in 1% FBS and exposed for 72 hours, using the 96 cell titer proliferation solution (Promega) assay. Cytotoxicity assays yielded LD50s of 9 μg/mL for HaCaT, 1.5 μg/mL for CRL 1675, 1.5 μg/mL for dendritic cells, 37 μg/mL for dermal fibroblasts, 0.48 μg/mL for HMEC, 50 μg/mL for THP-1 cells and 50 μg/mL for JKT-T cells. The peak proliferation was observed at 6 μg/mL for HaCaT and THP-1 cells, 0.19 μg/mL for CRL 1675, dendritic cells, and HMEC, and 1.5 μg/mL for dermal fibroblasts and Jurkat T cells. These results show that arsenic is toxic at high doses to keratinocytes, fibroblasts, monocytes and T cells, and toxic at lower doses to melanocytes, microvascular endothelial cells and dendritic cells. Proliferation studies showed sub-lethal doses of arsenic to be mitogenic. http://www.mdpi.com/1422-0067/4/1/13/ Thu, 30 Jan 2003 00:00:00 CET International Journal of Molecular Sciences 2003-01-30 4 1 Article 13 21 1422-0067 Cytotoxicity and Proliferation Studies with Arsenic in Established Human Cell Lines: Keratinocytes, Melanocytes, Dendritic Cells, Dermal Fibroblasts, Microvascular Endothelial Cells, Monocytes and T-Cells 2003-01-30 doi: 10.3390/i4010013 Barbara Graham-Evans Paul B. Tchounwou Hari H. P. Cohly http://www.mdpi.com/1422-0067/4/1/1/ Oxidative damage can lead to a number of diseases, and can be fatal. The blm1-1 mutation of Saccharomyces cerevisiae confers hypersusceptibility to lethal effects of the oxidative, anticancer and antifungal agent, bleomycin. For the current report, additional defects conferred by the mutation in meiosis and mitosis were investigated. The viability of spores produced during meiosis by homozygous normal BLM1/BLM1, heterozygous BLM1/blm1-1, and homozygous mutant blm1-1/blm1-1 diploid strains was studied and compared. Approximately 88% of the tetrads derived from homozygous blm1-1/blm1-1 mutant diploid cells only produced one or two viable spores. In contrast, just one tetrad among all BLM1/BLM1 and BLM1/blm1-1 tetrads only produced one or two viable spores. Rather, 94% of BLM1/BLM1 tetrads and 100% of BLM1/blm1-1 tetrads produced asci with four or three viable spores. Thus, at least one copy of the BLM1 gene is essential for the production of four viable spores after meiosis. During mitotic growth, mutant blm1-1 strains grew at reduced rates and produced cells with high frequencies of unusual morphologies compared to wild-type strains. These results indicated BLM1 is also essential for normal mitotic growth. We also investigated the suppression by the MSH4 gene, a meiosis-specific MutS homolog, of the bleomycin hypersusceptibility of blm1-1 mutant cells, and the relationship of MSH4 to BLM1. We screened a genomic library, and isolated the MSH4 gene on the basis of its ability to suppress lethal effects of bleomycin in blm1-1 cells. However, genetic mapping studies indicated that BLM1 and MSH4 are not the same gene. The possibility that chromosomal nondisjunction could be the basis for the inability of blm1-1/blm1-1 mutant cells to produce four viable spores after meiosis is discussed. http://www.mdpi.com/1422-0067/4/1/1/ Thu, 30 Jan 2003 00:00:00 CET International Journal of Molecular Sciences 2003-01-30 4 1 Article 1 12 1422-0067 Meiotic and Mitotic Phenotypes Conferred by the blm1-1 Mutation in Saccharomyces cerevisiae and MSH4 Suppression of the Bleomycin Hypersusceptibility 2003-01-30 doi: 10.3390/i4010001 Georgia Anyatonwu Ediberto Garcia Ajay Pramanik Marie Powell Carol Wood Moore http://www.mdpi.com/1422-0067/3/11/1188/ The x-ray structure of the Pneumocystis carinii dihydrofolate reductase (DHFR):trimethoprim:NADPH ternary complex obtained from the Protein Databank was used as a structural template to generate models for the following complexes: P. carinii DHFR:piritrexim:NADPH, P. carinii DHFR:epiroprim:NADPH, and P. carinii DHFR:trimetrexate:NADPH. Each of these complexes, including the original trimethoprim complex was then modeled in 60 angstrom cubes of explicit water and minimized to a rms gradient between 1.0 to 3.0 x 10-5 kcal/angstrom. Subsequently, each antifolate structure was subdivided into distinct substructural regions. The minimized complexes were used to calculate interaction energies for each intact antifolate and its corresponding substructural regions with the P. carinii DHFR binding site residues, the DHFR protein, the solvated complex ( which consists of P. carinii DHFR, NADPH, and solvent water), solvent water alone, and NADPH. Antifolate substructural regions which contained nitrogen and carbon atoms in an aromatic environment (i. e. the pteridyl, pyridopyrimidinyl, and diaminopyrimidinyl subregions) contributed most to the stability of antifolate interactions, while interaction energies for the hydrocarbon aromatic rings, methoxy, and ethoxy groups were much less stable. Additionally, interaction energy analyses were calculated for carbon and nitrogen atoms of the pteridyl, pyridopyrimidinyl, and diaminopyrimidinyl subregions and for the carbon and oxygen atoms of methoxy and ethoxy subregions. The contributions of hydrogen atoms were included with those of the carbon, nitrogen and oxygen atoms to which they are attached. These analyses revealed that the carbon atoms of the pteridyl, pyridopyrimidinyl, and diaminopyrimidinyl subregions generally contributed most to the stability of those regions. Carbon atoms also contributed favorably to the stability of the methoxy group interactions. Those substructural regions which exhibit relatively unfavorable interaction energies may constitute important modification targets in the design of improved P. carinii DHFR inhibitors. Interaction energies for different groups of atoms within the substructural regions suggest strategies for modification of the substructural regions. http://www.mdpi.com/1422-0067/3/11/1188/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1188 1202 1422-0067 Interaction Energy Analysis of Nonclassical Antifolates with Pneumocystis carinii Dihydrofolate Reductase 2002-11-30 doi: 10.3390/i3111188 Conrad Pitts Jian Yin Donnell Bowen Celia J. Maxwell William M. Southerland http://www.mdpi.com/1422-0067/3/11/1177/ Chemokines belong to a super family of inducible and secreted, pro-inflammatory cytokines. They act primarily as chemoattractants and activators of specific types of leukocytes and are involved in a variety of immune and inflammatory responses. The status and role of chemokines, macrophage inflammatory protein (MIP-1α) and RANTES (Regulated upon Activation Normal T-cell Expressed and Secreted) in the immunopathogenesis by caprine arthritis-encephalitis virus (CAEV) are not fully elucidated. The objectives of this study were to, 1) determine the expression MIP-1α in goat synovial membrane cells (GSM cells) infected in vitro, and peripheral blood mononuclear cells (PBMC) of CAEV infected goats by RT-PCR, and 2) effect of exogenous MIP-1α and on replication of CAEV in GSM cells in vitro. RT-PCR results indicated higher expression of MIP-1α in PBMC of CAEV-infected goats as compared to controls. Similarly, higher expression of MIP-1α was observed in GSMC infected in vitro with CAEV as compared to that in uninfected cells. Exogenous MIP-1α (20 ng/ml) and RANTES (20 ng/ml) significantly inhibited CAEV replication in GSM cells by 75% and 65%, respectively as compared to the replication in GSM cells not treated with the chemokines. Results of this study suggest that CAEV infection may alter the expression of chemokines in goats, which may suppress the replication of the virus. http://www.mdpi.com/1422-0067/3/11/1177/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1177 1187 1422-0067 Expression of Chemokines, MIP-1alpha and RANTES in Caprine Lentiviral Infection and Their Influence on Viral Replication 2002-11-30 doi: 10.3390/i3111177 S. Punna A. K. Jones P. G. Reddy http://www.mdpi.com/1422-0067/3/11/1162/ This study investigated gene regulation and unique gene products in both keloid (KDF) and normal (NDF) dermal fibroblasts in established cell lines. For gene regulation, NDF versus KDF were compared using Clontech's Atlas™ Human cDNA Expression Array while unique gene products were studied using RNA Fingerprinting Kit. RNA from each sample was converted to cDNA using oligo-dT primers. Down-regulated genes using Atlas Array in KDF were 1) 60 S ribosomal protein, 2) Thioredoxin dependent peroxidase, 3) Nuclease sensitive element DNA binding protein, 4) c-myc purine-binding transcription factor, 5) c-AMP dependent protein kinase, and, 6) Heat Shock Protein 90 kDa. Genes that are up regulated in KDF were 1) Tubulin and 2) Heat Shock Protein 27 kDa. With the differential display, we found 17 bands unique to both KDF and NDF. The specific gene and the manner in which they were differentially regulated have direct implications to understanding keloid fibroblast proliferation. http://www.mdpi.com/1422-0067/3/11/1162/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1162 1176 1422-0067 Differential Gene Expression of Fibroblasts: Keloid versus Normal 2002-11-30 doi: 10.3390/i3111162 Hari H. P. Cohly Heath Scott Kenneth Ndebele John K. Jenkins Michael F. Angel http://www.mdpi.com/1422-0067/3/11/1145/ We report the syntheses of antifungals containing the novel pharmacophores: oxaziridines, sulfonyloxaziridines, nitrones and nitronyl nitroxides. We hypothesized that multiple copies of the pharmacophore per molecule might be a prerequisite to enhance efficacy against the opportunistic pathogen, Pneumocystis carinii. Therefore structural optimization of the leads was based on this new “multivalency” approach. All bisoxaziridines were inactive, but a trisoxaziridine caused ca. 50% reduction of the number of P. carinii tropozoites, compared to TMP-SMX, and a hexaoxaziridine at 1 μg/ml showed activity comparable to the currently used drug, TMP-SMX. Insertion of three units of the nitronyl nitroxide pharmacophore per molecule afforded an antifungal triradical with activity comparable to TMP-SMX at 1 μg/ml; at 25 μg/ml and at 10 μg/ml the triradical was better. The results lend further support to the oxidoredox pharmacophore hypothesis, and the enhancement of activities observed demonstrates the high potential and benefits of applying the concept of multivalency to drug development. http://www.mdpi.com/1422-0067/3/11/1145/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1145 1161 1422-0067 Bioorganic Studies in AIDS: Synthetic Antifungals Against Pneumocystis carinii Based on the Multivalency Concept 2002-11-30 doi: 10.3390/i3111145 Langu Peng Cunxiang Chen Christian R. Gonzalez Valeria Balogh-Nair http://www.mdpi.com/1422-0067/3/11/1133/ 1-Aminopyrene (1-AP), a polycyclic aromatic hydrocarbons (PAH) compound, is a major metabolite during biotransformation of 1-nitropyrene by microflora in natural environment and in the guts of animals and humans. Under UV-A irradiation, 1-AP has been shown to cause light-induced DNA single strand cleavage. Humic acids (HA) in aquatic ecosystems can influence the bioavailability, toxicity, and fate of organic xenobiotics. Therefore, photochemical fate and effect of PAH in natural aquatic environment may differ significantly across sites. The objectives of this study are to assess the time course (TC; 18 and 90 minutes) influence of HA (0, 20, and 60 ppm) on microbial ecotoxicity of 1-AP (0 and 10 μM) during solar photolysis process (PP). Microbial ecotoxicity of 1-AP during different time courses in the presence and absence of HA was measured with spread plate counting and microbial mineralization of 14C-D-glucose. The experimental results were analyzed as factorial arrangements of treatment in a complete randomized design using General Linear Model by SAS. LSMEANS was used to separate means or combination of means. Significant effect on glucose mineralization was found by the following treatment interactions 1-AP*TC, 1-AP*PP, TC*PP, HA*1-AP*TC, HA*1-AP*PP, and HA*1-AP*TC*PP. The treatment interaction HA*1-AP was the only one affecting spread plate counting. In the groups exposed to 1-AP (10 μM), microbial heterotrophic mineralization of 14C-D-glucose was significantly inhibited in the presence of HA in light and in darkness. Exposure to HA in light and darkness, however, did not necessarily inhibit bacterial viability at the HA concentration range assayed. Therefore, inhibition on microbial activity could have been caused by multiple factors, instead of toxicity of HA alone. http://www.mdpi.com/1422-0067/3/11/1133/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1133 1144 1422-0067 Influence of Humic Acid on 1-Aminopyrene Ecotoxicity During Solar Photolysis Process 2002-11-30 doi: 10.3390/i3111133 Ana L. Balarezo Veleka N. Jones Hongtao Yu Huey-Min Hwang http://www.mdpi.com/1422-0067/3/11/1117/ Research in our laboratory has demonstrated that a trivalent form of arsenic such as arsenic trioxide (AT) has the ability to cause significant cytotoxicity, and induction of a significant number of stress genes in human liver carcinoma cells (HepG2). However, the literature also indicates that the toxicity of arsenic depends on its chemical form. To test this hypothesis, we further evaluated the cellular and molecular responses of HepG2 cells following exposure to monosodium acid methanearsonate (MSMA), a pentavalent and organic form of arsenic. Cytotoxicity was evaluated using the MTT-assay for cell viability, while the gene profile assay was performed to measure the degree of gene induction in 13 different recombinant cell lines generated from a parental HepG2 cell line. Cytotoxicity experiments yielded LC50 values of 11.9 + 2.6 μg/mL for AT, and 257.3 + 51.4μg/mL for MSMA; indicating that AT was about 20 times more toxic than MSMA. Exposure of HepG2 cells to MSMA also resulted in a significant reduction (p < 0.05) in the number of stress genes induced, compared to AT. Upon MSMA exposure, only 2 (HMTIIA and HSP70) out of the 13 constructs evaluated yielded inductions to statistically significant levels (p < 0.05), compared to 11 (GSTYa, XRE, HMTIIA, c-fos, NF-kBRE, HSP70, p53RE, GADD153, GADD45, and GRP78) for AT. These results greatly support the hypothesis that the toxicity of arsenic compounds highly depends on their chemical forms; with the inorganic forms being more potent than the organic ones. http://www.mdpi.com/1422-0067/3/11/1117/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1117 1132 1422-0067 Differential Cytotoxicity and Gene Expression in Human Liver Carcinoma (HepG2) Cells Exposed to Arsenic Trioxide, and Monosodium Acid Methanearsonate (MSMA) 2002-11-30 doi: 10.3390/i3111117 P. B. Tchounwou B. A. Wilson A. A. Abdelghani A. B. Ishaque A. K. Patlolla http://www.mdpi.com/1422-0067/3/11/1105/ Envelope glycoprotein (gp120) of the human immunodeficiency virus type one (HIV-1), has adverse effects on glial cells and neurons. This study reports on the direct effect of recombinant gp120 (r-gp120) produced from different expression systems on protein kinase C, as a measure of relative neurotoxicity. Brain cells were grown in vitro from explants of the cerebral cortex of newborn rats, and recombinant gp120 preparations expressed in mammalian cell/vaccinia virus and insect cell/baculovirus systems were applied to astrocyte-enriched cultures. The gp120 preparations activated protein kinase C (PKC) to similar levels in these cells. Mutant recombinant gp120 lacking the amino-terminal 29 amino acids produced from the mammalian and insect cells also activated PKC to similar levels as did the full-length protein. The recombinant proteins specifically activated PKC β and ζ, suggesting that they are able to induce both Ca2+-dependent and Ca2+-independent isoforms of this enzyme. Alteration of PKC activity in astrocytes by gp120 indicates its ability to modulate gene expression, which is associated with the neurotoxicity of this protein. Furthermore, the results suggest that the deletion of the first 29 residues of NH2-terminal end of the gp120 does not affect the functional activity of this protein with regard to modulation of signal transduction in astrocytes. http://www.mdpi.com/1422-0067/3/11/1105/ Sat, 30 Nov 2002 00:00:00 CET International Journal of Molecular Sciences 2002-11-30 3 11 Article 1105 1116 1422-0067 Neurotoxic Activity of the HIV-1 Envelope Glycoprotein: Activation of Protein Kinase C in Rat Astrocytes 2002-11-30 doi: 10.3390/i3111105 Oyewole Adeyemo Rong Wu Scott Parker Etty N. Benveniste Eric Hunter Isaac Adebayo http://www.mdpi.com/1422-0067/3/10/1095/ Methamphetamine (MAMPH) increases core body temperature at room temperature and decreases it in the cold room. MAMPH at doses ≥ 5.0 mg/kg also induces neural toxicity at room temperature, but not in the cold room. We hypothesized that the neural toxicity of the MAMPH is heat related. Thus, the objectives of these experiments were to investigate the dynamics of heat dissipation and conservation at various ambient temperatures. Forty male Sprague-Dawley rats were divided into four equal groups. Groups 1, 2 and 3 were injected intraperitoneally (i.p.) with saline and one hour later with an equivolume of MAMPH in doses of 2.5, 5.0, or 7.5 mg/kg bwt. Group four was injected with saline/saline. Core body (Tc) and tail skin (Ts) temperatures were recorded with thermistors (YSI series 700) at room temperature (21 ± 1°C) or in a cold room (7 ± 0.5°C) every five minutes for four hours. Tc was used as an index for total body heat, and Ts was used as an index for blood flow to the tail (a measure of heat dissipation /conservation) at various times during the experiment. Analysis of the data (ANOVA and post-hoc) showed that MAMPH at doses of 5.0 and 7.5 mg/kg bwt increased the Tc at room temperature, and decreased the Tc at doses of 2.5, 5.0 and 7.5 mg/kg bwt in the cold room in a dose dependent manner. Analysis of the tail effector mechanism for heat dissipation at room temperature, and for heat conservation in the cold room, demonstrated that Ts does not follow Tc at room temperature, but follows Tc in the cold room. In the cold room, MAMPH treated animals decreased Ts, or probably vasoconstricted the tail as the Tc falls. In contrast, at room temperature, although MAMPH raised the Tc of the animals, there was no evidence for a change in Ts, or no tail vasodilatation. Based on these data, we suggest that MAMPH (i.p.) impair heat dissipation, but not heat conservation. Hence, the accumulated heat in neural tissue may account, in part, for the reported neural toxicity of MAMPH. http://www.mdpi.com/1422-0067/3/10/1095/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1095 1104 1422-0067 The Influence of Environmental Temperatures on Neurotoxicity Induced by Methamphetamine in Male Rats 2002-10-31 doi: 10.3390/i3101095 Rymond A. Mohaghegh Jeurel Singleton Dolores Shockley http://www.mdpi.com/1422-0067/3/10/1082/ Menia El-Kamh province of the Sharkia Governorate constitutes one of the largest agricultural areas in Egypt. About 88% of the nearly 472,000 people living in this province rely on agricultural activities for subsistence. Several pesticides including organochloride, organophosphorus, carbamate, and pyrethroid insecticides, fungicides, and herbicides are commonly used in citrus, vegetable and other crop-growing areas to increase agricultural productivity. However, their use has also been associated with several cases of pesticide poisoning. In this research, we conducted a field survey to assess the knowledge, attitudes, and practices of the farmer’s community regarding the safe use of pesticides. We also evaluated the residual concentrations of selected pesticides in water, soil, milk, fish, and orange samples, and estimated the potential health risks associated with the exposure to these pesticides. Data obtained from the field survey indicate that more than 95% of farm workers do not practice safety precautions during pesticide formulation and application; leading to a considerable prevalence of pesticide-related illnesses in this agricultural community. Pesticide residues in various environmental samples varied greatly; from below detection levels (3-5 ng) to as high as 325 ppb depending on the matrix of interest, and the specific pesticide of concern. The analysis of health risk estimates indicated that chlorpyrifos, DDT, dimethoate, methomyl, and larvin did not pose a direct hazard to human health, although present in water, milk, orange, and/or fish. However, aldicarb, and carbosulfan levels exceeded the reference doses, indicating a great potential for systemic toxicity, especially in children who are considered to be the most vulnerable population subgroup. The upper-bound values of cancer risk from DDT exposure were estimated to be about 8 (adults), and 55 (children) excess cancers in a population of one million. http://www.mdpi.com/1422-0067/3/10/1082/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1082 1094 1422-0067 Health Risk Assessment of Pesticide Usage in Menia El-Kamh Province of Sharkia Governorate in Egypt 2002-10-31 doi: 10.3390/i3101082 Paul B. Tchounwou Bassem A. Ashour Curtina Moreland-Young Didair A. Ragheb Ahmed A. Romeh El-Adarosy Goma Sayed El-Sheikh Frances P. Lidell Olurominiyi Ibitayo Jean-Claude Assad http://www.mdpi.com/1422-0067/3/10/1073/ The cholinergic system has been proposed to participate in the development of dependence on opioids. The present study examined effects of dermal pretreatment with methyl parathion (MP), an acetylcholinesterase inhibitor, on the development of physical dependence on morphine. Opioid dependence was induced by continuous intracerebroventricular (i.c.v.) infusion of morphine (26 nmol/μl/h) for 3 days in adult male Sprague-Dawley rats. Each rat received two doses of MP, 12.5 mg/kg, dermally, initially, 3 days prior to initiation of i.c.v. morphine infusion and again on the first day of infusion. Withdrawal was precipitated after 3 days of infusion by administering an opioid antagonist, naloxone (48 nmol/5 μl, i.c.v.). Twelve of 23 MP-treated rats exhibited signs of acetylcholinesterase inhibitor intoxication (mild tremors) and showed reduced spontaneous locomotor activity (tested by an open field test), prior to naloxone. The brain cholinesterase activity in these 12 rats was 13% of levels in control rats. Eleven rats that did not show toxic signs, exhibited cholinesterase activities that were 20% of control (not significant versus toxic group). The group that showed signs of MP intoxication exhibited a significantly lower incidence of opioid withdrawal jumping, rearing and wet dog shakes compared with the non-toxic group. No differences between quantal withdrawal signs (ptosis, penis-licking, and vocalization) were noted between the two groups. The results suggest that toxic inhibition of acetylcholinesterase non-specifically reduces locomotor activity and may obscure certain behavioral signs of withdrawal from opioid dependence. This indicates that caution should be used in interpreting a direct involvement of acetylcholinesterase inhibition in preventing opioid dependence. http://www.mdpi.com/1422-0067/3/10/1073/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1073 1081 1422-0067 Methyl Parathion Masks Withdrawal from Physical Dependence on Morphine 2002-10-31 doi: 10.3390/i3101073 Hong Zhu Ing K. Ho Robert E. Kramer Rodney C. Baker Robin W. Rockhold http://www.mdpi.com/1422-0067/3/10/1058/ Unusual HIV-1 nef alleles were isolated from a woman and her vertically infected child. Both patients eventually progressed to develop AIDS. The child died at age 6.5 years, while the mother is currently alive, 13 years since her diagnosis with HIV-1. Predicted amino acid sequences of both mother and child Nefs diverged from the HIV-1 clade B consensus. In particular, they exhibited two separate 5-amino acid deletions bracketing a Cterminal dileucine regulatory motif and Trp-Gly mutations at the site for cleavage by the HIV-1 protease. The child’s Nef showed a modest ability to enhance HIV-1 infectivity in MAGI cells, whereas the mother’s Nef did not alter HIV-1 infectivity in the assay. Both Nefs were partially functional for CD4 down-regulation. The child’s Nef was fully functional for MHC-1 down-regulation, while the maternal Nef was non-functional. To our knowledge this study is the first to describe a functional divergence between Nef alleles in a case of mother-to-child HIV-1 transmission. http://www.mdpi.com/1422-0067/3/10/1058/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1058 1072 1422-0067 Functionally-Impaired HIV-1 Nef Alleles from a Mother-Child Transmission Pair 2002-10-31 doi: 10.3390/i3101058 William W. Roth Mafhuz Khan Romas Geleziunas Harold G. Stringer Jalal A. Zuberi Warner C. Greene Michael Powell Vincent C. Bond http://www.mdpi.com/1422-0067/3/10/1048/ Humic substances (HS) are ubiquitous in the environment, and can act as photosensitizers in the redox reactions of some photochemical processes. The influence of HS in these reactions varies with the HS type and concentration. The total organic carbon content (TOC) of some commercial HS (such as soil and river humic acid, and fulvic acid) was studied. 1-Aminopyrene (1-AP) and 1-hydoxypyrene (1-HP) are carcinogenic and slightly water-soluble polycyclic aromatic hydrocarbons (PAH). The impact of PAH on natural environment is related to their photolysis rates and photoproducts; therefore, it is of interest to study the photolysis of these compounds. Our previous study showed that the photolysis rate of 1-HP was inhibited by HS. In this study, photolysis of 1-AP was conducted with pure water, natural river water, and pure water containing commercial HS. It was found that the photolysis rate of 1-AP can be inhibited or enhanced by HS, depending on the type and concentration. The first order photolysis rate constant of 1-AP (10 μM) in phosphate buffer (pH 7.0, 1 mM) containing a humic acid (20-80 ppm) was enhanced by up to 5 folds. With a fulvic acid (20-80 ppm), it was enhanced by about 2 folds. With a soil humic acid, it was enhanced by about 2 folds at the concentration of 20 ppm and was inhibited by up to 4 folds at the concentration of 80 ppm. Atrazine (2-chloro-4-ethylamine-6-isopropylamino-s-triazine) is a widely used herbicide. It is toxic, often bioaccumulative and persistent. In this study, the effect of HS on the photochemical fate of atrazine was also studied. The results showed that photolysis of atrazine can be enhanced by humic acid, depending on the type and concentration of humic acid. The fulvic acid has no effect on its photolysis within 10 days. http://www.mdpi.com/1422-0067/3/10/1048/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1048 1057 1422-0067 Effect of Dissolved Humic Substances on the Photochemical Degradation Rate of 1-Aminopyrene and Atrazine 2002-10-31 doi: 10.3390/i3101048 Kui Zeng Huey-min Hwang Hongtao Yuzuri http://www.mdpi.com/1422-0067/3/10/1039/ Currently, serum is used more often than urine to detect prostate specific antigen (PSA). The need for a non-invasive test yielding similar results led us to develop a urine test that uses solar irradiated water as a reactant species. To develop this technology, seven reagents plus one control were produced by exposure of water for 40 days in sunlight to the colors of the visible spectrum through colored cellophane, control being an unwrapped bottle of sterile water. Patients (127) were examined for serum PSA and the urine was tested using the above reagents. A positive urine test was observed with yellow-filtered irradiated water which absorbed at 454nm. Twenty-five of the 45 patients with positive results for the urine test had PSA levels of 0.21-4.0 ng/ml. Thus, this pilot study describes a non-invasive urine test mainly positive in patients with PSA 0.21-4.0 ng/ml. http://www.mdpi.com/1422-0067/3/10/1039/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1039 1047 1422-0067 Pilot Study: A Non-Invasive Urine Test for Potential Prostate Abnormalities 2002-10-31 doi: 10.3390/i3101039 H. H. P. Cohly M. S. Koelle M. F. Angel S. K. Das W. B. Shingleton http://www.mdpi.com/1422-0067/3/10/1027/ The risk from chemical carcinogens and environmental toxins is dependent on the metabolic balance between bioactivation and detoxification enzymes. Therefore, agents that alter enzyme expression are critical factors in toxicity. Enhancement or suppression of enzyme activities through gene expression is in part regulated by interactions between specific DNA promoter response elements and specific transcription proteins. DNA-protein interactions are dependent upon translocation of proteins from the cytoplasm to the nucleus and the affinity of proteins for binding to transcription promoter sequences. A key factor in both processes is the intracellular redox state, which influences protein-protein interactions and protein-DNA binding and can be altered by exposure to electrophiles, antioxidants and oxidative stress. Oxidative stress levels can be readily detected by measurable effects on the intracellular glutathione (GSH):glutathione disulfide redox potential, the major intracellularredox buffer. Alterations in the GSH redox pool can directly affect enzyme activity by altering disulfide bonds in the transcription factors regulating enzyme expression. These may affect: 1) specific DNA-protein and protein-protein interactions, 2) cyst(e)ine redox state within transcriptional proteins and 3) translocation of transcription proteins from cytoplasmic to nuclear compartments within the cell. The studies reported here are designed to investigate the relative changes in enzyme expression in response to cellular redox potential changes using the new proteomics technology of surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI). Treatment of HeLa and HT29 human cell lines to increase the expression of enzymes that are upregulated by oxidative stress was used as a model system to determine the efficacy of the SELDI technology in measuring changes in transcriptional protein binding to transcriptional response elements. An important goal is to determine whether the SELDI will allow simultaneous studies of multiple transcriptional protein-DNA interactions in response to controlled oxidative stress. This will provide a better understanding of the effect of electrophilic carcinogens and oxidants on the balance between activation and detoxification mechanisms in chemical carcinogenesis. http://www.mdpi.com/1422-0067/3/10/1027/ Thu, 31 Oct 2002 00:00:00 CET International Journal of Molecular Sciences 2002-10-31 3 10 Article 1027 1038 1422-0067 SELDI-TOF-MS Analysis of Transcriptional Activation Protein Binding to Response Elements Regulating Carcinogenesis Enzymes 2002-10-31 doi: 10.3390/i3101027 Steve R. Bischoff Mahfuz B. Kahn Michael D. Powell Ward G. Kirlin http://www.mdpi.com/1422-0067/3/9/1019/ We have previously shown that riddelliine, a naturally occurring genotoxic pyrrolizidine alkaloid, induces liver tumors in rats and mice through a genotoxic mechanism mediated by the formation of a set of eight 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5Hpyrrolizine ( DHP)-derived DNA adducts. In this study we report the formation of these DHP-derived DNA adducts in blood DNA of rats fed riddelliine. In an adduct formation and removal experiment, male and female F344 rats (8 weeks of age) were administered riddelliine by gavage at a single dose of 10.0 mg/kg body weight in 0.1 M phosphate buffer. At 8, 24, 48, and 168 hrs after dosing, the levels of DHP-derived DNA adduct in blood and liver were determined by 32P-postlabeling/HPLC. Maximum DNA adduct formation occurred at 48 hr after treatment. From 48 to 168 hours, the adduct levels in female rat blood were 4-fold greater than those in male rats. In a dose response experiment, female rats were gavaged 0.1 and 1.0 mg/kg doses of riddelliine for three consecutive days and the DHPderived DNA adducts in blood DNA were assayed. The levels of the DHP-derived DNA adducts in blood of rats receiving 0.1 and 1.0 mg/kg doses were 12.9 and 51.8 adducts/107 nucleotides. These results suggest that: (i) leucocyte DNA can bind with DHP to form a set of DHP-derived DNA adducts generated in liver; (ii) DHP-derived DNA adducts in blood can serve as a potential non-invasive biomarkers for assessing the exposure to riddelliine. http://www.mdpi.com/1422-0067/3/9/1019/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 1019 1026 1422-0067 Detection of Riddelliine-Derived DNA Adducts in Blood of Rats Fed Riddelliine 2002-09-30 doi: 10.3390/i3091019 Jian Yan Jasyl Nichols Ya-Cheng Yang Peter P. Fu Ming W. Chou http://www.mdpi.com/1422-0067/3/9/1008/ Stereoselective metabolism of dibenzo[a,l]pyrene (DB[a,l]P), 2-chlorodibenzo[a,l]pyrene (2-Cl-DB[a,l]P) and 10-chlorodibenzo[a,l]pyrene (10-Cl-DB[a,l]P) by rat liver microsomes was studied and effects of the chloro substituent on the metabolism were determined. All three compounds produced trans-8,9-dihydrodiol, trans-11,12-dihydrodiol, and the 7-hydroxyl derivative as major metabolic products and several other phenolic derivatives as minor metabolites. The trans-8,9- and 11,12-dihydrodiols of DB[a,l]P and 2-Cl-DB[a,l]P preferentially adopted a quasidiequatorial conformation, whereas 10-Cl-DB[a,l]P trans-8,9- and 11,12-dihydrodiols preferentially adopted a quasidiaxial conformation. The yields of the trans-11,12-dihydrodiol metabolites are: DB[a,l]P trans-11,12-dihydrodiol > 2-Cl-DB[a,l]P trans-11,12-dihydrodiol >> 10-Cl-DB[a,l]P trans-11,12-dihydrodiol. Circular dichroism (CD) spectral analysis indicates that the trans-8,9-dihydrodiol and trans-11,12-dihydrodiol metabolites from DB[a,l]P, 2-Cl-DB[a,l]P, and 10-Cl-DB[a,l]P are optically active. Furthermore, the major enantiomeric DB[a,l]P trans-11,12-dihydrodiol and 2-Cl-DB[a,l]P trans-11,12-dihydrodiol had R,R absolute configuration. Based on the fact that DB[a,l]P trans-11,12-dihydrodiol is the proximate tumorigenic metabolite of DB[a,l]P, our results suggest that DB[a,l]P exhibits the highest tumorigenic potency followed by 2-Cl-DB[a,l]P, and 10-Cl-DB[a,l]P exhibits the lowest tumorigenicity. http://www.mdpi.com/1422-0067/3/9/1008/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 1008 1018 1422-0067 In Vitro Metabolism of Dibenzo[a,l]pyrene, 2-Chlorodibenzo [a,l]pyrene and 10-Chlorodibenzo[a,l]pyrene - Effects of Chloro Substitution 2002-09-30 doi: 10.3390/i3091008 Yuh-Shen Wu Guor-Cheng Fang Joanna Moody Linda S. Von Tungeln Peter P. Fu Huey-Min Hwang Hongtao Yu http://www.mdpi.com/1422-0067/3/9/992/ Pentachlorophenol (PCP) is a biocidal chemical with several industrial, agricultural, and domestic applications. There is accumulating evidence indicating that PCP is highly toxic to humans, with major target organs including the lung, liver, kidneys, heart, and brain. Little is known regarding the molecular basis by which PCP induces toxicity, mutagenesis, and carcinogenesis. Therefore, this research was designed to assess the cellular and molecular responses of HepG2 cells following exposure to PCP. The cytotoxicity experiment yielded a LD50 value of 23.4 + 9.7 μg PCP/mL upon 48 hrs of exposure, indicating that PCP is acutely toxic. A dose-response relationship was recorded with respect to gene induction. For example, fold inductions of CYP1A1 were 1.0 + 0.0, 1.0 + 0.0, 1.3 + 0.5, 6.3 + 4.3, and 22.5 + 3.5 for 0, 6.2, 12.5, 25, and 50 μg PCP/mL, respectively. Overall, five out of the thirteen recombinant cell lines tested showed inductions to statistically significant levels (p < 0.05). At 50 μg PCP/mL, the average fold inductions were 22.5 + 3.5, 52.8 + 2.5, 8.4 + 1.9, 6.16 + 2.4, and 12.5 + 6.8, for CYP1A1, XRE, HMTIIA, c-fos, and GADD153, respectively. These results indicate the potential of PCP to undergo Phase I biotransformation in the liver (CYP1A1, XRE), to cause cell proliferation (c-fos), growth arrest and DNA damage (GADD153), and to influence the toxicokinetics of metal ions (HMTIIA). Marginal inductions were recorded for HSP70, CRE, RARE, GADD45, and GRP78. Within the dose range (0-100 μg/mL) tested, no significant inductions (p < 0.05) were observed for GSTYa, NFkBRE, and p53RE. http://www.mdpi.com/1422-0067/3/9/992/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 992 1007 1422-0067 Transcriptional Activation of Stress Genes and Cytotoxicity in Human Liver Carcinoma (HepG2) Cells Exposed to Pentachlorophenol 2002-09-30 doi: 10.3390/i3090992 Waneene C. Dorsey Paul B. Tchounwou Ali B. Ishaque Elaine Shen http://www.mdpi.com/1422-0067/3/9/985/ The objective of this study is to determine if arterial endothelial injury can be attenuated by local application of 80 μg/ml turmerin at the site of injury and by oral administration of the same dose. Anesthetized Lewis rats (n =12) weighing 200 ± 4.0 gms randomly were assigned to two groups. After 5 min of air drying a segment of right carotid artery, six rats were treated locally 80μg/ml with turmerin and the rest were treated with 0.9% NaCl. Turmerin was then administered by gavage (80 μg) every 24 hrs for 14 days. Animals were sacrificed on day 14 and the carotid artery removed from the injured site for histological analysis and serum collected for lipid peroxidation analysis by measuring malondialdehyde (MDA) and conjugated dienes. This study showed no proliferation in the intima of one rat out of six rats treated with turmerin while there was significant variation between the treated rats and the controls. MDA for control was 0.593±0.02 nanomoles/ml while turmerin was 0.187±0.04 (p≤0.01); conjugated diene for control was 0.402±0.03 nanomoles/ml while turmerin was 0.212±0.04 nanomoles/ml (p ≤0.05). Although there was significant reduction in serum peroxidation activity, the histological findings indicate that attenuation of carotid artery injury may involve other factors than decreased lipid peroxidation. http://www.mdpi.com/1422-0067/3/9/985/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 985 991 1422-0067 Effect of Turmerin on Endothelial Denudation by Air Drying 2002-09-30 doi: 10.3390/i3090985 H. H. P. Cohly C. Hammet M. F. Angel V. Kanji A. Taylor H. Benghuzzi A. K. Markov http://www.mdpi.com/1422-0067/3/9/965/ Mercury is a non-essential element that exhibits a high degree of toxicity to humans and animals. Exposure to mercury has been associated with a significant number of adverse health effects including: cardiovascular disease, anemia, developmental abnormalities, neurobehavioral disorders, kidney and liver damage, and cancer in some cases. In several studies, the toxicity of mercury has been attributed to its high affinity to protein-containing sulfhydryl groups. However, little is known regarding the molecular mechanisms by which mercury exerts its toxicity, mutagenesis, and carcinogenesis. This research was therefore designed to assess the cellular and molecular responses of human liver carcinoma cells following exposure to mercury. Cytotoxicity was evaluated using the MTT-assay for cell viability, while the gene profile assay was performed to measure the transcriptional activation of stress genes in thirteen different recombinant cell lines generated from HepG2 cells. Cytotoxicity experiment yielded a LD50 value of 3.5 ± 0.6 μg/mL upon 48 hours of exposure, indicating that mercury is highly toxic. A dose response relationship was recorded with respect to both cytotoxicity and gene induction. Overall, nine out of the thirteen recombinant cell lines tested showed inductions to statistically significant levels (p < 0.05). At 2.5 μg/mL of mercury, the average fold inductions were 5.2 ± 0.9, 21.4 ± 3.9, 7.0 ± 6.2, 6.8 ± 1.1, 2.7 ± 1.0, 4.5 ± 2.0, 7.5 ± 6.0, 2.2 ± 0.7, and 2.5 ± 0.3, for GSTYa, HMTIIA, c-fos, HSP70, CRE, p53RE, GADD153, GADD45, and GRP78, respectively. These results indicate the potential of mercury to undergo Phase II biotransformation in the liver (GSTYa), and to cause protein damage (HMTIIA, HSP70, and GRP78), cell proliferation (c-fos), metabolic perturbation (CRE), growth arrest and DNA damage (GADD153, GADD45), and apoptosis (p53RE). No significant inductions (p > 0.05) were observed for CYP1A1, XRE, NFkBRE, and RARE. http://www.mdpi.com/1422-0067/3/9/965/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 965 984 1422-0067 Mercury Induces Cytotoxicity and Transcriptionally Activates Stress Genes in Human Liver Carcinoma (HepG2) Cells 2002-09-30 doi: 10.3390/i3090965 Dwayne J. Sutton Paul B. Tchounwou Nanuli Ninashvili Elaine Shen http://www.mdpi.com/1422-0067/3/9/948/ Plants that contain pyrrolizidine alkaloids are widely distributed in the world. Although pyrrolizidine alkaloids have been shown to be genotoxic and tumorigenic in experimental animals, the mechanisms of actions have not been fully understood. The results of our recent mechanistic studies suggest that pyrrolizidine alkaloids induce tumors via a genotoxic mechanism mediated by 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5Hpyrrolizine (DHP)-derived DNA adduct formation. This mechanism may be general to most carcinogenic pyrrolizidine alkaloids, including the retronecine-, heliotridine-, and otonecinetype pyrrolizidine alkaloids. It is hypothesized that these DHP-derived DNA adducts are potential biomarkers of pyrrolizidine alkaloid tumorigenicity. The mechanisms that involve the formation of DNA cross-linking and endogenous DNA adducts are also discussed. http://www.mdpi.com/1422-0067/3/9/948/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 948 964 1422-0067 Genotoxic Pyrrolizidine Alkaloids — Mechanisms Leading to DNA Adduct Formation and Tumorigenicity 2002-09-30 doi: 10.3390/i3090948 Peter P. Fu Qingsu Xia Ge Lin Ming W. Chou http://www.mdpi.com/1422-0067/3/9/934/ n/a http://www.mdpi.com/1422-0067/3/9/934/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Editorial 934 936 1422-0067 A Message from the Director 2002-09-30 doi: 10.3390/i3090934 Sidney A. McNairy http://www.mdpi.com/1422-0067/3/9/937/ Polycyclic aromatic hydrocarbons (PAHs) are a class of carcinogenic compounds that are both naturally and artificially produced. Many PAHs are pro-carcinogens that require metabolic activation. Recently, it has been shown that PAH can induce DNA single strand cleavage and formation of PAH-DNA covalent adduct upon irradiation with UVA light. The light-induced DNA cleavage parallels phototoxicity in one instance. The DNA photocleavage efficiency depends on the structure of the PAHs. This article reports the effect of both organic solvents and the presence of biologically relevant ions, Na+, Mg2+, Ca2+, K+, Fe3+, Cu2+, Zn+2, Mn2+, and I-, on the light-induced DNA cleavage by pyrene, 1-hydroxypyrene and 1-aminopyrene. Since both 1-hydroxypyrene (0.6 μM) and 1-aminopyrene (6 μM) dissolve well in the minimum organic solvents used (2% methanol, dimethylsulfoxide, and dimethylformamide), increasing the amount of the organic solvent resulted in the decrease of the amount of DNA single strand cleavage caused by the combination effect of 1-hydroxy or 1-aminopyrene and UVA light. The result with the less watersoluble pyrene shows that increase of the amount of the organic solvent can increase the amount of DNA single strand DNA photocleavage cause by the combination of pyrene and UVA light. Therefore, there are two effects by the organic solvents: (i) to dissolve PAH and (ii) to quench DNA photocleavage. The presence of Fe3+ and Zn2+ enhances, while the presence of Ca2+ and Mn2+ inhibits the DNA photocleavage caused by 1-aminopyrene and UVA light. Other metal ions have minimal effect. This means that the effect of ions on DNA photocleavage by PAHs is complex. The presence of KI enhances DNA photocleavage. This indicates that the triplet-excited state of 1-aminopyrene is involved in causing DNA cleavage http://www.mdpi.com/1422-0067/3/9/937/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Article 937 947 1422-0067 Effect of Organic Solvents and Biologically Relevant Ions on the Light-Induced DNA Cleavage by Pyrene and Its Amino and Hydroxy Derivatives 2002-09-30 doi: 10.3390/i3090937 Shiming Dong Shuguang Wang Gernerique Stewart Huey-Min Hwang Peter P. N. Fu Hongtao Yu http://www.mdpi.com/1422-0067/3/9/931/ n/a http://www.mdpi.com/1422-0067/3/9/931/ Mon, 30 Sep 2002 00:00:00 CEST International Journal of Molecular Sciences 2002-09-30 3 9 Editorial 931 933 1422-0067 Special Issue on Recent Advances in Environmental Health Research: Health Disparities, Toxicology and Carcinogenesis 2002-09-30 doi: 10.3390/i3090931 Paul B. Tchounwou Hongtao Yu