Table of Contents

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Abstract: The environment plays a pivotal role as a human health determinant and presence of hazardous pollutants in the environment is often implicated in human disease. That pollutants cause human diseases however is often controversial because data connecting exposure to environmental hazards and human diseases are not well defined, except for some cancers and syndromes such as asthma. Understanding the complex nature of human-environment interactions and the role they play in determining the state of human health is one of the more compelling problems in public health. We are becoming more aware that the reductionist approach promulgated by current methods has not, and will not yield answers to the broad questions of population health risk analysis. If substantive applications of environment-gene interactions are to be made, it is important to move to a systems level approach, to take advantage of epidemiology and molecular genomic advances. Systems biology is the integration of genomics, transcriptomics, proteomics, and metabolomics together with computer technology approaches to elucidate environmentally caused disease in humans. We discuss the applications of environmental systems biology as a route to solution of environmental health problems.

Abstract: Although nickel and cobalt compounds have been known to cause induction of the transcription factor hypoxia-inducible factor 1 (HIF-1) and activation of a battery of hypoxia-inducible genes in the cell, the molecular mechanisms of this induction remain unclear. The post-translational modification of HIF-1a, the oxygen-sensitive subunit of HIF-1, regulates stabilization, nuclear translocation, DNA binding activity, and transcriptional activity of the protein. Among the enzymes regulating the post-translational modification of HIF-1a, the factor inhibiting HIF-1 (FIH-1) hydroxylates the protein at asparagine 803, suppressing the interaction of HIF-1a with transcription coactivators p300/CBP and reducing the transcriptional activity of the protein. ARD-1, the acetyltransferase, acetylates HIF-1a at lysine 532, which enhances the interaction of HIF-1a with pVHL. Therefore, FIH-1 and ARD-1 negatively regulate the transcriptional activity and the stability of HIF-1a. We examined the mRNA levels of FIH-1 and ARD-1 genes after exposure nickel (II) or cobalt (II) to the cell and found that both genes were down-regulated by the chemical treatment, which may lead to reduced levels of both proteins and result in increased level of HIF-1a and its transcriptional activity.

Abstract: L1 and Alu elements are among the most active retroposons (mobile elements) in the human genome. Several human diseases, including certain forms of breast cancer and leukemia, are associated with L1 and Alu insertions in functionally important areas of the genome. We present data demonstrating that environmental pollutants, such as heavy metals, can stimulate L1 retrotransposition in a tissue culture system using two different types of assays. The response to these agents was equivalent when using a cell line with a stably integrated L1 vector (genomic) or a by introducing the L1 vector by transient transfection (episomal) of the cell. Reproducible results showed that mercury (HgS), cadmium (CdS), and nickel (NiO) increase the activity of L1 by an average of three (3) fold p<0.001. This observation is the first to link several carcinogenic agents with the increased retrotransposition activity of L1 as an alternate mechanism of generating genomic instability contributing to the process of carcinogenesis. Our results demonstrate that mobile element activation must be considered as one of the mechanisms when evaluating genomic damage/instability in response to environmental agents.

Abstract: Ultra–wideband (UWB) technology has increased with the use of various civilian and military applications. In the present study, we hypothesized that low-dose UWB electromagnetic radiation (UWBR) could elicit a mitogenic effect in AML-12 mouse hepatocytes, in vitro. To test this hypothesis, we exposed AML-12 mouse hepatocytes, to UWBR in a specially constructed gigahertz transverse electromagnetic mode (GTEM) cell. Cells were exposed to UWBR for 2 h at a temperature of 23°C, a pulse width of 10 ns, a repetition rate of 1 kHz, and field strength of 5-20 kV/m. UWB pulses were triggered by an external pulse generator for UWBR exposure but were not triggered for the sham exposure. We performed an MTT Assay to assess cell viability for UWBR-treated and sham-exposed hepatocytes. Data from viability studies indicated a time-related increase in hepatocytes at time intervals from 8-24 h post exposure. UWBR exerted a statistically significant (p < 0.05) dose-dependent response in cell viability in both serum-treated and serum free medium (SFM) -treated hepatocytes. Western blot analysis of hepatocyte lysates demonstrated that cyclin A protein was induced in hepatocytes, suggesting that increased MTT activity after UWBR exposure was due to cell proliferation. This study indicates that UWBR has a mitogenic effect on AML-12 mouse hepatocytes and implicates a possible role for UWBR in hepatocarcinoma.

Abstract: Nanotechnology and nanomaterials have become the new frontier world-wide over the past few years and prospects for the production and novel uses of large quantities of carbon nanotubes in particular are becoming an increasing reality. Correspondingly, the potential health risks for these and other nanoparticulate materials have been of considerable concern. Toxicological studies, while sparse, have been concerned with virtually uncharacterized, single wall carbon nanotubes, and the conclusions have been conflicting and uncertain. In this research we performed viability assays on a murine lung macrophage cell line to assess the comparative cytotoxicity of commercial, single wall carbon nanotubes (ropes) and two different multiwall carbon nanotube samples; utilizing chrysotile asbestos nanotubes and black carbon nanoaggregates as toxicity standards. These nanotube materials were completely characterized by transmission electron microscopy and observed to be aggregates ranging from 1 to 2 μm in mean diameter, with closed ends. The cytotoxicity data indicated a strong concentration relationship and toxicity for all the carbon nanotube materials relative to the asbestos nanotubes and black carbon. A commercial multiwall carbon nanotube aggregate exhibiting this significant cell response was observed to be identical in structure to multiwall carbon nanotube aggregates demonstrated to be ubiquitous in the environment, and especially in indoor environments, where natural gas or propane cooking stoves exist. Correspondingly, preliminary epidemiological data, although sparse, indicate a correlation between asthma incidence or classification, and exposure to gas stoves. These results suggest a number of novel epidemiological and etiological avenues for asthma triggers and related respiratory or other environmental health effects, especially since indoor number concentrations for multiwall carbon nanotube aggregates is at least 10 times the outdoor concentration, and virtually all gas combustion processes are variously effective sources. These results also raise concerns for manufactured carbon nanotube aggregates, and related fullerene nanoparticles.

Abstract: Cyanobacterial toxins have caused human poisoning in the Americas, Europe and Australia. There is accumulating evidence that they are present in treated drinking water supplies when cyanobacterial blooms occur in source waters. With increased population pressure and depleted groundwater reserves, surface water is becoming more used as a raw water source, both from rivers and lakes/reservoirs. Additional nutrients in water which arise from sewage discharge, agricultural run-off or storm water result in overabundance of cyanobacteria, described as a ‘water bloom’. The majority of cyanobacterial water-blooms are of toxic species, producing a diversity of toxins. The most important toxins presenting a risk to the human population are the neurotoxic alkaloids (anatoxins and paralytic shellfish poisons), the cyclic peptide hepatotoxins (microcystins) and the cytotoxic alkaloids (cylindrospermopsins). At the present time the only cyanobacteral toxin family that have been internationally assessed for health risk by the WHO are the microcystins, which cause acute liver injury and are active tumour promoters. Based on sub-chronic studies in rodents and pigs, a provisional Guideline Level for drinking water of 1μg/L of microcystin-LR has been determined. This has been adopted in legislation in countries in Europe, South America and Australasia. This may be revised in the light of future teratogenicity, reproductive toxicity and carcinogenicity studies. The other cyanobacterial toxin which has been proposed for detailed health risk assessment is cylindrospermopsin, a cytotoxic compound which has marked genotoxicity, probable mutagenicity, and is a potential carcinogen. This toxin has caused human poisoning from drinking water, and occurs in water supplies in the USA, Europe, Asia, Australia and South America. An initial health risk assessment is presented with a proposed drinking water Guideline Level of 1μg/L. There is a need for both increased monitoring data for toxins in drinking water and epidemiological studies on adverse health effects in exposed populations to clarify the extent of the health risk.

Abstract: Ultraviolet (UV)-induced cataracts are becoming a major environmental health concern because of the possible decrease in the stratospheric ozone layer. Experiments were designed to isolate gene(s) affected by UV irradiation in rabbit cornea tissues using fluorescent differential display-reverse transcription-polymerase chain reaction (FDDRT-PCR). The epithelial cells were grown in standard medium for 2 or 4 hours post treatment. Cornea epithelial cells were irradiated with UVB for 20 minutes. RNA was extracted and amplified by reverse transcriptase-polymerase chain reaction using poly A⁺ specific anchoring primers and random arbitrary primers. Polyacrylamide gel electrophoresis revealed several differentially expressed genes in untreated versus UV irradiated cells. Complimentary DNA (cDNA) fragments resulting from fluorescent differentially expressed mRNAs were eluted from the gel and re-amplified. The re-amplified PCR products were cloned directly into the PCR-TRAP cloning system. These data showed that FDDRT-PCR is a useful technique to elucidate UV-regulated gene expressions. Future experiments will involve sequence analysis of cloned inserts. The identification of these genes through sequence analysis could lead to a better understanding of cataract formation via DNA damage and mechanisms of prevention.

Abstract: Over the past several years, a great deal of interest has been focused on the harmful effects of ultraviolet (UV) radiation to human skin. UV light has been implicated in aging, sunburn and skin cancer. Few studies, however, have been done to determine the effects that UV light, in conjunction with other environmental contaminants, may have on human skin. Polycyclic Aromatic Hydrocarbons (PAHs) are a class of compounds that have been reported to be toxic, mutagenic and carcinogenic to many eukaryotic organisms. UV light is also known to increase the toxicity of PAHs through photo-activation and photo-modification. The purpose of this study was to assess the effects of UV-A irradiated pyrene (Pyr), 1-aminopyrene (1-AP) and 1-hydroxypyrene (1-HP) on human keratinocytes, the skin primary site of UV irradiated PAH exposure. Our findings indicate that simultaneous treatment of human keratinocyte cell line, HaCaT, with 1.0μg/ml pyrene, 1-AP or 1-HP and 3.9 J/cm²/min UV-A light resulted in significant inhibition of cell proliferation. Approximately 100% of the cells died in the case of UV-A irradiated 1-AP and 1-HP. In the case of UV-A irradiated pyrene, more than 70% of the cells died, indicating that UV-A is able to transform these PAHs into more harmful intermediates.

Abstract: Living in an environment that has been altered considerably by anthropogenic activities, fish are often exposed to a multitude of stressors including heavy metals. Copper ions are quite toxic to fish when concentrations are increased in environmental exposures often resulting in physiological, histological, biochemical and enzymatic alterations in fish, which have a great potential to serve as biomarkers. Esomus danricus was chosen as model in the present study and the metabolic rate, gill morphology, total glycogen, total protein, superoxide dismutase and catalase were critically evaluated. The 96h LC₅₀ value was found to be 5.5mg/L (Cu as 1.402mg/L). Fish groups were separately exposed to lethal (5.5mg/L) and sub lethal concentrations (0.55 mg/L) of copper sulphate over a period of 96h to examine the subtle effects caused at various functional levels. Controls were also maintained simultaneously. Significant decrease in the metabolic rate (p<0.001) of the fish was observed in both the concentrations studied. Studies employing Automated Video Tracking System revealed gross changes in the architecture of gill morphology like loss, fusion, clubbing of secondary gill lamellae, and detachment of gill rakers following softening of gill shaft in fish under lethal exposures indicating reduced respiratory surface area. Biochemical profiles like total glycogen and total protein in gills and muscle of fish exposed to 5.5 mg/L showed appreciable decrease (p<0.05 to 0.001) from control. Significant inhibition of superoxide dismutase (60.83%), catalase (71.57%) from control was observed in fish exposed to 5.5 mg/L at the end of 96h exposure only. Interestingly, in fish exposed to 0.55 mg/L enzyme activity is not affected except for catalase. Toxic responses evaluated at various functional levels are more pronounced in fish exposed to 5.5mg/L and these can serve as potential biomarkers for rapid assessment of acute copper toxicity in environmental biomonitoring.

Abstract: Pyrrolizidine alkaloids are naturally occurring genotoxic chemicals produced by a large number of plants. The high toxicity of many pyrrolizidine alkaloids has caused considerable loss of free-ranging livestock due to liver and pulmonary lesions. Chronic exposure of toxic pyrrolizidine alkaloids to laboratory animals induces cancer. This investigation studies the metabolic activation of retrorsine, a representative naturally occurring tumorigenic pyrrolizidine alkaloid, and shows that a genotoxic mechanism is correlated to the tumorigenicity of retrorsine. Metabolism of retrorsine by liver microsomes of F344 female rats produced two metabolites, 6, 7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), at a rate of 4.8 ± 0.1 nmol/mg/min, and retrorsine-N-oxide, at a rate of 17.6±0.5 nmol/mg/min. Metabolism was enhanced 1.7-fold by using liver microsomes prepared from dexamethasone-treated rats. DHP formation was inhibited 77% and retrorsine N-oxide formation was inhibited 29% by troleandomycin, a P450 3A enzyme inhibitor. Metabolism of retrorsine with lung, kidney, and spleen microsomes from dexamethasone-treated rats also generated DHP and the N-oxide derivative. When rat liver microsomal metabolism of retrorsine occurred in the presence of calf thymus DNA, a set of DHP-derived DNA adducts was formed; these adducts were detected and quantified by using a previously developed ³²P-postlabeling/HPLC method. These same DNA adducts were also found in liver DNA of rats gavaged with retrorsine. Since DHP-derived DNA adducts are suggested to be potential biomarkers of riddelliine-induced tumorigenicity, our results indicate that (i) similar to the metabolic activation of riddelliine, the mechanism of retrorsine-induced carcinogenicity in rats is also through a genotoxic mechanism involving DHP; and (ii) the set of DHP-derived DNA adducts found in liver DNA of rats gavaged with retrorsine or riddelliine can serve as biomarkers for the tumorigenicity induced by retronecine-type pyrrolizidine alkaloids.

Abstract: Arsenic is an environmental toxicant, and one of the major mechanisms by which it exerts its toxic effect is through an impairment of cellular respiration by inhibition of various mitochondrial enzymes, and the uncoupling of oxidative phosphorylation. Most toxicity of arsenic results from its ability to interact with sulfhydryl groups of proteins and enzymes, and to substitute phosphorus in a variety of biochemical reactions. Most toxicity of arsenic results from its ability to interact with sulfhydryl groups of proteins and enzymes, and to substitute phosphorus in a variety of biochemical reactions. Recent studies have pointed out that arsenic toxicity is associated with the formation of reactive oxygen species, which may cause severe injury/damage to the nervous system. The main objective of this study was to conduct biochemical analysis to determine the effect of arsenic trioxide on the activity of acetyl cholinesterase; a critical important nervous system enzyme that hydrolyzes the neurotransmitter acetylcholine. Four groups of six male rats each weighing an average 60 + 2 g were used in this study. Arsenic trioxide was intraperitoneally administered to the rats at the doses of 5, 10, 15, 20mg/kg body weight (BW), one dose per 24 hour given for five days. A control group was also made of 6 animals injected with distilled water without chemical. Following anaesthesia, blood specimens were immediately collected using heparinized syringes, and acetyl cholinesterase detection and quantification were performed in serum samples by spectrophotometry. Arsenic trioxide exposure significantly decreased the activity of cholinesterase in the Sprague-Dawley rats. Acetyl cholinesterase activities of 6895 + 822, 5697 + 468, 5069 + 624, 4054 + 980, and 3158 + 648 U/L were recorded for 0, 5, 10, 15, and 20 mg/kg, respectively; indicating a gradual decrease in acetyl cholinesterase activity with increasing doses of arsenic. These findings indicate that acetyl cholinesterase is a candidate biomarker for arsenic-induced neurotoxicity in Sprague-Dawley rats.

Abstract: Human health is a major concern when considering the disposal of large quantities of animal waste. Health concerns could arise from exposure to pathogens and excess nitrogen associated with this form of pollution. The objective was to collect and analyze health data related to selected bacterial infections associated with the use of animal waste in Louisiana. An analysis of adverse health effects has been conducted based on the incidence/prevalence rates of campylobacteriosis, E. coli O157:H7 infection, salmonellosis and shigellosis. The number of reported cases increased during the summer months. Analysis of health data showed that reported disease cases of E. coli O157:H7 were highest among Caucasian infants in the 0-4 year old age category and in Caucasian children in the 5-9 year old age category. Fatalities resulting from salmonellosis are low and increases sharply with age. The number of reported cases of shigellosis was found to be higher in African American males and females than in Caucasians. The high rate of identification in the younger population may result from the prompt seeking of medical care, as well as the frequent ordering of stool examination when symptoms become evident among this group of the population. The association with increasing age and fatality due to salmonellosis could be attributed to declining health and weaker immune systems often found in the older population. It is concluded that both animal waste and non-point source pollution may have a significant impact on human health.

Abstract: The objective of this research was to compare the chemical/physical parameters and bacterial qualities of selected surface water streams in Louisiana, including a natural stream (control) and an animal waste related stream. Samples were collected and analyzed for fecal coliforms. Fecal coliforms isolated from these samples were identified to the species level. Chemical analysis was performed following standard test protocols (LaMotte 2002). An analysis of biological oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total dissolved solids (TDS), conductivity, pH, temperature, ammonia nitrogen, nitrate nitrogen, iron, copper, phosphate, potassium, sulfate, turbidity, zinc and bacterial levels was performed following standard test protocols as presented in Standard Methods for the Examination of Water and Wastewater [9]. Results of the comparisons of the various surface water streams showed that phosphate levels, according to Mitchell and Stapp, were considered good for Lake Claiborne (control) and Bayou Dorcheat. The levels were found to be .001 mg/L and .007 mg/L respectively. Other streams associated with animal waste, had higher phosphate levels of 2.07 mg/L and 2.78 mg/L, respectively. Conductivity and total dissolved solids (TDS) levels were the lowest in Lake Claiborne and highest in the Hill Farm Research Station stream. It can be concluded from the data that some bacterial levels and various nutrient levels can be affected in water resources due to non-point source pollution. Many of these levels will remain unaffected.

Abstract: The major concern for the halogenated compounds is their widespread distribution, in addition to occupational exposures. Several chlorinated alkanes and alkenes were found to induce toxic effects. In this study, we investigated the genotoxic potential of 1,1-dichloroethane in the bone marrow cells obtained from Swiss-Webster mice, using chromosomal aberrations (CA), mitotic index (MI), and micronuclei (MN) formation as toxicological endpoints. Five groups of three male mice each, weighing an average of 24 + 2 g, were injected intraperitoneally, once with doses of 100, 200, 300, 400, 500 mg/kg body weight (BW) of 1,1-dichloroethane dissolved in ethanol. A control group was also made of three animals injected with ethanol (1%) without the chemical. All animals were sacrificed 24 hours after the treatment. Chromosome and micronuclei preparations were obtained from bone marrow cells following standard protocols. Chromatid and chromosome aberrations were investigated in 100 metaphase cells per animal and percent micronuclei frequencies were investigated in 1,000 metaphase cells per animal. 1,1-dichloroethane exposures significantly increased the number of chromosomal aberrations and the frequency of micronucleated cells in the bone marrow cells of Swiss-Webster mice. Percent chromosomal aberrations of 2.67 + 0.577, 7.66 + 2.89, 8.33 + 2.08, 14.67 + 2.51, 20.3 + 3.21, 28 + 3.61; mitotic index of 9.4%, 7.9%, 6.2%, 4.3%, 3.0%, 2.6% and micronuclei frequencies of 3.33 + 0.7, 7.33 + 0.9, 8.00 + 1.0, 11.67 + 1.2, 15.33 + 0.7, 18.00 + 1.7 were recorded for the control, 100, 200, 300, 400, and 500 mg/kg BW respectively; indicating a gradual increase in number of chromosomal aberrations and micronuclei formation, with increasing dose of 1,1,-dichloroethane. Our results indicate that 1,1-dichloroethane has a genotoxic potential as measured by the bone marrow CA and MN tests in Swiss- Webster mice.

Abstract: Exposure to particulate matter (PM_2.5-10), including diesel exhaust particles (DEP) has been reported to induce lung injury and exacerbation of asthma and chronic obstructive pulmonary disease. Alveolar macrophages play a major role in the lung’s response to inhaled particles and therefore, are a primary target for PM_2.5-10 effect. The molecular and cellular events underlying DEP-induced toxicity in the lung, however, remain unclear. To determine the effect of DEP on alveolar macrophages, RAW 264.7 cells were grown in RPMI 1640 with supplements until confluency. RAW 264.7 cultures were exposed to Hank’s buffered saline solution (vehicle), vehicle containing an NF-κB inhibitor, BAY11-7082 (25μM with 11/2 hr pre-incubation), or vehicle containing DEP (250μg/ml) in the presence or absence of BAY11-7082 (25μM with 11/2 hr pre-incubation) for 4 hr and TNF-α release was determined by enzyme-linked immunosorbent assay and confirmed by western blots. RAW 264.7 apoptotic response was determined by DNA fragmentation assays. U937 cells treated with campothecin (4 μg/ml x 3 hr), an apoptosis-inducing agent, were used as positive control. We report that exposure to the carbonaceous core of DEP induces significant release of TNF-α in a concentration-dependent fashion (31 ± 4 pg/ml, n = 4, p = 0.08; 162 ± 23 pg/ml, n = 4, p < 0.05; 313 ± 31 pg/ml, n = 4, p < 0.05 at 25, 100, and 250 μg/ml, respectively). DEP exposure, however, failed to induce any apoptotic response in RAW 264.7 cells. Moreover, inhibition of NF-κB binding activity has resulted in DEP-induced apoptotic response in alveolar macrophages, as demonstrated by the NF-κB inhibitor, BAY11-7082 studies. The results of the present study indicate that DEP induce the release of TNF-α in alveolar macrophages, a primary target for inhaled particles effect. DEP-induced TNF-α gene expression is regulated at the transcriptional level by NF-κB. Furthermore, DEP-induced increase in NF-κB-DNA binding activity appears to protect against apoptosis.

Abstract: DMBA, 7,12-dimethylbenz[a]anthracene, is a widely studied polycyclic aromatic hydrocarbon that has long been recognized as a probable human carcinogen. It has been found that DMBA is phototoxic in bacteria as well as in animal or human cells and photomutagenic in Salmonella typhimurium strain TA102. This article tempts to explain the photochemistry and photomutagenicity mechanism. Light irradiation converts DMBA into several photoproducts including benz[a]anthracene-7,12-dione, 7-hydroxy-12-keto-7-methylbenz[a]anthracene, 7,12-epidioxy-7,12-dihydro-DMBA, 7-hydroxymethyl-12-methylbenz[a]anthracene and 12-hydroxymethyl-7-methylbenz[a]anthracene. Structures of these photoproducts have been identified by either comparison with authentic samples or by NMR/MS. At least four other photoproducts need to be assigned. Photo-irradiation of DMBA in the presence of calf thymus DNA was similarly conducted and light-induced DMBA-DNA adducts were analyzed by ³²P-postlabeling/TLC, which indicates that multiple DNA adducts were formed. This indicates that formation of DNA adducts might be the source of photomutagenicity of DMBA. Metabolites obtained from the metabolism of DMBA by rat liver microsomes were reacted with calf thymus DNA and the resulting DNA adducts were analyzed by ³²P-postlabeling/TLC under identical conditions. Comparison of the DNA adduct profiles indicates that the DNA adducts formed from photo-irradiation are different from the DNA adducts formed due to the reaction of DMBA metabolites with DNA. These results suggest that photo-irradiation of DMBA can lead to genotoxicity through activation pathways different from those by microsomal metabolism of DMBA.

Abstract: Although the role of systemic proinflammatory cytokines, IL-1β and TNF-α, and their up-regulation of adhesion molecules, ICAM-1, VCAM-1 and E-Selectin, in the pathogenesis of cerebral malaria (CM) is well established, the role of local cytokine release remain unclear. Immunohistochemistry (IHC) was used to compare the expression of ICAM-1, VCAM-1, E-Selectin, IL-1β, TNF-α and TGF- β at light microscopic level in cerebral, cerebellar and brainstem postmortem cryostat sections from 10 CM, 5 severe malarial anemia (SMA), 1 purulent bacterial meningitis (PBM), 2 non-central nervous system infections (NCNSI) and 3 non-infections (NI) deaths in Ghanaian children. Fatal malaria and Salmonella sepsis showed significantly higher vascular expression of all 3 adhesion molecules, with highly significant co-localization with sequestration in the malaria cases. However, there was negligible difference between CM and SMA. TGF-β showed intravascular and perivascular distribution in all cases, but expression was most intense in the PBM case and CM group. TNF-α and IL-1β showed prominent brain parenchymal staining, in addition to intravascular and perivascular staining, in only the PBM case and CM group. The maximal expression of all 6 antigens studied was in the cerebellar sections of the malaria cases. Endothelial activation is a feature of fatal malaria and Salmonella sepsis, with adhesion molecule expression being highly correlated with sequestration. IL-1β and TNF-α are upregulated in only cases with neurodegenerative lesions, whilst TGF-β is present in all cases. Both cytokines and adhesion molecules were maximally upregulated in the cerebellar sections of the malaria cases.

Abstract: Inorganic ions, coenzymes, amino acids, and saccharides could co-exist with toxic environmental chemicals, such as polycyclic aromatic hydrocarbons (PAHs), in the cell. The presence of these co-existing chemicals can modulate the toxicity of the PAHs. One of the genotoxic effects by PAHs is light-induced cleavage, or photocleavage, of DNA. The effect of inorganic ions I^-, Na⁺, Ca²⁺, Mg²⁺, Fe³⁺, Mn²⁺, Cu²⁺, and Zn²⁺ and biological molecules riboflavin, histidine, mannitol, nicotinamide adenine dinucleotide (NAD), glutathione, and glutamic acid on the DNA photocleavage by pyrene, 1-hydroxypyrene (1-HP), and 1-aminopyrene (1-AP), is studied. The non-transition metal ions Na⁺, Ca²⁺, and Mg²⁺, usually have very little inhibitory effects, while the transition metal ions Fe³⁺, Cu²⁺, and Zn²⁺ enhance, Mn²⁺ inhibits the DNA photocleavage. The effect by biological molecules is complex, depending on the photochemical reaction mechanisms of the compounds tested (1-AP, 1-HP and pyrene) and on the chemical nature of the added biological molecules. Riboflavin, histidine, and mannitol enhance DNA photocleavage by all three compounds, except that mannitol has no effect on the photocleavage of DNA by pyrene. Glutathione inhibits the DNA photocleavage by 1-AP and 1-HP, but has no effect on that by pyrene. NAD enhances the DNA photocleavage by 1-AP, but has no effect on that by 1-HP and pyrene. Glutamic acid enhances the DNA photocleavage by 1-AP and pyrene, but inhibits that by 1-HP. These results show that the co-existing chemicals may have a profound effect on the toxicity of PAHs, or possibly on the toxicity of many other chemicals. Therefore, if one studies the toxic effects of PAHs or other toxic chemicals, the effect of the co-existing chemicals or ions needs to be considered.

Abstract: Chemical carcinogenesis studies are powerful tools to obtain information on potential mechanisms of chemical factors for malignancies. In this study Western blot analyses, using monoclonal antibodies specific for three different cytochrome P450 (CYP) isozymes (CYP1A1, CYP1A2 and CYP2B), were employed to examine the effect(s) of 3-methylcholanthrene and/or pristane (2,6,10,14-tetramethylpentadecane) on the basal and inducible levels of expression of CYP proteins within Copenhagen rat tissues. Pristane exposure led to tissue specific differences in the CYP isozymes expressed and elicited increased CYP protein expression over 3-methylcholanthrene induced levels in microsomes isolated from liver, Peyer's Patches, and thymus. Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose. The data suggest that pristane treatment affects CYP isozyme expression. This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

Abstract: Sunlight is a known human carcinogen. Many cosmetics contain retinoid-based compounds, such as retinyl palmitate (RP), either to protect the skin or to stimulate skin responses that will correct skin damaged by sunlight. However, little is known about the photodecomposition of some retinoids and the toxicity of these retinoids and their sunlight-induced photodecomposition products on skin. Thus, studies are required to test whether topical application of retinoids enhances the phototoxicity and photocarcinogenicity of sunlight and UV light. Mechanistic studies are needed to provide insight into the disposition of retinoids in vitro and on the skin, and to test thoroughly whether genotoxic damage by UV-induced radicals may participate in any toxicity of topically applied retinoids in the presence of UV light. This paper reports the update information and our experimental results on photostability, photoreactions, and phototoxicity of the natural retinoids including retinol (ROH), retinal, retinoid acid (RA), retinyl acetate, and RP (Figure 1).

Abstract: In Eastern cultures, such as India, it is traditionally recommended that women but not men cover their heads while working in the scorching sun. The purpose of this pilot study was to determine whether there was any scientific basis for this cultural tradition. We examined the differential cytotoxic effects of ultraviolet A light (UVA) on an established T cell line treated with female and male sex hormones. CD4⁺ Jurkat T cells were plated in 96 well plates at 2 x 10⁶ cells/ml and treated with 17β-estradiol (EST) or testosterone (TE). These cells were irradiated by UVA light with an irradiance of 170 J/cm² for 15min at a distance of 6 cm from the surface of the 96-well plate. Controls included cells not treated with hormones or UVA. The effects of EST and TE were investigated between 1 and 20 ng/mL. Cytotoxicity by fluorescein-diacetate staining and COMET assay generating single strand DNA cleavage, tail length and tail moment measurements were examined. The effect of estrogen (5ng/mL) on apoptosis and its mediators was further studied using DNA laddering and western blotting for bcl-2 and p53. We found that EST alone, without UVA, enhanced Jurkat T cell survival. However, EST exhibited a dose-related cytotoxicity in the presence of UVA; up to 28% at 20 ng/ml. TE did not alter UVA-induced cytotoxicity. Since TE did not alter cell viability in the presence of UVA further damaging studies were not performed. COMET assay demonstrated the harmful effects of EST in the presence of UVA while EST without UVA had no significant effect on the nuclear damage. Apoptosis was not present as indicated by the absence of DNA laddering on agarose gel electrophoresis at 5ng/ml EST or TE ± UVA. Western blot showed that estrogen down regulated bcl-2 independently of UVA radiation while p53 was down regulated in the presence of UVA treatment. EST and TE have differential effects on UVA-induced cytotoxicity in Jurkat T-lymphocyte which suggested that women may be more susceptible to the harmful effects of solar irradiation than men.

Abstract: Exposure to lead has been well recognized in a number of work environments, but little is known about lead exposure associated with machining brass keys containing lead. The brass that is widely used for key manufacturing usually contains 1.5% - 2.5 % of lead. Six (6) licensed locksmiths and 6 case-matched controls successfully completed the pilot study to assess the prevalence of increased body lead burden of professional locksmiths. We measured both Blood Lead (atomic absorption spectrometry), bone-lead (KXRF) and had each subject complete a health and lead exposure risk questionnaire. One locksmith had not cut keys during the past two years, therefore this subject and case-matched control was excluded from the blood lead analysis only. The average blood-lead concentration (+SEM) for the 5 paired subjects was 3.1 (± 0.4) μg /dL and 2.2 (± 0.3) μg /dL for controls. Bone measurements, including all 6 paired subjects, showed tibia lead concentration (+SEM) for locksmiths and controls was 27.8 (± 2.3) μg /g and 13.7 (± 3.3) μg /g, respectively; average calcaneus lead concentration for locksmiths and controls was 31.9 (± 3.7) μg /g and 22.6 (± 4.1) μg /g, respectively: The t-test shows a significantly higher tibia lead (p<0.05) and blood lead (p<0.05) for locksmiths than for their matched controls, but no significant difference for calcaneus lead (p>0.10). Given that the mean tibia bone lead concentration was 13.1μg/g higher in locksmiths than in their matched controls, this average difference in the two groups would translate to an OR of increased hypertension in locksmiths of between 1.1 and 2.3, based on the published literature. Even with the very small number of subjects participating in this pilot study, we were able to demonstrate that locksmiths had significantly higher current exposure to lead (blood lead concentration) and significantly higher past exposure to lead (tibia lead concentration) than their age, sex and ethnically matched controls. Additional research is needed to fully identify the prevalence and associated risk factors for occupational exposure of lead in this previously understudied profession.

Abstract: This investigation involved the synthesis of metal complexes to test the hypothesis that structural changes and metal coordination in pyridine thiosemicarbazones affect cell growth and cell proliferation in vitro. Thiosemicarbazones are well known to possess antitumor, antiviral, antibacterial, antimalarial, and other activities. Extensive research has been carried out on aliphatic, aromatic, heterocyclic and other types of thiosemicarbazones and their metal complexes. Due to the pronounced reactivity exhibited by metal complexes of heterocyclic thiosemicarbazones, synthesis and structural characterization of di-2-pyridylketone ⁴N-phenyl thiosemicarbazone and diphenyl tin (Sn) and platinum (Pt) complexes were undertaken. Shewanella oneidensis MR-1, a metal ion-reducing bacterium, was used as a model organism to explore the biological activity under aerobic conditions. A comparision of the cytotoxic potential of selected ligand and metal-complex thiosemicarbazones on cell growth in wild type MR-1 and mutant DSP-010 Shewanella oneidensis strains at various concentrations (0, 5, 10, 15, 20 or 25 ppm) was performed. The wild type (MR-1) grown in the presence of increasing concentrations of Sn- thiosemicarbazone complexes was comparatively more sensitive (mean cell number = 4.8 X 10⁸ + 4.3 X 10⁷ SD) than the DSP-010, a spontaneous rifampicillin derivative of the parent strain (mean cell number = 5.6 x 10⁸ + 6.4 X 10⁷ SD) under comparable aerobic conditions (p=0.0004). No differences were observed in the sensitivity of the wild and mutant types when exposed to various concentrations of diphenyl Pt- thiosemicarbazone complex (p= 0.425) or the thiosemicarbazone ligand (p=0.313). Growth of MR-1 in the presence of diphenyl Sn- thiosemicarbazone was significantly different among treatment groups (p=0.012). MR-1 cell numbers were significantly higher at 5ppm than at 10 to 20ppm (p = 0.05). The mean number of DSP-010 variant strain cells also differed among diphenyl Sn- thiosemicarbazone complex treated groups (p=0.051). In general, there was an increasing trend in the number of cells from about 5.0 X 10⁸ cells (methanol control group) to about 6.0 X 10⁸ cells (25ppm). The number of cells in methanol control group was significantly lower than cell numbers at 20ppm and 25ppm (p = 0.05), and numbers at 5ppm treatment were lower than at 20 and 25ppm (p = 0.05). Furthermore, a marginally significant difference in the number of MR-1 cells was observed among diphenyl Pt- thiosemicarbazone complex treatment groups (p = 0.077), and an increasing trend in the number of cells was noted from ~5.0 X 10⁸ cells (methanol control group) to ~5.8 X 10⁸ cells (20ppm). In contrast, the DSP-010 variant strain showed no significant differences in cell numbers when treated with various concentrations of diphenyl Pt- thiosemicarbazone complex (p = 0.251). Differences in response to Sn- metal complex between MR-1 and DSP-010 growing cultures indicate that biological activity to thiosemicarbazone metal complexes may be strain specific.

Abstract: In an effort towards adapting new and defensible methods for assessing and managing the risk posed by microbial pollution, we evaluated the utility of oligonucleotide microarrays for bacterial source tracking (BST) of environmental Enterococcus sp. isolates derived from various host sources. Current bacterial source tracking approaches rely on various phenotypic and genotypic methods to identify sources of bacterial contamination resulting from point or non-point pollution. For this study Enterococcus sp. isolates originating from deer, bovine, gull, and human sources were examined using microarrays. Isolates were subjected to Box PCR amplification and the resulting amplification products labeled with Cy5. Fluorescent-labeled templates were hybridized to in-house constructed nonamer oligonucleotide microarrays consisting of 198 probes. Microarray hybridization profiles were obtained using the ArrayPro image analysis software. Principal Components Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were compared for their ability to visually cluster microarray hybridization profiles based on the environmental source from which the Enterococcus sp. isolates originated. The PCA was visually superior at separating origin-specific clusters, even for as few as 3 factors. A Soft Independent Modeling (SIM) classification confirmed the PCA, resulting in zero misclassifications using 5 factors for each class. The implication of these results for the application of random oligonucleotide microarrays for BST is that, given the reproducibility issues, factor-based variable selection such as in PCA and SIM greatly outperforms dendrogram-based similarity measures such as in HCA and K-Nearest Neighbor KNN.

Abstract: Despite consented efforts in prevention, mycotoxins remain a problem of human health concern in several parts of the world including developed countries. Within the same range of toxins concentrations in the blood some people develop a disease while others do not. Could this inequality in front of mycotoxins effects be explained by environment factors and/or genetic predisposition? Among recent advances in environmental health research Correlation between chronic diseases and mycotoxins in humans deserves attention through several questions: Are genetic factors involved in disease causation of mycotoxins? How much are these factors currently taken into account for mycotoxins risk assessment and how much should we involve them? Answers are still to come. Genetic and environment factors deserve therefore more attention when dealing with regulatory limits, since among the general population, those who are at risk and will develop specific diseases are likely those bearing genetic predispositions. We have addressed these questions for the specific case of ochratoxin A in humans by investigating in Tunisia, county of Jelma, in four rural families forming a household of 21 persons all exposed to ochratoxin A in diet. Our results confirm that ochratoxin A induces chronic tubular nephropathy in humans and mainly point at those having the HLA haplotype A3, B27/35, DR7 to be more sensitive to the disease for quantitatively similar or lower exposure. Persons with such haplotype were found to bear chronic interstitial nephropathy with tubular karyomegalic cells while others were apparently healthy. Godin et al. (1996) in France have also found in sibling (a sister and her brother from urban area) that have similar HLA haplotype B35-patern, OTA-related renal tubulopathy with mild proteinuria including β2-microglobulinuria. Several mechanisms are discussed that could be put ahead to explain how the HLA haplotype could lead to tubular cells lyses and renal failure. In the mean time it is urgent to search for mass screening biomarkers for mycotoxins in humans and related genetic factors to set-up more appropriate regulation.