[Show abstract][Hide abstract] ABSTRACT: In urban areas with a predominance of early to mid-20th century housing stock, islands of children possessing blood lead levels (PbB) in excess of CDC guidelines (>10μg/dL) exist. Many of these children are also exposed to environmental tobacco smoke (ETS). The current study examined the impact of Pb-exposure (PbB levels of 1-55μg/dL) with/without concurrent ETS exposure on immune system function in 318 children aged 6-84 months from the urban area of Springfield-Greene County, MO. In this population, 36.5% of children possessed PbB levels >10μg/dL, 62.9% of children came from smoking homes, 51.9% of children were under 2 years of age, and the population was WIC eligible and predominantly of white, non-Hispanic ethnicity. Multiple immune function markers including cell counts, IgE levels, sCD25 (sIL2R) and IL4 concentrations, and titers to common childhood immunizations were analyzed for correlation with Pb and/or ETS exposure. Increased IgE levels (p<0.01) were found in children with PbB levels within CDC Classes II-IV - this finding was primarily attributable to elevated IgE levels in the subpopulation of children with concurrent Pb and ETS exposure. A trend (0.05<p<0.01) of increases in % total T-cells (p=0.06) was also found in children with concurrent elevated PbB levels and ETS exposure. This trend was not found in the subset of children without ETS exposure nor was it present in the analysis of the entire population set. Conversely, alterations in median values for % lymphocytes, % granulocytes, and % activated T-cells across Pb classes were present in the subpopulation of children expose to Pb alone (without concurrent ETS exposure) though a clear trend was not evident. In the entire population set, a statistically significant correlation between ETS and PbB levels was found. This study indicates that prior reports of a correlation between elevated PbB levels and serum IgE levels may be strongly influenced by exposure to ETS. Findings from this study also indicate that Pb is an immune modulator and PbB levels may be influenced by ETS exposure.
[Show abstract][Hide abstract] ABSTRACT: The current study examined the impact of sub-chronic lead (Pb)-exposure upon global protein profile in rodent kidney (blood Pb levels ~50 μg/dL; 5 weeks oral Pb-acetate exposure). Utilizing 2D SDS-PAGE for kidney protein separation, greater than 500 protein spots were analyzed by densitometry following background noise removal, spot alignment, and intensity filtering. Approximately 100 protein spots were identified by ESI-MS/MS with mitochondrial, chaperone, antioxidant, and Pb-binding proteins included. Forty-eight protein spots exhibited significant alterations in abundance (18 identified by ESI-MS/MS) including the increased protein abundance of ketohexokinase, enolase, protein disulfide-isomerase, lamda crystallin, lactamase, and glycerol-3-phosphate dehydrogenase. Decreased protein abundances were observed for α-2 microglobulin, glutamate cysteine ligase, prohibitin, homogentisate 1,2-dioxygenase, alpha-ETF, argininosuccinate synthetase and ATP synthase (H+ transporting). These data support the hypothesis that protein profiles in the kidney are altered following sub-chronic physiologically relevant Pb-exposure.
[Show abstract][Hide abstract] ABSTRACT: Oxidative stress has been implicated as an important factor in many neurological diseases. Oxidative toxicity in a number of these conditions is induced by excessive glutamate release and subsequent glutamatergic neuronal stimulation. This, in turn, causes increased generation of reactive oxygen species (ROS), oxidative stress, excitotoxicity, and neuronal damage. Recent studies indicate that the glutamatergic neurotransmitter system is involved in lead-induced neurotoxicity. Therefore, this study aimed to (1) investigate the potential effects of glutamate on lead-induced PC12 cell death and (2) elucidate whether the novel thiol antioxidant N-acetylcysteine amide (NACA) had any protective abilities against such cytotoxicity. Our results suggest that glutamate (1 mM) potentiates lead-induced cytotoxicity by increased generation of ROS, decreased proliferation (MTS), decreased glutathione (GSH) levels, and depletion of cellular adenosine-triphosphate (ATP). Consistent with its ability to decrease ATP levels and induce cell death, lead also increased caspase-3 activity, an effect potentiated by glutamate. Exposure to glutamate and lead elevated the cellular malondialdehyde (MDA) levels and phospholipase-A(2) (PLA(2)) activity and diminished the glutamine synthetase (GS) activity. NACA protected PC12 cells from the cytotoxic effects of glutamate plus lead, as evaluated by MTS assay. NACA reduced the decrease in the cellular ATP levels and restored the intracellular GSH levels. The increased levels of ROS and MDA in glutamate-lead treated cells were significantly decreased by NACA. In conclusion, our data showed that glutamate potentiated the effects of lead-induced PC12 cell death by a mechanism involving mitochondrial dysfunction (ATP depletion) and oxidative stress. NACA had a protective role against the combined toxic effects of glutamate and lead by inhibiting lipid peroxidation and scavenging ROS, thus preserving intracellular GSH.
[Show abstract][Hide abstract] ABSTRACT: High dose, acute radiation exposure, as in radiation accidents, induces three clinical syndromes that reflect consequences of oxidative protein, lipid, and DNA damage to tissues such as intestine, lung, and liver. In the present study, we irradiated C57BL/6 mice with 18 Gy whole-body radiation (XRT) and evaluated N-acetyl cysteine (NAC) isomers LNAC and DNAC as potential radioprotectors under conditions that would model the gastrointestinal syndrome. We focused on tissues thought not immediately involved in the gastrointestinal syndrome. Both LNAC and DNAC protected the lung and red blood cells (RBC) from glutathione (GSH) depletion following radiation exposure. However, only LNAC also supplemented the spleen GSH levels following XRT. Protection from increased malondialdehyde (MDA) levels (lung) and increased 8-hydroxy-deoxyguanosine (8-oxo-dG) presence (liver) following XRT was observed with treatment by either isomer of NAC. These results imply that either NAC isomer can act as a radioprotectant against many aspects of oxidative damage; chirality is only important for certain aspects. This pattern would be consistent with direct action of NAC in many radioprotection and repair processes, with a delimited role for NAC in GSH synthesis in some aspects of the problem.
Free Radical Biology and Medicine 04/2003; 34(6):689-95. DOI:10.1016/S0891-5849(02)01372-2 · 5.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In vitro administration of lead acetate (PbA) to cultures of Chinese hamster ovary (CHO) cells had a concentration-dependent inhibitory effect on colony formation. Colony formation was returned to control levels in lead-treated cultures that were supplemented with 1 mM N-actylcysteine (NAC), a well-documented synthetic antioxidant. In order to investigate the nature of NAC's protective effect, we measured L-gamma-glutamyl-L-cysteinylglycine (GSH), oxidized glutathione (GSSG), malondialdehyde (MDA) and catalase activity both in the presence and absence of NAC in lead-exposed CHO cells. Increases in both MDA levels (p < 0.05) and catalase activity (P < 0.05) were observed in cultures that received only PbA, but supplementation with NAC returned these measures to pretreatment levels. The ratio of GSH to GSSG increased in lead-exposed cells incubated in NAC-enhanced media, but declined in cultures treated with PbA only. Our results suggest that NAC can confer protection against lead-induced oxidative stress to CHO cells, possibly through the enhancement of the cell's own antioxidant defense mechanisms.