Search

In this study, we used porcine aortic endothelial cells (PAECs) as an in vitro system to investigate the role of intracellular GSH status in arsenite-induced vascular endothelial damage. Exposure of PAECs to l-buthionine sulfoximine (BSO), an inhibitor of γ-glutamylcysteine synthetase (γ-GCS), markedly enhanced the arsenite-induced cytotoxicity. The data implied that intracellular GSH might play an important role in protection of PAECs from arsenite-induced cytotoxicity. Low concentrations of arsenite exposure increased intracellular GSH concentrations, whereas high concentrations of arsenite exposure decreased intracellular GSH concentrations. We further modulated intracellular GSH concentration by using GSH modulators. N-Acetyl cysteine (NAC) and l-cystine (oxidized l-cysteine), by up-regulating intracellular GSH concentrations, were shown to protect PAECs from arsenite-induced cytotoxicity. On the other hand, BSO and monosodium glutamate (MSG), which down-regulated the intracellular GSH concentrations, further potentiated arsenite-induced cytotoxicity. Moreover, exposure of PAECs to NAC alleviated the arsenite-induced JNK/AP-1 activation and apoptosis, whereas exposure of PAECs to BSO enhanced the arsenite-induced JNK/AP-1 activation and apoptosis. These results indicated that an increase in GSH content represented one of the detoxification mechanisms responding to arsenite exposure and probably played critical roles in the regulation of stress−response signaling molecules as well as in protection of PAECs from arsenite attack.

Arsenic (As) is widely distributed in nature, and its contamination in drinking water remains a major public health problem. Exposure to As may lead to degenerative peripheral vascular diseases. The purpose of this study is to clarify the role of As in modulating cell proliferation and in vitro angiogenesis in human umbilical vein endothelial cells (HUVECs) and to scrutinize the contributing factors of these events. The results revealed that lower concentrations (up to 1 μM) of sodium arsenite stimulated HUVEC cell growth. An in vitro angiogenesis assay indicated that low concentrations of As increased vascular tubular formation, which was abrogated by hemoglobin, a potent nitric oxide scavenger. In contrast, higher concentrations of As (>5 μM) revealed cytotoxicity and inhibition to angiogenesis. We also demonstrated that lower concentrations of As upregulated the expression of constitutive nitric oxide synthase (NOS3) at both transcriptional and translational levels and that lower concentrations of As implicated a modulatory role in vascular endothelial growth factor (VEGF) expression. In addition, low concentrations of As (<1 μM) increased von Willebrand Factor (vWF) antigen expression, whose elevation paralleled the onset of angiogenesis and was considered an early indicator of endothelial activation in tumor metastasis. VEGF and basic fibroblast growth factor can synergistically upregulate the vWF gene expression. Therefore, we conclude that the treatment of HUVECs with As leads to cell proliferation and activation, which preferentially enhances angiogenesis in vitro, possibly via the VEGF−NOS signaling pathway. The molecular mechanism(s) by which As facilitates angiogenesis remains to be elucidated.

Both β-cyclodextrin and 2,3-methylated-β-cyclodextrin bonded stationary phases effectively separate a variety of structural and geometrical isomeric compounds in the reversed phase mode. The retention of neutral structural isomeric compounds, as well as substituted phenols and anilines, was usually longer on the methylated cyclodextrin stationary phase. Conversely, the retention of all substituted carboxylic acids was greater on the native β-cyclodextrin stationary phase. The selectivity differences between the native β-cyclodextrin and its 2,3-methylated analogue were not as great as expected for the structural isomers. In general, the structural isomer that was retained longest on the native β-cyclodextrin stationary phase also was retained longest on the 2,3-methylated cyclodextrin stationary phase.

The enantioselectivity of native β-cyclodextrin and its 2,3-methylated analogue were examined in both the "polar-organic" mode and the reversed phase mode. By comparing these two chiral selectors, the function of the secondary 2,3-hydroxyl groups at the mouth of the cyclodextrin can be examined (in regard to selectivity and retention). In the "polar-organic" mode, compounds that are easily resolved on the native β-cyclodextrin chiral stationary phase (CSP) cannot be resolved on the methylated CSP. These results, as well as the retention data, lend support to the previously proposed "noninclusion" mechanism. In the reversed phase mode, many more compounds could be resolved on the native β-cyclodextrin CSP than on the methylated analogue. However, a few compounds were resolved only on the 2,3-methylated cyclodextrin CSP. In these cases, steric interactions at the mouth of the cyclodextrin cavity may be more important to chiral recognition than hydrogen bonding.

Infectious bovine rhinotracheitis virus (IBRV) has been shown in this report to have thirty-three polypeptides. Ten of the eleven polypeptides which can be labeled with (3H)-glucosamine are located on the surface of the virus since they can be surface labeled with sodium boro(3H)hydride. In order to define the immunologically important viral proteins, monoclonal antibodies were prepared against the virus and selected for their ability to neutralize infectivity. Four such hybridoma lines were obtained for characterization of the antigens that elicit neutralizing antibodies. The viral polypeptides were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the specificity of each monoclonal antibody was determined by “Western” blot analysis and/or by immunoprecipitation of (35S)-methionine and (3H)-glucosamine labeled infected cell lysates by the monoclonal antibodies. One monoclonal antibody reacted with two glycoproteins, gp135 and gp78a, on the “Western” blot but immunoprecipitated three glycoproteins, gp135, gp78a, and gp54 from labeled infected cell lysates. The other three monoclonal antibodies immunoprecipitated a single glycoprotein, gp78b, from (3H)-glucosamine labeled infected cell lysates but not from (35S)-methionine labeled infected cell lysates.

The elution of a series of common atmospheric organic pollutants was tested on a 1.25%-deactivated Florisil column. It was found that phthalate esters and dieldrin could be eluted from the column with 50% (v/v) diethyl ether in petroleum ether. Other chlorinated hydroarbons, aliphatic hydrocarbons, and polyaromatic hydrocarbons are eluted first with petroleum ether followed by 5% (v/v) diethyl ether in petroleum ether. This procedure was used to successfully separate a mixture of chlorinated hydrocarbons and phthalate esters found in ambient air along the Texas Gulf Coast.

When given to rats, both organic and inorganic mercury compounds were found to be neurotoxic. After CH3HgCl intoxication, focal cytoplasmic degradation was the most characteristic lesion observed in the neurons of the dorsal root ganglion. A large cytoplasmic vacuole was formed in many neurons as a result of such lesions.

An optical-type electrical phase-locked-loop system based on a cascade electro-optic modulator has been demonstrated. By using this technique, a set of optical-type phase detectors, operating at any harmonic frequencies of two applied phase-modulation signals, has been implemented.

By means of experiments of instability of a uniform cylindrical soap film, Boys had showed that the bubble molded by the film is unstable when its length is greater than its circumference. Recently that is generally called the Rayleigh Criterion. In this paper, a linear theory in hydrodynamics is applied to analyze the stability of the cylindrical soap film supported by two equal size disks; all conditions of the stationary wave on the end plates of two disks are given. From here we get that the Rayleigh Criterion on the stability of the cylindrical soap film is proved.

The aim of this study was to investigate dioxin and dioxin-like polychlorinated biphenyls (PCBs) levels in human milk and their correlation with indicator PCBs concentrations and associated factors.

A new and convenient method for the synthesis of N‐chloro fatty amides (II) by reacting an emulsion of the amides (I) with chlorine in boiling water is described.

The capability to perform absorption spectroscopy with hard x-rays was added to the synchrotron imaging Spectromicroscopy technique. We present several successful test cases. First, the EXAFS (extended x-ray absorption fine structure) analysis was implemented in areas as small as few µm2for transition-metal K edge absorption spectra. The corresponding structural information was complemented by chemical information from the near-edge region. Specifically, in the case of a cross-sectional cut steel different Fe oxidation states were found at different depths. Tests on a PVD grown TiN film revealed areas with oxidized Ti. Overall, these tests demonstrate the feasibility of combining structural and chemicals analysis with hard-x-ray absorption and high lateral resolution.