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Artificial Mixtures (artificial + mixture)

Distribution by Scientific Domains

Life Sciences	60%

Selected Abstracts

INCREASING WATER SUPPLY BY MIXING OF FRESH AND SALINE GROUND WATERS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2003
Zekai Sen
ABSTRACT: The quality of ground water in any aquifer takes its final form due to natural mixture of waters, which may originate from different sources. Water quality varies from one aquifer to another and even within the same aquifer itself. Different ground water quality is obtained from wells and is mixed in a common reservoir prior to any consumption. This artificial mixing enables an increase in available ground water of a desired quality for agricultural or residential purposes. The question remains as to what proportions of water from different wells should be mixed together to achieve a desired water quality for this artificial mixture. Two sets of laboratory experiments were carried out, namely, the addition of saline water to a fixed volume of fresh water. After each addition, the mixture volume and the electric conductivity value of the artificially mixed water were recorded. The experiments were carried out under the same laboratory temperature of 20°C. A standard curve was developed first experimentally and then confirmed theoretically. This curve is useful in determining either the volume or discharge ratio from two wells to achieve a predetermined electrical conductivity value of the artificial mixture. The application of the curve is given for two wells within the Quaternary deposits in the western part of the Kingdom of Saudi Arabia. [source]

Effect of artificial mixtures of environmental polycyclic aromatic hydrocarbons present in coal tar, urban dust, and diesel exhaust particulates on MCF-7 cells in culture

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2004
Brinda Mahadevan
Abstract Human exposure to polycyclic aromatic hydrocarbons (PAHs) occurs through complex mixtures. The National Institute of Standards and Technology has established standard reference materials (SRMs) for selected PAH mixtures that are composed of carcinogenic, noncarcinogenic, and weakly carcinogenic compounds, such as those derived from coal tar (SRM 1597), atmospheric particulate matter (SRM 1649), and diesel particulate matter (SRM 1650). To study the effects of PAHs with different carcinogenic potential in complex mixtures, and to investigate the metabolic activation of noncarcinogenic and weakly carcinogenic PAHs to DNA-binding derivatives, artificial mixtures (1597H, 1649H, and 1650H) were prepared in the laboratory. These artificial mixtures contained the same relative ratios of noncarcinogenic and weakly carcinogenic PAHs present in SRM 1597, SRM 1649, and SRM 1650. The human mammary carcinoma-derived cell line MCF-7 was treated with these artificial mixtures and analyzed for PAH-DNA adduct formation and the induction of cytochrome P450 (CYP) enzymes. We found that the artificial mixtures formed lower but detectable levels of DNA adducts 24 and 48 hr after treatment than benzo[a]pyrene. Induction of CYP enzyme activity was measured by the ethoxyresorufin- O -deethylase assay, and the expression of CYP1A1 and CYP1B1 was confirmed by immunoblots. Both noncarcinogenic and weakly carcinogenic PAHs present in the artificial mixtures have the ability to induce CYP1A1 and CYP1B1 in MCF-7 cells and contribute to DNA binding. Therefore, it is necessary to take into account the noncarcinogenic and weakly carcinogenic PAHs present in environmental mixtures in assessing the potential risk associated with human exposure. Environ. Mol. Mutagen. 44:99,107, 2004. © 2004 Wiley-Liss, Inc. [source]

Development and application of the human intestinal tract chip, a phylogenetic microarray: analysis of universally conserved phylotypes in the abundant microbiota of young and elderly adults

ENVIRONMENTAL MICROBIOLOGY, Issue 7 2009
-Stojanovi, Mirjana Rajili
Summary In this paper we present the in silico assessment of the diversity of variable regions of the small subunit ribosomal RNA (SSU rRNA) gene based on an ecosystem-specific curated database, describe a probe design procedure based on two hypervariable regions with minimal redundancy and test the potential of such probe design strategy for the design of a flexible microarray platform. This resulted in the development and application of a phylogenetic microarray for studying the human gastrointestinal microbiota , referred as the human intestinal tract chip (HITChip). Over 4800 dedicated tiling oligonucleotide probes were designed based on two hypervariable regions of the SSU rRNA gene of 1140 unique microbial phylotypes (< 98% identity) following analysis of over 16 000 human intestinal SSU rRNA sequences. These HITChip probes were hybridized to a diverse set of human intestinal samples and SSU rRNA clones to validate its fingerprinting and quantification potential. Excellent reproducibility (median Pearson's correlation of 0.99) was obtained following hybridization with T7 polymerase transcripts generated in vitro from SSU rRNA gene amplicons. A linear dose,response was observed with artificial mixtures of 40 different representative amplicons with relative abundances as low as 0.1% of total microbiota. Analysis of three consecutively collected faecal samples from ten individuals (five young and five elderly adults) revealed temporal dynamics and confirmed that the adult intestinal microbiota is an individual-specific and relatively stable ecosystem. Further analysis of the stable part allowed for the identification of a universal microbiota core at the approximate genus level (90% sequence similarity). This core consists of members of Actinobacteria, Bacteroidetes and Firmicutes. Used as a phylogenetic fingerprinting tool with the possibility for relative quantification, the HITChip has the potential to bridge the gaps in our knowledge in the quantitative and qualitative description of the human gastrointestinal microbiota composition. [source]

Antibody Labeling of Cholesterol/Ceramide Ordered Domains in Cell Membranes

CHEMBIOCHEM, Issue 18 2007
Luana Scheffer Dr.
Abstract A monoclonal antibody raised against mixed monolayers of 60:40 mol,% cholesterol/C16-ceramide of known structure was used to label cholesterol/ceramide-rich domains in cell membranes. The antibody, Cer,Chol 405F specifically recognizes the mixed crystalline and homogeneous phase in monolayers, but it does not interact with either of the components separately. It interacts differently with mixed monolayers that contain ceramides of different acyl chain length. When used on cells, the antibody labeling is sensitive to changes in cholesterol and ceramide levels, as well as to over-expression of specific ceramides; this is in agreement with the results that were obtained on lipid monolayers. This represents a proof of concept of the applicability of a new approach to the structural characterization of lipid microdomains in cell membranes. The approach consists of raising antibodies that recognize specific structural organizations of lipids in artificial mixtures, characterizing the antibody/ordered domain complexes in vitro, and subsequently using them to detect the presence of the same (or similar) domains in cell membranes. [source]