70 research outputs found
Comparison of transcriptional responses in liver tissue and primary hepatocyte cell cultures after exposure to hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine
BACKGROUND: Cell culture systems are useful in studying toxicological effects of chemicals such as Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), however little is known as to how accurately isolated cells reflect responses of intact organs. In this work, we compare transcriptional responses in livers of Sprague-Dawley rats and primary hepatocyte cells after exposure to RDX to determine how faithfully the in vitro model system reflects in vivo responses. RESULTS: Expression patterns were found to be markedly different between liver tissue and primary cell cultures before exposure to RDX. Liver gene expression was enriched in processes important in toxicology such as metabolism of amino acids, lipids, aromatic compounds, and drugs when compared to cells. Transcriptional responses in cells exposed to 7.5, 15, or 30 mg/L RDX for 24 and 48 hours were different from those of livers isolated from rats 24 hours after exposure to 12, 24, or 48 mg/Kg RDX. Most of the differentially expressed genes identified across conditions and treatments could be attributed to differences between cells and tissue. Some similarity was observed in RDX effects on gene expression between tissue and cells, but also significant differences that appear to reflect the state of the cell or tissue examined. CONCLUSION: Liver tissue and primary cells express different suites of genes that suggest they have fundamental differences in their cell physiology. Expression effects related to RDX exposure in cells reflected a fraction of liver responses indicating that care must be taken in extrapolating from primary cells to whole animal organ toxicity effects
Hepatocyte heterogeneity: The coming of age from the description of a biological curiosity to a partial understanding of its physiological meaning and regulation
No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38338/1/1840090124_ftp.pd
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WELDED-WELDED FRAMING ANGLE CONNECTIONS
Results of tension and compression tests on angle segments are used to generate moment-rotation curves for welded-welded double framing angle connections. The beam line concept is then used to determine the connection moments for connection depths of 18 to 32 inches. With the connection moments known, the two welds, denoted as Weld A and Weld B in the AISC Manual Table IV are evaluated. Because the analytical model used to generate the weld sized published in the AISC Manual and analytical model used in this research differ, it was found that the capacities of the connection designs in the AISC Manual for Weld B have factors of safety ranging from 2.5 to 3.0. Design aids are included which give the connection moments for a variety of designs as a function of the length to depth ratio of the beam for the case of uniform loading
Protein synthesis in the rat liver acinus after injection of actinomycin D: A radioautographic study
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