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Alterations in the cellular protein PrP underlie sporadic, heritable, and transmissible prion diseases. This protein normally traffics through the endoplasmic reticulum to reach the cell membrane; however, misfolding of the protein leads to retrograde transport of the protein into the cytosol, where it is degraded in proteosomes. Treating neuroblastoma cells with proteosome inhibitors caused accumulation of PrP in cells, and this material was highly toxic. Mice transgenic for a form of PrP that cannot be transported into the endoplasmic reticulum and therefore localizes in the cytosol developed ataxia and cerebellar atrophy. These findings show that the wild type PrP protein is neutrotoxic when it accumulates in the cytoplasm of neurons even at very low levels. Thus, any perturbation of PrP metabolism that leads to cytosolic accumulation of PrP can cause neurodegeneration.
Ma J, Wollmann R, Lidquist S. Neurotoxicity and neurodegeneration when PrP accumulates in the cytosol. Science 298:1781–1785, 2002
It has long been known that caloric restriction dramatically improves the health and increases the life span of laboratory rodents. In a recent study, investigators used microarray techniques to compare the expression of almost ten thousand genes in the hearts of young mice fed ad libitum, aged mice fed ad libitum, and aged mice after 16 months of caloric restriction. They identified a variety of changes associated with aging and showed that caloric restriction prevented many of these changes. Caloric restriction reduced age-related expression of structural protein genes and genes involved in immunity and modulated the expression of a variety of genes involved in DNA repair and apoptosis. These studies suggest that caloric restriction protects cardiac myocytes from age-associated death.
Lee CK, Allison DB, Brand J, Weindruch R, Prolla TA: Transcriptional profiles associated with aging and middle age-onset caloric restriction in mouse hearts. Proc Natl Acad Sci USA 99:14988–14993, 2002
The tissue microarray is a valuable method for rapid immunohistochemical staining of very large numbers of tissue samples. However, management of the data generated and analysis of the results obtained can be challenging. Investigators recently described an analysis approach that combined a commercially available spreadsheet program (Excel) and custom software (TMA-Deconvoluter) to produce formatted immunohistochemical data suitable for sophisticated statistical analysis and for long term storage. This technique will be valuable in using tissue microarrays to verify the results of gene expression microarray and in testing diagnostic and prognostic markers.
Liu CL, Prapong W, Natkunam Y, Alizadeh A, Montgomery K, Gilks CB, van de Rijn M: Software tools for high-throughput analysis and archiving of immunohistochemistry staining data obtained with tissue microarrays. Am J Pathol 161:1557–1565, 2002
Scientists at the University of California have developed a microarray-based system for the simultaneous detection and identification of numerous viral pathogens from clinical samples. RNA was isolated from clinical specimens, amplified by a random PCR protocol, and used to probe microarrays consisting of 70-mer oligonucleotide sequences. This technique successfully detected a wide range of viruses and distinguished among multiple serotypes of the same virus. The technique offers great promise for diagnosis in clinical situations involving multiple viral pathogens. Furthermore, it is possible to modify this technique for viral discovery by designing oligonucelotides that detect highly conserved regions of viral genomes.
Wang D, Coscoy L, Zylberberg M, Avila PC, Boushey HA, Ganem D, DeRisi JL: Microarray-based detection and genotyping of viral pathogens. Proc Natl Acad Sci USA 99:15687–15692, 2002
Antibodies are generally considered to function by binding to target antigens, thus activating the effector systems, such as complement and phagocytes, that ultimately destroy the antigens. However, a group of international investigators recently reported that antibody molecules themselves can catalyze the generation of potent oxidants from singlet oxygen and water by means of redox reactions. The process does not require the presence of antigen or antibody specificity. Some of the oxidants generated readily kill bacteria. Ozone appears to be the effective bacteriocidal oxidant generated by antibody-mediated catalysis.
Wentworth P, McDunn JE, Wentworth AD, Takeuchi C, Nieva J, Jones T, Bautista C, Ruedi JM, Gutierrez A, Janda KD, Mabior BM, Eschenmoser A, Lerner RA. Evidence for antibody-catalyzed ozone formation in bacterial killing and inflammation. Science 298:2195–2199, 2002
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