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Topic: Attenuation (biology)

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Attenuation - Wikipedia, the free encyclopedia In biology, attenuation is a mechanism in the regulation of gene expression In telecommunication, attenuation is the decrease in intensity of a signal, beam, or wave as a result of absorption of energy and of scattering out of the path to the detector, but not including the reduction due to geometric spreading. In physical oceanography, light attenuation is the decrease in light intensity with depth in the water column due to absorption (by water molecules) and scattering (by suspended particulates). en.wikipedia.org /wiki/Attenuation

Biology 216 - Host Parasite Interactions Basic perspective of Host/Parasite interactions A. Balance: Host defenses (health) <-----------> Microbe factors (disease) Infection is the rule/disease is the exception Lives of a cell (Lewis Thomas): Bad business to kill your host; Evolutionary tendency towards attenuation. Formed outside host (intoxications) - botulism, staph food poisoning Formed on surface - cholera, diphtheria Formed inside host - tetanus ADP-ribosylating toxins (about 1/2 of known exotoxins) NAD + X (cell target) --> ADP-ribose-X (inactive) + nicotinamide Ex. Infection - colonization of host by microbe (may or may not lead to disease). www.csuchico.edu /biol/personnel/Hanne/MedBactNotes/Lect07HostDef.html   (715 words)

Molecular Viral Biology Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID), NIH We are also investigating the molecular mechanisms responsible for dengue virus attenuation in humans through analysis of mutations present in virus strains selected by serial passage in mouse brain, because earlier investigators showed that these mouse-passaged virus strains exhibited significant attenuation for humans. Mutants containing deletions that reduce the capacity of virus replication in cell culture or conditional mutants should also prove valuable for evaluation of the attenuation phenotype. Similarly, full-length cDNA clones of Langat virus, a member of tick-borne encephalitis virus group, are also employed to investigate the immunogenicity and virulence in animal models. www.niaid.nih.gov /dir/labs/lid/lai.htm   (715 words)

Ancient Origin of the Tryptophan Operon and the Dynamics of Evolutionary Change -- Xie et al. 67 (3): 303 -- Microbiology and Molecular Biology Reviews (i) a trp RNA-binding attenuation protein (TRAP) encoded by Trp as a corepressor moiety, (ii) an attenuation mechanism mediated The trpAa and trpAbBD operons are regulated by attenuation mmbr.asm.org /cgi/content/full/67/3/303   (715 words)

Generalized Linear Measure Error Models It is well known that such errors lead to attenuation of estimated effects, and the new commands adjust for that attenuation to produce correct standard errors and test statistics. He is also Director of Biostatistics Research at the Center for Environmental and Rural Health (NIEHS) and Director of the Training Program in Biology, Bioinformatics, and Nutrition for the National Cancer Institute, both at Texas AandM University. Measurement error, GLMs, and notational conventions, by James Hardin and Raymond Carroll www.stata.com /merror   (1168 words)

Medical terahertz imaging: The interaction of terahertz radiation with biological tissue We have developed two alternative theoretical models for the attenuation of terahertz radiation and compared the results with experimental measurements. Materials that mimic the attenuation properties of tissues have been identified. An overview of the Leeds programme of terahertz pulsed imaging in medicine and biology www.comp.leeds.ac.uk /comir/research/terahertz/GRN39678.html   (375 words)

Hydrogeology Research Group, University of Tennessee, Knoxville The research includes both field-scale evaluation of natural attenuation of TCE in an existing 50 m long plume and laboratory scale experiments to investigate geochemical and microbial controls on TCE degradation in these materials. Research combines techniques from hydrogeology, microbiology, and molecular biology to address the issue of biodegradation of trichloroethylene (TCE) in fractured clay-rich materials. Evaluation of natural attenuation of TCE in fractured and weathered shale bedrock at a former disposal site at Oak Ridge Reservation, Oak Ridge, TN. web.utk.edu /~lmckay/melissa.html   (1058 words)

Center for Computational Biology A second factor that contributes to synaptic integration in the interneuron is its "electroanatomy." The efficacy with which a particular synaptic input can influence the output of a neuron is determined by the attenuation of the PSP between the input and the spike-initiating zone (SIZ). Inputs to acoustic interneurons in the nucleus laminaris of the chick auditory system are organized tonotopically across the nucleus, and the position of an interneuron is correlated with its optimal response frequency (Rubel and Parks, 1975; Young and Rubel, 1983). The primary afferent input to this interneuron is from sensory neurons associated with filiform hairs on the cerci (Edwards and Palka, 1974) located at the end of the abdomen of the cricket. cns.montana.edu /research/pub/intmech86   (1058 words)

Publications Related to Ozone & UV-B Effects on Marine Health The synthesis of mycosporine-like amino acids in response to exposure to UV in Anthopleura elegantissima and Cassiopeia xamachana, Journal of Experimental Marine Biology 1995, 194, 233-250. Mitchell, B. G., Action spectra of ultraviolet photoinhibition of Antarctic phytoplankton and a model of spectral diffuse attenuation coefficients, in Response of Marine Phytoplankton to Natural Variations in UV-B Flux Mitchell, B. G., Holm-Hansen, O., Sobolev, I., eds., Chem. Dohler, G., UV-effects on the nitrogen metabolism of marine phytoplankton and adaption to UV radiation, in Stratospheric ozone depletion/UV-B radiation in the biosphere Biggs, R. and Joyner, M. B., eds., Springer-Verlag, Berlin, 1994, pp. disc.gsfc.nasa.gov /acdisc/ozone/pubs/theme/marinehealth_pubs.shtml   (3458 words)

A role for cyclin D3 in the endomitotic cell cycle -- Zimmet et al. 17 (12): 7248 -- Molecular and Cellular Biology Rooney, R. Cell Cycle Attenuation by p120E4F Is Accompanied by Increased Mitotic Dysfunction. Ballester, A., Frampton, J., Vilaboa, N., Cales, C. Heterologous Expression of the Transcriptional Regulator Escargot Inhibits Megakaryocytic Endomitosis. Geddis, A. E., Kaushansky, K. Megakaryocytes express functional Aurora-B kinase in endomitosis. mcb.asm.org /cgi/content/abstract/17/12/7248   (3458 words)

BCH5425 Molecular Biology and Biotechnology Attenuation depends on the interplay between ribosome binding and translation of the nascent mRNA transcript and the formation of a particular stem-loop structure in the mRNA leader sequence. A ribosome translating the nascent trp polycistronic mRNA stalls at the codons for tryptophan in the leader mRNA sequence. A ribosome translating the nascent trp polycistronic mRNA does not stall at segment 1 (the region with codons coding for tryptophan). wine1.sb.fsu.edu /bch5425/lect18/lect18.htm   (3458 words)

Seismic signals in a courting male jumping spider (Araneae: Salticidae) -- Elias et al. 206 (22): 4029 -- Journal of Experimental Biology Frohlich, C. and Buskirk, R. Transmission and attenuation of vibration in orb spider webs. Fusani, L., Hutchison, R. and Hutchison, J. Vocal-postural co-ordination of a sexually dimorphic display in a monomorphic species: the barbary dove. jeb.biologists.org /cgi/content/full/206/22/4029   (5212 words)

Prophet or Madman: Tickle U. Tickle U. The psychology of tickling: The following quote comes from a Queen's University (Canada) press release about an article in PLoS Biology: I'm betting that this "sensory attenuation" occurs in many other areas of life, too. Prophet or Madman: Tickle U. Notify Blogger about objectionable content. prophetmadman.blogspot.com /2006/01/tickle-u.html   (141 words)

ScienceWeek Soliton research has been conducted in fields as diverse as particle physics, molecular biology, geology, oceanography, astrophysics, and nonlinear optics. Khaykovich et al (Ecole Normale Sup‚rieure Paris, FR) discuss matter waves, the authors making the following points: 1) Solitons are localized waves that travel over long distances with neither attenuation nor change of shape, as their dispersion is compensated by nonlinear effects. 2) Excitons are quasiparticles: in semiconductors, electrons can be excited from the valence band to the conduction band using optical fields; this conduction electron is attracted, through the Coulomb interaction, to the positively charged hole left behind in the valence band. scienceweek.com /2003/sw030404.htm   (10906 words)

BCH5425 Molecular Biology and Biotechnology The second regulation mechanisms of trp operon by transcription attenuation: a mechanism involves tight coupling between translation and translation to enable the Rho-independent termination. The essence of this mechanism is premature termination of transcription. When tryptophan is present, and the operon is repressed, the few transcripts which are made are actually quite short and do not encompass the entire polycistronic message of the trp operon. www.sb.fsu.edu /~hongli/BCH5425/note7.html   (10906 words)

Feedback and Hormonal Regulation of Hepatic 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase: The Concept of Cholesterol Buffering Capacity -- Ness and Chambers 224 (1): 8 -- Experimental Biology and Medicine Attenuation of plasma low-density lipoprotein cholesterol by select 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in mice devoid of low-density lipoprotein receptors. Hydroxymethylglutaryl coenzyme A reductase containing hepatocytes are distributed periportally in normal and mevinolin-treated rat livers. Skalnik DG, Brown DA, Brown PC, Friedman RL, Hardeman EC, Schimke RT, Simoni RD. Mechanisms of 3-hydroxy-3-methylglutaryl coenzyme A reductase overaccumulation in three compactin-resistant cell lines. www.ebmonline.org /cgi/content/full/224/1/8   (10906 words)

From Birds to Humans: New Concepts on Airways Relative to Alveolar Surfactant -- Bernhard et al. 30 (1): 6 -- American Journal of Respiratory Cell and Molecular Biology Inhibitory effect of porcine surfactant on the respiratory burst oxidase in human neutrophils: attenuation of p47phox and p67phox membrane translocation as the mechanism. Pulmonary surfactant is a surface-active mixture of phospholipids Pulmonary surfactant in birds: coping with surface tension in a tubular lung. ajrcmb.atsjournals.org /cgi/content/full/30/1/6   (4109 words)

Biological control of chestnut blight: an example of virus-mediated attenuation of fungal pathogenesis -- Nuss 56 (4): 561 -- Microbiology and Molecular Biology Reviews Peng, C.-W., Peremyslov, V. V., Mushegian, A. R., Dawson, W. O., Dolja, V. Functional Specialization and Evolution of Leader Proteinases in the Family Closteroviridae. mmbr.asm.org /cgi/content/abstract/56/4/561   (4109 words)

Endometrial Glands Are Required for Preimplantation Conceptus Elongation and Survival -- Gray et al. 64 (6): 1608 -- Biology of Reproduction Attenuation of calcitonin gene expression in pregnant rat uterus leads to a block in embryonic implantation. Role of embryonic signals in the establishment of pregnancy. Endometrial glands are present in all mammalian uteri and develop www.biolreprod.org /cgi/content/full/64/6/1608   (3694 words)

NAD(P)H Oxidase Mediates Angiotensin II-Induced Vascular Macrophage Infiltration and Medial Hypertrophy -- Liu et al. 23 (5): 776 -- Arteriosclerosis, Thrombosis, and Vascular Biology attenuation in rats treated with gp91ds-tat (Figure 2D). Role of NADPH oxidase in the vascular hypertrophic and oxidative stress response to angiotensin II in mice. Figure 3D) in all segments of the aortic wall. atvb.ahajournals.org /cgi/content/full/23/5/776   (3694 words)

Citations: A general model for the origin of allometric scaling laws in biology - West, Brown, Enquist (ResearchIndex) West, G. B., Brown, J. H., and Enquist, B. A general model for the origin of allometric scaling laws in biology, Science 276, 122--126 (1997). Air and water are assigned attenuation values of 1000 Hu and 0 Hu respectively, giving bone a range of values from around 80 Hu to 1000 Hu.... West, J. Brown and B. Enquist, " A general model for the origin of allometric scaling laws in biology ", Science 276, 122--126 (1997). citeseer.ist.psu.edu /context/1199660/0   (3694 words)

Ali Can Lasek, D. arowski, J. Turner, B. Roysam, “A Robust Two-View Method for Increasing the Imaging Depth and Correcting for Signal Attenuation in Confocal Microscopes,” Proceedings Microscopy and Microanalysis, Microscopy Society of America 58th Annual Meeting, Philadelphia, Pennsylvania, pp. Can, H. Singh, G. Chen, “Simulation of four-dimensional effects in radiation therapy: The dose in intensity modulated beam delivery under organ motion,” International Journal of Radiation Oncology, Biology, and Physics, Salt Lake City, Utah, October 2003. Awarded the best paper award by the IEEE Computer Society, and the Allen B. DuMont Prize by RPI, my Ph.D. research leaded to a 1.3 million dollar NSF grant, and NIH R1-trust under the investigation of Prof. www.cs.rpi.edu /~cana   (1793 words)

Ocean Physics Laboratory, University of California Santa Barbara (89) Chang, G.C. and T.D. Dickey, 1999, Partitioning in situ total spectral absorption by use of moored spectral absorption-attenuation meters, Appl. (71) Petrenko, A.A., B.H. Jones, T.D. Dickey, M. LeHaitre, and C. Moore, 1997, Effects of a sewage plume on the biology, optical characteristics, and particle size distributions of coastal waters, J. Geophys. (116) Kinkade, C.S., J. Marra, T.D. Dickey, and R. Weller, 2001, An annual cycle of phytoplankton biomass in the Arabian Sea, 1994-1995, as determined by moored optical sensors, Deep-Sea Res. www.opl.ucsb.edu /tommy/publications.html   (4370 words)

Research: Solange Gauthier Karsh Laboratory Robert G. Korneluk obtained his Ph.D. in developmental biology from the University of Toronto in 1982. Attenuation of ischemia-induced cellular and behavioral deficits by XIAP overexpression in the rat hippocampus. Genomic characterization of the mouse inhibitor of apoptosis protein-1and 2 genes. www.cheori.org /research_solange_lab_korneluk.html   (4370 words)

Transcription Attenuation: Once Viewed as a Novel Regulatory Strategy -- Yanofsky 182 (1): 1 -- The Journal of Bacteriology The effects of leader peptide sequence and length on attenuation control of the trp operon of Escherichia coli. Neidhardt, R. Curtiss III, J. Ingraham, E. Lin, K. Low, B. Magasanik, W. Reznikoff, M. Riley, M. Schaecter, and H. Umbarger (ed.), Escherichia coli and Salmonella: cellular and molecular biology, vol. Lin, and A. Lynch (ed.), Regulation of gene expression in Escherichia coli. jb.asm.org /cgi/content/full/182/1/1   (4370 words)

Hypothalamic Alterations and Reproductive Aging in Female Rats: Evidence of Altered Luteinizing Hormone-Releasing Hormone Neuronal Function -- Rubin 63 (4): 968 -- Biology of Reproduction sensitivity to LHRH that could, in turn, contribute to the attenuation LHRH pulse generation may be intrinsic to LHRH neurons. LHRH neurons express cJun protein during the proestrous surge of luteinizing hormone. www.biolreprod.org /cgi/content/full/63/4/968   (4370 words)

Amazon.fr : Chroniques et points de vue Livres en anglais: Molecular Biology of Bacterial Infection: Current Status and Future Perspectives The broad scope of the volume encompasses normal flora and colonization resistance, evolution of pathogenic mechanisms, genetic approaches to understanding bacterial pathogenesis and in vivo studies of mutants, antigenic variation, bacterial invasion, toxins, environmental control of gene expression, regulatory networks in gene control, and attenuation of virulence through auxotrophy. The book will provide a state of the art reference for researchers in all areas concerned with bacterial infection and will also be useful as an advanced text. www.amazon.fr /exec/obidos/tg/detail/-/english-books/0521432987/reviews   (4370 words)

Tumor Necrosis Factor Alpha Transcription in Macrophages Is Attenuated by an Autocrine Factor That Preferentially Induces NF-kappa B p50 -- Baer et al. 18 (10): 5678 -- Molecular and Cellular Biology may reflect chronic induction of the autocrine attenuation mechanism The data are from a representative experiment; similar results were obtained in two independent experiments. the idea that an autocrine feedback system in LPS-activated macrophages mcb.asm.org /cgi/content/full/18/10/5678   (4370 words)

Journal of Cerebral Blood Flow & Metabolism - GABAA Receptor Activation Attenuates Excitotoxicity but Exacerbates Oxygen-Glucose Deprivation-Induced Neuronal Injury In Vitro Choi DW, Koh J and Peters S. (1988) Pharmacology of glutamate neurotoxicity in cortical cell culture: attenuation by NMDA antagonists. Department of Neurology and Center for the Study of Nervous System Injury, Washington University School of Medicine, St. Louis, Missouri, U.S.A. Center of Molecular Biology, University of Heidelberg, Heidelberg, Germany. Consistent with an earlier study (Choi et al., 1988), exposure of mixed neuron/glial cortical cell cultures to 100 µM NMDA for 5 min resulted in degeneration of a majority (50−75%) of the neuronal population 20−24 h later. www.nature.com /jcbfm/journal/v16/n6/full/9590144a.html   (4370 words)

Attenuation of Corticotropin-Releasing Hormone and Arginine Vasopressin Responsiveness During Late-Gestation Pregnancy in Sheep -- Young and Rose 66 (6): 1805 -- Biology of Reproduction ACTH secretagogues, AVP and CRH, are attenuated in late-gestation Arginine vasopressin is a much more potent stimulus to ACTH release from ovine anterior pituitary cells than ovine corticotropin-releasing factor. Studies of the secretion of corticotropin-releasing factor and arginine vasopressin into the hypophysial-portal circulation of the conscious sheep. www.biolreprod.org /cgi/content/full/66/6/1805   (4370 words)

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