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Major Functions (major + function)
Selected AbstractsContinuous perfusion microfluidic cell culture array for high-throughput cell-based assaysBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2005Paul J. Hung Abstract We present for the first time a microfluidic cell culture array for long-term cellular monitoring. The 10 × 10 array could potentially assay 100 different cell-based experiments in parallel. The device was designed to integrate the processes used in typical cell culture experiments on a single self-contained microfluidic system. Major functions include repeated cell growth/passage cycles, reagent introduction, and real-time optical analysis. The single unit of the array consists of a circular microfluidic chamber, multiple narrow perfusion channels surrounding the main chamber, and four ports for fluidic access. Human carcinoma (HeLa) cells were cultured inside the device with continuous perfusion of medium at 37°C. The observed doubling time was 1.4 ± 0.1 days with a peak cell density of ,2.5*105 cells/cm2. Cell assay was demonstrated by monitoring the fluorescence localization of calcein AM from 1 min to 10 days after reagent introduction. Confluent cell cultures were passaged within the microfluidic chambers using trypsin and successfully regrown, suggesting a stable culture environment suitable for continuous operation. The cell culture array could offer a platform for a wide range of assays with applications in drug screening, bioinformatics, and quantitative cell biology. © 2004 Wiley Periodicals, Inc. [source] Transcriptional activities of mutant p53: When mutations are more than a lossJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2004Ella Kim Abstract The dominant oncogenic properties of mutant p53 have been recognized as a phenomenon associated with tumor progression a long time ago, even before it was realized that the major function of wild type p53 is that of a tumor suppressor. Recent advances in this fascinating area in tumor cell biology reveal that the community of mutant p53 proteins is comprised of proteins that are extremely diverse both structurally and functionally, and elicit a multitude of cellular responses that not only are entirely distinct from those mediated by wild type p53, but also vary among different mutant p53 proteins. Aberrant regulation of transcription is one of the mechanisms underlying the ability of some mutant p53 proteins to act as oncogenic factors. Systematic analyses of the transcriptional activities of mutant p53 suggest that not the loss of transcriptional activity as such, but alterations of target DNA selectivity may be the driving force of mutant p53 specific transcription underlying the growth-promoting effects of mutant p53. This article focuses on mechanistic aspects of mutp53 "gain-of-function" with the emphasis on possible mechanisms underlying transcriptional activation by mutp53. © 2004 Wiley-Liss, Inc. [source] Delineation of pilin domains required for bacterial association into microcolonies and intestinal colonization by Vibrio choleraeMOLECULAR MICROBIOLOGY, Issue 4 2000Thomas J. Kirn The toxin-co-regulated pilus (TCP), a type 4 pilus that is expressed by epidemic strains of Vibrio cholerae O1 and O139, is required for colonization of the human intestine. The TCP structure is assembled as a polymer of repeating subunits of TcpA pilin that form long fibres, which laterally associate into bundles. Previous passive immunization studies have suggested that the C-terminal region of TcpA is exposed on the surface of the pilus fibre and has a critical role in mediating the colonization functions of TCP. In the present study, we have used site-directed mutagenesis to delineate two domains within the C-terminal region that contribute to TCP structure and function. Alterations in the first domain, termed the structural domain, result in altered pilus stability or morphology. Alterations in the second domain, termed the interaction domain, affect colonization and/or infection by CTX-bacteriophage without affecting pilus morphology. In vitro and in vivo analyses of the tcpA mutants revealed that a major function of TCP is to mediate bacterial interaction through direct pilus,pilus contact required for microcolony formation and productive intestinal colonization. The importance of this function is supported by the finding that intragenic suppressor mutations that restore colonization ability to colonization-deficient mutants simultaneously restore pilus-mediated bacterial interactions. The alterations resulting from the suppressor mutations also provide insight into the molecular interactions between pilin subunits within and between pilus fibres. [source] Staphylococcus aureus ClpC ATPase is a late growth phase effector of metabolism and persistencePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2009Indranil Chatterjee Dr. Abstract Staphylococcus aureus Clp ATPases (molecular chaperones) alter normal physiological functions including an aconitase-mediated effect on post-stationary growth, acetate catabolism, and entry into death phase (Chatterjee et al., J. Bacteriol. 2005, 187, 4488,4496). In the present study, the global function of ClpC in physiology, metabolism, and late-stationary phase survival was examined using DNA microarrays and 2-D PAGE followed by MALDI-TOF MS. The results suggest that ClpC is involved in regulating the expression of genes and/or proteins of gluconeogenesis, the pentose-phosphate pathway, pyruvate metabolism, the electron transport chain, nucleotide metabolism, oxidative stress, metal ion homeostasis, stringent response, and programmed cell death. Thus, one major function of ClpC is balancing late growth phase carbon metabolism. Furthermore, these changes in carbon metabolism result in alterations of the intracellular concentration of free NADH, the amount of cell-associated iron, and fatty acid metabolism. This study provides strong evidence for ClpC as a critical factor in staphylococcal energy metabolism, stress regulation, and late-stationary phase survival; therefore, these data provide important insight into the adaptation of S. aureus toward a persister state in chronic infections. [source] REVIEW ARTICLE: The Unique Properties of Uterine NK CellsAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2010Irit Manaster Citation Manaster I, Mandelboim O. The unique properties of uterine NK cells. Am J Reprod Immunol 2009 Abstract Natural killer (NK) cells are lymphocytes of the innate immunity system that are able to kill various hazardous pathogens and tumors. However, it is now widely accepted that NK cells also possess non-destructive functions, as has been demonstrated for uterine NK cells. Here, we review the unique properties of the NK cells in the uterine mucosa, prior to and during pregnancy. We discuss the phenotype and function of mouse and human endometrial and decidual NK cells and suggest that the major function of decidual NK cells is to assist in fetal development. We further discuss the origin of decidual NK cells and suggest several possibilities that might explain their accumulation in the decidua during pregnancy. [source] Interferon-, treatment of female (NZW × BXSB)F1 mice mimics some but not all features associated with the Yaa mutationARTHRITIS & RHEUMATISM, Issue 4 2009Meera Ramanujam Objective Male (NZW × BXSB)F1 mice develop antiphospholipid syndrome (APS) and proliferative glomerulonephritis that is markedly accelerated by the Yaa locus encoding an extra copy of Tlr7. Female (NZW × BXSB)F1 mice with only 1 active copy of Tlr7 develop late-onset glomerulonephritis but not APS. Because a major function of Toll-like receptor 7 is to induce type I interferons (IFNs), our goal was to determine whether IFN, can induce or accelerate the manifestations of systemic lupus erythematosus (SLE) in female (NZW × BXSB)F1 mice. Methods Eight-week-old female (NZW × BXSB)F1 mice were injected with a single dose of adenovirus expressing IFN,. Mice were monitored for the development of thrombocytopenia and proteinuria. Sera were tested for anticardiolipin and anti-Sm/RNP antibodies. Mice were killed at 17 or 22 weeks of age, and their kidneys and hearts were examined histologically and by immunohistochemistry. Spleen cells were phenotyped, and enzyme-linked immunospot assays for autoantibody-producing B cells were performed. Results IFN, markedly accelerated nephritis and death in female (NZW × BXSB)F1 mice. A significant increase in spleen cell numbers associated with a striking increase in the number of activated B and T cells was observed. Marginal-zone B cells were retained. IFN,-induced increased titers of autoantibodies were observed, but thrombocytopenia was not observed. Cardiac damage was milder than that in male mice. Conclusion IFN, accelerates the development of renal inflammatory disease in female (NZW × BXSB)F1 mice but induces only mild APS and does not induce thrombocytopenia. The effect of IFN, on SLE disease manifestations is strain dependent. These findings are relevant to our understanding of the physiologic significance of the IFN signature. [source] Near-atomic resolution analysis of BipD, a component of the type III secretion system of Burkholderia pseudomalleiACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2010M. Pal Burkholderia pseudomallei, the causative agent of melioidosis, possesses a type III protein secretion apparatus that is similar to those found in Salmonella and Shigella. A major function of these secretion systems is to inject virulence-associated proteins into target cells of the host organism. The bipD gene of B. pseudomallei encodes a secreted virulence factor that is similar in sequence and is most likely to be functionally analogous to IpaD from Shigella and SipD from Salmonella. Proteins in this family are thought to act as extracellular chaperones at the tip of the secretion needle to help the hydrophobic translocator proteins enter the target cell membrane, where they form a pore and may also link the translocon pore with the secretion needle. BipD has been crystallized in a monoclinic crystal form that diffracted X-rays to 1.5,Å resolution and the structure was refined to an R factor of 16.1% and an Rfree of 19.8% at this resolution. The putative dimer interface that was observed in previous crystal structures was retained and a larger surface area was buried in the new crystal form. [source] Crystallization and preliminary X-ray diffraction analysis of BipD, a virulence factor from Burkholderia pseudomalleiACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2006M. J. Knight Burkholderia pseudomallei, the causative agent of melioidosis, possesses a protein-secretion apparatus that is similar to those found in Salmonella and Shigella. A major function of these secretion systems is to secrete virulence-associated proteins into target cells of the host organism. The BipD gene of B. pseudomallei encodes a secreted virulence factor that is similar in sequence and most likely functionally analogous to IpaD from Shigella and SipD from Salmonella. Thus, the BipD protein is likely to be a component of a type III protein-secretion system (TTSS) in B. pseudomallei. Proteins in the same class as BipD, such as IpaD and SipD, are thought to act as extracellular chaperones to help the hydrophobic translocator proteins enter the target cell membrane, where they form a pore and might even link the translocon pore with the secretion needle. There is evidence that the translocator proteins also bind an integrin which stimulates actin-mediated insertion of the bacterium into the host-cell membrane. Native BipD has been crystallized in a monoclinic crystal form that diffracts X-rays to 2.5,Å resolution. BipD protein which incorporates selenomethionine (SeMet-BipD) has also been expressed and forms crystals which diffract to a higher resolution of 2.1,Å. [source] Functions and effectors of the Salmonella pathogenicity island 2 type III secretion systemCELLULAR MICROBIOLOGY, Issue 8 2003Scott R. Waterman Summary Salmonella enterica uses two functionally distinct type III secretion systems encoded on the pathogenicity islands SPI-1 and SPI-2 to transfer effector proteins into host cells. A major function of the SPI-1 secretion system is to enable bacterial invasion of epithelial cells and the principal role of SPI-2 is to facilitate the replication of intracellular bacteria within membrane-bound Salmonella -containing vacuoles (SCVs). Studies of mutant bacteria defective for SPI-2-dependent secretion have revealed a variety of functions that can be attributed to this secretion system. These include an inhibition of various aspects of endocytic trafficking, an avoidance of NADPH oxidase-dependent killing, the induction of a delayed apoptosis-like host cell death, the control of SCV membrane dynamics, the assembly of a meshwork of F-actin around the SCV, an accumulation of cholesterol around the SCV and interference with the localization of inducible nitric oxide synthase to the SCV. Several effector proteins that are translocated across the vacuolar membrane in a SPI-2-dependent manner have now been identified. These are encoded both within and outside SPI-2. The characteristics of these effectors, and their relationship to the physiological functions listed above, are the subject of this review. The emerging picture is of a multifunctional system, whose activities are explained in part by effectors that control interactions between the SCV and intracellular membrane compartments. [source] Automation in an addiction treatment research clinic: Computerised contingency management, ecological momentary assessment and a protocol workflow systemDRUG AND ALCOHOL REVIEW, Issue 1 2009MASSOUD VAHABZADEH Abstract Introduction and Aims. A challenge in treatment research is the necessity of adhering to protocol and regulatory strictures while maintaining flexibility to meet patients' treatment needs and to accommodate variations among protocols. Another challenge is the acquisition of large amounts of data in an occasionally hectic environment, along with the provision of seamless methods for exporting, mining and querying the data. Design and Methods. We have automated several major functions of our outpatient treatment research clinic for studies in drug abuse and dependence. Here we describe three such specialised applications: the Automated Contingency Management (ACM) system for the delivery of behavioural interventions, the transactional electronic diary (TED) system for the management of behavioural assessments and the Protocol Workflow System (PWS) for computerised workflow automation and guidance of each participant's daily clinic activities. These modules are integrated into our larger information system to enable data sharing in real time among authorised staff. Results. ACM and the TED have each permitted us to conduct research that was not previously possible. In addition, the time to data analysis at the end of each study is substantially shorter. With the implementation of the PWS, we have been able to manage a research clinic with an 80 patient capacity, having an annual average of 18 000 patient visits and 7300 urine collections with a research staff of five. Finally, automated data management has considerably enhanced our ability to monitor and summarise participant safety data for research oversight. Discussion and Conclusions. When developed in consultation with end users, automation in treatment research clinics can enable more efficient operations, better communication among staff and expansions in research methods. [Vahabzadeh M, Lin J-L, Mezghanni M, Epstein DH, Preston KL. Automation in an addiction treatment research clinic: Computerised contingency management, ecological momentary assessment and a protocol workflow system. Drug Alcohol Rev 2009;28:3,11] [source] The Effects of Steroid Hormones on the Transcription of Genes Encoding Enzymes of Oxidative PhosphorylationEXPERIMENTAL PHYSIOLOGY, Issue 1 2003Klaus Scheller Regulation of energy metabolism is one of the major functions of steroid hormones. In this process, mitochondria, by way of oxidative phosphorylation, play a central role. Depending on the energy needs of the cell, on the tissue, on the developmental stage and on the intensity of the hormonal stimulus, the response can be an activation of pre-existing respiratory chain components, an increased transcription of nuclear-encoded and/or mitochondrial-encoded respiratory chain enzyme (OXPHOS) genes and of biosynthesis of the respective enzyme subunits or, in extreme cases of high energy needs, an increase in the number of mitochondria and mitochondrial DNA content per cell. Some of the hormonally regulated systems involving effects on nuclear and mitochondrial OXPHOS genes are reviewed in this paper. The possible molecular mechanisms of steroid hormone action on nuclear and mitochondrial gene transcription and possible ways of coordination of transcription in these two separate cell compartments involving direct interaction of steroid receptors with hormone response elements in nuclear OXPHOS genes and in mitochondria and induction/activation of nuclear-encoded regulatory factors affecting mitochondrial gene transcription are presented. [source] A Framework for Understanding Consensus-Building InitiationNEGOTIATION JOURNAL, Issue 3 2002Jean Poitras The potential of cosnensus building is dependent upon overcoming difficulties associated with the challenges in getting parties to the table. This article builds a framework for understanding the factors and vaiables most fundamentally involved in the initial of consensus-building efforts. Nine factors involved at the beginning of a consensus-building process are identified and outlined. The framework is structured on three major functions of the initiation phase: the definition of the porblem, the stucture of negotiation, and the motivation to participate. [source] From the Fabulous Baker Boys to the Master of Disaster: The White House Chief of Staff in the Reagan and G. H. W. Bush AdministrationsPRESIDENTIAL STUDIES QUARTERLY, Issue 3 2002DAVID B. COHEN Chiefs of staff in the modern presidency usually assume three major roles during their tenure: administrator, adviser, and guardian. Through original survey data, this article explores these roles by examining six chiefs of staff who served during the Reagan-Bush era: James Baker, Donald Regan, Howard Baker, Kenneth Duberstein, John Sununu, and Samuel Skinner. Based on the evidence, Howard Baker and James Baker were perceived as the most effective chiefs of staff in performing these three major functions. Not surprisingly, the Reagan administration prospered during both Bakers'tenures. [source] Assessing effectiveness and efficiency of academic interventions in school psychology journals: 1995,2005PSYCHOLOGY IN THE SCHOOLS, Issue 2 2010Ron Bramlett This article reviews research in the four major school psychology journals: Journal of School Psychology, Psychology in the Schools, School Psychology Quarterly, and School Psychology Review. The function of the review was to provide school psychologists with a summary of academic interventions published through years 1995,2005, synthesize the commonalities of empirically based interventions, and report on the extent to which each article provides the reader the opportunity to understand the effects of the intervention with regard to the amount of instructional time required to implement it. Results of the review suggest that reading is most heavily investigated followed by math and, to a much lesser degree, written expression. Moreover, studies use a variety of designs including single subject and group designs. Finally, it is clear that a limited number of studies evaluate the effectiveness of an intervention with regard to the amount of instructional time needed to implement the intervention. In light of these findings and in addition to the two major functions of the review, recommendations for practice and future research are presented. © 2009 Wiley Periodicals, Inc. [source] Molecular and Cellular Mechanisms of Ectodomain SheddingTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 6 2010Kazutaka Hayashida Abstract The extracellular domain of several membrane-anchored proteins is released from the cell surface as soluble proteins through a regulated proteolytic mechanism called ectodomain shedding. Cells use ectodomain shedding to actively regulate the expression and function of surface molecules, and modulate a wide variety of cellular and physiological processes. Ectodomain shedding rapidly converts membrane-associated proteins into soluble effectors and, at the same time, rapidly reduces the level of cell surface expression. For some proteins, ectodomain shedding is also a prerequisite for intramembrane proteolysis, which liberates the cytoplasmic domain of the affected molecule and associated signaling factors to regulate transcription. Ectodomain shedding is a process that is highly regulated by specific agonists, antagonists, and intracellular signaling pathways. Moreover, only about 2% of cell surface proteins are released from the surface by ectodomain shedding, indicating that cells selectively shed their protein ectodomains. This review will describe the molecular and cellular mechanisms of ectodomain shedding, and discuss its major functions in lung development and disease. Anat Rec, 293:925,937, 2010. © 2010 Wiley,Liss, Inc. [source] Development of the blood-brain barrier: A historical point of viewTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2006Domenico Ribatti Abstract Although there has been considerable controversy since the observation by Ehrlich more than 100 years ago that the brain did not take up dyes from the vascular system, the concept of an endothelial blood-brain barrier (BBB) was confirmed by the unequivocal demonstration that the passage of molecules from blood to brain and vice versa was prevented by endothelial tight junctions (TJs). There are three major functions implicated in the term "BBB": protection of the brain from the blood milieu, selective transport, and metabolism or modification of blood- or brain-borne substances. The BBB phenotype develops under the influence of associated brain cells, especially astrocytic glia, and consists of complex TJs and a number of specific transport and enzyme systems that regulate molecular traffic across the endothelial cells. The development of the BBB is a complex process that leads to endothelial cells with unique permeability characteristics due to high electrical resistance and the expression of specific transporters and metabolic pathways. This review article summarizes the historical background underlying our current knowledge of the cellular and molecular mechanisms involved in the development and maintenance of the BBB. Anat Rec (Part B: New Anat) 289B:3,8, 2006. © 2006 Wiley-Liss, Inc. [source] Nutrition and immunity: an updateAQUACULTURE RESEARCH, Issue 3 2010Viviane Verlhac Trichet Abstract Immunity encompasses all mechanisms and responses used by the organism to defend itself against bacteria, viruses or parasites. Adequate supply and balance of nutrients are required for proper efficiency of the host defences. Research has identified dietary factors that affect human and animal immune responses like amino acids, fatty acids, minerals and vitamins. Some of these nutrients have been proven to have specific actions on immunity when provided at pharmacological doses. This paper will review these nutrients and their current use in aquaculture. The immune system is an efficient but complex system. Its complexity has made the assessment of the effects of diets difficult. Nevertheless, the standardization of methodology as well as the use of new techniques at the cell or the gene level should help to better understand the mechanisms of immune modulation. This paper will review the major functions of fish and shrimp immune system and the methodologies used. Cellular and humoral functions including cytokines will be discussed in relation to potential means to modulate them and the underlying mechanism. A better understanding of the mechanisms of modulation of the immune functions should help in the discovery of new dietary factors to improve the immune status of the animal, leading to better disease resistance. [source] Recognition of Pixelized Chinese Characters Using Simulated Prosthetic VisionARTIFICIAL ORGANS, Issue 3 2007Xinyu Chai Abstract:, The rehabilitation of the reading ability of the blind with a limited number of stimulating electrodes is regarded as one of the major functions of the envisioned visual prosthesis. This article systematically studied how many pixels of individual Chinese characters should be needed for correct and economic recognition by blind Chinese subjects. In this study, 40 normal-sighted subjects were tested on a self-developed platform HanziConvertor (Institute for Laser Medicine & Bio-photonics, Shanghai Jiaotong University, China) with digital imaging processing capacities to convert images of printed text into various pixelized patterns made up of discrete dots, and present them orderly on a computer screen. It was found that various complicated factors such as pixel number, character typeface, stroke number, etc., can obviously affect the recognition accuracy. It was also found that optimal recognition accuracy occurs at a specific size of binary pixel array, due to a trade-off between a strictly limited number of stimulation electrodes and character sampling resolution. The results showed that (i) recognition accuracy of pixelized characters is optimal with at least 12 × 12 binary pixels, and therefore it is recommended to apply a minimum of 150 discrete and functioning electrodes for restoring the reading ability of blind Chinese individuals in the visual prosthesis; (ii) fonts of Song Ti and Hei Ti are clearer and more effective than other typefaces; and (iii) characters with fewer strokes lead to better accuracy. [source] The granin family of uniquely acidic proteins of the diffuse neuroendocrine system: comparative and functional aspectsBIOLOGICAL REVIEWS, Issue 4 2004Karen B. Helle ABSTRACT The chromogranins A (CgA) and B (CgB) and secretogranin II (SgII) constitute the main members of a family of uniquely acidic secretory proteins in elements of the diffuse neuroendocrine system. These genetically distinct proteins, CgA, CgB, SgII and the less well known secretogranins III,VII are collectively referred to as,granins'and characterised by numerous pairs of basic amino acids as potential cleavage sites for processing by the co-stored prohormone converting enzymes PC 1/3 and PC2. This review is directed towards comparative and functional aspects of the granins with emphasis on their phylogenetically conserved sequences. Recent developments provide ample evidence of widely different effects and targets for the intact granins and their derived peptides, intracellularly in the directed trafficking of storage components during granule maturation and extracellularly in autocrine, paracrine and endocrine interactions. Most of the effects assigned to the granin derived peptides fit into patterns of direct or indirect inhibitory modulations of major functions. So far, peptides derived from CgA (vasostatins, chromacin, pancreastatin, WE-14, catestatin and parastatin), CgB (secretolytin) and SgII (secretoneurin) are the most likely candidates for granin-derived regulatory peptides, of postulated relevance not only for homeostatic processes, but also for tissue assembly and repair, inflammatory responses and the first line of defence against invading microorganisms. [source] | |||||||||||||||||||