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Cell System (cell + system)
Kinds of Cell System Selected AbstractsA Pumpless Methanol Feeding Method for Application in Direct Methanol Fuel Cell SystemsFUEL CELLS, Issue 4 2010J. Geng Abstract This paper presents a simple and reliable pumpless methanol feeding (PLMF) method for application in direct methanol fuel cell (DMFC) systems. The primary feature and advantage of the PLMF is as follows: it employs an approach that allows the cathode gas pressure to be connected with a fuel container for supplying the methanol fuel into the anode fuel loop, instead of using any feeding pump or other specially designed apparatuses. The PLMF has been used in a portable 25,W DMFC system and realised feeding methanol in real time for meeting the requirements of the system. The PLMF method not only is suitable for the DMFC system, but also can be used in other liquid-feeding fuel cell systems. [source] Thermo-Economic Modelling and Optimisation of Fuel Cell Systems,FUEL CELLS, Issue 1 2005F. Marechal Abstract This paper describes and illustrates the application of a methodology for thermo-economic design and optimisation of fuel cell systems. This methodology combines the use of process simulation and process integration techniques to compute thermo-economic performances of fuel cell systems that will be used in a multi-objective optimisation framework. The method allows the generation of integrated fuel cell system configurations and their corresponding optimal operating conditions. It should be used as a preliminary design methodology, allowing the identification of promising system configurations, which would be further analysed. The methodology and the thermo-economic models are described and demonstrated for the design of PEMFC hybrid systems, combining fuel cell and gas turbine technologies. [source] FLOX® Steam Reforming for PEM Fuel Cell Systems,FUEL CELLS, Issue 4 2004H.-P. Schmid Abstract Primary energy savings and CO2 reduction is one of the key motivations for the use of fuel cell systems in the energy sector. A benchmark of domestic cogeneration by PEMFC with existing large scale power production systems such as combined steam-gas turbine cycle, clearly reveals that only fuel cell systems optimising overall energy efficiency (>,85%) and electrical efficiencies (>,35%) show significant primary energy savings, about 10%, compared with the best competing technology. In this context, fuel processing technology plays a dominant role. A comparison of autothermal and steam reforming concepts in a PEMFC system shows inherent advantages in terms of efficiency at low complexity for the latter. The main reason for this is that steam reforming allows for the straightforward and effective use of the anode-off gas energy in the reformer burner. Consequently, practical electrical system efficiencies over 40% seem to be achievable, most likely by steam reformers. FLOX®-steam reforming technology has reached a high state of maturity, offering diverse advantages including: compact design, stable anode off-gas usage, high efficiency, as well as simple control behaviour. Scaling of the concept is straightforward and offers an opportunity for efficient adaptation to smaller (1,kW) and larger (50,kW) units. [source] Single-cell gene profiling of planarian stem cells using fluorescent activated cell sorting and its "index sorting" function for stem cell researchDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2010Tetsutaro Hayashi To achieve an integrated understanding of the stem cell system of planarians at both the cellular and molecular levels, we developed a new method by combining "fluorescent activated cell sorting (FACS) index sorting" analysis and single-cell reverse transcription,polymerase chain reaction (RT,PCR) to detect the gene expression and cell cycle state of stem cells simultaneously. Single cells were collected using FACS, and cDNAs of each cell were used for semi-quantitative RT,PCR. The results were plotted on the FACS sorting profile using the "index sorting" function, which enabled us to analyze the gene expression in combination with cell biological data (such as cell cycle phase) for each cell. Here we investigated the adult stem cells of planarians using this method and obtained findings suggesting that the stem cells might undergo commitment during S to G2/M phase. This method could be a powerful and straightforward tool for examining the stem cell biology of not only planarians but also other organisms, including vertebrates. [source] Comparative mechanisms of zearalenone and ochratoxin A toxicities on cultured HepG2 cells: Is oxidative stress a common process?ENVIRONMENTAL TOXICOLOGY, Issue 6 2009Emna El Golli Bennour Abstract Zearalenone (ZEN) and Ochratoxin A (OTA) are structurally diverse fungal metabolites that can contaminate feed and foodstuff and can cause serious health problems for animals as well as for humans. In this study, we get further insight of the molecular aspects of ZEN and OTA toxicities in cultured human HepG2 hepatocytes. In this context, we have monitored the effects of ZEN and OTA on (i) cell viability, (ii) heat shock protein (Hsp) 70 and Hsp 27 gene expressions as a parameter of protective and adaptive response, (iii) oxidative damage, and (iv) cell death pathways. Our results clearly showed that both ZEN and OTA inhibit cell proliferation. For ZEN, a significant induction of Hsp 70 and Hsp 27 was observed. In the same conditions, ZEN generated an important amount of reactive oxygen species (ROS). Antioxidant supplements restored the major part of cell mortality induced by ZEN. However, OTA treatment downregulated Hsp 70 and Hsp 27 protein and mRNA levels and did not induce ROS generation. Antioxidant supplements did not have a significant effect on OTA-induced cell mortality. Using another cell system (Vero monkey kidney cells), we demonstrated that OTA downregulates three members of HSP 70 family: Hsp 70, Hsp 75, and Hsp 78. Our findings showed that oxidative damage seemed to be the predominant toxic effect for ZEN, while OTA toxicity seemed to be rather because of the absence of Hsps protective response. Furthermore, the two mycotoxins induced an apoptotic cell death. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] Two-stage detection of partitioned random CDMAEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2008Lukasz Krzymien Random Code Division Multiple Access (CDMA) with low complexity two-stage joint detection/decoding is considered. A sequence partitioning approach is used for modulation, where every spreading sequence is divided into M sections (partitions) which are interleaved prior to transmission. This setup, called partitioned CDMA, can be understood as a generalisation of (chip) interleave division multiple access (IDMA). An analysis of a low-complexity iterative cancellation receiver is presented for arbitrary received power distributions. It is shown that for equal rate and equal power users the asymptotic performance of partitioned CDMA is equal to the performance of CDMA with optimal a posteriori probability (APP) detection for system loads K/N,<,1.49. Effects of asynchronous signal transmission are quantified for standard pulse shaping filters and it is shown that the signal-to-noise ratios achievable in an asynchronous system are improved with respect to fully synchronous transmission. The effect of unequal received powers is examined and considerable gains in performance are obtained by judicious choices of power distributions. For certain power distribution, partitioned CDMA with iterative detection can achieve arbitrary system loads, that is detection is no longer fundamentally interference limited. The practical near-far resistance of the proposed system is illustrated using an example of a receiver with a circular receive footprint and uniformly distributed transmitters (single cell system). Copyright © 2008 John Wiley & Sons, Ltd. [source] Identification of amino acids in antiplasmin involved in its noncovalent ,lysine-binding-site'-dependent interaction with plasminFEBS JOURNAL, Issue 9 2003Haiyao Wang The lysine-binding-site-mediated interaction between plasmin and antiplasmin is of great importance for the fast rate of this reaction. It also plays an important part in regulating the fibrinolytic enzyme system. To identify structures important for its noncovalent interaction with plasmin, we constructed seven single-site mutants of antiplasmin by modifying charged amino acids in the C-terminal part of the molecule. All the variants were expressed in the Drosophila S2 cell system, purified, and shown to form stable complexes with plasmin. A kinetic evaluation revealed that two mutants of the C-terminal lysine (K452E or K452T) did not differ significantly from wild-type antiplasmin in their reactions with plasmin, in either the presence or absence of 6-aminohexanoic acid, suggesting that this C-terminal lysine is not important for this reaction. On the other hand, modification of Lys436 to Glu decreased the reaction rate about fivefold compared with wild-type. In addition, in the presence of 6-aminohexanoic acid, only a small decrease in the reaction rate was observed, suggesting that Lys436 is important for the lysine-binding-site-mediated interaction between plasmin and antiplasmin. Results from computerized molecular modelling of the C-terminal 40 amino acids support our experimental data. [source] Fire calorimetry relying on the use of the fire propagation apparatus.FIRE AND MATERIALS, Issue 2 2006Part I: early learning from use in Europe Abstract The fire propagation apparatus (FPA) is the bench scale fire calorimeter that was recently described in its updated version in ASTM E 2058. The apparatus was originally developed in the USA by Tewarson and co-workers from the mid 1970s, under the name ,50 kW lab-scale flammability apparatus', and is therefore still known in Europe as the ,Tewarson apparatus'. The paper focuses on the experience achieved so far with the first modern version of the apparatus implemented in Europe (France). Part I in this series of articles reports on the main results achieved during the commissioning period of the apparatus. In a first step, preliminary experiments were carried out in order to check and calibrate different sub-equipment of the calorimeter. The results are principally presented for the load cell system and the infrared heating system which are essential pieces of sub-equipment. In a second step, a set of fire tests using methane or acetone as fuel was carried out in order to check and calibrate the overall working of the calorimeter in well-fire conditions. The performance of the calorimeter was also checked when it operates in under-ventilated fires. Relevant testing procedures and potential technical problems are discussed. A set of recommendations are derived from the early learning obtained at the INERIS fire laboratory in order to check the consistency of the results obtained from bench-scale fire tests. These recommendations are thought to be applicable to all types of bench scale fire calorimeters. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fuel Cell Vehicle Simulation , Part 1: Benchmarking Available Fuel Cell Vehicle Simulation ToolsFUEL CELLS, Issue 3 2003K.H. Hauer Abstract Fuel cell vehicle simulation is one method for systematic and fast investigation of the different vehicle options (fuel choice, hybridization, reformer technologies). However, a sufficient modeling program, capable of modeling the different design options, is not available today. Modern simulation programs should be capable of serving as tools for analysis as well as development. Shortfalls of the existing programs, initially developed for internal combustion engine hybrid vehicles, are: (i)Insufficient modeling of transient characteristics; (ii) Insufficient modeling of the fuel cells system; (iii) Insufficient modeling of advanced hybrid systems; (iv) Employment of a non-causal (backwards looking) structure; (v) Significant shortcomings in the area of controls. In the area of analysis, a modeling tool for fuel cell vehicles needs to address the transient dynamic interaction between the electric drive train and the fuel cell system. Especially for vehicles with slow responding on-board fuel processor, this interaction is very different from the interaction between a battery (as power source) and an electric drive train in an electric vehicle design. Non-transient modeling leads to inaccurate predictions of vehicle performance and fuel consumption. When applied in the area of development, the existing programs do not support the employment of newer techniques, such as rapid prototyping. This is because the program structure merges control algorithms and component models, or different control algorithms (from different components) are lumped together in one single control block and not assigned to individual components as they are in real vehicles. In both cases, the transfer of control algorithms from the model into existing hardware is not possible. This paper is the first part of a three part series and benchmarks the "state of the art" of existing programs. The second paper introduces a new simulation program, which tries to overcome existing barriers. Specifically it explicitly recognizes the dynamic interaction between fuel cell system, drive train and optional additional energy storage. [source] Endothelial cell-specific molecule 2 (ECSM2) modulates actin remodeling and epidermal growth factor receptor signalingGENES TO CELLS, Issue 3 2009Fanxin Ma Endothelial cell-specific molecules (ECSMs) play a pivotal role in the pathogenesis of many angiogenesis-related diseases. Since its initial discovery, the exact function of human ECSM2 has not been defined. In this study, by database mining, we identified a number of hypothetical proteins across species exhibiting substantial sequence homology to the human ECSM2. We showed that ECSM2 is preferentially expressed in endothelial cells and blood vessels. Their characteristic structures and unique expression patterns suggest that ECSM2 is an evolutionarily conserved gene and may have important functions. We further explored the potential roles of human ECSM2 at the molecular and cellular level. Using a reconstitution mammalian cell system, we demonstrated that ECSM2 mainly resides at the cell membrane, is critically involved in cell-shape changes and actin cytoskeletal rearrangement, and suppresses tyrosine phosphorylation signaling. More importantly, we uncovered that ECSM2 can cross-talk with epidermal growth factor receptor (EGFR) to attenuate the EGF-induced cell migration, possibly via inhibiting the Shc-Ras-ERK (MAP kinase) pathway. Given the importance of growth factor and receptor tyrosine kinase-mediated signaling and cell migration in angiogenesis-related diseases, our findings regarding the inhibitory effects of ECSM2 on EGF-mediated signaling and cell motility may have important therapeutic implications. [source] Competitive Hebbian learning and the hippocampal place cell system: Modeling the interaction of visual and path integration cuesHIPPOCAMPUS, Issue 3 2001Alex Guazzelli Abstract The hippocampus has long been thought essential for implementing a cognitive map of the environment. However, almost 30 years since place cells were found in rodent hippocampal field CA1, it is still unclear how such an allocentric representation arises from an egocentrically perceived world. By means of a competitive Hebbian learning rule responsible for coding visual and path integration cues, our model is able to explain the diversity of place cell responses observed in a large set of electrophysiological experiments with a single fixed set of parameters. Experiments included changes observed in place fields due to exploration of a new environment, darkness, retrosplenial cortex inactivation, and removal, rotation, and permutation of landmarks. To code for visual cues for each landmark, we defined two perceptual schemas representing landmark bearing and distance information over a linear array of cells. The information conveyed by the perceptual schemas is further processed through a network of adaptive layers which ultimately modulate the resulting activity of our simulated place cells. In path integration terms, our system is able to dynamically remap a bump of activity coding for the displacement of the animal in relation to an environmental anchor. We hypothesize that path integration information is computed in the rodent posterior parietal cortex and conveyed to the hippocampus where, together with visual information, it modulates place cell activity. The resulting network yields a more direct treatment of partial remapping of place fields than other models. In so doing, it makes new predictions regarding the nature of the interaction between visual and path integration cues during new learning and when the system is challenged with environmental changes. Hippocampus 2001;11:216,239. © 2001 Wiley-Liss, Inc. [source] Harnessing human dendritic cell subsets for medicineIMMUNOLOGICAL REVIEWS, Issue 1 2010Hideki Ueno Summary:, Immunity results from a complex interplay between the antigen-non-specific innate immune system and the antigen-specific adaptive immune system. The cells and molecules of the innate system employ non-clonal recognition receptors including lectins, Toll-like receptors, NOD-like receptors, and helicases. B and T lymphocytes of the adaptive immune system employ clonal receptors recognizing antigens or their derived peptides in a highly specific manner. An essential link between innate and adaptive immunity is provided by dendritic cells (DCs). DCs can induce such contrasting states as immunity and tolerance. The recent years have brought a wealth of information on the biology of DCs revealing the complexity of this cell system. Indeed, DC plasticity and subsets are prominent determinants of the type and quality of elicited immune responses. In this article, we summarize our recent studies aimed at a better understanding of the DC system to unravel the pathophysiology of human diseases and design novel human vaccines. [source] Molecular versatility of antibodiesIMMUNOLOGICAL REVIEWS, Issue 1 2002Henry Metzger Summary: As immunology developed into a discrete discipline, the principal experimental efforts were directed towards uncovering the molecular basis of the specificity exhibited by antibodies and the mechanism by which antigens induced their production. Less attention was given to how antibodies carry out some of their effector functions, although this subject presents an interesting protein-chemical and evolutionary problem; that is, how does a family of proteins that can bind a virtually infinite variety of ligands, many of which the species producing that protein has never encountered, reproducibly initiate an appropriate response? The experimental data persuasively suggested that aggregation of the antibody was a necessary and likely sufficient initiating event, but this only begged the question: how does aggregation induce a response? I used the IgE:mast cell system as a paradigm to investigate this subject. Data from our own group and from many others led to a molecular model that appears to explain how a cell ,senses' that antigen has reacted with the IgE. The model is directly applicable to one of the fundamental questions cited above, i.e. the mechanism by which antigens induce the production of antibodies. Although the model is conceptually simple, incorporating the actual molecular events into a quantitatively accurate scheme represents an enormous challenge. [source] Epstein-Barr virus infection in immortalized nasopharyngeal epithelial cells: Regulation of infection and phenotypic characterizationINTERNATIONAL JOURNAL OF CANCER, Issue 7 2010Chi Man Tsang Abstract Epstein-Barr virus (EBV) infection has been postulated to be an early event involved in the pathogenesis of nasopharyngeal carcinomas (NPC). The lack of representative premalignant nasopharyngeal epithelial cell system for EBV infection has hampered research investigation into the regulation and involvement of EBV infection in NPC pathogenesis. We have compared the efficiency of EBV infection in nasopharyngeal epithelial cells with different biological properties including immortalized, primary and cancerous nasopharyngeal epithelial cells. EBV infection could be achieved in all the nasopharyngeal epithelial cells examined with variable infection rate. TGF-, effectively enhanced EBV infection into nasopharyngeal epithelial cells both in the immortalized and primary nasopharyngeal epithelial cells. Stable infection of EBV was achieved in a telomerase-immortalized nasopharyngeal epithelial cell line, NP460hTert. The expression pattern of EBV-encoded genes and biological properties of this EBV infected cell line on long-term propagation were monitored. The EBV-infected nasopharyngeal epithelial cells acquired anchorage-independent growth and exhibited invasive growth properties on prolonged propagation. A distinguished feature of this EBV-infected nasopharyngeal epithelial cell model was its enhanced ability to survive under growth factor and nutrient starvation. This was evidenced by the suppressed activation of apoptotic markers and sustained activation of pAkt of EBV-infected cells compared to control cells under nutrient starvation. Examination of cytokine profiles of EBV-infected NP460hTert cells to nutrient and growth factor deprivation revealed upregulation of expression of MCP-1 and GRO-,. The establishment of a stable EBV infection model of premalignant nasopharyngeal epithelial cells will facilitate research investigation into the pathogenic role of EBV in NPC development. [source] Mismatch repair system decreases cell survival by stabilizing the tetraploid G1 arrest in response to SN-38INTERNATIONAL JOURNAL OF CANCER, Issue 12 2010Mandar Ramesh Bhonde Abstract The role of the mismatch repair (MMR) system in correcting base,base mismatches is well established; its involvement in the response to DNA double strand breaks, however, is less clear. We investigated the influence of the essential component of MMR, the hMLH1 protein, on the cellular response to DNA-double strand breaks induced by treatment with SN-38, the active metabolite of topoisomerase I inhibitor irinotecan, in a strictly isogenic cell system (p53wt, hMLH1+/p53wt, hMLH1,). By using hMLH1 expressing clones or cells transduced with the hMLH1-expressing adenovirus as well as siRNA technology, we show that in response to SN-38-induced DNA damage the MMR proficient (MMR+) cells make: (i) a stronger G2/M arrest, (ii) a subsequent longer tetraploid G1 arrest, (iii) a stronger activation of Chk1 and Chk2 kinases than the MMR deficient (MMR,) counterparts. Both Cdk2 and Cdk4 kinases contribute to the basal tetraploid G1 arrest in MMR+ and MMR, cells. Although the Chk1 kinase is involved in the G2/M arrest, neither Chk1 nor Chk2 are involved in the enhancement of the tetraploid G1 arrest. The long-lasting tetraploid G1 arrest of MMR+ cells is associated with their lower clonogenic survival after SN-38 treatment, the abrogation of the tetraploid G1 arrest resulted in their better clonogenic survival. These data show that the stabilization of the tetraploid G1 arrest in response to double strand breaks is a novel function of the MMR system that contributes to the lesser survival of MMR+ cells. [source] Dynamic characteristics of a PEM fuel cell system for individual housesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2006S. ObaraArticle first published online: 1 AUG 200 Abstract The method of determination of the control variables for a system controller, which controls the electric power output of a solid-polymer-membrane (PEM) fuel cell system during electric power load fluctuations, was considered. The operation was clarified for the response characteristics of electric power generation for setting the control variables of proportional action and integral action considered to be the optimal for the system controller. The power load pattern of an individual house consists of loads usually moved up and down rapidly for a short time. Until now, there have been no examples showing the characteristics of the power generation efficiency of a system that follows a load pattern that moves up and down rapidly. Therefore, this paper investigates the relation of the control variables and power generation efficiency when adding change that simulates the load of a house to PEM fuel cell cogeneration. As a result, it was shown that an operation, minimally influenced by load fluctuations, can be performed by changing the control variables using the value of the electric power load of a system. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Complex Nature of Protein PhosphatasesIUBMB LIFE, Issue 6 2002Alistair T. R. Sim Abstract Protein phosphatases are integrally associated with the regulation of cellular signaling. The mechanisms underlying the specific regulatory roles are likely to be unique to each cell system. Nevertheless, analysis of phosphatase regulation in a number of systems has identified phosphatase targeting through association with a wide range of binding partners to be a fundamental mechanism of regulation. Using protein phosphatase 2A (PP2A) as an example, this snapshot summarizes these fundamental mechanisms of protein phosphatase regulation. [source] Dysregulation of the BMP-p38 MAPK Signaling Pathway in Cells From Patients With Fibrodysplasia Ossificans Progressiva (FOP),,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2006Jennifer L Fiori Abstract FOP is a disabling disorder in which skeletal muscle is progressively replaced with bone. Lymphocytes, our model system for examining BMP signaling, cannot signal through the canonical Smad pathway unless exogenous Smad1 is supplied, providing a unique cell type in which the BMP,p38 MAPK pathway can be examined. FOP lymphocytes exhibit defects in the BMP,p38 MAPK pathway, suggesting that altered BMP signaling underlies ectopic bone formation in this disease. Introduction: Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by progressive heterotopic ossification of connective tissues. Whereas the primary genetic defect in this condition is unknown, BMP4 mRNA and protein and BMP receptor type IA (BMPRIA) protein are overexpressed in cultured lymphocytes from FOP patients, supporting that altered BMP signaling is involved in this disease. In this study, we examined downstream signaling targets to study the BMP,Smad and BMP,p38 mitogen-activated protein kinase (MAPK) pathways in FOP. Materials and Methods: Protein phosphorylation was assayed by immunoblots, and p38 MAPK activity was measured by kinase assays. To examine BMP target genes, the mRNA expression of ID1, ID3, and MSX2 was determined by quantitative real-time PCR. Statistical analysis was performed using Student's t -test or ANOVA. Results: FOP lymphocytes exhibited increased levels of p38 phosphorylation and p38 MAPK activity in response to BMP4 stimulation. Furthermore, in response to BMP4, FOP cells overexpressed the downstream signaling targets ID1 by 5-fold and ID3 by 3-fold compared with controls. ID1 and ID3 mRNA induction was specifically blocked with a p38 MAPK inhibitor, but not extracellular signal-related kinase (ERK) or c-Jun N-terminal kinase (JNK) inhibitors. MSX2, a known Smad pathway target gene, is not upregulated in control or FOP cells in response to BMP, suggesting that lymphocytes do not use this limb of the BMP pathway. However, introduction of Smad1 into lymphocytes made the cells competent to regulate MSX2 mRNA after BMP4 treatment. Conclusions: Lymphocytes are a cell system that signals primarily through the BMP,p38 MAPK pathway rather than the BMP,Smad pathway in response to BMP4. The p38 MAPK pathway is dysregulated in FOP lymphocytes, which may play a role in the pathogenesis of FOP. [source] Identification of a Parathyroid Hormone in the Fish Fugu rubripes,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2003Janine A Danks Abstract A PTH gene has been isolated from the fish Fugu rubripes. The encoded protein of 80 amino acid has the lowest homology with any of the PTH family members. Fugu PTH(1,34) had 5-fold lower potency than human PTH(1,34) in a mammalian cell system. Introduction: Parathyroid hormone (PTH) is the major hypercalcemic hormone in higher vertebrates. Fish lack parathyroid glands, but there have numerous attempts to identify and isolate PTH from fish. Materials and Methods: Polymerase chain reaction (PCR) was performed with primers based on preliminary data from the Joint Genome Institute database. PCR amplification was performed on genomic DNA isolated from Fugu rubripes. PCR products were purified and DNA was sequenced. All sequence was confirmed from more than one independently amplified PCR product. Multiple sequence alignments were carried out, and the percentage of identities and similarities were calculated. An unrooted phylogenetic tree, using all the known PTH and PTH-related protein (PTHrP) amino acid sequences, was determined. Synthetic peptides were tested in a biological assay that measured cyclic adenosine 3,,5,-monophosphate formation in UMR106.1 cells. Rabbit polyclonal antisera specific for N-terminal human PTHrP and one rabbit polyclonal antiserum specific for N terminus hPTH were used to test the cross-reactivity with fPTH(1,34) in immunoblots. [source] Cancellous Bone Remodeling Occurs in Specialized Compartments Lined by Cells Expressing Osteoblastic MarkersJOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2001Ellen M. Hauge Abstract We describe a sinus, referred to as a bone remodeling compartment (BRC), which is intimately associated with cancellous bone remodeling. The compartment is lined on its marrow side by flattened cells and on its osseous side by the remodeling bone surface, resembling a roof of flattened cells covering the bone surface. The flat marrow lining cells are in continuity with the bone lining cells at the margins of the BRC. We examined a large number of diagnostic bone biopsy specimens received during recent years in the department. Furthermore, 10 patients (8 women and 2 men, median age 56 [40,69] years) with the high turnover disease of primary hyperparathyroidism who were treated with parathyroidectomy and followed for 3 years were included in the histomorphometric study. Bone samples for the immuno-enzyme staining were obtained from an amputated extremity of child. The total cancellous bone surface covered by BRC decreases by 50% (p < 0.05) following normalization of turnover and is paralleled by a similar 50% decrease in remodeling surface (p < 0.05). The entire eroded surface and two-thirds of the osteoid surface are covered by a BRC. BRC-covered uncompleted walls are 30% (p < 0.05) thinner than those without a BRC. This indicates that the BRC is invariably associated with the early phases of bone remodeling, that is, bone resorption, whereas it closes during the late part of bone formation. Immuno-enzyme staining shows that the flat marrow lining cells are positive for alkaline phosphatase, osteocalcin, and osteonectin, suggesting that they are bone cells. The first step in cancellous bone remodeling is thought to be the lining cells digesting the unmineralized matrix membrane followed by their disappearance and the arrival of the bone multicellular unit (BMU). We suggest that the lining cell barrier persists during bone remodeling; that the old lining cells become the marrow lining cells, allowing bone resorption and bone formation to proceed under a common roof of lining cells; that, at the end of bone formation, new bone lining cells derived from the flattened osteoblasts replace the marrow lining cells thereby closing the BRC; and that the two layers of lining cells eventually becomes a single layer. The integrity of the osteocyte-lining cell system is reestablished by the new generation of lining cells. The BRC most likely serves multiple purposes, including efficient exchange of matrix constituents and minerals, routing, monitoring, or modulating bone cell recruitment, and possibly the anatomical basis for the coupling of bone remodeling. [source] HSPA1A is an important regulator of the stability and function of ZNF198 and its oncogenic derivative, ZNF198,FGFR1JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2007Chitta S. Kasyapa Abstract Mass spectroscopy analysis demonstrated that the HSPA1A protein is found in complex with the ZNF198 protein which is involved in a chromosome rearrangement with the FGFR1 gene in an atypical myeloproliferative disease. HSPA1A is a member of the HSP70 family of genes which has been shown to be inducible in a variety of circumstances. Exogenous expression of the ZNF198,FGFR1 fusion kinase gene as well as ZNF198 in a model cell system results in a large (>650-fold) increase in HSP70 mRNA levels. Using KNK437, a specific inhibitor of HSP70 transcription, we have demonstrated that an important function of HSPA1A is to stabilize the ZNF198 and ZNF198,FGFR1 proteins. In the absence of HSPA1A, specific functions of ZNF198,FGFR1 such as STAT3 phosphorylation is also lost. Treatment of cells with KNK437 in the presence of MG132, an inhibitor of proteasomal degradation of proteins, suggested that only the ZNF198,FGFR1 protein is subject to the proteasomal degradation pathway, while ZNF198 is not. These observations suggest an important role for HSPA1A in ZNF198 and ZNF198,FGFR1 mediated cellular function. J. Cell. Biochem. 102: 1308,1317, 2007. © 2007 Wiley-Liss, Inc. [source] Loss of E-cadherin mediated cell,cell adhesion as an early trigger of apoptosis induced by photodynamic treatmentJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2005Sergio Galaz Photodynamic treatment with different photosensitizers (PSs) can result in the specific induction of apoptosis in many cell types. It is commonly accepted that this apoptotic response depends on the mitochondrial accumulation of the PS. Accumulation in other cellular organelles, such as lysosomes or the Golgi complex, and subsequent photodamage resulting in an apoptotic process has been also described. However, the role played by cell adhesion in apoptosis induced in epithelial cells after photodynamic treatment is not well characterized. Here, we have used a murine keratinocyte line, showing a strong dependence on E-cadherin for cell,cell adhesion and survival, to analyze the relevance of this adhesion complex in the context of zinc(II)-phthalocyanine (ZnPc) photodynamic treatment. We report that under apoptotic conditions, ZnPc phototreatment induces a rapid disorganization of the E-cadherin mediated cell,cell adhesion, which largely preceded both the detachment of cells from the substrate, via ,-1 integrins and the induction of apoptotic mitochondrial markers. Therefore, the alteration in E-cadherin, ,- and ,-catenins adhesion proteins preceded the release of cytochrome c (cyt c) from mitochondria to the cytosol and the activation of caspase 3. In addition, blocking E-cadherin function with a specific antibody (Decma-1) induced apoptosis in this cell system. These results strongly suggest that the E-cadherin adhesion complex could be the primary target of ZnPc phototreatment, and that loss of E-cadherin mediated cell adhesion after early photodamage triggers an apoptotic response. © 2005 Wiley-Liss, Inc. [source] Over-expression of glycerol dehydrogenase and 1,3-propanediol oxidoreductase in Klebsiella pneumoniae and their effects on conversion of glycerol into 1,3-propanediol in resting cell systemJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2009Li Zhao Abstract BACKGROUND: Glycerol dehydrogenase [EC.1.1.1.6] and 1,3-propanediol oxidoreductase [EC.1.1.1.202] were proved to be two of the key enzymes for glycerol conversion to 1,3-propanediol in Klebsiella pneumoniae under anaerobic conditions. For insight into their significance on 1,3-propanediol production under micro-aerobic conditions, these two enzymes were over-expressed in K. pneumoniae individually, and their effects on conversion of glycerol into 1,3-propanediol in a resting cell system under micro-aerobic conditions were investigated. RESULTS: In the resting cell system, over-expression of 1,3-propanediol oxidoreductase led to faster glycerol conversion and 1,3-propanediol production. After a 12 h conversion process, it improved the yield of 1,3-propanediol by 20.4% (222.1 mmol L,1 versus 184.4 mmol L,1) and enhanced the conversion ratio of glycerol into 1,3-propanediol from 50.8% to 59.8% (mol mol,1). Over-expression of glycerol dehydrogenase in K. pneumoniae had no significant influence both on 1,3-propanediol yield and on the conversion ratio of glycerol into 1,3-propanediol in the resting cell system. CONCLUSION: The results were important for an understanding of the significance of glycerol dehydrogenase and 1,3-propanediol oxidoreductase in 1,3-proanediol production under micro-aerobic conditions, and for developing better strategies to improve 1,3-propanediol yield. Copyright © 2008 Society of Chemical Industry [source] Using the extended quarter degree grid cell system to unify mapping and sharing of biodiversity dataAFRICAN JOURNAL OF ECOLOGY, Issue 3 2009R. Larsen Abstract Information on the distribution of animal populations is essential for conservation planning and management. Unfortunately, shared coordinate-level data may have the potential to compromise sensitive species and generalized data are often shared instead to facilitate knowledge discovery and communication regarding species distributions. Sharing of generalized data is, unfortunately, often ad hoc and lacks scalable conventions that permit consistent sharing at larger scales and varying resolutions. One common convention in African applications is the Quarter Degree Grid Cells (QDGC) system. However, the current standard does not support unique references across the Equator and Prime Meridian. We present a method for extending QDGC nomenclature to support unique references at a continental scale for Africa. The extended QDGC provides an instrument for sharing generalized biodiversity data where laws, regulations or other formal considerations prevent or prohibit distribution of coordinate-level information. We recommend how the extended QDGC may be used as a standard, scalable solution for exchange of biodiversity information through development of tools for the conversion and presentation of multi-scale data at a variety of resolutions. In doing so, the extended QDGC represents an important alternative to existing approaches for generalized mapping and can help planners and researchers address conservation issues more efficiently. Résumé L'information sur la distribution des populations animales est essentielle pour la planification de la conservation et la gestion. Malheureusement, les données partagées au niveau des coordonnées risquent de compromettre les espèces sensibles, et les données généralisées sont souvent partagées pour faciliter la découverte et la communication des connaissances concernant la distribution des espèces. Le partage de données généralisées est, malheureusement, souvent opportuniste et manque de conventions mesurables qui permettraient le partage cohérent sur une plus grande échelle et à des résolutions variées. Une convention commune pour des applications africaines est le système de Quarter Degree Grid Cells (QDGC). Cependant, la norme actuelle ne supporte pas l'emploi des références uniques à travers l'Equateur et le premier méridien. Nous présentons une méthode pour étendre la nomenclature QDGC pour soutenir l'adoption de références uniques à l'échelle du continent, en Afrique. Le QDGC étendu fournit un instrument pour partager les données généralisées sur la biodiversité là où les lois, les réglementations et les autres considérations formelles empêchent ou interdisent la distribution de l'information au niveau coordonné. Nous disons dans quelle mesure le QDGC étendu peut être utilisé comme norme, une solution mesurable pour l'échange d'informations sur la biodiversité grâce au développement d'instruments pour la conversion et la présentation de données àéchelle multiple à des résolutions diverses. Ce faisant, le QDGC étendu représente une alternative importante aux approches existantes pour la cartographie généralisée et il peut aider les planificateurs et les chercheurs à traiter les problèmes de conservation plus efficacement. [source] Invasiveness and Intracellular Growth of Multidrug-Resistant Salmonella and Other Pathogens in Caco-2 CellsJOURNAL OF FOOD SCIENCE, Issue 2 2007S.-H. Kim ABSTRACT:, The increase of multidrug-resistant pathogens of human and animal origins is a major public health concern. For a better understanding of the health consequences of multidrug-resistant bacteria transmitted from animal products to humans, the host interaction of zoonotic Salmonella isolates along with other pathogenic and commensal bacteria was evaluated using a human intestinal Caco-2 cell system. Multidrug-resistant S. Agona, S. Heidelberg, and S. Typhimurium possessed plasmid-mediated class 1 integrons. The S. Typhimurium DT104 isolate from ground beef showed the well-known genotypic and phenotypic resistance characteristics of the species, and contained the chromosomally located class 1 integron. Among the multidrug-resistant Salmonella isolates, the S. Heidelberg 219 had the highest invasion number at 1.0 × 104 CFU/mL, followed by the S. Typhimurium DT104 isolate at 7.7 × 103 CFU/mL. Listeria monocytogenes was the best performer among the tested species in invading the Caco-2 cell. Multidrug-resistant opportunistic pathogens Klebsiella pneumoniae and Pseudomonas aeruginosa were also able to invade the cells. The invasion of S. Heidelberg 219, S. Typhimurium DT104, L. monocytogenes, K. pneumoniae, and P. aeruginosa into the Caco-2 cells was not affected even in the presence of commensal E. coli. During the intracellular growth of S. Heidelberg 219, S. Typhimurium DT104, and L. monocytogenes, the bacterial counts increased 2 log cycles in 9 h in the Caco-2 cells. Therefore, these strains could rapidly proliferate after their invasion into the cells. [source] Inhibition of Oxidative and Antioxidative Enzymes by Trans-ResveratrolJOURNAL OF FOOD SCIENCE, Issue 2 2001X. Fan ABSTRACT: Trans-resveratrol, a phytoalexin produced by a variety of plants, has been shown to inhibit oxidative enzymes in an animal cell system. Its effect on several oxidative and antioxidative enzymes from plants was investigated using in vitro assays. Trans-resveratrol inhibited superoxide dismutase, lipoxygenase, catalase, peroxidase, polyphenol oxidase, and 1-aminocyclopropane-1-carboxylic acid oxidase with apparent KI's of 10, 90, 100, 255, 305, and 350 ,M, respectively. Trans-resveratrol inhibited lipoxygenase activity more effectively than other lipoxygenase inhibitors, including propyl gallate, ibuprofen, ursolic acid, acetylsalicylic acid, and salicylhydroxamic acid. [source] Comparing the antibody responses against recombinant hemagglutinin proteins of avian influenza A (H5N1) virus expressed in insect cells and bacteria,JOURNAL OF MEDICAL VIROLOGY, Issue 11 2008Shuo Shen Abstract The hemagglutinin (HA) of influenza A virus plays an essential role in mediating the entry of the virus into host cells. Here, recombinant full-length HA5 protein from a H5N1 isolate (A/chicken/hatay/2004(H5N1)) was expressed and purified from the baculovirus-insect cell system. As expected, full-length HA5 elicits strong neutralizing antibodies, as evaluated in micro-neutralization tests using HA5 pseudotyped lentiviral particles. In addition, two fragments of HA5 were expressed in bacteria and the N-terminal fragment, covering the ectodomain before the HA1/HA2 polybasic cleavage site, was found to elicit neutralizing antibodies. But the C-terminal fragment, which covers the remaining portion of the ectodomain, did not. Neutralizing titer of the anti-serum against the N-terminal fragment is only four times lower than the anti-serum against the full-length HA5 protein. Using a novel membrane fusion assay, the abilities of these antibodies to block membrane fusion were found to correlate well with the neutralization activities. J. Med. Virol. 80:1972,1983, 2008. © 2008 Wiley-Liss, Inc. [source] Cost analysis of proton exchange membrane fuel cell systemsAICHE JOURNAL, Issue 7 2008Ai-Jen Hung Abstract Tradeoff between capital cost and the operating cost can be seen in the design of proton exchange membrane fuel cell systems. The polarization curve indicates that operating in the region of lower current densities implies less operating cost (hydrogen fuel) and higher capital cost (larger membrane electrode assembly area). The opposite effects are observed when one operates in the region of higher current densities. Therefore, an appropriate design should take both factors into account and the optimality depends on the corresponding costs of hydrogen and membrane area. An analytical cost model is constructed to describe such an economic balance in a proton exchange membrane fuel cell system. The objective function of the optimization is the total annual cost. Six scenarios are used to illustrate the optimal design based on the total annual cost as cost and materials factors fluctuate. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Straight-chain naltrexone ester prodrugs: Diffusion and concurrent esterase biotransformation in human skinJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2002Audra L. Stinchcomb Abstract Naltrexone (NTX) is an opioid antagonist used for treatment of narcotic dependence and alcoholism. Transdermal naltrexone delivery is desirable to help improve patient compliance. The purpose of this study was to increase the delivery rate of NTX across human skin by using lipophilic alkyl ester prodrugs. Straight-chain naltrexone-3-alkyl ester prodrugs of 2,7 carbons in chain length were synthesized and evaluated. In vitro human skin permeation rates were measured using a flow-through diffusion cell system. The melting points, solubilities, and skin disposition of the drugs were determined. The prodrugs were almost completely hydrolyzed on passing through the skin and appeared as NTX in the receiver compartment. The mean NTX flux from the prodrug-saturated solutions exceeded the flux of NTX base by ,2,7-fold. The amount of drug detected in the skin was significantly greater after treatment with the prodrug solutions compared with treatment with NTX base. The extent of parent drug (NTX) regeneration in the intact skin ranged from 28 to 91%. Higher NTX regeneration percentages in skin appeared to correlate with increased drug delivery rates. Definitively, the highly oil-soluble prodrugs provide a higher NTX flux across human skin in vitro and undergo significant metabolic conversion in the skin. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:2571,2578, 2002 [source] Surface-enhanced resonance Raman scattering using pulsed and continuous-wave laser excitationJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Rachael E. Littleford Abstract Pulsed and continuous-wave (CW) lasers were compared as excitation sources for surface-enhanced resonance Raman scattering (SERRS). CW excitation provided SERRS spectra with a greater signal-to-noise ratio and more sensitive detection by a factor of ,50 compared with the high peak power, low repetition rate pulsed configuration used. The SERRS intensity using a pulsed laser produced a non-linear response with respect to changes in power of the laser. At powers of less than ,0.012 mW, the absolute intensity under the peaks of the CW and pulsed SERRS spectra converged, suggesting that lower peak power, high repetition rate systems may be more effective excitation sources for SERRS. Transmission electron microscopy of pulsed laser-irradiated silver particles showed significant sample damage and morphological changes. This problem was overcome with the use of a recirculating large-volume flow cell system, providing a fresh sample for each measurement. A picosecond-resolved time delay experiment found that SERRS intensity decreased by ,60% when exposed to a 400 nm pump pulse and probed with a 529 nm pulse. As the time delay between pump and probe increased the system recovered gradually to ,60% of the original SERRS intensity after 50 ps, where it remained constant. This suggests that the surface bonding between the silver and the dye is significantly perturbed, with some nanoscale diffusion occurring of the dye away from the metal surface. Hence chemical enhancement is temporarily prevented and electromagnetic enhancement is reduced as a function of 1/r3 as the dye moves away from the surface. Additionally, transient heating of the colloidal particles caused by the pulsed laser may also lead to plasmon shifts and changes in absorption intensity. Other factors such as surface annealing or decomposition of the silver particle or dye due the extreme temperature conditions may account for the permanent loss in SERRS intensity. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||