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Cell Physiology (cell + physiology)
Selected AbstractsImpairment of Eye Lens Cell Physiology and Optics by Broadband Ultraviolet A,Ultraviolet B Radiation,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2002O. M. Oriowo ABSTRACT The phototoxicity of ultraviolet A (UVA) alone and UVA plus ultraviolet B (UVB) combined on cultured porcine lenses was investigated by analyzing cellular function as measured with a fluorescence bioassay approach and optical integrity, in terms of sharpness of the lens focus as measured with a scanning laser system. The bioassay consisted of carboxyfluorescein diacetate-acetoxymethyl ester and alamarBlue fluorescent dyes. Aseptically dissected porcine lenses were maintained in modified medium 199 without phenol red supplemented with 1% penicillin,streptomycin and 4% porcine serum. At 1 week of preincubation, baseline measurements were obtained. Then the lenses were treated with single exposures of different UVA and UVB energy levels. The lenses treated with 86 J/cm2 UVA alone showed a significant (P < 0.05) decrease in cellular and optical integrity at 48 h after exposure, whereas those treated with 43 J/cm2 UVA alone did not show significant phototoxic effect. Lenses treated with 15.63 J/cm2 UVA plus 0.019 J/cm2 UVB combined showed significant adverse effects beginning from 48 h after exposure. Also, there was no recovery. These findings show that a high UVA dose alone and relatively low UVA in combination with low UVB radiant exposure can impair lens cellular and optical functions, respectively. [source] High-level extracellular production of penicillin acylase by genetic engineering of Escherichia coliJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2001Wen-Jer Lin Abstract The extracellular production of penicillin acylase (PAC) in genetically engineered Escherichia coli by coexpression of the brp gene encoding bacteriocin release protein (BRP) and the pac gene was demonstrated. Cell physiology was affected while PAC was released into the medium, depending on the strategy for brp expression. The performance for the production and release of PAC was optimized by taking several culture parameters, including host, inducer (mitomycin C) concentration, and induction timing for brp expression, into consideration. The effect of PAC release on inclusion body formation was also investigated. It was observed that the amount of inclusion bodies was significantly affected by brp expression. A reason for the limitation of PAC production and a strategy for resolving this problem are proposed. © 2001 Society of Chemical Industry [source] Physiological Improvement to Enhance Escherichia coli Cell-Surface Display via Reducing Extracytoplasmic StressBIOTECHNOLOGY PROGRESS, Issue 2 2008Niju Narayanan Cell physiology was impaired when enhanced yellow fluorescence protein (EYFP) was displayed on the Escherichia coli cell surface, resulting in growth arrest and poor display performance. Coexpression of Skp, a periplasmic chaperone known to interact with several outer membrane proteins for their transport and insertion in the outer membrane, was demonstrated to be effective to restore cell physiology. When Skp was coexpressed with EYFP display, host cells became less sensitive to ethylenediaminetetraacetic acid and sodium dodecyl sulfate, implying that cell physiology was improved. Most importantly, the display performance was highly enhanced as a result of the increased specific fluorescence intensity without growth arrest. The results of transmission electron microscopy indicate that the density of surface-displayed EYFP was highly increased upon Skp coexpression. Cells with EYFP display experienced extracytoplasmic stress, as reflected by the induced promoter activities of three stress-responsive genes, degP, cpxP, and rpoH. The extracytoplasmic stress reflected by the degP promoter activity appears to be consistent with the cell physiology observed phenotypically under various culture conditions for cell-surface display. Therefore, the PdegP:: lacZ allele was proposed to be a suitable "sensor" for monitoring the extracytoplasmic stress and cell physiology during the course of E. coli cell-surface display. [source] Cancer chronotherapy: Principles, applications, and perspectivesCANCER, Issue 1 2003Marie-Christine Mormont Ph.D. Abstract BACKGROUND Cell physiology is regulated along the 24-hour timescale by a circadian clock, which is comprised of interconnected molecular loops involving at least nine genes. The cellular clocks are coordinated by the suprachiasmatic nucleus, a hypothalamic pacemaker that also helps the organism adjust to environmental cycles. The rest-activity rhythm is a reliable marker of the circadian system function in both rodents and humans. This circadian organization is responsible for predictable changes in the tolerability and efficacy of anticancer agents, and possibly also may be involved in tumor promotion or growth. METHODS Expected least toxic times of chemotherapy were extrapolated from experimental models to human subjects with reference to the rest-activity cycle. The clinical relevance of the chronotherapy principle (i.e., treatment administration as a function of rhythms) has been investigated previously in randomized multicenter trials. RESULTS In the current study, chronotherapeutic schedules were used to safely document activity of the combination of oxaliplatin, 5-fluorouracil, and leucovorin against metastatic colorectal carcinoma and to establish new medicosurgical management for this disease, and were reported to result in unprecedented long-term survival. CONCLUSIONS Chronotherapy concepts appear to offer further potential to improve current cancer treatment options as well as to optimize the development of new anticancer or supportive agents. Cancer 2003;97:155,69. © 2003 American Cancer Society. DOI 10.1002/cncr.11040 [source] Cytoprotection of beta cells: rational gene transfer strategiesDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 3 2006Cillian McCabe Abstract Gene transfer to pancreatic islets may prove useful in preventing islet cell destruction and prolonging islet graft survival after transplantation in patients with type 1 diabetes mellitus (T1DM). Potentially, a host of therapeutically relevant transgenes may be incorporated into an appropriate gene delivery vehicle and used for islet modification. An increasing understanding of the molecular pathogenesis of immune-mediated beta cell death has served to highlight molecules which have become suitable candidates for promoting islet cell survival in the face of oxidative stress. This review aims to give an overview of some conventional gene transfer strategies aimed at promoting islet cell survival in the face of cytokine onslaught. These strategies target three aspects of islet cell physiology: redox status and antioxidant defence, anti-apoptotic gene expression and mediators of cytokine signal transduction pathways. Copyright © 2006 John Wiley & Sons, Ltd. [source] Degradation of alkanes by bacteriaENVIRONMENTAL MICROBIOLOGY, Issue 10 2009Fernando Rojo Summary Pollution of soil and water environments by crude oil has been, and is still today, an important problem. Crude oil is a complex mixture of thousands of compounds. Among them, alkanes constitute the major fraction. Alkanes are saturated hydrocarbons of different sizes and structures. Although they are chemically very inert, most of them can be efficiently degraded by several microorganisms. This review summarizes current knowledge on how microorganisms degrade alkanes, focusing on the biochemical pathways used and on how the expression of pathway genes is regulated and integrated within cell physiology. [source] Redundant role for Zap70 in B cell development and activationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2008Farnaz Fallah-Arani Dr. Abstract Expression of the Syk family tyrosine kinase Zap70 is strongly correlated with poor clinical outcome in chronic lymphocytic leukemia, the most common human leukemia characterized by B cell accumulation. The expression of Zap70 may reflect the specific cell of origin of the tumor or may contribute to pathology. Thus, the normal role of Zap70 in B cell physiology is of great interest. While initial studies reported that Zap70 expression in the mouse was limited to T and NK cells, more recent work has shown expression in early B cell progenitors and in splenic B cells, suggesting that the kinase may play a role in the development or activation of B cells. In this study, we show that Zap70 is expressed in all developing subsets of B cells as well as in recirculating B cells, marginal zone B cells and peritoneal B1 cells. Analysis of Zap70-deficient mice shows no unique role for Zap70 in either the development of B cells or in their in vitro and in vivo activation. However, we show that Zap70 can rescue the defective positive selection of immature B cells into the recirculating pool in Syk-deficient mice, demonstrating functional redundancy between these two kinases. [source] Positively Charged Material Surfaces Generated by Plasma Polymerized Allylamine Enhance Vinculin Mobility in Vital Human Osteoblastss,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Henrike Rebl Abstract Several studies suggest that the modification of an implant surface by chemical means plays an important role in bone tissue engineering. Previously we have shown that osteoblast cell adhesion and spreading can strongly be increased by a positively charged surface. Cell adhesion and migration are two vital processes that are completely dependent on coordinated formation of focal adhesions. Changes in the organization of the actin cytoskeleton and the focal adhesions are essential for numerous cellular processes including cell motility and tissue morphogenesis. We examined the mobility of the cytoskeletally associated protein vinculin on functionalized surfaces using plasma polymerized allylamine (PPAAm), a homogenous plasma polymer layer with randomly distributed amino groups. In living, GFP,vinculin transfected osteoblastic cells we determined a significant increase in vinculin mobility and vinculin contact length on PPAAm compared to collagen I coated surfaces during the initial adhesion phase. We suggest that positive charges control the cell physiology which seems to be dominant over the integrin receptor binding to collagen I. The results emphasize the role of the surface charge for the design of artificial scaffolds in bone repair. [source] Calcium-independent cytoskeleton disassembly induced by BAPTAFEBS JOURNAL, Issue 15 2004Yasmina Saoudi In living organisms, Ca2+ signalling is central to cell physiology. The Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane- N,N,N,,N,-tetraacetic acid (BAPTA) has been widely used as a probe to test the role of calcium in a large variety of cell functions. Here we show that in most cell types BAPTA has a potent actin and microtubule depolymerizing activity and that this activity is completely independent of Ca2+ chelation. Thus, the depolymerizing effect of BAPTA is shared by a derivative (D-BAPTA) showing a dramatically reduced calcium chelating activity. Because the extraordinary depolymerizing activity of BAPTA could be due to a general depletion of cell fuel molecules such as ATP, we tested the effects of BAPTA on cellular ATP levels and on mitochondrial function. We find that BAPTA depletes ATP pools and affects mitochondrial respiration in vitro as well as mitochondrial shape and distribution in cells. However, these effects are unrelated to the Ca2+ chelating properties of BAPTA and do not account for the depolymerizing effect of BAPTA on the cell cytoskeleton. We propose that D-BAPTA should be systematically introduced in calcium signalling experiments, as controls for the known and unknown calcium independent effects of BAPTA. Additionally, the concomitant depolymerizing effect of BAPTA on both tubulin and actin assemblies is intriguing and may lead to the identification of a new control mechanism for cytoskeleton assembly. [source] Vascular endothelium: the battlefield of dengue virusesFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2008Atanu Basu Abstract Increased vascular permeability without morphological damage to the capillary endothelium is the cardinal feature of dengue haemorrhagic fever (DHF)/dengue shock syndrome (DSS). Extensive plasma leakage in various tissue spaces and serous cavities of the body, including the pleural, pericardial and peritoneal cavities in patients with DHF, may result in profound shock. Among various mechanisms that have been considered include immune complex disease, T-cell-mediated, antibodies cross-reacting with vascular endothelium, enhancing antibodies, complement and its products, various soluble mediators including cytokines, selection of virulent strains and virus virulence, but the most favoured are enhancing antibodies and memory T cells in a secondary infection resulting in cytokine tsunami. Whatever the mechanism, it ultimately targets vascular endothelium (making it a battlefield) leading to severe dengue disease. Extensive recent work has been done in vitro on endothelial cell monolayer models to understand the pathophysiology of vascular endothelium during dengue virus (DV) infection that may be translated to help understand the pathogenesis of DHF/DSS. The present review provides a broad overview of the effects of DV infection and the associated host responses contributing towards alterations in vascular endothelial cell physiology and damage that may be responsible for the DHF/DSS. [source] Nucleocytoplasmic protein traffic and its significance to cell functionGENES TO CELLS, Issue 10 2000Yoshihiro Yoneda In eukaryotic cells, cell functions are maintained in an orderly manner through the continuous traffic of various proteins between the cell nucleus and the cytoplasm. The nuclear import and export of proteins occurs through nuclear pore complexes and typically requires specific signals: the nuclear localization signal and nuclear export signal, respectively. The transport pathways have been found to be highly divergent, but are known to be largely mediated by importin ,-like transport receptor family molecules. These receptor molecules bind to and carry their cargoes directly or via adapter molecules. A small GTPase Ran ensures the directionality of nuclear transport by regulating the interaction between the receptors and their cargoes through its GTP/GDP cycle. Moreover, it has been recently elucidated how the transport system is involved in various functions of cell physiology, such as cell cycle control. [source] Karyotypic similarity identified by multiplex-FISH relates four prostate adenocarcinoma cell lines: PC-3, PPC-1, ALVA-31, and ALVA-41GENES, CHROMOSOMES AND CANCER, Issue 4 2001Marileila Varella-Garcia Recently developed molecular cytogenetic techniques for karyotyping are providing new and important insights regarding the chromosomal changes that occur in solid tumors. We used multiplex-FISH to analyze four adenocarcinoma cell lines, PC-3, PPC-1, ALVA-31, and ALVA-41, in which the characterization of a large number of rearranged chromosomes was partially or substantially inconclusive by G-banding. Although the original descriptions of these lines depict them as distinct entities established from different patients, this study demonstrates that these four lines share numerous, highly rearranged chromosomes, strongly supporting the conclusion that they are derived from the same patient material. Our analysis indicates that PPC-1, ALVA-31, and ALVA-41 were derived from PC-3 through mechanisms involving clonal progression represented by sequential changes and clonal diversion represented by differing patterns of changes. Extensive cellular heterogeneity was detected in all four lines, and most rearrangements included segments derived from multiple chromosomes. Each line also showed a set of unique derivative chromosomes. However, a limited number of metaphase cells (approximately 10) was analyzed for each line, and numerous single-cell abnormalities were detected in all of them. Therefore, it is plausible that the number of clonal, shared, and/or unique rearrangements has been underestimated. These cell lines have been utilized as models for understanding the biology of prostate cancer and reportedly differ in their cell physiology. Rather than detracting from their value, a complete understanding of the interrelationships of these lines to one another may provide the opportunity to define the molecular changes that have led to their individual malignant phenotypes. © 2001 Wiley-Liss, Inc. [source] Specific dynamic and noninvasive labeling of pancreatic , cells in reporter miceGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 4 2005Ahmi Ben-Yehudah Abstract Noninvasive detection of differentiated cells is increasingly demanded for accurate and reliable assessments of both in vitro and in vivo experimental systems. Here we present an efficient, innovative approach for imaging the , cells of the pancreatic islets of Langerhans. The main physiologic function of , cells is glucose-stimulated insulin secretion. This function is facilitated through the synthesis and storage of insulin in secretory vesicles of , cells, which then release their contents when , cells are exposed to hyperglycemic conditions. To visualize , cells in vivo in the mouse, we used targeted mutagenesis techniques to construct a modified insulin II (InsII) gene allele, InsIIEGFP, that expresses a proinsulin-EGFP (enhanced green fluorescent protein) fusion peptide. The EGFP portion of this fusion is entirely within the C-peptide portion of the proinsulin peptide. This fusion protein is processed in , cells to insulin and EGFP-tagged C peptide, which are stored together in cytoplasmic secretory vesicles. The large amount of vesicular EGFP-tagged C peptide is evident as a characteristic robust and specific fluorescence pattern in the , cells of InsIIEGFP mice. This innovative method of visualizing , cells will be a useful tool in the study of both , cell physiology and the development of the endocrine cells of the pancreas.genesis 43:166,174, 2005. © 2005 Wiley-Liss, Inc. [source] Potential and Bottlenecks of Bioreactors in 3D Cell Culture and Tissue ManufacturingADVANCED MATERIALS, Issue 32-33 2009David Wendt Abstract Over the last decade, we have witnessed an increased recognition of the importance of 3D culture models to study various aspects of cell physiology and pathology, as well as to engineer implantable tissues. As compared to well-established 2D cell-culture systems, cell/tissue culture within 3D porous biomaterials has introduced new scientific and technical challenges associated with complex transport phenomena, physical forces, and cell,microenvironment interactions. While bioreactor-based 3D model systems have begun to play a crucial role in addressing fundamental scientific questions, numerous hurdles currently impede the most efficient utilization of these systems. We describe how computational modeling and innovative sensor technologies, in conjunction with well-defined and controlled bioreactor-based 3D culture systems, will be key to gain further insight into cell behavior and the complexity of tissue development. These model systems will lay a solid foundation to further develop, optimize, and effectively streamline the essential bioprocesses to safely and reproducibly produce appropriately scaled tissue grafts for clinical studies. [source] Small interfering RNA (siRNA) inhibits the expression of the Her2/neu gene, upregulates HLA class I and induces apoptosis of Her2/neu positive tumor cell linesINTERNATIONAL JOURNAL OF CANCER, Issue 1 2004Aniruddha Choudhury Abstract Silencing of a specific mRNA using double stranded RNA oligonucleotides represents one of the newest technologies for suppressing a specific gene product. Small interfering RNA (siRNA) are 21 nucleotides long, double stranded RNA fragments that are identical in sequence to the target mRNA. We designed 3 such siRNA against the Her2/neu (HER2) gene. The HER2 gene is known to play an important role in the oncogenesis of several types of cancers, such as breast, ovarian, colon and gastric cancers. Introduction of the siRNA into HER2 positive tumor lines in vitro greatly reduced the cell surface expression of the HER2 protein. Concurrently, a range of effects on cell physiology, such as growth inhibition or apoptosis, was observed. The expression of HLA class I was observed to be upregulated when HER2 was silenced with siRNA. Treatment of SKBr3 and MCF7/HER2 tumor cell lines with the HER2 siRNA resulted in growth arrest of cells in the late G1/S-phase. Our results suggest that siRNA may be an effective method of abrogating the effect of HER2 in tumorigenesis. © 2003 Wiley-Liss, Inc. [source] Peptidase activity in various species of dairy thermophilic lactobacilliJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004M. Gatti Abstract Aims:, The aim of the present work was to evaluate the enzymatic potential manifested by aminopeptidase activity of different thermophilic Lactobacillus biotypes and to measure the influence of cell growth phase on enzyme expression. Methods and Results:, The activities were evaluated by the hydrolysis of , -naphthylamide substrates for both whole and mechanically disrupted cells of L. helveticus, L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis strains, collected from both the exponential and the stationary growth phase. In general, activities were higher for cells in the exponential rather than in the stationary phase and the disrupted cells showed higher activities than the whole cells. The highest activity expressed by all strains corresponded to X-prolyl-dipeptidyl aminopeptidase while a moderate activity was observed towards Arg- ,Na, Lys- ,Na and Leu- ,Na. The lowest activity was observed for Pro- ,Na. Conclusions:, It may be inferred that the cell structure and the cell physiology are crucial to define the level of efficiency of expression for aminopeptidase activity. The two species may be characterized by a different enzymatic system that hydrolyses N-terminal leucine. Significance and Impact of the Study:, The differences of peptidase activities in L. helveticus and L. delbrueckii species acquires an importance to comprehend their role in the biochemical events occurring in cheese ripening. [source] HIF-1 and p53: communication of transcription factors under hypoxiaJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2004Tobias Schmid Abstract Oxygen sensing and reactivity to changes in the concentration of oxygen is a fundamental property of cell physiology. The lack of O2 (hypoxia) is transmitted into many adaptive responses, a process that is largely controlled by a transcription factor known as hypoxia inducible factor-1 (HIF-1). More recent reports suggest that besides its traditional regulation via proteasomal degradation other signaling pathways contribute to stability regulation of the HIF-1, subunit and/or HIF-1 transactivation. These regulatory circuits allow for the integration of HIF-1 into scenarios of cell-survival vs. cell-death with the rule of the thumb that short-term mild hypoxia maintains cell viability while prolonged and severe hypoxia provokes cell demise. Cell death pathways are associated with stabilization of the tumor suppressor p53, a response also seen under hypoxic conditions. Here we summarize recent information on accumulation of HIF-1, and p53 under hypoxia and provide a model to explain the communication between HIF-1 and p53 under (patho)physiological conditions. [source] S100A6 (calcyclin) deficiency induces senescence-like changes in cell cycle, morphology and functional characteristics of mouse NIH 3T3 fibroblastsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2010omnicki, ukasz P. S Abstract S100A6 (calcyclin) is a calcium binding protein with two EF-hand structures expressed mostly in fibroblasts and epithelial cells. We have established a NIH 3T3 fibroblast cell line stably transfected with siRNA against S100A6 to examine the effect of S100A6 deficiency on non-transformed cell physiology. We found that NIH 3T3 fibroblasts with decreased level of S100A6 manifested altered cell morphology and proliferated at a much slower pace than the control cells. Cell cycle analysis showed that a large population of these cells lost the ability to respond to serum and persisted in the G0/G1 phase. Furthermore, fibroblasts with diminished S100A6 level exhibited morphological changes and biochemical features of cellular senescence as revealed by ,-galactosidase and gelatinase assays. Also, S100A6 deficiency induced changes in the actin cytoskeleton and had a profound impact on cell adhesion and migration. Thus, we have shown that the S100A6 protein is involved in multiple aspects of fibroblast physiology and that its presence ensures normal fibroblast proliferation and function. J. Cell. Biochem. 109: 576,584, 2010. © 2009 Wiley-Liss, Inc. [source] Rcl is a novel ETV1/ER81 target gene upregulated in breast tumorsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2008Sook Shin Abstract ETV1 (ER81) is a transcription factor that can be activated by HER2/Neu, a proto-oncoprotein often overexpressed in metastatic breast tumors. Here, we demonstrate that ETV1 downregulation suppresses proliferation of HER2/Neu-positive MDA-MB-231 breast cancer cells in vitro and tumor formation in vivo, proving for the first time the existence of a critical role of ETV1 in breast cancer cell physiology. A screen for novel ETV1 target genes hinted at Rcl, an enzyme involved in nucleotide metabolism. To characterize the human Rcl gene, we cloned its promoter and found that ETV1 and HER2/Neu cooperated in activating the Rcl promoter, whereas a dominant-negative ETV1 molecule suppressed the Rcl promoter. Moreover, ETV1 and HER2/Neu synergized to upregulate the endogenous Rcl gene. ETV1 also bound to the Rcl promoter in vivo, indicating that Rcl is a bona fide target gene of ETV1. Hybridization of Rcl cDNA to a breast cancer array revealed that Rcl is overexpressed in ,40% of all breast tumors. Importantly, its expression significantly escalates with increasing tumor grade, strongly implicating that Rcl contributes to breast tumorigenesis. Since joint overexpression of Rcl with vascular endothelial growth factor, another target gene of ETV1, has been shown to induce tumor formation, Rcl may be one crucial effector of ETV1 and HER2/Neu in breast tumors. Furthermore, given its expression pattern and enzymatic function in nucleotide metabolism, Rcl presents itself as a novel target in breast cancer therapy via modulation of its activity by small molecule drugs. J. Cell. Biochem. 105: 866,874, 2008. © 2008 Wiley-Liss, Inc. [source] Cross-talk between the insulin-like growth factor (IGF) axis and membrane integrins to regulate cell physiologyJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2010James Beattie The biology of cross-talk between activated growth factor receptors and cell-surface integrins is an area which has attracted much interest in recent years (Schwartz and Ginsberg, 2002). This review discusses the relationship between the insulin-like growth factor (IGF) axis and cell-surface integrin receptors in the regulation of various aspects of cell physiology. Key to these interactions are signals transmitted between integrins and the IGF-I receptor (IGF-IR) when either or both are bound to their cognate ligands and we will review the current state of knowledge in this area. The IGF axis comprises many molecular components and we will also discuss the potential role of these species in cross-talk with the integrin receptor. With respect to integrin ligands, we will mainly focus on the well-characterized interactions of the two extracellular matrix (ECM) glycoproteins fibronectin (FN) and vitronectin (VN) with cell-surface ligands, and, how this affects activity through the IGF axis. However, we will also highlight the importance of other integrin activation mechanisms and their impact on IGF activity. J. Cell. Physiol. 224: 605,611, 2010. © 2010 Wiley-Liss, Inc. [source] Synthetic retinoids as inducers of apoptosis in ovarian carcinoma cell linesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2004William F. Holmes Apoptosis is also known as programmed cell death. Apoptosis plays an essential role in maintaining normal tissue and cell physiology in multicellular organisms. Clearance of aberrant or pre-cancerous cells occurs through the induction of apoptosis. It has been reported that many tumors and tumor cell lines have dysfunctional apoptosis signaling, causing these tumors to escape immune monitoring and internal cellular control mechanisms. One potential cause of this dysfunctional apoptosis is the tumor suppressor p53, an important regulator of growth arrest and apoptosis that is mutated in over 50% of all cancers. Retinoids have great potential in the areas of cancer therapy and chemoprevention. While some tumor cells are sensitive to the growth inhibitory effects of natural retinoids such as all- trans -retinoic acid (ATRA), many ovarian tumor cells are not. 6-[3-(1-Admantyl)]-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437) and fenretinide N -[4-hydroxyphenyl] retinamide (4-HPR) are conformationally restricted synthetic retinoids that induce growth arrest and apoptosis in both ATRA-sensitive and ATRA-resistant ovarian tumor cell lines. Recently, we have identified the molecular pathways of apoptosis induced by treatment of ovarian carcinoma cells with mutated p53 by CD437 and 4-HPR. © 2004 Wiley-Liss, Inc. [source] A short history of blebbingJOURNAL OF MICROSCOPY, Issue 3 2008G.T. CHARRAS Summary Blebs are protrusions of the cell membrane. They are the result of actomyosin contractions of the cortex, which cause either transient detachment of the cell membrane from the actin cortex or a rupture in the actin cortex. Then, cytosol streams out of the cell body and inflates the newly formed bleb. During expansion, which lasts ,30 s, the bleb is devoid of actin and the surface area increases through further tearing of membrane from the cortex and convective flows of lipids in the plane of the membrane through the bleb neck. Once expansion slows, an actin cortex is reconstituted. First actin-membrane linker proteins, such as ezrin, are recruited to the bleb, then actin, actin-bundling proteins and finally myosin motor proteins. Retraction lasts ,2 min and is powered by myosin motor proteins. Though it has been less studied than other actin-based membrane protrusions such as lamellipodia or filopodia, blebbing is a common feature of cell physiology during cell movement, cytokinesis, cell spreading and apoptosis. This review will succinctly attempt to summarize what we know about the mechanisms involved in blebbing, when it appears in cell physiology and what open questions remain. [source] Evaluation of rapid volume changes of substrate-adherent cells by conventional microscopy 3D imagingJOURNAL OF MICROSCOPY, Issue 3 2004F. BOUDREAULT Summary Precise measurement of rapid volume changes of substrate-adherent cells is essential to understand many aspects of cell physiology, yet techniques to evaluate volume changes with sufficient precision and high temporal resolution are limited. Here, we describe a novel imaging method that surveys the rapid morphology modifications of living, substrate-adherent cells based on phase-contrast, digital video microscopy. Cells grown on a glass substrate are mounted in a custom-designed, side-viewing chamber and subjected to hypotonic swelling. Side-view images of the rapidly swelling cell, and at the end of the assay, an image of the same cell viewed from a perpendicular direction through the substrate, are acquired. Based on these images, off-line reconstruction of 3D cell morphology is performed, which precisely measures cell volume, height and surface at different points during cell volume changes. Volume evaluations are comparable to those obtained by confocal laser scanning microscopy (,Volume , 14%), but our method has superior temporal resolution limited only by the time of single-image acquisition, typically ,100 ms. The advantages of using standard phase-contrast microscopy without the need for cell staining or intense illumination to monitor cell volume make this system a promising new tool to investigate the fundamentals of cell volume physiology. [source] Immunohistochemical evidence of PTEN in oral squamous cell carcinoma and its correlation with the histological malignancy grading systemJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 7 2002Cristiane Helena Squarize Abstract PTEN is a tumor suppressor gene that encodes a dual phosphatase protein capable of modulating membrane receptors and interaction of the cell and extracellular stimuli. PTEN regulates cell physiology such as division, differentiation/apoptosis and also migration and adhesion. The expression of PTEN was evaluated by immunohistochemistry in OSCC and compared to a well-established histological malignancy grading system. The well-differentiated OSCC were 59.1% and poorly differentiated were 40.9%. According to PTEN expression, the cases were 45.5% positive (the entire tumor showed stained), 22.7% mixed (both negative and positive cells were present) and 31.8% negative (no staining was seen in the tumor cells). PTEN expression in OSCC was related to the malignancy grade (P < 0.0005). Aggressive tumors with a high score of malignancy did not express PTEN, and clearly, the PTEN expression was present in the epithelium adjacent to the tumor. Negative cells were in the invasion border of the tumor. This result suggests that PTEN is related to histologic pattern and biological behavior of OSCC and may be a used as a prognostic marker in the future. The role of PTEN during carcinogenesis and as a biomarker should be further investigated. [source] Critical role of the vascular endothelial cell in health and disease: a review articleJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 2 2004Todd C. Duffy DVM Abstract Objective: To review the human and veterinary literature on the role of the vascular endothelial cell in health, as well as during hypoxic and inflammatory disease states. Data sources: Data from human and veterinary literature were reviewed through a Pubmed search and a manual search of the references listed in articles covering some aspect of vascular endothelial cell function. Human data synthesis: The development of techniques that allow the maintenance and growth of endothelial cells in culture has produced an explosion of new research in the area of endothelial cell physiology. This plethora of data has revealed the critical role that vascular endothelial cells play in both health and disease states. Interspecies variations can occur with respect to the vascular endothelial cell physiology and its response to pathologic conditions. Veterinary data synthesis: There is a paucity of information regarding the role of the vascular endothelial cell in health or disease of small animals. Many human studies use species cared for by veterinarians, providing information that may be applied to small animals and that may be used to construct future studies. Conclusion: An organ system itself, the vascular endothelium is an essential component of all organs in the body. The endothelial cell lining functions to maintain selective permeability between the blood and the tissue it supplies, regulate vascular tone, sustain blood fluidity through regulation of coagulation, and modulate interaction of leukocytes with the interstitium and inflammatory reactions. During disease states, the endothelial cell functions locally to limit the boundaries of the disease process. If these functions are not controlled, they can become a part of the pathogenic process, contributing to blood stasis and thrombosis, potentiation of local inflammation and interstitial edema formation, subsequent tissue hypoxia, and multiple organ dysfunction. Pharmacological investigations targeting the modulation of endothelial function during disease states have not yet advanced treatment protocols. Since all critically ill animals are at risk for some degree of endothelial cell dysfunction, treatment regimens should focus on promoting capillary blood flow and tissue oxygen delivery. [source] Epidermal growth factor receptor and claudin-2 participate in A549 permeability and remodeling: Implications for non-small cell lung cancer tumor colonizationMOLECULAR CARCINOGENESIS, Issue 6 2009Yakov Peter Abstract Tumor colonization involves changes in cell permeability and remodeling. Paracellular permeability is regulated by claudins, integrated tight junction (TJ) proteins, located on the apicolateral portion of epithelial cells. Epidermal growth factor (EGF) was reported to modify cellular claudin levels and induce remodeling. To investigate a role for EGF receptor (EGFR) activation in tumor colonization we studied the effect of EGF and claudin-2 overexpression on permeability and cell reorganization in the human A549 non-small cell lung cancer (NSCLC) cell line. Our data demonstrated that A549 cells possess functional TJs and that EGF treatment increased levels of claudin-2 expression by 46%. Furthermore, EGFR signaling reduced monolayer permeability to choline and triggered cellular remodeling. The mitogen-activated protein kinase inhibitor PD98059 blocked the effect on A549 permeability and remodeling. EGF stimulation also exacerbated a fourfold increase in cell colonization elicited by claudin-2 upregulation. Our findings are consistent with the hypothesis that EGFR signaling plays an important role in A549 cell physiology and acts synergistically with claudin-2 to accelerate tumor colonization. Understanding the influence of EGF on A549 cell permeability and reorganization will help shed light on NSCLC tumor colonization and contribute to the development of novel anti-cancer treatments. © 2008 Wiley-Liss, Inc. [source] Proteolysis during long-term glucose starvation in Staphylococcus aureus COLPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 19 2009Stephan Michalik Abstract A combination of pulse-chase experiments and 2-D PAGE revealed that protein degradation appears to play a crucial role for the cell physiology of Staphylococcus aureus COL during extended periods of glucose starvation. The synthesis rate of virtually all cytosolic and radioactively labeled proteins from growing cells seemed dramatically reduced in the first 3.5,h of glucose starvation. The stability of proteins synthesized in growing cells was monitored by a pulse-chase approach on a proteome wide scale. Especially, enzymes involved in nucleic acid and amino acid biosyntheses, energy metabolism and biosynthesis of cofactors were found rather rapidly degraded within the onset of the stationary phase, whereas the majority of glycolytic and tricarboxylic acid cycle enzymes remained more stable. Furthermore, single enzymes of biosynthetic pathways were differentially degraded. A metabolite analysis revealed that glucose completely depleted from the medium in the transient phase, and amino acids such as alanine and glycine were taken up by the cells in the stationary phase. We suggest that vegetative proteins no longer required in non-growing cells and thus no longer protected by integration into functional complexes were degraded. Proteolysis of putative non-substrate-bound or "unemployed" proteins appears to be a characteristic feature of S. aureus in order to access nutrients as an important survival strategy under starvation conditions. [source] 900 MHz modulated electromagnetic fields accelerate the clathrin-mediated endocytosis pathwayBIOELECTROMAGNETICS, Issue 3 2009Mihaela G. Moisescu Abstract We report new data regarding the molecular mechanisms of GSM-induced increase of cell endocytosis rate. Even though endocytosis represents an important physical and biological event for cell physiology, studies on modulated electromagnetic fields (EMF) effects on this process are scarce. In a previous article, we showed that fluid phase endocytosis rate increases when cultured cells are exposed to 900 MHz EMF similar to mobile phones' modulated GSM signals (217 Hz repetition frequency, 576 µs pulse width) and to electric pulses similar to the GSM electrical component. Trying to distinguish the mechanisms sustaining this endocytosis stimulation, we exposed murine melanoma cells to Lucifer Yellow (LY) or to GSM,EMF/electric pulses in the presence of drugs inhibiting the clathrin- or the caveolin-dependent endocytosis. Experiments were performed at a specific absorption rate (SAR) of 3.2 W/kg in a wire patch cell under homogeneously distributed EMF field and controlled temperature (in the range of 28.5,29.5 °C). Thus, the observed increase in LY uptake was not a thermal effect. Chlorpromazine and ethanol, but not Filipin, inhibited this increase. Therefore, the clathrin-dependent endocytosis is stimulated by the GSM,EMF, suggesting that the cellular mechanism affected by the modulated EMF involves vesicles that detach from the cell membrane, mainly clathrin-coated vesicles. Bioelectromagnetics 30:222,230, 2009. © 2008 Wiley-Liss, Inc. [source] Windows to cell function and dysfunction: Signatures written in the boundary layersBIOESSAYS, Issue 6 2010Peter J. S. Smith Abstract The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand. [source] Dynamic analysis of GS-NS0 cells producing a recombinant monoclonal antibody during fed-batch cultureBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2007Scott H. Stansfield Abstract In this study we have analyzed the dynamic covariation of the mammalian cell proteome with respect to functional phenotype during fed-batch culture of NS0 murine myeloma cells producing a recombinant IgG4 monoclonal antibody. GS-NS0 cells were cultured in duplicate 10 L bioreactors (36.5°C, 15% DOT, pH 7.0) for 335 h and supplemented with a continuous feed stream after 120 h. Cell-specific growth rate declined continuously after 72 h of culture. Cell-specific recombinant monoclonal antibody production rate (qP) varied sixfold through culture. Whilst qP correlated with relative recombinant heavy chain mRNA abundance up to 216 h, qP subsequently declined, independent of recombinant heavy chain or light chain mRNA abundance. GS-NS0 cultures were sampled at 48 h intervals between 24 and 264 h of culture for proteomic analyses. Total protein abundance and nascent polypeptide synthesis was determined by 2D PAGE of unlabeled proteins visualized by SYPRO® Ruby and autoradiography of 35S-labeled polypeptides, respectively. Covariation of nascent polypeptide synthesis and abundance with biomass-specific cell growth, glucose and glutamate consumption, lactate and Mab production rates were then examined using two partial least squares regression models. Most changes in polypeptide synthesis or abundance for proteins previously identified by mass spectrometry were positively correlated with biomass-specific growth rate. We conclude that the substantial transitions in cell physiology and qP that occur during culture utilize a relatively constant complement of the most abundant host cell machines that vary primarily with respect to induced changes in cell growth rate. Biotechnol. Bioeng. 2007;97: 410,424. © 2006 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||||||||||||||