bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prevention of polyurethane valve cusp calcification with covalently attached bisphosphonate diethylamino moieties
Authors: Alferiev Ivan , Stachelek Stanley J. , Lu Zhibin , Fu Angela L. , Sellaro Tiffany L. , Connolly Jeanne M. , Bianco Richard W. , Sacks Michael S. , Levy Robert J. 
Published: July 2003

AbstractObjective: Calcification of polyurethane prosthetic valve leaflets causes a major functional impairment. Previously we showed that polyurethane heart valves modified with covalently linked bisphosphonate groups were resistant to calcification in vivo. However, we also found that the highly polar anionic bisphosphonate groups on the polyurethane surface attracted sodium counter ion adsorption, and thereby increased the elastomer's water absorption to 20% of total weight. In this study we address the increased water absorption by investigating the hypothesis that covalently attaching cationic diethylamino groups to the bisphosphonate‐modified polyurethane will reduce water absorption. Thus we evaluated the mechanical and in vivo anticalcification properties of heart‐valve leaflets composed of this modified polymer. Methods: Diethylamino and bisphosphonate groups (DBP) were appended to the polyurethane Biospan's hard segment using previously published bromoalkylation methodology. Water absorption and biaxial mechanical and uniaxial failure testing were used to determine the mechanical properties of the DBP‐modified polymer. Rat subdermal implants (60 days) and extended (150 days) single pulmonary leaflet replacements in juvenile sheep provided in vivo assessments of the bisphosphonate‐modified polyurethane. Results: The water absorption properties of the DBP‐modified polymers and unmodified polyurethanes were 1.86 and 2.3 %, respectively. Biaxial mechanical tests showed the DBP‐modified polymer was more compliant than the unmodified control material, but all polymeric material had similar uniaxial failure properties. In both rat subdermal and sheep circulatory implants, the DBP‐modified polyurethane resisted calcification, as assessed by scanning electron microscopy, with complete calcification inhibition in prosthetic sheep valve leaflet replacements. Conclusion: DBP polyurethane possesses physical (water absorption) and biomechanical properties comparable to unmodified polyurethane and can resist intrinsic heart‐valve leaflet calcification in blood‐stream implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 385–395, 2003
Initiation of translation and cellular localization of Theileria annulata casein kinase IIα: Implication for its role in host cell transformation
Authors: Biermann Reinhild , Schnittger Leonhard , Beyer Doreen , Ahmed Jabbar S. 
Published: July 2003

AbstractTheileria annulata and T. parva are protozoa that infect bovine leukocytes which leads to subsequent transformation and uncontrolled proliferation of these cells. It has been proposed that the CKIIα subunit of T. parva induces mitogenic pathways of host leukocytes by being exported into the host cell. The evidence for this is the existence of a predicted N‐terminal secretion signal‐like peptide. We tested this hypothesis by analyzing gene structure, translation, and protein localization of the T. annulata CKIIα (TaCKIIα). The determined TaCKIIα‐ORF potentially codes for a 50 kDa protein with an N‐terminal extension including a possible signal sequence not present in CKIIα proteins of non‐Theileria species. However, antisera raised against TaCKIIα recognized a protein of a molecular weight of about 40 kDa and, therefore, inconsistent with this predicted molecular weight. We demonstrate by in vitro transcription/translation that this discrepancy is due to translation from a downstream initiation site omitting the putative N‐terminal signal sequence and thus excluding the notion that the protein product is secreted via the classical secretory pathway. In corroboration immunofluorescence investigations suggest that the TaCKIIα subunit is confined to the parasite schizonts within the host cell. On the basis of the above findings it seems highly unlikely that export via the classical pathway of the parasite CKIIα is the way in which this protein possibly contributes to host cell transformation. J. Cell. Physiol. 196: 444–453, 2003. © 2003 Wiley‐Liss, Inc.
Mechanism of stem cells in the central nervous system
Authors: Johansson Clas B. 
Published: July 2003

AbstractInjury to the central nervous system (CNS) can result in severe functional impairment. The brain and spinal cord, which constitute the CNS, have been viewed for decades as having a very limited capacity for regeneration. However, over the last several years, the body of evidence supporting the concept of regeneration and continuous renewal of neurons in specific regions of the CNS has increased. This evidence has significantly altered our perception of the CNS and has offered new hope for possible cell therapy strategies to repair lost function. Transplantation of stem cells or the recruitment of endogenous stem cells to repair specific regions of the brain or spinal cord is the next exciting research challenge. However, our understanding of the existing stem cell pool in the adult CNS remains limited. This review will discuss the identification and characterization of CNS stem cells in the adult brain and spinal cord. J. Cell. Physiol. 196: 409–418, 2003. © 2003 Wiley‐Liss, Inc.
Gastrin and EGF synergistically induce cyclooxygenase‐2 expression in Swiss 3T3 fibroblasts that express the CCK2 receptor
Authors: Slice Lee W. , Hodikian Raffi , Zhukova Elena 
Published: July 2003

AbstractOver‐expression of cyclooxygenase‐2 (COX‐2) has been demonstrated to be tumorigenic in transgenic mice. Chronic treatment with NSAIDs is chemoprotective for colorectal cancer. Gastrin is a growth factor for gastric mucosa and has been shown to promote proliferation of colorectal cells. Recent studies suggest that COX‐2 expression levels could mediate the growth effects of gastrin. Here, we report that gastrin increased PGE2 secretion in Swiss 3T3 cells expressing the CCK2 receptor. Gastrin dose dependently induced COX‐2 protein levels in a time dependent manner. COX‐2 mRNA levels were rapidly induced by a dose dependent increase in gastrin. Prior treatment of the cells with the CCK2 receptor specific antagonist, L365,260, inhibited gastrin‐induced COX‐2 protein and mRNA expression. Pretreatment with L364,714, the CCK1 receptor specific antagonist did not block COX‐2 induction by gastrin. Inhibition of de novo protein synthesis by cycloheximide did not block COX‐2 mRNA induction by gastrin. Also, gastrin‐dependent COX‐2 expression did not require PKC activity, activation of ERK, or transactivation of EGFR. However, co‐stimulation with EGF and gastrin synergistically induced COX‐2 protein and mRNA expression and PGE2 secretion. Measurements of COX‐2 mRNA stability and COX‐2 gene transcription reveal that EGF significantly increased the half‐life of COX‐2 mRNA with only a slight increase in the COX‐2 transcription rate. Conversely, gastrin significantly increased COX‐2 gene transcription rates but did not enhance COX‐2 mRNA stability. J. Cell. Physiol. 196: 454–463, 2003. © 2003 Wiley‐Liss, Inc.
Inhibition of cell proliferation and induction of apoptosis by ExFABP gene targeting
Authors: Di Marco Eddi , Sessarego Nadia , Zerega Barbara , Cancedda Ranieri , Descalzi Cancedda Fiorella 
Published: July 2003

AbstractEx‐FABP, an extracellular fatty acid binding lipocalin, is physiologically expressed by differentiating chicken chondrocytes and myoblasts. Its expression is enhanced after cell treatment with inflammatory stimuli and repressed by anti‐inflammatory agents, behaving as an acute phase protein. Chicken liver fragments in culture show enhanced protein expression after bacterial endotoxin treatment. To investigate the biological role of Ex‐FABP, we stably transfected proliferating chondrocytes with an expression vector carrying antisense oriented Ex‐FABP cDNA. We observed a dramatic loss of cell viability and a strong inhibition of cell proliferation and differentiation. When chondrocytes were transfected with the antisense oriented Ex‐FABP cDNA we observed that Ex‐FABP down‐modulation increased apoptotic cell number. Myoblasts transfected with the same expression vector showed extensive cell death and impaired myotube formation. We suggest that Ex‐FABP acts as a constitutive survival protein and that its expression and activation are fundamental to protect chondrocytes from cell death. J. Cell. Physiol. 196: 464–473, 2003. © 2003 Wiley‐Liss, Inc.
Vasopressin‐induced intracellular redistribution of protein kinase D in intestinal epithelial cells
Authors: Rey Osvaldo , Zhukova Elena , Sinnett‐Smith James , Rozengurt Enrique 
Published: July 2003

AbstractThe spatio‐temporal changes of signaling molecules in response to G protein‐coupled receptors (GPCR) stimulation is a poorly understood process in intestinal epithelial cells. Here we investigate the dynamic mechanisms associated with GPCR signaling in living rat intestinal epithelial cells by characterizing the intracellular translocation of protein kinase D (PKD), a serine/threonine protein kinase involved in mitogenic signaling in intestinal epithelial cells. Analysis of the intracellular steady‐state distribution of green fluorescent protein (GFP)‐tagged PKD indicated that in non‐stimulated IEC‐18 cells, GFP‐PKD is predominantly cytoplasmic. However, cell stimulation with the GPCR agonist vasopressin induces a rapid translocation of GFP‐PKD from the cytosol to the plasma membrane that is accompanied by its activation via protein kinase C (PKC)‐mediated process and posterior plasma membrane dissociation. Subsequently, active PKD is imported into the nuclei where it transiently accumulates before being exported into the cytosol by a mechanism that requires a competent Crm1 nuclear export pathway. These findings provide evidence for a mechanism by which PKC coordinates in intestinal epithelial cells the translocation and activation of PKD in response to vasopressin‐induced GPCR activation. J. Cell. Physiol. 196: 483–492, 2003. © 2003 Wiley‐Liss, Inc.
Dynamic visualization of expressed gene networks
Authors: Remy Ingrid , Michnick Stephen W. 
Published: July 2003

AbstractCellular biochemical machineries, what we call pathways, consist of dynamically assembling and disassembling macromolecular complexes. While our models for the organization of biochemical machines are derived largely from in vitro experiments, do they reflect their organization in living cells? We have developed a general experimental strategy that addresses this question by allowing the quantitative probing of molecular interactions in intact living cells. The experimental strategy is based on protein fragment complementation assays (PCA), a method whereby protein interactions are coupled to refolding of enzymes from cognate fragments where reconstitution of enzyme activity acts as the detector of a protein interaction. A biochemical machine or pathway is defined by grouping interacting proteins into those that are perturbed in the same way by common factors (hormones, metabolites, enzyme inhibitors, etc). In this review, we describe how we go from descriptive to quantitative representations of biochemical networks at an individual to whole genome level and how our approach will lead ultimately to better descriptions of the biochemical machineries that underlie living processes. J. Cell. Physiol. 196: 419–429, 2003. © 2003 Wiley‐Liss, Inc.
Cytoplasmic complex of p53 and eEF2
Authors: Yin Xia , Fontoura Beatriz M.A. , Morimoto Takashi , Carroll Robert B. 
Published: July 2003

AbstractWe have shown previously that cytoplasmic p53 is covalently linked to 5.8S rRNA. The covalent complex is associated with a small subset of polyribosomes, which includes polyribosomes translating p53 mRNA. Because 5.8S rRNA resides in or near the ribosomal P site, our findings suggested involvement of p53 in translational regulation. Ninety‐seven kiloDaltons eEF2 was found to coimmunoprecipitate in a salt‐stable complex with p53. The 97 kDa species was identified as eEF2, because it was (1) recognized by a polyclonal antiserum specific for eEF2, (2) ADP‐ribosylated by diphtheria toxin (DT), and (3) radiolabeled by γ‐32P‐azido‐GTP and UV‐irradiation. p53 and eEF2 sedimented in sucrose gradients in both polyribosomal and subribosomal fractions. Subribosomal p53 can bind eEF2 without the mediation of ribosomes, because (1) it binds subribososomal eEF2, (2) it binds phosphorylated eEF2, and (3) subribosomal p53‐bound eEF2 can be ADP‐ribosylated by DT. No effect of p53 activation was found on eEF2 expression or phosphorylation. However, the binding of eEF2 to p53 decreased when cytoplasmic p53 migrated to the nucleus. Renaturation of temperature sensitive A135V mutant p53 (ts‐p53) was found to alter the sensitivity of p53 mRNA translation, but not bulk mRNA translation, to the translocation‐specific elongation inhibitor, cycloheximide (Cx). The association of p53 with two translational components involved in ribosomal translocation, eEF2 and 5.8S rRNA, and the effect of p53 on sensitivity to the translocation inhibitor, Cx, as well as the known molecular interactions of these components in the ribosome suggest involvement of p53 in elongation. J. Cell. Physiol. 196: 475–482, 2003. © 2003 Wiley‐Liss, Inc.
Effects of collagen density on cardiac fibroblast behavior and gene expression
Authors: Loftis Melissa Joy , Sexton Dacia , Carver Wayne 
Published: July 2003

AbstractInteractions between cells and the extracellular matrix (ECM) play essential roles in modulating cell behavior during development and disease. The myocardial ECM is composed predominantly of interstitial collagen type I and type III. The composition, organization, and accumulation of these collagens are altered concurrent with cardiovascular development and disease. Changes in these parameters are thought to play significant roles in myocardial function. While a number of studies have examined how changes in the ECM affect myocardial function as a whole, much less is known regarding the response at the cellular level to changes in the collagenous ECM. Experiments were carried out to determine the effects of alterations in collagen density and ECM stiffness on the behavior of isolated heart fibroblasts. In vitro bioassays were performed to measure the effects of changes in collagen concentration (0.75–1.25 mg/ml) on adhesion, migration, spreading, and gene expression by heart fibroblasts. Increased density of collagen in 3‐dimensional gels resulted in more efficient adhesion, spreading, and migration by heart fibroblasts. These experiments indicated that the density of the collagen matrix has a significant impact on fibroblast function. These studies begin to elucidate the effects of ECM density at the cellular level in the myocardium. J. Cell. Physiol. 196: 504–511, 2003. © 2003 Wiley‐Liss, Inc.
Rap1, a small GTP‐binding protein is upregulated during arrest of proliferation in human keratinocytes
Authors: D'Silva N.J. , Mitra R.S. , Zhang Z. , Kurnit D.M. , Babcock C.R. , Polverini P.J. , Carey T.E. 
Published: July 2003

AbstractRap1 is a small GTP‐binding protein (SMG) that exists in two 95% homologous isoforms, rap1A and rap1B. The functions of the rap1 proteins are not well understood. In this report we examined expression and function of rap1 in primary (HOKs) and immortalized (IHOKs) human oral keratinocytes under different growth conditions. In HOKs, rap1 increased with passage number, suggesting a role in differentiation and arrest of proliferation. Similarly, when inhibition of proliferation and differentiation were induced in HOKs by 1.2 mM CaCl2, both rap1 and involucrin increased with increasing concentrations of CaCl2. However, when similar experiments were done with IHOKs, which continue to proliferate in the presence of 1.2 mM CaCl2, the increase in involucrin expression was similar to HOKs but there was no substantial increase in rap1, suggesting that increased expression of rap1 is linked to inhibition of proliferation rather than differentiation of keratinocytes. Upon transfection of immortalized keratinocytes with rapGAP, which inactivates both isoforms of endogenous active rap1, enhanced proliferation was observed. Thus, we conclude that rap1 inhibits proliferation in keratinocytes. J. Cell. Physiol. 196: 532–540, 2003. © 2003 Wiley‐Liss, Inc.
Cell surface expression of C1qRP/CD93 is stabilized by O‐glycosylation
Authors: Park Minha , Tenner Andrea J. 
Published: July 2003

AbstractC1qRP/CD93 is a cell surface receptor predominantly expressed on monocytes, neutrophils, endothelial cells, and early stem cell precursors. In phagocytic cells, it has been characterized as contributing to the enhancement of FcR‐ and CR1‐induced phagocytosis triggered by innate immune system defense collagens such as C1q and mannose binding lectin (MBL). Previously, we demonstrated a high level of glycosylation on C1qRP/CD93 that was predominantly O‐linked. In this study, we investigate the role of glycosylation in C1qRP/CD93 stability first by inhibiting O‐glycosylation by addition of benzyl 2‐acetamido‐2‐deoxy‐α‐D‐galactopyranoside (BAG) to the human histiocytic cell line U937, and secondly, by expression of C1qRP/CD93 in the CHO‐derived cell line ldlD which has a reversible defect in protein glycosylation. In both U937 cells and in ldlD cells transfected to express C1qRP/CD93, glycosylation deficiency caused cell surface expression levels of C1qRP/CD93 to decrease, concomitant with the detection of C1qRP/CD93 reactivity in the culture media. Metabolic labeling studies show that when glycosylation is absent, C1qRP/CD93 is synthesized and rapidly released into the culture supernatant or degraded. These studies demonstrate that O‐glycosylation is important in the stable cell surface expression of C1qRP/CD93. J. Cell. Physiol. 196: 512–522, 2003. © 2003 Wiley‐Liss, Inc.
Endothelial cell functions
Authors: Michiels Carine 
Published: July 2003

AbstractEndothelial cells play a wide variety of critical roles in the control of vascular function. Indeed, since the early 1980s, the accumulating knowledge of the endothelial cell structure as well as of the functional properties of the endothelial cells shifted their role from a passive membrane or barrier to a complex tissue with complex functions adaptable to needs specific in time and location. Hence, it participates to all aspects of the vascular homeostasis but also to physiological or pathological processes like thrombosis, inflammation, or vascular wall remodeling. Some of the most important endothelial functions will be described in the following review and more specifically, their role in blood vessel formation, in coagulation and fibribolysis, in the regulation of vascular tone as well as their participation in inflammatory reactions and in tumor neoangiogenesis. J. Cell. Physiol. 196: 430–443, 2003. © 2003 Wiley‐Liss, Inc.
The non‐homologous end‐joining pathway is not involved in the radiosensitization of mammalian cells by heat shock
Authors: Dynlacht Joseph R. , Bittner M. Eric , Bethel Jody A. , Beck Brian D. 
Published: July 2003

AbstractA synergistic increase in cell killing is observed when a heat‐shock is administered prior to, during, or immediately after exposure to ionizing radiation (IR). This phenomenon, known as heat‐radiosensitization, is believed to be mediated by inhibition of repair of radiation‐induced double strand breaks (DSB) when cells are exposed to temperatures above 42°C. However, the mechanism by which heat inhibits DSB repair is unclear. The bulk of radiation‐induced DSBs are repaired via the non‐homologous end‐joining pathway (NHEJ). Several reports indicate that the Ku70 and Ku80 subunits of the mammalian DNA‐dependent protein kinase (DNA‐PK), a complex involved in NHEJ, appear to be susceptible to a heat‐induced loss of DNA‐binding activity, with Ku80 representing the heat‐sensitive component. Since the heat‐induced loss and subsequent recovery of Ku–DNA binding activity correlates well with heat‐radiosensitization, a role for Ku80 and NHEJ in heat‐radiosensitization has been proposed. However, direct evidence implicating Ku80 (and NHEJ) in heat‐radiosensitization has been indeterminate. In this study, we demonstrate that equitoxic heat treatments at 42.5–45.5°C induce a similar amount of aggregation of Ku80 in human U‐1 melanoma cells. These data suggest that the time–temperature‐dependent relationship between heat lethality and Ku80 aggregation are similar. However, the aggregation/disaggregation of Ku80 and its transient or permanent inactivation is unrelated to heat‐radiosensitization. When survival curves were obtained for irradiated or irradiated and heated Ku80−/− mouse embryo fibroblasts (MEFs) and compared with survival curves obtained for wild‐type (WT) cells, we found that heat‐radiosensitization was not reduced in the Ku80−/− cells, but actually increased. Thus, our findings indicate that Ku80 is not essential for heat‐radiosensitization. Non‐involvement of Ku‐dependent or Ku‐independent NHEJ pathways in heat‐radiosensitization was confirmed by comparing clonogenic survival between DNA ligase IV‐defective and WT human cells. Our data therefore implicate homologous recombination in inhibition of repair of radiation‐induced DSBs and as a target for heat‐radiosensitization. J. Cell. Physiol. 196: 557–564, 2003. © 2003 Wiley‐Liss, Inc.
Tumor suppressor pRB functions as a co‐repressor of the CCAAT displacement protein (CDP/cut) to regulate cell cycle controlled histone H4 transcription
Authors: Gupta Sunita , Luong Mai X. , Bleuming Sylvia A. , Miele Angela , Luong Michael , Young Daniel , Knudsen Erik S. , van Wijnen Andre J. , Stein Janet L. , Stein Gary S. 
Published: July 2003

AbstractThe CCAAT displacement protein (CDP‐cut/CUTL1/cux) performs a key proliferation‐related function as the DNA binding subunit of the cell cycle controlled HiNF‐D complex. HiNF‐D interacts with all five classes (H1, H2A, H2B, H3, and H4) of the cell‐cycle dependent histone genes, which are transcriptionally and coordinately activated at the G1/S phase transition independent of E2F. The tumor suppressor pRB/p105 is an intrinsic component of the HiNF‐D complex. However, the molecular interactions that enable CDP and pRB to form a complex and thus convey cell growth regulatory information onto histone gene promoters must be further defined. Using transient transfections, we show that CDP represses the H4 gene promoter and that pRB functions with CDP as a co‐repressor. Direct physical interaction between CDP and pRB was observed in glutathione‐S‐transferase (GST) pull‐down assays. Furthermore, interactions between these proteins were established by yeast and mammalian two‐hybrid experiments and co‐immunoprecipitation assays. Confocal microscopy shows that subsets of each protein are co‐localized in situ. Using a series of pRB mutants, we find that the CDP/pRB interaction, similar to the E2F/pRB interaction, utilizes the A/B large pocket (LP) of pRB. Thus, several converging lines of evidence indicate that complexes between CDP and pRB repress cell cycle regulated histone gene promoters. J. Cell. Physiol. 196: 541–556, 2003. © 2003 Wiley‐Liss, Inc.