bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fibrin‐filled scaffolds for bone‐tissue engineering: An in vivo study
Authors: Karp Jeffrey M. , Sarraf Feryal , Shoichet Molly S. , Davies John E. 
Published: August 2004

AbstractRecently, fibrin sealants that typically contain supra physiological concentrations of fibrinogen and thrombin have been investigated as matrices to facilitate the delivery of cells within biodegradable scaffolds for tissue engineering applications. It is well known from in vitro experiments that the thrombin concentration present during fibrin polymerization influences the structural properties of fibrin, and these can affect cell invasion. This study was conducted to determine whether the structural properties of fibrin can affect bony wound healing in vivo. Drill hole defects were created in the distal femurs of 20 rats. Four experimental groups were used: nontreated defects, scaffolds alone, and scaffolds filled with fibrin polymerized with either a low thrombin concentration [fibrin(low T)] or a high thrombin concentration [fibrin(high T)]. The area of bone formed at 2, 5, and 11 days after implantation was determined histomorphometrically. After 5 days, scaffolds filled with fibrin(high T) were infiltrated with less bone than empty scaffolds (p < 0.05), but no statistical difference was found between the empty scaffolds and the scaffolds filled with fibrin(low T). After 11 days, both fibrin‐filled scaffolds significantly delayed bony wound healing (p < 0.004). Reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of the two fibrin formulations showed no difference in γ‐γ crosslink formation. This work demonstrates that fibrin sealants in their present state are not ideal for enhancing bone‐tissue invasion into scaffolds, and that the structural properties of fibrin matrices may be an important design parameter for maximizing host tissue invasion during wound healing. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 162–171, 2004
Osteogenic protein‐1 enhances osseointegration of titanium implants coated with peri‐apatite in rabbit femoral defect
Authors: Zhang Renwen , An Yuehuei , Toth Carol A. , Draughn Robert A. , Dimaano Nena M. , Hawkins Monica V. 
Published: August 2004

AbstractThis study evaluated the effect of osteogenic protein‐1 (OP‐1) carried by Peri‐Apatite (PA) on bone healing in the gap surrounding implants in a rabbit model. Cylindrical titanium implants (3 × 9 mm) were uniformly coated with PA precipitated from a calcium and phosphate solution. OP‐1 solution containing 60 μg OP‐1 was directly loaded on the implants immediately before implantation for the experimental group, whereas buffer solution was loaded on the implants for the control. The implant was placed in the distal femur and surrounded by a 1‐mm gap. The implants were retrieved and examined 6 weeks after implantation. Mechanical testing (push‐out) data showed that OP‐1 enhanced implant fixation by 80%. Histomorphometric measurements indicated that bone ingrowth in the initial gap expressed as a percentage of the whole gap was significantly higher in the specimens treated with OP‐1 than the control group (25.4% vs. 8.9%, p < 0.05). The percentage of the surface of implants, which was covered by bone, was significantly higher in the OP‐1‐treated group compared to the control group (65% vs. 25%, p < 0.05). This study suggests that OP‐1 can be loaded on orthopedic implants through PA to enhance the osseointegration of orthopedic implant. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 408–413, 2004
FTIR study of carbonate loss from carbonated apatites in the wide temperature range
Authors: Rau J.V. , Cesaro S. Nunziante , Ferro D. , Barinov S.M. , Fadeeva I.V. 
Published: August 2004

AbstractThe mineral constituent of bone tissue is a carbonate‐substituted apatite (CHA). The thermal stability of the CHA has been revealed to depend on the substitution type and degree, although relatively little is known about this behavior. The aim of this study was to investigate the carbonate loss from synthetic CHAs in equilibrium conditions in a wide temperature range. An approach based on FTIR spectroscopy of condensed gas phase was applied to evaluate the CO and CO2 release with increasing temperature. Four different CHAs were studied, which were prepared by either precipitation from solution or the solid‐state interaction. The samples differ from each other by the substitution degree. In one of the samples calcium was partially substituted by magnesium. Decomposition was shown to start at surprisingly low temperature, about 400°C, and the CO content increases monotonously with the increase of temperature. The CO2 content goes through a maximum due to its decomposition into carbon monoxide and oxygen, the temperature of this maximum being strongly dependent on the chemical synthesis route. Therefore, control of the sintering atmosphere with respect to the CO2/CO ratio is needed when preparing the carbonated apatite bioceramics. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 441–447, 2004
In vivo performance of dual ligand augmented endothelialized expanded polytetrafluoroethylene vascular grafts
Authors: Chan Bernard P. , Liu Wenge , Klitzman Bruce , Reichert William M. , Truskey George A. 
Published: August 2004

AbstractIn this study, we examined combinations of three approaches to improve the adhesion of endothelial cells (EC) onto expanded polytetrafluoroethylene (ePTFE) vascular grafts placed at the femoral artery of rats: (1) high‐affinity receptor‐ligand binding of RGD–streptavidin (SA) and biotin to supplement integrin‐mediated EC adhesion; (2) cell sodding to pressurize the seeded EC into the interstices of the ePTFE grafts; and (3) longer postseeding attachment time from 1 to 24 h prior to implantation. An in vitro system, which accounts for cell loss due to both graft handling and shear stress, was designed to optimize conditions for in vivo experiments. Results suggest that longer in vitro attachment time enabled the adherent EC to endure mechanical stresses by forming strong adhesions to the underlying extracellular matrix substrates; cell sodding helped to retain the adherent EC by physically docking the cells against the graft interstices; and the SA–biotin interaction enhanced the early attachment of EC but did not lead to better cell retention or reduced surface coverage of blood clot in the current study. Mechanical manipulation of cells during implantation is a limiting factor in maintaining a confluent EC layer on synthetic vascular grafts. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 52–63, 2005
Bone morphogenetic proteins in vertebrate hematopoietic development
Authors: Snyder Alexandra , Fraser Stuart T. , Baron Margaret H. 
Published: August 2004

AbstractDuring embryonic development, the hematopoietic system is the first to generate terminally differentiated, functional cell types. The urgent necessity for the early formation of blood and blood vessels during embryogenesis means that the induction, expansion, and maturation of these systems must be rapidly and precisely controlled. Bone morphogenic proteins (BMPs) have been implicated in hematopoietic development in the vertebrate embryo and stimulate the proliferation and/or differentiation of human cord blood hematopoietic stem cells (HSC) and embryonic stem cells in vitro. Here we review the mechanisms of action and potential roles of these soluble signaling molecules in vertebrate hematopoiesis. © 2004 Wiley‐Liss, Inc.
Interactions among IQGAP1, Cdc42, and the cadherin/catenin protein complex regulate Sertoli‐germ cell adherens junction dynamics in the testis
Authors: Lui Wing Yee , Mruk Dolores D. , Cheng C. Yan 
Published: August 2004

AbstractThe movement of developing germ cells across the seminiferous epithelium during spermatogenesis involves extensive adherens junction (AJ) restructuring between Sertoli cells, as well as between Sertoli and germ cells. In this report, we show that the intricate interactions between Cdc42 (a Rho family protein of Mr ∼23 kDa originally identified in membranes of human platelets and placenta, and is the homolog of CDC42Sc, which is known to regulate of bud‐site assembly in Saccharomyces cerevisiae) and its effector, IQ motif containing GTPase activating protein (IQGAP1, Mr ∼189 kDa, it is also an actin‐binding protein known to interact with Cdc42 and Rac1 GTPases), regulate Sertoli‐germ cell, but not Sertoli‐Sertoli cell, AJ dynamics. Using testis lysates for immunoprecipitation (IP), IQGAP1 was shown to associate with E‐cadherin, N‐cadherin, and β‐catenin (but not β1‐integrin and nectin‐2), as well as with actin and vimentin (but not α‐tubulin). Moreover, IQGAP1 was found to localize to the periphery of both Sertoli and germ cells in the seminiferous epithelium, at sites of cell–cell contacts. Using fluorescent microscopy with dual fluorescent probes, IQGAP1 was found to co‐localize, at least in part, with N‐cadherin in the seminiferous epithelium consistent with their localization at the basal and apical ES. Using Sertoli‐germ cell cocultures, it was demonstrated that AJ assembly associated with a transient induction of Cdc42 and IQGAP1, which was not found when Sertoli cells were cultured alone. Lastly, a shift in the interactions of Cdc42, IQGAP1, β‐catenin, and N‐cadherin was detected in Sertoli‐germ cell cocultures using an Ca2+‐induced AJ disruption model, which was used to examine AJ disassembly and its reassembly. In the presence of Ca2+, IQGAP1 bound preferentially to Cdc42 rather than to β‐catenin. However, when Ca2+ was depleted from cocultures using EGTA, a Ca2+ chelating agent, IQGAP1 lost its affinity for Cdc42 and became tightly associated with β‐catenin, destabilizing cadherin‐mediated AJs between Sertoli and germ cells. Yet this shift of protein–protein interaction was not detected in Sertoli cells cultured alone. These results illustrate that the interactions among IQGAP1, Cdc42, and β‐catenin are crucial to the regulation of Sertoli‐germ cell, but not Sertoli‐Sertoli cell, AJ dynamics in the seminiferous epithelium. © 2005 Wiley‐Liss, Inc.
Chondrocytes isolated from tibial dyschondroplasia lesions and articular cartilage revert to a growth plate‐like phenotype when cultured in vitro
Authors: Wu Licia N.Y. , Ishikawa Yoshinori , Genge Brian R. , Wuthier Roy E. 
Published: August 2004

AbstractWe report here a comparative study of the development and behavior of chondrocytes isolated from normal growth plate tissue, tibial dyschondroplasic lesions, and from articular cartilage. The objective of these studies was to determine whether the properties exhibited by chondrocytes in dysplasic lesions or in articular cartilage were due to their cellular phenotype, their environment, or both. We had previously analyzed the electrolytes and amino acid levels in the extracellular fluid of avian growth plate chondrocytes. Using these data, we constructed a culture medium (DATP5) in which growth plate cells essentially recapitulate their normal behavior in vivo. Here, we used DATP5 to examine the behavior of chondrocytes isolated from lesions of tibial dyschondroplasia (TD). We found that once isolated from lesion and grown in this supportive medium, dysplasic chondrocytes behaved essentially like normal growth plate cells. These findings suggest that the cause of TD is local factors operating in vivo to prevent these cells from developing normally. With respect to articular chondrocytes, our data indicate that they more closely retain normal protein and proteoglycan synthesis when grown in serum‐free media. These cells readily induced mineral formation in vitro, both in the presence and absence of serum. However, in serum‐containing media, mineralization was significantly enhanced when the cells were exposed to retinoic acid (RA) or osteogenic protein‐1 (OP‐1). Our studies support previous work indicating the presence of autocrine factors produced by articular chondrocytes in vivo that prevent mineralization and preserve matrix integrity. The lack of inhibitory factors and the presence of supporting factors are likely reasons for the induction of mineralization by articular chondrocytes in vitro. © 2005 Wiley‐Liss, Inc.
Expression and localization of Muc4/sialomucin complex (SMC) in the adult and developing rat intestine: Implications for Muc4/SMC function
Authors: Rong Min , Rossi Edmund A. , Zhang Jin , McNeer Richard R. , van den Brande Jan M.H. , Yasin Mohammad , Weed Donald T. , Carothers Carraway Coralie A. , Thompson John F. , Carraway Kermit L. 
Published: August 2004

AbstractMuc4/sialomucin complex (SMC) is a high molecular mass heterodimeric membrane mucin, encoded by a single gene, and originally discovered in a highly metastatic ascites rat mammary adenocarcinoma. Subsequent studies have shown that it is a prominent component of many accessible and vulnerable epithelia, including the gastrointestinal tract. Immunoblot and immunofluorescence analyses demonstrated that Muc4/SMC expression in the rat small intestine increases from proximal to distal regions and is located predominantly in cells at the base of the crypts. These cells were postulated to be Paneth cells, based on their location, morphology, and secretory granule content. Immunohistochemistry indicated the presence of Muc4/SMC in these granules. Muc4/SMC expression was higher in the rat colon than small intestine and was abundantly present in colonic goblet cells, but not in goblet cells in the small intestine. Immunohistochemistry also suggested the presence of MUC4 in human colonic goblet cells. Biochemical analyses indicated that rat colonic Muc4/SMC is primarily the soluble form of the membrane mucin. Analyses of Muc4/SMC during development of the rat gastrointestinal tract showed its appearance at embryonic day 14 of the esophagus and at day 15 at the surface of the undifferentiated stratified epithelium at the gastroduodenal junction, then later at cell surfaces in the more distal regions of the differentiated epithelium of the small intestine, culminating in expression as an intracellular form in the crypts of the small intestine at about day 21. Limited expression in the colon was observed during development before birth at cell surfaces, with expression as an intracellular form in the goblet cells arising during the second week after birth. These results suggest that membrane mucin Muc4/SMC serves different functions during development of the intestine in the rat, but is primarily a secreted product in the adult animal. © 2005 Wiley‐Liss, Inc.
Lineage‐negative bone marrow cells travel bidirectionally in the olfactory migratory stream but maintain hematopoietic phenotype
Authors: Moore Brian E. , Colvin Gerald A. , Dooner Mark S. , Quesenberry Peter J. 
Published: August 2004

AbstractThe mammalian olfactory system is a physiologically plastic region of the brain with the potential to support implanted stem cells. We performed direct injection of lineage‐negative (lin‐neg), green fluorescent protein‐positive (GFP+) bone marrow cells into the olfactory bulb to assess cell survival and motility within the central nervous system (CNS). Before direct injection of 100,000 lin‐neg cells, some of the C57/Bl mice received 1,000 cGy brain irradiation with the aim of disabling the endogenous reservoir of periventricular neural progenitor cells. Brain harvest took place up to 2 weeks after cell implantation. Brains were evaluated for presence of GFP positivity via fluorescence microscopy. Many GFP+ cells were identified within the turbinate neuroepithelium, olfactory bulb, and frontal lobe. Most of the cells that had traveled from the implantation site adopted an elongated, arborizing morphology consistent with cellular extensions arrayed in the direction of the rostral migratory stream (RMS). No difference was seen in brain‐irradiated versus non‐irradiated mice. Antibody staining revealed that these cells did not take on a neural, glial, or endothelial phenotype, while largely retaining their hematopoietic lineage as demonstrated by CD45 positivity. © 2005 Wiley‐Liss, Inc.
Establishment of human gastric epithelial (HGE) cell lines exhibiting barrier function, progenitor, and prezymogenic characteristics
Authors: Chailler Pierre , Ménard Daniel 
Published: August 2004

AbstractThe unavailability of human cell lines representative of the gastric glandular epithelium while able to form a functional barrier restricts the application of a cell culture approach to the field of gastric epithelial physiology. In the current study, we have characterized new non‐transfected clones isolated from gastric carcinoma cell lines known to express functional markers of the human gastric mucosa (J Cell Biochem 2001;81:241). Twenty‐one clones exhibiting epithelial‐type junctions (renamed HGE cell lines) were isolated from NCI‐N87 (ATCC CRL 5822), whereas only squamous cell lines could be generated from other native strains. Of these 21 clones, HGE‐17 and HGE‐20 formed dense coherent monolayers and displayed true epithelial phenotype. E‐cadherin and ZO‐1 proteins were consistently localized at the periphery of all cells which also generated transepithelial electrical resistance. Moreover, growth factors known to be trophic for the gastric mucosa were able to stimulate mitogenesis at subconfluence. HGE‐17 exhibited a poorly differentiated precursor‐like status and responded strongly to EGF/TGFα treatment in restitution assays. HGE‐20 cells, on the other hand, exhibited a higher degree of differentiation at the ultrastructural level as well as higher gastric lipase and pepsinogen levels. These latter zymogens were compartmentalized into granules which also contained mucin‐6 (MUC6, prezymogenic‐like status). Exogenous hormones, i.e., 1 μg/ml hydrocortisone and 5 μM retinoic acid, significantly increased enzyme levels in HGE‐20. In conclusion, HGE‐17 and HGE‐20 represent the first human gastric cell lines with true epithelial characteristics, opening a venue to important applications for the study of re‐epithelization, permeability, and regulation of digestive functions in the context of gastric physiology and pathology. © 2005 Wiley‐Liss, Inc.
Animal models for the study of adenosine receptor function
Authors: Yaar R. , Jones M.R. , Chen J.‐F. , Ravid Katya 
Published: August 2004

AbstractAdenosine receptors represent a family of G‐protein coupled receptors that are ubiquitously expressed in a wide variety of tissues. This family contains four receptor subtypes: A1 and A3, which mediate inhibition of adenylyl cyclase; and A2a and A2b, which mediate stimulation of this enzyme. Currently, all receptor subtypes have been genetically deleted in mouse models except for the A2b adenosine receptor, and some have been overexpressed in selective tissues of transgenic mice. Studies involving these transgenic mice indicated that receptor levels are rate limiting, as effects were amplified upon increases in receptor level. The knockout models pointed to clusters of activities related to the physiologies of the cardiovascular and the nervous systems, which are either reduced or enhanced upon specific receptor deletion. Interestingly, the trend of effects on these systems is similar in the A1 and A3 adenosine receptor knockout mice and opposite to the effects observed in the A2a adenosine receptor knockout model. This review summarizes in vitro studies on pathways affected by each adenosine receptor, and primarily focuses on the above in vivo models generated to investigate the physiologic role of adenosine receptors. Furthermore, it illustrates the need for multiple adenosine receptor subtype deficiency studies in mice and the deletion of the A2b subtype. © 2005 Wiley‐Liss, Inc.
Involvement of the Fhit gene in the ionizing radiation‐activated ATR/CHK1 pathway
Authors: Hu Baocheng , Han Shuang‐Yin , Wang Xiang , Ottey Michelle , Potoczek Magdalena B. , Dicker Adam , Huebner Kay , Wang Ya 
Published: August 2004

AbstractFragile Histidine Triad (Fhit) gene deletion, methylation, and reduced Fhit protein expression occur in about 70% of human epithelial tumors and, in some cancers, are clearly associated with tumor progression. Specific Fhit signal pathways have not been identified, although it has been shown that Fhit overexpression leads to apoptosis in many cancer cell lines. We report in this study that Fhit−/− cells derived from gene knockout mice show much stronger S and G2 checkpoint responses than their wild type counterparts. The strong checkpoint responses are regulated by the ATR/CHK1 pathway, which contributes to the radioresistance of Fhit−/− cells. These results indicate an association of Fhit gene inactivation with increased survival after DNA damage, which is related to the over‐active checkpoints regulated by the ATR/CHK1 pathway. These results also suggest the potential effects of Fhit‐dependent DNA damage response on tumor progression. © 2004 Wiley‐Liss, Inc.
Complex H2AX phosphorylation patterns by multiple kinases including ATM and DNA‐PK in human cells exposed to ionizing radiation and treated with kinase inhibitors
Authors: Wang Hongyan , Wang Minli , Wang Huichen , Böcker Wilfried , Iliakis George 
Published: August 2004

AbstractIn eukaryotic cells, DNA double strand breaks (DSBs) cause the prompt phosphorylation of serine 139 at the carboxy terminus of histone H2AX to generate γ‐H2AX, detectable by Western blotting or immunofluorescence. The consensus sequence at the phosphorylation site implicates the phosphatidylinositol 3‐like family of protein kinases in H2AX phosphorylation. It remains open whether ATM (ataxia telangiectasia mutated) is the major H2AX kinase, or whether other members of the family, such as DNA‐PK (DNA dependent protein kinase) or ATR (ATM and Rad3 related), contribute in a functionally complementary manner. To address this question, we measured global H2AX phosphorylation in cell lysates and foci formation in individual cells of either wild type or mutant (ATM or DNA‐PK) genetic background. Normal global phosphorylation kinetics is observed after irradiation in cells defective either in ATM or DNA‐PK alone, suggesting a complementary contribution to H2AX phosphorylation. This is further supported by the observation that initial H2AX phosphorylation is delayed when both kinases are inhibited by wortmannin, as well as when ATM is inhibited by caffeine in DNA‐PK deficient cells. However, robust residual global phosphorylation is detectable under all conditions of genetic or chemical inhibition suggesting the function of additional kinases, such as ATR. Treatment with wortmannin, caffeine, or UCN‐01 produces a strong DNA‐PK dependent late global hyperphosphorylation of H2AX, uncoupled from DNA DSB rejoining and compatible with an inhibition of late steps in DNA DSB processing. Evaluation of γ‐H2AX foci formation confirms the major conclusions made on the basis of global H2AX phosphorylation, but also points to differences particularly several hours after exposure to IR. The results in aggregate implicate DNA‐PK, ATM and possibly other kinases in H2AX phosphorylation. The functional significance and the mechanisms of coordination in space and time of these multiple inputs require further investigation. © 2004 Wiley‐Liss, Inc.