bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of PDGF‐stimulated and matrix‐mediated proliferation of human vascular smooth muscle cells by SPARC is independent of changes in cell shape or cyclin‐dependent kinase inhibitors
Authors: Motamed Kouros , Funk Sarah E. , Koyama Hidenori , Ross Russell , Raines Elaine W. , Sage E. Helene 
Published: August 2002

AbstractInteractions among growth factors, cells, and extracellular matrix regulate proliferation during normal development and in pathologies such as atherosclerosis. SPARC (secreted protein, acidic, and rich in cysteine) is a matrix‐associated glycoprotein that modulates the adhesion and proliferation of vascular cells. In this study, we demonstrate that SPARC inhibits human arterial smooth muscle cell proliferation stimulated by platelet‐derived growth factor or by adhesion to monomeric type I collagen. Binding studies with SPARC and SPARC peptides indicate specific and saturable interaction with smooth muscle cells that involves the C‐terminal Ca2+‐binding region of the protein. We also report that SPARC arrests monomeric collagen‐supported smooth muscle cell proliferation in the late G1‐phase of the cell cycle in the absence of an effect on cell shape or on levels of cyclin‐dependent kinase inhibitors. Cyclin‐dependent kinase‐2 activity, p107 and cyclin A levels, and retinoblastoma protein phosphorylation are markedly reduced in response to the addition of exogenous SPARC and/or peptides derived from specific domains of SPARC. Thus, SPARC, previously characterized as an inhibitor of platelet‐derived growth factor binding to its receptor, also antagonizes smooth muscle cell proliferation mediated by monomeric collagen at the level of cyclin‐dependent kinase‐2 activity. J. Cell. Biochem. 84: 759–771, 2002. © 2002 Wiley‐Liss, Inc.
Smoothelin contains a novel actin cytoskeleton localization sequence with similarity to troponin T
Authors: Quensel Christina , Krämer Jochen , Cardoso Maria Cristina , Leonhardt Heinrich 
Published: August 2002

AbstractSmoothelin, a cytoskeletal protein, exists in a large isoform specifically expressed in vascular smooth muscle cells, and a small visceral isoform generated by a downstream transcriptional start site. Using fusions to the green fluorescent protein, we could show that both smoothelin isoforms are localized at actin containing filaments and mapped two domains that are each sufficient for localization at the actin cytoskeleton. The first domain is located in the vascular‐specific, N‐terminal half of smoothelin and the second in the common, C‐terminal half. The second domain shares clear sequence similarity with a domain of troponin T involved in actin filament association. These results suggest that the tissue‐specific expression of smoothelin isoforms might contribute to the different contractile properties of smooth muscle cells. J. Cell. Biochem. 85: 403–409, 2002. © 2002 Wiley‐Liss, Inc.
Molecular identification of NMDA glutamate receptors expressed in bone cells
Authors: Itzstein Cécile , Cheynel Hervé , Burt‐Pichat Brigitte , Merle Blandine , Espinosa Léon , Delmas Pierre D. , Chenu Chantal 
Published: August 2002

AbstractThe N‐methyl‐D‐aspartate (NMDA) subtype of the glutamate receptor has recently been identified in bone, but the molecular composition of this receptor expressed by bone cells is unknown. NMDA receptor (NMDAR) is a hetero‐oligomeric protein composed of two classes of subunits, the essential subunit NR1 and NR2A to D subunits that do not by themselves produce functional channels but potentiate NR1 activity and confer functional variability to the receptor. These subunits coassemble in different combinations to form functionally distinct NMDAR. In this study, we have investigated the molecular composition of NMDAR expressed by osteoblasts and osteoclasts in culture, using RT‐PCR analysis, in situ hybridization and immunocytochemistry. Specific probes were designed for the different subunits of the NMDAR, and we showed by RT‐PCR analysis that mammalian osteoclasts expressed NR2B and NR2D subunits mRNAs but not NR2A and NR2C mRNAs. Rat calvaria and MG63 osteoblastic cells also expressed several NR2 subunits mRNAs, namely NR2A, NR2B, and NR2D. In situ hybridization on isolated rabbit osteoclasts and MG63 cells has confirmed the localization of NR1, NR2B, and NR2D transcripts in osteoclasts and NR1, NR2A, NR2B, and NR2D transcripts in MG63 cells. The expression of NR2D protein by bone cells was shown by immunofluorescence. These results demonstrate for the first time that osteoblasts and osteoclasts express several NR2 subunits, suggesting a molecular diversity of NMDAR channels similar to what was shown for brain. The presence of distinct functional NMDAR on bone cells may be associated with various states of bone cell differentiation and function. J. Cell. Biochem. 82: 134–144, 2001. © 2001 Wiley‐Liss, Inc.
Non‐natural CBP2 binding peptides and peptomers modulate carcinoma cell adhesion and invasion
Authors: Hebert Carla , Coletta Ricardo D. , Norris Kathleen , Nikitakis Nikolaos , Lopes Marcio , Sauk John J. 
Published: August 2002

AbstractA combinatorial approach that utilized a repertoire of bacteriophage‐peptides has identified a number of non‐natural CBP2 binding peptides. Moreover, co‐localization of some of these peptides with CBP2 in a number of tumor cell lines demonstrated that the peptides were directed to an intracellular location spatially coincident with the normal distribution of CBP2 [Sauk et al., 2000]. From among these sequences WHYPWFQNWAMA and LDSRYSLQAAMY were the most effective CBP2 binding peptides and best fulfilled the combinatorial motif containing deep hydrophobic pockets. When the hydropathic profiles of collagen α1(IV) and α2 (IV) were compared with these dodecapeptides, the hydropathic profiles of WHYPWFQNWAMA and LDSRYSLQAAMY closely matched those of α1(IV) 414–452 and α1(IV)531–543. These peptides were shown to be functional peptidomimics and possessed the ability to alter cell adhesion and invasion of human squamous cell carcinoma cell lines. Peptomers were formed of these non‐natural peptides to explore the role that a repetitive peptide may have on cell adhesion. The enhanced cell adhesion observed with the peptomers required both CBP2 antibodies and integrin antibodies for inhibition. The enhanced adhesion observed even in the face of combined antibody inhibition was consistent with such complexes possessing correspondingly slower dissociation rates. Thus, suggesting that peptomers may function in a like manner to multimeric peptide MHC complexes (tetramers) binding more than one cell receptor on a specific cell. These findings evoke both peptidomimics of native ligands and their peptomers as potential reagents by which to target tumor cells for chemotherapy, imaging, or retargeting viral vectors for gene therapy. J. Cell. Biochem. 82: 145–154, 2001. © 2001 Wiley‐Liss, Inc.
Iron‐induced oxidative stress up‐regulates calreticulin levels in intestinal epithelial (Caco‐2) cells
Authors: Núñez Marco T. , Osorio Andrea , Tapia Victoria , Vergara Alexander , Mura Casilda V. 
Published: August 2002

AbstractCalreticulin, a molecular chaperone involved in the folding of endoplasmic reticulum synthesized proteins, is also a shock protein induced by heat, food deprivation, and chemical stress. Mobilferrin, a cytosolic isoform of calreticulin, has been proposed to be an iron carrier for iron recently incoming into intestinal cells. To test the hypothesis that iron could affect calreticulin expression, we investigated the possible associations of calreticulin with iron metabolism. To that end, using Caco‐2 cells as a model of intestinal epithelium, the mass and mRNA levels of calreticulin were evaluated as a function of the iron concentration in the culture media. Increasing the iron content in the culture from 1 to 20 μM produced an increase in calreticulin mRNA and a two‐fold increase in calreticulin. Increasing iron also induced oxidative damage to proteins, as assessed by the formation of 4‐hydroxy‐2‐nonenal adducts. Co‐culture of cells with the antioxidants quercetin, dimethyltiourea and N‐acetyl cysteine abolished both the iron‐induced oxidative damage and the iron‐induced increase in calreticulin. We postulate that the iron‐induced expression of calreticulin is part of the cellular response to oxidative stress generated by iron. J. Cell. Biochem. 82: 660–665, 2001. © 2001 Wiley‐Liss, Inc.
Regulated expression of GRP78 during vasopressin‐induced hypertrophy of heart‐derived myocytes
Authors: Brostrom Margaret A. , Mourad Fadi , Brostrom Charles O. 
Published: August 2002

AbstractAlthough the development of cellular hypertrophy is widely believed to involve Ca2+ signaling, potential supporting roles for sequestered Ca2+ in this process have not been explored. H9c2 cardiomyocytes respond to arginine vasopressin with an initial mobilization of Ca2+ stores and reduced rates of mRNA translation followed by repletion of Ca2+ stores, up‐regulation of translation beyond initial rates, and the development of hypertrophy. Rates of synthesis of the endoplasmic reticulum (ER) chaperones, GRP78 and GRP94, were found to increase preferentially at early times of vasopressin treatment. Total GRP78 content increased 2‐ to 3‐fold within 8 h after which the chaperone was subject to post‐translational modification. Preferential synthesis of GRP78 and the increase in chaperone content both occurred at pM vasopressin concentrations and were abolished at supraphysiologic Ca2+ concentrations. Co‐treatment with phorbol myristate acetate decreased vasopressin‐dependent Ca2+ mobilization and slowed appearance of new GRP78 molecules in response to the hormone, whereas 24 h pretreatment with phorbol ester prolonged vasopressin‐dependent Ca2+ mobilization and further increased rates of GRP78 synthesis in response to the hormone. Findings did not support a role for newly synthesized GRP78 in translational up‐regulation by vasopressin. However up‐regulation, which does not depend on Ca2+ sequestration, appeared to expedite chaperone expression. This report provides the first evidence that a Ca2+‐mobilizing hormone at physiologic concentrations signals increased expression of GRP78. Translational tolerance to depletion of ER Ca2+ stores, typifying a robust ER stress response, did not accompany vasopressin‐induced hypertrophy. J. Cell. Biochem. 83: 204–217, 2001. © 2001 Wiley‐Liss, Inc.
Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus I. Localization of nER‐II in snRNP
Authors: Sebastian Thomas , Thampan Raghava Varman 
Published: August 2002

AbstractExposure of goat uterine nuclei to estradiol in vitro results in an immediate exit of ribonucleoproteins (RNP) from the nuclei to the medium. This RNP exit appears to be mediated by an estrogen receptor localized in small nuclear ribonucleoproteins containing U1 and U2 snRNA. Available evidence indicates that the estrogen receptor involved is not the ERα, but an alternative form, which is also a 66 kDa protein. This is the nuclear estrogen receptor II (nER‐II) that has no DNA‐binding capacity. The transport is estrogen‐specific since non‐estrogenic steroids do not stimulate the transport of the RNP where the receptor is localized. J. Cell. Biochem. 84: 217–226, 2002. © 2001 Wiley‐Liss, Inc.
Isolation of transcriptionally active chromatin from human breast cancer cells using Sulfolink coupling gel chromatography
Authors: Sun Jian‐Min , Chen Hou Yu , Davie James R. 
Published: August 2002

AbstractThe process of transcription unfolds the nucleosome. The unfolded nucleosome structure will be maintained as long as the histones are in a highly acetylated state. Typically the cysteine residue at position 110 of histone H3 is buried in the interior of the nucleosome. However, the transcribed unfolded nucleosome has its H3 cysteine exposed, offering a tag to isolate and study transcribed nucleosomes. In this study, we applied Sulfolink Coupling Gel chromatography to isolate unfolded nucleosomes from estrogen dependent human cancer T5 cells. Inhibition of histone deacetylase activity did not enhance the yield of unfolded nucleosomes from these cells. We show that the estrogen receptor and c‐myc transcribed DNA sequences are associated with unfolded nucleosomes. In chromatin immunoprecipitation (ChIPs) assays, we found that the coding regions of the estrogen receptor and c‐myc genes are bound to highly acetylated H3 and H4 in cultured T5 Cells. We conclude that in cultured T5 breast cancer cells H3 and H4 are in highly acetylated states maintaining the unfolded structure of the transcribed nucleosome and facilitating subsequent rounds of elongation. J. Cell. Biochem. 84: 439–446, 2002. © 2001 Wiley‐Liss, Inc.
Just say no to psychotropic drugs!
Authors: Albee George W. 
Published: August 2002

AbstractPrescribing drugs for mental disorders by psychologists means accepting an invalid model—the brain disease, biological‐defect explanation of psychopathology—that is advanced by political conservatives and accepted by some naive, well‐intentioned, but misinformed moderates who have not thought critically about the issue. Conservative psychiatry serves the ruling class by rejecting or ignoring the fact that most mental disorders are learned in the context of social and economic injustice, and familiar dysfunction. If we accept the fallacy of brain disease and genetic defect as the major causes of mental disorder and succeed in getting prescription privileges we will have sold our soul to the devil! © 2002 Wiley Periodicals, Inc. J Clin Psychol 58: 635–648, 2002.
Assessing basic HIV transmission risks and the contextual factors associated with HIV risk behavior in men who have sex with men
Authors: Suarez Troy , Kauth Michael R. 
Published: August 2002

AbstractHIV/AIDS remains a substantial health threat to men who have sex with men. Although new HIV medications have provided great benefits for many HIV‐positive individuals, they have done little to protect HIV‐negative men. Consequently, changing one's sexual practices remains the most effective way to reduce risk for HIV. However, to develop an effective intervention for reducing HIV risk, it is important to fully understand risk behavior. In this article, we detail the essential elements for conducting an HIV risk assessment as well as those contextual factors that may support risk behaviors. Further, we discuss the importance of procuring an HIV test and the critical issues that may arise because of testing for HIV as well as the critical issues that may result from testing HIV‐positive. Finally, we illustrate how we integrate an HIV health risk assessment into a clinical interview. © 2001 John Wiley & Sons, Inc. J Clin Psychol/In Session 57: 655–669, 2001.
Insulin‐like growth factor (IGF) binding protein‐3 regulation of IGF‐I is altered in an acidic extracellular environment
Authors: Forsten Kimberly E. , Akers R. Michael , San Antonio James D. 
Published: August 2002

AbstractWhile extracellular acidification within solid tumors is well‐documented, how reduced pH impacts regulation of insulin‐like growth factor‐I (IGF‐I) has not been studied extensively. Because IGF‐I receptor binding is affected by IGF binding proteins (IGFBPs), we examined how pH impacted IGFBP‐3 regulation of IGF‐I. IGF‐I binding in the absence of IGFBP‐3 was diminished at reduced pH. Addition of IGFBP‐3 reduced IGF‐I cell binding at pH 7.4 but increased surface association at pH 5.8. This increase in IGF‐I binding at pH 5.8 corresponded with an increase in IGFBP‐3 cell association. This, however, was not due to an increase in affinity of IGFBP‐3 for heparin at reduced pH although both heparinase III treatment and heparin addition reduced IGFBP‐3 enhancement of IGF‐I binding. An increase in IGF‐I binding to IGFBP‐3, though, was seen at reduced pH using a cell‐free assay. We hypothesize that the enhanced binding of IGF‐I at pH 5.8 is facilitated by increased association of IGFBP‐3 at this pH and that the resulting cell associated IGF‐I is IGFBP‐3 and not IGF‐IR bound. Increased internalization and nuclear association of IGF‐I at pH 5.8 in the presence of IGFBP‐3 was evident, yet cell proliferation was reduced by IGFBP‐3 at both pH 5.8 and 7.4 indicating that IGFBP‐3‐cell associated IGF‐I does not signal the cell to proliferate and that the resulting transfer of bound IGF‐I from IGF‐IR to IGFBP‐3 results in diminished proliferation. Solution binding of IGF‐I by IGFBP‐3 is one means by which IGF‐I‐induced proliferation is inhibited. Our work suggests that an alternative pathway exists by which IGF‐I and IGFBP‐3 both associate with the cell surface and that this association inhibits IGF‐I‐induced proliferation. © 2001 Wiley‐Liss, Inc.
Gap junctions, homeostasis, and injury
Authors: De Maio Antonio , Vega Virginia L. , Contreras Jorge E. 
Published: August 2002

AbstractGap junctions (Gj) play an important role in the communication between cells of many tissues. They are composed of channels that permit the passage of ions and low molecular weight metabolites between adjacent cells, without exposure to the extracellular environment. These pathways are formed by the interaction between two hemichannels on the surface of opposing cells. These hemichannels are formed by the association of six identical subunits, named connexins (Cx), which are integral membrane proteins. Cell coupling via Gj is dependent on the specific pattern of Cx gene expression. This pattern of gene expression is altered during several pathological conditions resulting in changes of cell coupling. The regulation of Cx gene expression is affected at different levels from transcription to post translational processes during injury. In addition, Gj cellular communication is regulated by gating mechanisms. The alteration of Gj communication during injury could be rationalized by two opposite theories. One hypothesis proposes that the alteration of Gj communication attenuates the spread of toxic metabolites from the injured area to healthy organ regions. The alternative proposition is that a reduction of cellular communication reduces the loss of important cellular metabolisms, such as ATP and glucose. © 2002 Wiley‐Liss, Inc.
Functional role of matrix metalloproteinases (MMPs) in mammary epithelial cell development
Authors: Lee Ping‐Ping H. , Hwang Jiuan‐Jiuan , Mead Lawrence , Ip Margot M. 
Published: August 2002

AbstractThe extracellular matrix (ECM) is an important regulator of mammary epithelial cell (MEC) function and is remodeled by matrix metalloproteinases (MMPs). To investigate the significance and regulation of MMP activity in normal MEC, we utilized a primary culture model in which rat MEC were grown three dimensionally within a reconstituted basement membrane (RBM) in defined serum‐free medium. Zymograms of culture medium demonstrated that five major gelatinases of 97, 80, 74, 69, and 65 kDa were secreted by MEC and were distinct from gelatinases of RBM origin. Based on molecular weight, p‐aminophenylmercuric acid activation, immunoblotting with MMP‐specific antibodies, inhibition by EDTA, a peptide containing the prodomain sequence of MMP (TMRKPRCGNPDVAN) and two synthetic MMP inhibitors (BB‐94 and CGS 27023A), these were classified as inactive and active forms of MMP‐9 and MMP‐2. The maximal MMP activities occurred when MEC were in a rapid proliferation and branching phase and declined after they underwent functional differentiation. Known regulators of MEC growth and differentiation were evaluated for their ability to modulate gelatinase activity in primary culture. Secretion of one or both MMPs was inhibited by EGF, TGFα, prolactin, and hydrocortisone and stimulated by progesterone. Furthermore, the functional significance of MMPs was demonstrated since three MMP inhibitors blocked branching morphogenesis elicited by the absence of hydrocortisone. Additionally, two synthetic MMP inhibitors not only inhibited epithelial cell growth but also inhibited normal alveolar development of the MEC. Finally, these drugs were found to enhance MMP secretion from MEC, although the activity of the secreted MMPs was inhibited as long as the drug was present. © 2001 Wiley‐Liss, Inc.
Functional characterization of P2Y and P2X receptors in human eosinophils
Authors: Idzko Marco , Dichmann Stefan , Panther Elisabeth , Ferrari Davide , Herouy Yared , Virchow, Jr. Christian , Luttmann Werner , Di Virgilio Francesco , Norgauer Johannes 
Published: August 2002

AbstractActivation of purinoceptor by ATP induces in eosinophils various cell responses including calcium transients, actin polymerization, production of reactive oxygen metabolites, CD11b‐expression, and chemotaxis. Here, the effect of ion channel‐gated P2X and/or G protein‐coupled P2Y receptor agonists ATP, ATPγS, α,β‐meATP, 2‐MeSATP, BzATP, ADP, CTP, and UTP on the intracellular Ca2+‐mobilization, actin polymerization, production of reactive oxygen metabolites, CD11b expression and chemotaxis of human eosinophils were measured and the biological activity was analyzed. Although all tested nucleotides were able to induce all these cell responses, the biological activity of the analyzed nucleotides were distinct. Agonists of the G protein‐coupled P2Y receptors such as 2‐MeSATP, UTP, and ADP have a higher biological activity for production of reactive oxygen metabolites, actin polymerization and chemotaxis in comparison to the ion channel‐gated P2X agonists αβ‐meATP, BzATP, and CTP. In contrast, P2Y and P2X agonist showed similar potencies in respect to intracellular calcium transient and CD11b up‐regulation. This conclusion was further supported by experiments with receptor iso‐type antagonist KN62, EGTA or with the Gi protein‐inactivating pertussis toxin. These findings indicate participation of different purinorecptors in the regulation of cell responses in eosinophils. © 2001 Wiley‐Liss, Inc.
Functional stabilization of cellulase by covalent modification with chitosan
Authors: Darias Rodolfo , Villalonga Reynaldo 
Published: August 2002

AbstractChitosan was linked to cellulase (EC 3.2.1.4) from Trichoderma viride by covalent conjugation to periodate‐activated carbohydrate moieties of the enzyme. The modified enzyme contained about 1.5 mol of polymer per mol of protein. The specific activity of the conjugate prepared was 39.8% of the native cellulase. The optimum pH and temperature for cellulase remained unaltered after modification. The thermostability was increased by 8.9 °C for the cellulase–chitosan complex. Thermal inactivation at different temperatures ranging from 65 °C to 80 °C was markedly increased for the polymer‐modified enzyme. The stability within the pH range 1.0–3.2 was also improved for the modified enzyme.© 2001 Society of Chemical Industry
Stabilization of penicillin V acylase from Streptomyces lavendulae by covalent immobilization
Authors: Torres‐Bacete Jesús , Arroyo Miguel , Torres‐Guzmán Raquel , Mata Isabel de la , Castillón M Pilar , Acebal Carmen 
Published: August 2002

AbstractPenicillin V acylase from the actinomycete Streptomyces lavendulae ATCC 13664 has been immobilized to epoxy‐activated acrylic beads (Eupergit C®) by covalent binding. Further linkage of bovine serum albumin after enzyme immobilization was carried out in order to remove the remaining oxirane groups of the support. The obtained immobilized biocatalyst displayed double exponential deactivation kinetics at temperatures below 55 °C, while the native enzyme followed single exponential decay at the same temperatures. We concluded that soluble penicillin acylase was deactivated in one step, whereas the immobilized enzyme showed an enzymatic intermediate state which is highly thermostable. As a consequence of the immobilization process, the enzyme displayed a 10‐fold increase in its half‐life at 40 °C. At this temperature, the enzymatic intermediate state was progressively destabilized as the pH of the medium was increased. Thus, the optimum pH range for the immobilized enzyme preparation was established as being from 7.0 to 8.0. Higher pH values led to quicker enzyme deactivation.© 2001 Society of Chemical Industry