bluuebunny/crossref_metadata_2025 huggingface dataset:
TGF‐β‐induced protein βig‐h3 is upregulated by high glucose in vascular smooth muscle cells
Authors: Ha Sung‐Woo , Bae Jong‐Sup , Yeo Hye‐Jin , Lee Suk‐Hee , Choi Je‐Yong , Sohn Yoon‐Kyung , Kim Jung‐Guk , Kim In‐San , Kim Bo‐Wan
Published: February 2003

TGF‐β‐induced gene‐h3 (βig‐h3) is an adhesive molecule that interacts with integrins. Because TGF‐β plays an important role in diabetic complications and βig‐h3 serves as a cell substrate, we hypothesized that diabetic conditions might increase βig‐h3 synthesis in vascular smooth muscle cells (VSMCs), which may subsequently contribute to the pathogenesis of diabetic angiopathy. The concentrations of βig‐h3 and TGF‐β were measured in conditioned media using an enzyme‐linked immunosorbent assay. An immunohistochemical study showed that βig‐h3 was expressed in the VSMCs and the matrix of rat aortas. TGF‐β stimulated βig‐h3 production, and high glucose induced βig‐h3 as well as TGF‐β production in the VSMCs. The high glucose‐induced βig‐h3 expression was almost entirely blocked by an anti‐TGF‐β antibody. βig‐h3 protein mediated the adhesion, spreading, migration, and proliferation of rat VSMCs. These results suggest that the high glucose‐induced βig‐h3 in VSMCs regulates VSMC functions and may play an important role in diabetic angiopathy. © 2002 Wiley‐Liss, Inc.
Characterization of the neuropilin‐1 promoter; gene expression is mediated by the transcription factor Sp1
Authors: Rossignol Mireille , Pouysségur Jacques , Klagsbrun Michael
Published: February 2003

Neuropilin‐1 (NRP1) is a receptor for the vascular endothelial growth factor (VEGF) family of angiogenesis factors and for the semaphorin family of secreted neuronal guidance polypeptides. Very little is known, however, about how NRP1 gene expression is regulated. In this study, it was demonstrated that the tumor promoter, TPA (12‐O‐tetradecanoylphorbol‐13‐acetate) significantly up‐regulated NRP1 mRNA levels by increasing its gene transcription rate in a manner dependent on de novo protein synthesis. To determine which elements regulate functional NRP1 expression, the promoter regions of human and mouse NRP1 genes were cloned and characterized. Promoter‐reporter gene transfection experiments using deletion and point mutations demonstrated that two Sp1 elements are major contributors to both the constitutive and TPA‐induced activity of the NRP1 promoter. Gel shift analysis showed a specific binding of the Sp1 transcription factor to those elements. Further mutational analysis revealed that an AP‐1, and a CCAAT box also contributed to NRP1 constitutive and TPA‐induced promoter activity. It was concluded that NRP1 expression is regulated by the cooperation of several regulatory elements including AP‐1, Sp1, and a CCAAT box. © 2002 Wiley‐Liss, Inc.
A unified model for the action of leptin on bone turnover
Authors: Gordeladze Jan O. , Reseland Janne E.
Published: February 2003

Leptin has been advocated as a centrally acting factor responsible for inhibiting accumulation of bone mass. However, recent investigations unequivocally establish leptin as a local (autocrine) factor expressed by osteoblasts. Exogenously added leptin causes osteoblastic cell proliferation and differentiation, while also rendering osteoblasts more efficacious in terms of mineralization. Leptin acts as an anti‐apoptotic agent, and augments messages responsible for the remodelling of bone tissue, i.e., mRNAs for osteoprotegerin (OPG) and the interleukin IL‐6. Furthermore, leptin message is readily expressed in osteoblasts subjected to mechanical strain. In this respect, osteoblasts, which are unilaterally stretched proliferate and differentiate, a phenomenon being potentiated by exposure of the cells to differentiating humoral factors. This article discusses a unified model of dually acting leptin through the central nervous system and the mechanostat principle applied to osteoblasts. The proposed model may account for the finely tuned bone homeostasis maintained within rather narrow limits, depending on exposure to humoral factors and the prevailing mechanostat usage mode. © 2002 Wiley‐Liss, Inc.
Chondrogenesis induced by actin cytoskeleton disruption is regulated via protein kinase C‐dependent p38 mitogen‐activated protein kinase signaling
Authors: Lim Young‐Bin , Kang Shin‐Sung , An Won Gun , Lee Young‐Sup , Chun Jang‐Soo , Sonn Jong Kyung
Published: February 2003

Disruption of the actin cytoskeleton in subconfluent mesenchymal cells induces chondrogenic differentiation via protein kinase C (PKC) α signaling. In this study, we investigated the role of p38 mitogen‐activated protein (MAP) kinase in the chondrogenic differentiation of mesenchymal cells that is induced by depolymerization of the actin cytoskeleton. Treatment of mesenchymal cells derived from chick embryonic limb buds with cytochalasin D (CD) disrupted the actin cytoskeleton with concomitant chondrogenic differentiation. The chondrogenesis was accompanied by an increase in p38 MAP kinase activity and inhibition of p38 MAP kinase with SB203580 blocked chondrogenesis. Together these results suggest an essential role for p38 MAP kinase in chondrogenesis. In addition, inhibition of p38 MAP kinase did not alter CD‐induced increased expression and activity of PKCα, whereas down‐regulation of PKC by prolonged exposure of cells to phorbol ester inhibited CD‐induced p38 MAP kinase activation. Our results therefore suggest that PKC is involved in the regulation of chondrogenesis induced by disruption of the actin cytoskeleton via a p38 MAP kinase signaling pathway. © 2002 Wiley‐Liss, Inc.
Role of catenins in the development of gap junctions in rat cardiomyocytes
Authors: Wu Jiahn‐Chun , Tsai Ru‐Yin , Chung Tun‐Hui
Published: February 2003

Gap junctions are intercellular communicating channels responsible for the synchronized activity of cardiomyocytes. Recent studies have shown that the membrane‐associated guanylate kinase protein, zonula occludens‐1 (ZO‐1) can bind to catenins in epithelial cells and act as an adapter for the transport of the connexin isotype, Cx43 during gap junction formation. The significance of catenins in the development of gap junctions and whether complexes between catenins and ZO‐1 are formed in cardiomyocytes are not clear. In this study, immunofluorescence and confocal microscopy showed sequential redistribution of α‐catenin, β‐catenin, ZO‐1, and Cx43 to the plasma membrane when rat cardiomyocytes were cultured in low Ca2+ (<5 μM) medium, then shifted to 1.8 mM Ca2+ medium (Ca2+ switch). Diffuse cytoplasmic staining of α‐catenin, β‐catenin, ZO‐1, and Cx43 was seen in the cytoplasm when cardiomyocytes were cultured in low Ca2+ medium. Staining of α‐catenin, β‐catenin, and ZO‐1 was detected at the plasma membrane of cell–cell contact sites 10 min after Ca2+ switch, whereas Cx43 staining was first detected, colocalized with ZO‐1 at the plasma membrane, 30 min after Ca2+ switch. Distinct junctional and extensive cytoplasmic staining of α‐catenin, β‐catenin, ZO‐1, and Cx43 was seen 2 h after Ca2+ switch. Immunoprecipitation of Triton X‐100 cardiomyocyte extracts using anti‐β‐catenin antibodies showed that β‐catenin was associated with α‐catenin, ZO‐1, and Cx43 at 2 h after Ca2+ switch. Intracellular application of antisera against α‐catenin, β‐catenin, or ZO‐1 by electroporation of cardiomyocytes cultured in low Ca2+ medium inhibited the redistribution of Cx43 to the plasma membrane following Ca2+ switch. These results suggest the formation of a catenin–ZO‐1–Cx43 complex in rat cardiomyocytes and that binding of catenins to ZO‐1 is required for Cx43 transport to the plasma membrane during the assembly of gap junctions. © 2002 Wiley‐Liss, Inc.
Up‐regulation of cDK5/p35 by oxidative stress in human neuroblastoma IMR‐32 cells
Authors: Strocchi Paola , Pession Annalisa , Dozza Barbara
Published: February 2003

Cdk5, a member of the cyclin‐dependent kinase (cdk) family, is predominately active in neurons, where its activity is tightly regulated by the binding of its neuronal activators p35 and p39. Cdk5 is implicated in regulating the proper neuronal function; a deregulation of cdk5 has been found associated with Alzheimer's disease and amyotrophic lateral sclerosis. As oxidative stress products have been seen co‐localized with pathological hallmarks of neurodegenerative diseases, we studied the effect of oxidative stress on the cdk5 enzyme in human neuroblastoma IMR‐32 cells. We evaluated the effects of 4‐hydroxynonenal and Ascorbate plus FeSO4 on cdk5 activity and on the expression of cdk5 and p35 proteins. We report here that oxidative stress stimulates cdk5 activity and induces an upregulation of its regulatory and catalytic subunit expression in IMR‐32 vital cells, showing that the cdk5 enzyme is involved in the signaling pathway activated by oxidative stress. © 2002 Wiley‐Liss, Inc.
Biochemical regulation of breast cancer cell expression of S1P2 (Edg‐5) and S1P3 (Edg‐3) G protein‐coupled receptors for sphingosine 1‐phosphate
Authors: Dolezalova Hana , Shankar Geetha , Huang Mei‐Chuan , Bikle Daniel D. , Goetzl Edward J.
Published: February 2003

G protein‐coupled receptors (GPCRs) for lysophosphatidic acid (LPA) and sphingosine 1‐phosphate (S1P) transduce signals to many functions of normal cells. Most human cancer cells upregulate S1P and LPA GPCRs, in patterns distinctive for each type of tumor. The findings that 1‐alpha, 25‐dihydroxy‐vitamin D3 (VD3) and all‐trans retinoic acid (RA) differentially alter expression of the predominant S1P3 (Edg‐3) R and S1P2 (Edg‐5) R in human breast cancer cells (BCCs) permitted analyses of their individual activities, despite a lack of selective pharmacological probes. S1P‐evoked increases in [Ca2+]i in S1P3 R‐predominant BCCs were suppressed by concentrations of VD3 and RA which decreased expression of S1P3 Rs, despite RA‐induced increases in S1P2 Rs. S1P‐elicited chemokinetic migration of S1P3 R‐predominant BCCs across a type IV collagen‐coated micropore filter also was inhibited by concentrations of VD3 and RA which decreased expression of S1P3 Rs. The RA‐induced increase in expression of S1P2 Rs did not prevent suppression by RA of S1P‐elicited chemokinesis, which appears to be mediated by S1P3 Rs, but instead exposed S1P2 R‐mediated inhibition of epidermal growth factor‐stimulated chemotaxis of BCCs. In contrast, expression of the predominant LPA2 Rs, LPA‐evoked increase in [Ca2+]i and LPA‐stimulated chemokinetic migration were suppressed concomitantly by RA but not VD3. Thus two structurally‐homologous S1P Rs of BCCs differ in coupling to [Ca2+]i signaling and have opposite effects on protein growth factor‐stimulated chemotaxis. © 2002 Wiley‐Liss, Inc.
Insulin‐like and non‐insulin‐like selenium actions in 3T3‐L1 adipocytes
Authors: Heart Emma , Sung Chin K.
Published: February 2003

In insulin‐sensitive 3T3‐L1 adipocytes, selenium stimulates glucose transport and antilipolysis and these actions of selenium, like insulin actions, are sensitive to wortmanin, an inhibitor of phosphatidylinositol‐3‐kinase (PI3K). Selenium stimulates PI3K activity that is sustained up to 24 h. Selenium after 5–10 min increases tyrosine phosphorylation of selective cellular proteins, but after 24 h overall tyrosine phosphorylation is increased. Tyrosine phosphorylation of insulin receptor substrate 1 is detected when enriched by immunoprecipitation with anti‐PI3K antibody. Selenium, however, does not stimulate insulin receptor tyrosine kinase activity. Selenium also increases phosphorylation of other insulin signaling proteins, including Akt and extracellular signal regulated kinases. Selenium‐stimulated glucose transport is accompanied by increases in glucose transporter‐1 content in the plasma membrane. These data are consistent with similar selenium action in glucose transport in 3T3‐L1 fibroblasts expressing mainly GLUT1. In chronic insulin‐induced insulin resistant cells, selenium unlike insulin fully stimulates glucose transport. In summary, selenium stimulates glucose transport and antilipolysis in a PI3K‐dependent manner, but independent of insulin receptor activation. Selenium exerts both insulin‐like and non‐insulin‐like actions in cells. © 2002 Wiley‐Liss, Inc.
Chromatin remodeling as a guide to transcriptional regulatory networks in mammals
Authors: Urnov Fyodor D.
Published: February 2003

An important challenge of genome biology is a dissection of transcriptional regulatory networks that operate inside the nucleus during ontogeny and disease (Wyrick and Young [2002] Curr. Opin. Genet. Dev. 12:130). Limitations of existing experimental tools greatly complicate such analysis in the human genome: for example, genome‐wide expression profiling of cells responding to a stimulus fails to reveal a majority of the genes involved in the functional network of responding to that stimulus [Giaver et al., 2002; Birrell et al., 2002]. This article discusses recent advances in analyzing mammalian transcriptional regulatory circuits [Nikiforov et al., 2002; Weinmann et al., 2002; Ren et al., 2000]. As evidenced by these and other data, paucity of information about the location of regulatory DNA elements in the human genome presents an obstacle to comprehensive transcription network analysis. It has been known since the late 1970s that chromatin over active regulatory DNA stretches is stably remodeled into “nuclease hypersensitive sites” [Elgin, 1988; Gross and Garrard 1988]. Massively parallel analysis of such remodeling in cell nuclei identifies regulatory DNA that is difficult to map comprehensively using other approaches, reveals genes poised for rapid activation, and offers a novel perspective on the “epigenome”—the regulatory program being executed by the genome in a given cell type. J. Cell. Biochem. 88: 684–694, 2003. © 2003 Wiley‐Liss, Inc.
Calcyclin (S100A6) regulates pulmonary fibroblast proliferation, morphology, and cytoskeletal organization in vitro
Authors: Breen Ellen C. , Tang Kechun
Published: February 2003

Calcyclin (S100A6) is a member of the S100A family of calcium binding proteins. While the precise function of calcyclin is unknown, calcyclin expression is associated with cell proliferation and calcyclin is expressed in several types of cancer phenotypes. In the present study, the functional role of calcyclin was further elucidated in pulmonary fibroblasts. Antisense S100A6 RNA expression inhibited serum and mechanical strain‐induced fibroblast proliferation. This attenuated proliferative response was accompanied by a flattened, spread cell morphology, and disruption of tropomyosin labeled microfilaments. Changes in cytoskeletal organization did not correspond with a decrease in tropomyosin levels. These observations suggest a role for calcyclin in modulating calcium dependent signaling events that regulate progression through the cell cycle. J. Cell. Biochem. 88: 848–854, 2003. © 2003 Wiley‐Liss, Inc.
G1 tetraploidy checkpoint and the suppression of tumorigenesis
Authors: Margolis Robert L. , Lohez Olivier D. , Andreassen Paul R.
Published: February 2003

Checkpoints suppress improper cell cycle progression to ensure that cells maintain the integrity of their genome. During mitosis, a metaphase checkpoint requires the integration of all chromosomes into a metaphase array in the mitotic spindle prior to mitotic exit. Still, mitotic errors occur in mammalian cells with a relatively high frequency. Metaphase represents the last point of control in mitosis. Once the cell commits to anaphase there are no checkpoints to sense segregation defects. In this context, we will explore our recent finding that non‐transformed mammalian cells have a checkpoint that acts subsequent to mitotic errors to block the proliferation of cells that have entered G1 with tetraploid status. This arrest is dependent upon both p53 and pRb, and may represent an important function of both p53 and pRb as tumor suppressors. Further, we discuss the possibility that this mechanism may similarly impose G1 arrest in cells that become aneuploid through errors in mitosis. © 2002 Wiley‐Liss, Inc.
Role of testicular interstitial macrophages in regulating testosterone release in hyperprolactinemia
Authors: Huang William J. , Yeh Jiun‐Yih , Kan Shu‐Fen , Chang Luke S. , Wang Paulus S.
Published: February 2003

Hyperprolactinemia‐induced hypogonadism has been linked to a dysfunction of the hypothalamus‐pituitary‐testis axis. The direct inhibitory effects of prolactin on the testicular release of testosterone have also been demonstrated, though their mechanisms remain unclear. Incubation of rat testicular interstitial cells (TICs) with prolactin stimulated the release of testosterone. TICs from rats with anterior pituitary‐grafting‐induced hyperprolactinemia release lower amounts of testosterone than controls. However, Leydig cells isolated from anterior pituitary‐grafted rats release a greater amount of testosterone. These paradoxical observations have remained unexplained. This study examined the roles of testicular interstitial macrophages and of their product, tumor necrosis factor‐α (TNF‐α), in regulating Leydig cells under condition of hyperprolactinemia. Hyperprolactinemia was induced by grafting two anterior pituitary glands of rats under the renal capsule. Control animals were grafted with rat cortex tissue. The rats were sacrificed 6 weeks later. TICs and macrophages, and Leydig cells were isolated for in vitro incubation and drugs challenge. Testosterone released by testicular interstitial or Leydig cells was measured by radioimmunoassay. TNF‐α concentration in the medium of TICs or macrophages was measured by enzyme‐linked immunosorbent assay (ELISA). A dose‐dependent stimulation of TNF‐α secretion in the medium of TICs or macrophages by the prolactin challenge was observed. Higher amounts of TNF‐α were released by TICs in the anterior pituitary‐grafted rats than in the control group. In contrast, the release of TNF‐α by testicular interstitial macrophages isolated from the anterior pituitary‐ and cortex‐grafted groups was quantitatively similar. Challenge with human chorionic gonadotropin did not modify the TNF‐α release by testicular interstitial macrophages in either group. Challenge of Leydig cells with TNF‐α inhibited their release of testosterone stimulated by human chorionic gonadotropin, but not their basal testosterone release. These different patterns of testosterone release in TICs versus Leydig cells cultures in anterior pituitary‐grafted rats may be due to the influence of testicular interstitial macrophages. These observations correlate with in vivo conditions, where prolactin increases the release of TNF‐α by testicular interstitial macrophages, which, in turn, decreases the human chorionic gonadotropin‐stimulated release of testosterone by Leydig cells. In summary, hyperprolactinemia‐induced hypogonadism involves a mechanism of prolactin‐originated, macrophage‐mediated inhibitory regulation of testosterone release by Leydig cells. TNF‐α, one of the cytokines secreted by macrophages, may play a key role in this mechanism. © 2002 Wiley‐Liss, Inc.
Lysyl oxidase: Properties, specificity, and biological roles inside and outside of the cell
Authors: Kagan Herbert M. , Li Wande
Published: February 2003

Lysyl oxidase (LO) plays a critical role in the formation and repair of the extracellular matrix (ECM) by oxidizing lysine residues in elastin and collagen, thereby initiating the formation of covalent crosslinkages which stabilize these fibrous proteins. Its catalytic activity depends upon both its copper cofactor and a unique carbonyl cofactor and has been shown to extend to a variety of basic globular proteins, including histone H1. Although the three‐dimensional structure of LO has yet to be determined, the present treatise offers hypotheses based upon its primary sequence, which may underlie the prominent electrostatic component of its unusual substrate specificity as well as the catalysis‐suppressing function of the propeptide domain of prolysyl oxidase. Recent studies have demonstrated that LO appears to function within the cell in a manner, which strongly modifies cellular activity. Newly discovered LO‐like proteins also likely play unique roles in biology. © 2002 Wiley‐Liss, Inc.
Conservative segregation of maternally inherited CS histone variants in larval stages of sea urchin development
Authors: Oliver María Isabel , Rodríguez Carla , Bustos Paula , Morín Violeta , Gutierrez Soraya , Montecino Martín , Genevière Anne Marie , Puchi Marcia , Imschenetzky María
Published: February 2003

Three sets of histone variants are coexisting in the embryo at larval stages of sea urchin's development: the maternally inherited cleavage stage variants (CS) expressed during the two initial cleavage divisions, the early histone variants, which are recruited into embryonic chromatin from middle cleavage stages until hatching and the late variants, that are fundamentally expressed from blastula stage onward. Since the expression of the CS histones is confined to the initial cleavage stages, these variants represent a very minor proportion of the histones present in the plutei larvae, whereas the late histone variants are predominant. To determine the position of these CS in the embryonic territories, we have immunolocalized the CS histone variants in plutei larvas harvested 72 h post‐fertilization. In parallel, we have pulse labeled the DNA replicated during the initial cleavage cycle with bromodeoxyuridine (BrdU) and its position was further determined in the plutei larvas by immunofluorescence. We have found that the CS histone variants were segregated to specific territories in the plutei. The position in which the CS histone variants were found to be segregated was consistent with the position in which the DNA molecules that were replicated during the initial cleavage divisions were localized. These results strongly suggest that a specification of embryonic nuclei occurs at the initial cleavage divisions which is determined by a chromatin organized by CS histone variants. © 2002 Wiley‐Liss, Inc.
New insights into the mechanisms of vitamin D action
Authors: Christakos Sylvia , Dhawan Puneet , Liu Yan , Peng Xiaorong , Porta Angela
Published: February 2003

The biologically active metabolite of vitamin D, 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) is a secosteroid whose genomic mechanism of action is similar to that of other steroid hormones and is mediated by stereospecific interaction of 1,25(OH)2D3 with the vitamin D receptor (VDR) which heterodimerizes with the retinoid X receptor (RXR). After interaction with the vitamin D response element (VDRE) in the promoter of target genes, transcription proceeds through the interaction of VDR with coactivators and with the transcription machinery. The identification of the steps involved in this process has been a major focus of recent research in the field. However, the functional significance of target proteins as well as the functional significance of proteins involved in the transport and metabolism of vitamin D is also of major importance. Within the past few years much new information has been obtained from studies using knockout and transgenic mice. New insight has been obtained using this technology related to the physiological significance of the vitamin D binding protein (DBP), used to transport vitamin D metabolites, as well as the physiological significance of target proteins including 25‐hydroxyvitamin D3 24‐hydroxylase (24(OH)ase), 25‐hydroxyvitamin D3‐1α‐hydroxylase (1α‐(OH)ase), VDR, and osteopontin. The crystal structure of the DBP and the ligand binding domain of the VDR have recently been reported, explaining, in part, the unique properties of these proteins. In addition novel 1,25(OH)2D3 target genes have been identified including the epithelial calcium channel, present in the proximal intestine and in the distal nephron. Thus in recent years a number of exciting discoveries have been made that have enhanced our understanding of mechanisms involved in the pleiotropic actions of 1,25(OH)2D3. © 2002 Wiley‐Liss, Inc.
SPARC regulates cell cycle progression in mesangial cells via its inhibition of IGF‐dependent signaling
Authors: Francki Aleksandar , Motamed Kouros , McClure Timothy D. , Kaya Marcus , Murri Carrie , Blake David J. , Carbon Juliet G. , Sage E. Helene
Published: February 2003

Glomerular mesangial cells both synthesize and respond to insulin‐like growth factor‐1 (IGF‐1). Increased activity of the IGF signaling pathway has been implicated as a major contributor to renal enlargement and subsequent development of diabetic nephropathy. Secreted protein acidic and rich in cysteine (SPARC), a matricellular protein, has been shown to modulate the interaction of cells with growth factors and extracellular matrix. We have reported that primary glomerular mesangial cells derived from SPARC‐null mice exhibit an accelerated rate of proliferation and produce substantially decreased levels of transforming growth factor β1 (TGF‐β1) in comparison to their wild‐type counterparts (Francki et al. [1999] J. Biol. Chem. 274: 32145–32152). Herein we present evidence that SPARC modulates IGF‐dependent signaling in glomerular mesangial cells. SPARC‐null mesangial cells produce increased amounts of IGF‐1 and ‐2, as well as IGF‐1 receptor (IGF‐1R) in comparison to wild‐type cells. Addition of recombinant SPARC to SPARC‐null cells inhibited IGF‐1‐stimulated mitogen activated protein kinase (MAPK) activation and DNA synthesis. We also show that the observed accelerated rate of basal and IGF‐1‐stimulated proliferation in mesangial cells derived from SPARC‐null animals is due, at least in part, to markedly diminished levels of cyclin D1 and the cyclin‐dependent kinase (cdk) inhibitors p21 and p27. Since expression of SPARC in the glomerulus is especially prominent during renal injury, our findings substantiate previous claims that SPARC is involved in glomerular remodeling and repair, a process commonly associated with mesangioproliferative glomerulonephritis and diabetic nephropathy. © 2003 Wiley‐Liss, Inc.
Differential roles of hydrogen peroxide and superoxide in mediating IL‐1‐induced NF‐κB activation and iNOS expression in bovine articular chondrocytes
Authors: Mendes Alexandrina Ferreira , Caramona M. Margarida , Carvalho A. Pato , Lopes M. Celeste
Published: February 2003

Our previous studies showed that reactive oxygen species (ROS) are required for the pro‐inflammatory cytokine interleukin‐1β (IL‐1) to induce the activity of the Nuclear transcription Factor‐kappaB (NF‐κB) and the expression of the inducible isoform of the nitric oxide synthase (iNOS) in bovine articular chondrocytes. This study aimed at elucidating the role of hydrogen peroxide (H2O2) and the superoxide radical, two major ROS, in mediating those IL‐1‐induced responses. The results obtained show that chondrocytes produce both H2O2 and superoxide radical in response to IL‐1. Treatment of the chondrocyte cultures with H2O2 alone did not induce NF‐κB activation or iNOS expression. Addition of H2O2 simultaneously with IL‐1 did neither enhance nor inhibit NF‐κB activation and iNOS expression, relatively to treatment with IL‐1 alone. Accordingly, treatment with catalase did not inhibit those IL‐1‐induced responses. Treatment with superoxide dismutase, however, effectively prevented IL‐1‐induced IκB‐α degradation and iNOS expression. Taken together, the results obtained indicate that superoxide mediates IL‐1‐induced IκB‐α degradation and the consequent NF‐κB activation and iNOS expression in chondrocytes, whereas H2O2 does not seem to participate in those IL‐1‐induced responses. In conclusion, the present study identifies the superoxide radical as the ROS involved in mediating the IL‐1‐induced signaling pathway that leads to NF‐κB activation and to the expression of NF‐κB‐dependent genes in bovine articular chondrocytes. © 2003 Wiley‐Liss, Inc.
Expression of interleukin‐1β and interleukin‐1 receptor antagonist in oxLDL‐treated human aortic smooth muscle cells and in the neointima of cholesterol‐fed endothelia‐denuded rabbits
Authors: Lin Shing‐Jong , Yen Hui‐Tzu , Chen Yung‐Hsiang , Ku Hung‐Hai , Lin Feng‐Yen , Chen Yuh‐Lien
Published: February 2003

The migration of vascular smooth muscle cells (VSMCs) from the media to the intima and the proliferation of intimal VSMCs are key events in restenotic lesion development. These events, which are preceded and accompanied by inflammation, are modulated by the proinflammatory cytokine, interleukin‐1β (IL‐1β), which induces vascular smooth muscle cells to express adhesion molecules and to proliferate. IL‐1β action is complex and regulated, in part, by its naturally occurring inhibitor, the IL‐1 receptor antagonist (IL‐1ra). Whether there was a temporal and spatial correlation between IL‐1β and IL‐1ra expression in, and release by, oxidized low density lipoproteins (oxLDL)‐stimulated human aortic smooth muscle cells (HASMCs) was determined by using ELISA and Western blot. In addition, IL‐1β and IL‐1ra expression was detected in the neointima of endothelia‐denuded cholesterol‐fed New Zealand white rabbits by immunohistochemistry and Western blot. In HASMCs, oxLDL induced IL‐β and IL‐1ra expression and release in a dose‐ and time‐dependent manner. Treatment with 20 μg/ml oxLDL resulted in increased IL‐1β release after 6 h, which peaked at 24 h, and in increased IL‐1ra release, first seen after 12 h, but continuing to increase for at least 48 h. In the cells, IL‐β expression showed a similar pattern to release, whereas IL‐1ra expression was seen in unstimulated cells and was not increased by oxLDL treatment. Confocal microscopy showed colocalization of IL‐β and IL‐1ra expression in oxLDL‐stimulated HASMCs. oxLDL caused significant induction of nuclear factor kappa B and activator protein‐1 DNA binding activity in HASMCs (6.6‐ and 3.3‐fold, respectively). In cholesterol‐fed endothelia‐denuded rabbits, the notably thickened intima showed significant IL‐1β and IL‐1ra expression. These results provide further support for the role of IL‐1 system in the pathogenesis of restenosis. This is the first demonstration of IL‐1β and IL‐1ra expression and secretion of oxLDL‐treated HASMCs and their expression in the rabbit neointima, suggesting that the smooth muscle cells of the intima are an important source of these factors. © 2003 Wiley‐Liss, Inc.
Vitamin D receptor is not required for the rapid actions of 1,25‐dihydroxyvitamin D3 to increase intracellular calcium and activate protein kinase C in mouse osteoblasts
Authors: Wali Ramesh K. , Kong Juan , Sitrin Michael D. , Bissonnette Marc , Li Yan Chun
Published: February 2003

The rapid, non‐genomic actions of 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] have been well described, however, the role of the nuclear vitamin D receptor (VDR) in this pathway remains unclear. To address this question, we used VDR(+/+) and VDR(−/−) osteoblasts isolated from wild‐type and VDR null mice to study the increase in intracellular calcium ([Ca2+]i) and activation of protein kinase C (PKC) induced by 1,25(OH)2D3. Within 1 min of 1,25(OH)2D3 (100 nM) treatment, an increase of 58 and 53 nM in [Ca2+]i (n = 3) was detected in VDR(+/+) and VDR(−/−) cells, respectively. By 5 min, 1,25(OH)2D3 caused a 2.1‐ and 1.9‐fold increase (n = 6) in the phosphorylation of PKC substrate peptide acetylated‐MBP4–14 in VDR(+/+) and VDR(−/−) osteoblasts. The 1,25(OH)2D3‐induced phosphorylation was abolished by GF109203X, a general PKC inhibitor, in both cell types, confirming that the secosteroid induced PKC activity. Moreover, 1,25(OH)2D3 treatment resulted in the same degree of translocation of PKC‐α and PKC‐δ, but not of PKC‐ζ, from cytosol to plasma membrane in both VDR(+/+) and VDR(−/−) cells. These experiments demonstrate that the 1,25(OH)2D3‐induced rapid increases in [Ca2+]i and PKC activity are neither mediated by, nor dependent upon, a functional nuclear VDR in mouse osteoblasts. Thus, VDR is not essential for these rapid actions of 1,25(OH)2D3 in osteoblasts. © 2003 Wiley‐Liss, Inc.
Inflammatory T cells rapidly induce differentiation of human bone marrow stromal cells into mature osteoblasts
Authors: Rifas Leonard , Arackal Sophia , Weitzmann M. Neale
Published: February 2003

Activated T cells secrete multiple osteoclastogenic cytokines which play a major role in the bone destruction associated with rheumatoid arthritis. While the role of T cells in osteoclastogenesis has received much attention recently, the effect of T cells on osteoblast formation and activity is poorly defined. In this study, we investigated the hypothesis that in chronic inflammation activated T cells contribute to enhanced bone turnover by promoting osteoblastic differentiation. We show that T cells produce soluble factors that induce alkaline phosphatase activity in bone marrow stromal cells and elevated expression of mRNA for Runx2 and osteocalcin. This data indicate that T cell derived factors have the capacity to stimulate the differentiation of bone marrow stromal cells into the osteoblast phenotype. RANKL mRNA was undetectable under any conditions in highly purified bone marrow stromal cells. In contrast, RANKL was constitutively expressed in primary osteoblasts and only moderately up‐regulated by activated T cell conditioned medium. Interestingly, both bone marrow stromal cells and osteoblasts expressed mRNA for RANK, which was strongly up‐regulated in both cell types by activated T cell conditioned medium. Although, mRNA for the RANKL decoy receptor, osteoprotegerin, was also up‐regulated by activated T cell conditioned medium, it's inhibitory effects may be mitigated by a simultaneous rise in the osteoprotegerin competitor TNF‐related apoptosis‐inducing ligand. Based on our data we propose that during chronic inflammation, T cells regulate bone loss by a dual mechanism involving both direct stimulation of osteoclastogenesis, by production of osteoclastogenic cytokines, and indirectly by induction of osteoblast differentiation and up‐regulation of bone turnover via coupling. J. Cell. Biochem. 88: 650–659, 2003. © 2003 Wiley‐Liss, Inc.
Cell cycle dependent regulation of protein kinase CK2 signaling to the nuclear matrix
Authors: Wang Huamin , Yu Shihui , Davis Alan T. , Ahmed Khalil
Published: February 2003

Protein kinase CK2 is a ubiquitous protein serine/threonine kinase that is involved in cell growth and proliferation as well as suppression of apoptosis. Several studies have suggested that the kinase plays a role in cell cycle progression; however, changes in enzyme activity during phases of cell cycle have not been detected. Nuclear matrix is a key locus for CK2 signaling in the nucleus. We therefore examined CK2 signaling to the nuclear matrix in distinct phases of cell cycle by employing synchronized ALVA‐41 prostate cancer cells. Removal of serum from the culture medium resulted in G0/G1 arrest, and a reduction in the nuclear matrix‐associated CK2 activity which was rapidly reversed on addition of serum. Arresting the cells in G0/G1 phase with hydroxyurea and subsequent release to S phase by serum gave similar results. Cells arrested in the G2/M phase by treatment with nocodazole demonstrated an extensive reduction in the nuclear matrix‐associated CK2 which was reversed rapidly on addition of serum. Changes in the immunoreactive CK2 protein were concordant with the activity data reflecting a dynamic trafficking of the kinase in distinct phases of cell cycle. Under the same conditions, CK2 activity in total cellular lysate remained essentially unaltered. These results provide the first direct evidence of discrete modulations of CK2 in the nuclear matrix during the cell cycle progression. Inducible overexpression of CK2 in CHO cells yielded only a modest increase in CK2 activity even though a significant increase in expression was apparent at the level of CK2α‐specific message. Stably transfected ALVA‐41 cells, however, did not show a significant change in CK2 levels despite increased expression at the message level. Not surprisingly, both types of the stably transfected cells failed to show any alteration in cell cycle progression. Distribution of the CK2 activity in the cytosolic versus nuclear matrix fractions in normal cells appears to be different from that in the cancer cells such that the ratio of nuclear matrix to cytosolic activity is much higher in the latter. Considering that nuclear matrix is central to several nuclear functions, this pattern of intracellular distribution of CK2 may have implications for its role in the oncogenic process. Published 2003 Wiley‐Liss, Inc.
The use of strategic tools by small and medium‐sized enterprises: an Australasian study
Authors: Frost Frederick A.
Published: February 2003

This paper reviews the range of strategic tools and techniques available to strategic planners.

The study focuses on strategic planning tool usage by small and medium‐sized enterprises (SMEs) in Western Australia, Singapore, Hong Kong and Malaysia.

A six‐stage strategic framework was used to provide for 36 core strategic tasks.

Results are contrasted with a previous study published in this journal that considered the use of strategic tools by organizations in the United Kingdom and New Zealand.

SMEs were found to use a restricted range of strategic tools. There is a need for a wider understanding of the tools available and their application to strategy development.

Copyright © 2003 John Wiley & Sons, Ltd.
Outsourcing: the supplier viewpoint
Authors: Hussey David , Jenster Per
Published: February 2003

Outsourcing, which is the process of shifting tasks and services previously performed in‐house to outside vendors, is hardly a new idea in management. But the volume, extent and character of outsourcing has been changing rapidly.

Outsourcing is now a fashionable activity and has become a management fad as much as a reasoned decision. It can offer great opportunities to both the buyer and supplier when used wisely. When it becomes a mantra and used without thought, it can do great damage to both parties.

Copyright © 2003 John Wiley & Sons, Ltd.
The impact of Internet technologies on the airline industry: current strategies and future developments
Authors: McIvor Ronan , O'Reilly Dolores , Ponsonby Sharon
Published: February 2003

This paper examines the impact of Internet technologies on value creation in the airline industry and focuses on the Internet strategies of two European low‐cost and two traditional operators.

Four notable value drivers in the aviation context are identified, namely efficiency, complementarities, lock‐in and novelty.

The Internet represents a powerful technology for commerce and communication between airlines and consumers and the paper highlights the implications for corporate strategists as customer expectations increase over time and the boundaries of the airline industry become increasingly blurred.

This paper examines how Internet technologies are impacting upon airline companies at the customer interface. The analysis focuses on a number of airline companies that have been exploiting Internet technologies. It is shown how airline operators are using the Internet to provide innovative exchange mechanisms and transaction structures with customers. The adoption of the Internet is increasing the expectations of customers as to what and how these organizations offer products and services. In fact, the Internet has become central to the strategic development of the airline companies analysed. The scope and boundaries of the airline industry have become less clear as a result of the adoption of Internet technologies at the customer interface. The offering of a range of products and services is creating industry convergence that has significant implications for the formulation of corporate strategy. Exploitation of the Internet at the customer interface has become a key catalyst in the transformation of the airline industry. Further exploitation of the Internet will lead to higher levels of sophistication that in turn will increase the expectations of the customer on what and how these organizations offer products and services. Copyright © 2003 John Wiley & Sons, Ltd.
Owner–managers: freedoms and constraints
Authors: Wahlgrén Asta , Stewart Rosemary
Published: February 2003

This paper explores freedom and its constraints as perceived by owner–managers.

Freedom is defined as the opportunity to choose. The concept of ‘choice’ combines ideas from the three literatures used in this paper: discussion of freedom by philosophers, studies of managerial work and behaviour and writings about owner–managers and entrepreneurs.

Owner–managers' perceptions of freedom and its constraints are illustrated and analysed through qualitative data obtained in Finland from four in‐depth interviews and twenty‐four essays.

The perceptions of these owner–managers imply that freedom in managerial work has many aspects. The constraints perceived vary except that the importance of profitability is highlighted by all those studied.

One of the primary aims of this paper is to help owner–managers to understand and appraise how they see and do their jobs. The research discussed here is of Finnish owner–managers. However, there seems no reason to think that the conclusions are not applicable in other countries.

Copyright © 2003 John Wiley & Sons, Ltd.
A time domain analysis of wave motions in chiral materials
Authors: Athanasiadis Christodoulos , Roach Gary F. , Stratis Ioannis G.
Published: February 2003

A time domain analysis of the equations governing wave propagation in an unbounded chiral medium is presented by a spectral family approach and by a direct eigenfunction expansion using Beltrami–Moses fields.
Linear elliptic boundary value problems in varying domains
Authors: Bochniak Marius
Published: February 2003

The paper is devoted to the study of solutions to linear elliptic boundary value problems in domains depending smoothly on a small perturbation parameter. To this end we transform the boundary value problem onto a fixed reference domain and obtain a problem in a fixed domain but with differential operators depending on the perturbation parameter. Using the Fredholm property of the underlying operator we show the differentiability of the transformed solution under the assumption that the dimension of the kernel does not depend on the perturbation parameter. Furthermore, we obtain an explicit representation for the corresponding derivative.
Full asymptotic expansion of the heat trace for non–self–adjoint elliptic cone operators
Authors: Gil Juan B.
Published: February 2003

The operator e–tA and its trace Tr e–tA, for t > 0, are investigated in the case when A is an elliptic differential operator on a manifold with conical singularities. Under a certain spectral condition (parameter–ellipticity) we obtain a full asymptotic expansion in t of the heat trace as t → 0+. As in the smooth compact case, the problem is reduced to the investigation of the resolvent (A–λ)–1. The main step consists in approximating this family by a parametrix of A – λ constructed within a suitable parameter–dependent calculus.
A boundedness result for twisted convolution
Authors: Karapetyants Alexey , de Arellano Enrique Ramírez
Published: February 2003

We consider twisted convolution operators with kernels having singularities on a sphere and having as Fourier transform the oscillatory symbol mα(|ξ|) = |ξ|–αei|ξ|, 0 ≤ ℜ︁α < 2n. We give integral representations for such operators and, as a principal result, we study Lp–Lq estimates for them.
Dimensions for random self–conformal sets
Authors: Liu Yan–Yan , Wu Jun
Published: February 2003

A set is called regular if its Hausdorff dimension and upper box–counting dimension coincide. In this paper, we prove that the random self–conformal set is regular almost surely. Also we determine the dimensions for a class of random self–conformal sets.
A quasilinear Neumann problem with discontinuous nonlinearity
Authors: Papalini Francesca
Published: February 2003

In this paper we study a quasilinear boundary value problem of Neumann type with discontinuous terms. In particular we consider a problem in which the p–Laplacian is involved. In order to prove the existence of solutions we replace this problem with a multivalued approximation of it and, using a variational approach for locally Lipschitz functionals, we prove two existence results for it.
Remarks on a theorem of Taskinen on spaces of continuous functions
Authors: Villanueva Ignacio
Published: February 2003

We clarify and prove in a simpler way a result of Taskinen about symmetric operators on C(Kn), K an uncountable metrizable compact space. To do this we prove that, for any compact space K and any n ∈ ℕ, the symmetric injective n–tensor product of C(K), $ \widehat {\bigotimes} ^n _{s, \epsilon} C(K) $, is complemented in C(BC(K)*), a result of independent interest. The techniques we develop allow us to extend the result in several directions. We also show that the hypothesis of metrizability and uncountability cannot be removed.
Smooth perturbations the self–adjoint operators defined by the ℋ︁–2–construction
Authors: Watanabe Kazuo
Published: February 2003

The existence of the wave operators for the self–adjoint operator constructed by ℋ︁–2–construction is discussed in the abstract theory by using Kato's smooth perturbation method. Moreover, the s–matrix is calculated explicitly.
A 5.8‐GHz ISM band active 90° hybrid and variable attenuator
Authors: Avitabile G. , Chellini B. , Limiti E. , Giannini F.
Published: February 2003

The paper introduces an MMIC 90° hybrid based on MIM capacitors and active inductors. The component has been used to implement an integrated variable attenuator operating at 5.8 GHz. Simulations and experimental results are reported to describe the design process and validate the proposed configuration. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 325–327, 2003
A novel capacitance formula of the microstrip line using synthetic asymptote
Authors: Kwok S. K. , Tsang K. F. , Chow Y. L.
Published: February 2003

Capacitance formulas of the microstrip line are usually curve‐fitted from numerical solutions, resulting in multiple arbitrary coefficients and multiple equations. Such complexity in equations obscures their physical insight. By using the novel technique of synthetic asymptote, a single formula with just one arbitrary constant is obtained. In this paper, the formula for the line capacitance of arbitrary substrate dielectric constant, thickness, and strip width is investigated. Important parameters of the microstrip line, such as impedance and propagation, are inferred from this capacitance formula. The average errors of the calculated parameters are only 1%. The derived capacitance formula provides insight to enable us to distinguish between the parallel plate field and the fringe field and will find important application in microwave integrated circuit design. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 327–330, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10756
Microwave‐driven thunder materials
Authors: Song Kyo D. , Yi Won J. , Chu Sang‐Hyon , Choi Sang H.
Published: February 2003

An experimental study of a smart‐materials actuator driven by a microwave is presented in this paper. A proof‐of‐concept experiment using a smart material, such as thin layer composite unimorph ferroelectric driver and sensor (THUNDER), has been demonstrated with wirelessly transmitted microwave power. Such an advance system will offer a new class of smart devices that are remotely controlled via wirelessly transmitted power. Thus, a system of this nature autonomously functions without an onboard power infrastructure. Potential applications are integrated sensors, actuators, and smart flight control in space applications, as well as biologically‐inspired systems. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 331–333, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10757