bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced glycation end-products increase monocyte adhesion to retinal endothelial cells through vascular endothelial growth factor-induced ICAM-1 expression: inhibitory effect of antioxidants
Authors: Mamputu J C , Renier G
Published: March 2004

Accumulating evidence indicates a role for advanced glycation end-products (AGEs) in the development of diabetic retinopathy. In the present study, we examined the in vitro effect of AGEs on human monocyte adhesion to bovine retinal endothelial cells (BRECs) and the molecular mechanisms involved in this effect. Treatment of cultured BRECs with AGEs led to a significant increase in monocyte adhesion and intercellular cell adhesion molecule-1 (ICAM-1) expression. These effects were inhibited by antioxidants including gliclazide and vitamins C and E. On the basis of the stimulatory effect of AGEs on vascular endothelial growth factor (VEGF) secretion by retinal endothelial cells, the role of this growth factor as mediator of AGE-induced monocyte adhesion to BRECs was next investigated. Incubation of BRECs with VEGF increased monocyte adhesion to these cells and enhanced ICAM-1 expression. Treatment of BRECs with an anti-VEGF antibody abrogated AGE-induced monocyte adhesion and ICAM-1 expression. Finally, incubation of BRECs with protein kinase C (PKC) and nuclear factor (NF)-κB inhibitors suppressed monocyte adhesion and ICAM-1 expression elicited by AGEs and VEGF. Taken together, these data indicate that AGEs increase monocyte adhesion to BRECs and that this effect is mediated through VEGF-induced ICAM-1 expression. They also demonstrate that this effect is oxidative stress-sensitive and involves PKC and NF-κB-dependent signaling pathways.
CD38 low IgG-secreting cells are precursors of various CD38 high-expressing plasma cell populations
Authors: Arce Sergio , Luger Elke , Muehlinghaus Gwendolin , Cassese Giuliana , Hauser Anja , Horst Alexander , Lehnert Katja , Odendahl Marcus , Hönemann Dirk , Heller Karl-Dieter , Kleinschmidt Harald , Berek Claudia , Dörner Thomas , Krenn Veit , Hiepe Falk , Bargou Ralf , Radbruch Andreas , Manz Rudolf A
Published: March 2004

Despite the important role immunoglobulin G (IgG)-secreting plasma cells play in memory immune responses, the differentiation and homeostasis of these cells are not completely understood. Here, we studied the differentiation of human IgG-secreting cells ex vivo and in vitro, identifying these cells by the cellular affinity matrix technology. Several subpopulations of IgG-secreting cells were identified among the cells isolated from tonsils and bone marrow, particularly differing in the expression levels of CD9, CD19, and CD38. CD38 low IgG-secreting cells were present exclusively in the tonsils. A major fraction of these cells appeared to be early plasma cell precursors, as upon activation of B cells in vitro, IgG secretion preceded up-regulation of CD38, and on tonsillar sections, IgG-containing, CD38 low cells with a plasmacytoid phenotype were found in follicles, where plasma cell differentiation starts. A unitary phenotype of migratory peripheral blood IgG-secreting cells suggests that all bone marrow plasma cell populations share a common precursor cell. These data are compatible with a multistep model for plasma cell differentiation and imply that a common CD38 low IgG-secreting precursor gives rise to a diverse plasma cell compartment.
Eosinophil degranulation in the allergic lung of mice primarily occurs in the airway lumen
Authors: Clark Kristopher , Simson Ljubov , Newcombe Nicole , Koskinen Aulikki M L , Mattes Joerg , Lee Nancy A , Lee James J , Dent Lindsay A , Matthaei Klaus I , Foster Paul S
Published: March 2004

Eosinophil degranulation is thought to play a pivotal role in the pathogenesis of allergic disorders. Although mouse models of allergic disorders have been used extensively to identify the contribution of eosinophils to disease, ultrastructural evidence of active granule disassembly has not been reported. In this investigation, we characterized the degree of eosinophil activation in the bone marrow, blood, lung tissue, and airways lumen [bronchoalveolar lavage fluid (BALF)] of ovalbumin-sensitized and aero-challenged wild-type and interleukin-5 transgenic mice. Degranulation was most prominent in and primarily compartmentalized to the airways lumen. Eosinophils released granule proteins by the process of piecemeal degranulation (PMD). Accordingly, recruitment and activation of eosinophils in the lung correlated with the detection of cell-free eosinophil peroxidase in BALF and with the induction of airways hyper-reactivity. As in previous studies with human eosinophils, degranulation of isolated mouse cells did not occur until after adherence to extracellular matrix. However, higher concentrations of exogenous stimuli appear to be required to trigger adherence and degranulation (piecemeal) of mouse eosinophils when compared with values reported for studies of human eosinophils. Thus, mouse eosinophils undergo PMD during allergic inflammation, and in turn, this process may contribute to pathogenesis. However, the degranulation process in the allergic lung of mice is primarily compartmentalized to the airway lumen. Understanding the mechanism of eosinophil degranulation in the airway lumen may provide important insights into how this process occurs in human respiratory diseases.
Expression of CD45RB functionally distinguishes intestinal T lymphocytes in inflammatory bowel disease
Authors: ten Hove Tessa , The F Olle , Berkhout Marloes , Bruggeman Joost P , Vyth-Dreese Florry A , Slors J Frederik M , van Deventer Sander J H , te Velde Anje A
Published: March 2004

The importance of CD45RB expression on T cells was already shown in mice where CD45RBhigh expression determines pathogenic potential. In this study, we analyzed the expression of CD45RA, CD45RB, and CD45RO on CD4+ T lymphocytes in the intestinal mucosa and in the circulation of patients with inflammatory bowel disease (IBD). In addition, we studied the cytokine profile of these cells. In the circulation, virtually all CD4+CD45RBhigh T cells expressed the naive marker CD45RA, and circulating CD4+CD45RBlow cells expressed the memory marker CD45RO in IBD patients and a control patient population. In contrast, the intestinal CD4+ CD45RBhigh T cells are in normal controls for 90% CD45RO+. However, in IBD, 27.7% [Crohn’s disease (CD)] and 49% [ulcerative colitis (UC)] of the intestinal CD4+ CD45RBhigh T cells are CD45RA+. This special CD4CD45RA+ T cell in IBD can be found in the lamina propria as well as in lymphoid follicles (confocal laser-scanning microscopy). The CD4+CD45RBhigh T lymphocytes produce significantly less interleukin (IL)-10 and IL-4 and produce more tumor necrosis factor α than CD45RBlow T lymphocytes in control patients. CD4+CD45RBlow T cells from IBD patients produced less IL-10 than CD4+CD45RBlow T lymphocytes of controls, and interferon-γ production by both T lymphocyte subsets was decreased in IBD. These data indicate that CD and UC are characterized by an influx of CD4+CD45RBhigh T lymphocytes. These CD4+CD45RBhigh T lymphocytes seem to be important in the pathogenesis of IBD, as they produce more proinflammatory cytokines and less anti-inflammatory cytokines compared with CD4+CD45RBlow T lymphocytes.
MCP-1-dependent signaling in CCR2−/− aortic smooth muscle cells
Authors: Schecter Alison D , Berman Adriane B , Yi Lin , Ma Harry , Daly Christine M , Soejima Kenzo , Rollins Barrett J , Charo Israel F , Taubman Mark B
Published: March 2004

Monocyte chemoattractant protein-1 (MCP-1, CCL2) is a mediator of inflammation that has been implicated in the pathogenesis of a wide variety of human diseases. CCR2, a heterotrimeric G-coupled receptor, is the only known receptor that functions at physiologic concentrations of MCP-1. Despite the importance of CCR2 in mediating MCP-1 responses, several recent studies have suggested that there may be another functional MCP-1 receptor. Using arterial smooth muscle cells (SMC) from CCR2−/− mice, we demonstrate that MCP-1 induces tissue-factor activity at physiologic concentrations. The induction of tissue factor by MCP-1 is blocked by pertussis toxin and 1,2-bis(O-aminophenyl-ethane-ethan)-N,N,N′,N′-tetraacetic acid-acetoxymethyl ester, suggesting that signal transduction through the alternative receptor is Gαi-coupled and dependent on mobilization of intracellular Ca2+. MCP-1 induces a time- and concentration-dependent phosphorylation of the mitogen-activated protein kinases p42/44. The induction of tissue factor activity by MCP-1 is blocked by PD98059, an inhibitor of p42/44 activation, but not by SB203580, a selective p38 inhibitor. These data establish that SMC possess an alternative MCP-1 receptor that signals at concentrations of MCP-1 that are similar to those that activate CCR2. This alternative receptor may be important in mediating some of the effects of MCP-1 in atherosclerotic arteries and in other inflammatory processes.
Estrogen receptor-α deficiency promotes increased TNF-α secretion and bacterial killing by murine macrophages in response to microbial stimuli in vitro
Authors: Lambert K Chad , Curran Edward M , Judy Barbara M , Lubahn Dennis B , Estes D Mark
Published: March 2004

In this series of studies, we determined the potential role of intracellular estrogen receptors (ER), ERα and ERβ, on macrophage function in response to bacterial stimuli. The sex hormone 17β-estradiol (E2) and ER have been shown to modulate inflammatory responses as well as T helper cell type 1 (TH1)/TH2 responses. The mechanisms E2 and its receptors use to alter these immune functions remain largely unknown. ERα and ERβ possess complex actions in tissues where they are expressed. We have characterized the receptor repertoire of murine dendritic cells and thioglycollate-elicited peritoneal macrophages (PM). Both cell types express mRNA for ERα. Neither cell type expressed detectable amounts of ERβ mRNA, as determined by reverse transcriptase-polymerase chain reaction using exon-specific primers spanning each of the seven intron/exon junctions. Primary macrophages from ERα- and ERβ-deficient severe combined immunodeficiency mice [ERα knockout (KO) and ERßKO, respectively] were used to delineate the effects and potential mechanisms via which steroid receptors modulate macrophage function. ERα-deficient PM exposed ex vivo to lipopolysaccharide or Mycobacterium avium exhibited significant increases in tumor necrosis factor α (TNF-α) secretion as well as reduction in bacterial load when compared with wild-type (WT) PM. In contrast, ERβ-deficient PM possessed no significant difference in TNF-α secretion or in bacterial load when compared with WT littermates. These studies suggest that ERα, but not ERβ, modulates murine PM function.
Antagonism of the α4 integrin subunit attenuates the acute inflammatory response to stent implantation yet is insufficient to prevent late intimal formation
Authors: Ma Xiaoli , O’Brien Edward R
Published: March 2004

Mononuclear leukocytes infiltrate the artery wall via integrin-mediated mechanisms and play an integral role in intimal formation after stenting. We sought to determine if acute antagonism of the α4 subunit of very late antigen-4 is sufficient for the late attenuation of stent intimal area (IA). Twenty-four hypercholesterolemic rabbits underwent iliac artery balloon injury, followed 2 weeks later by stent implantation, and the animals were randomized to receive an anti-α4 antibody (HP1/2) or a nonspecific isotypic control immunoglobulin (1E6) intravenously 1 h before stenting. Compared with controls, HP1/2-treated rabbits showed 50%, 51%, and 44% reductions in the percentage on intimal cells that were macrophages on days 3, 7, and 28 after stenting and a 59% reduction in intimal proliferation on day 3. Although stent IA was reduced by 63% and 48% in the antibody-treated group compared with the control group on days 3 and 7, this difference was not present on day 28. These data highlight the need for sustained, anti-inflammatory therapies for the prevention of stent intimal formation.
VIP/PACAP oppositely affects immature and mature dendritic cell expression of CD80/CD86 and the stimulatory activity for CD4+ T cells
Authors: Delgado Mario , Reduta Allan , Sharma Vikas , Ganea Doina
Published: March 2004

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) released within lymphoid organs from nerve terminals and/or immune cells play a significant, anti-inflammatory role by inhibiting macrophage-induced inflammatory reactions and promoting T helper cell type 2 (Th2) responses. However, dendritic cells (DC) and not macrophages often are the major antigen-presenting cells and link between innate and adaptive immunity. The role of VIP/PACAP in DC development and function is mostly unknown. Here, we report that bone marrow-derived DC express VIP/PACAP receptors and that VIP and PACAP exert a differential effect on immature DC (iDC) and lipopolysaccharide (LPS)-treated DC. In iDC, VIP/PACAP up-regulates CD86 expression and enables them to stimulate T cell proliferation and differentiation into Th2 effectors in vivo and in vitro. In contrast, VIP/PACAP down-regulates CD80/CD86 expression in LPS-stimulated DC and strongly reduces their capacity to stimulate T cell proliferation and secretion of Th1 and Th2 cytokines. The VIP/PACAP effects on iDC and LPS-stimulated DC are mediated primarily through the VIP receptor 1. These results indicate that neuropeptides such as VIP and PACAP can differentially affect the function of iDC and mature DC. In the absence of an ongoing immune response, VIP/PACAP contributes to the initiation of Th2-type immunity, whereas in the presence of a full-blown, inflammatory reaction, VIP/PACAP act as anti-inflammatory agents.
Heparin-disaccharide affects T cells: inhibition of NF-κB activation, cell migration, and modulation of intracellular signaling
Authors: Hecht Iris , Hershkoviz Rami , Shivtiel Shoham , Lapidot Tzvi , Cohen Irun R , Lider Ofer , Cahalon Liora
Published: March 2004

We previously reported that disaccharides (DS), generated by enzymatic degradation of heparin or heparan sulfate, inhibit T cell-mediated immune reactions in rodents and regulate cytokine [tumor necrosis factor α (TNF-α), interleukin (IL)-8, and IL-1β] secretion by T cells, macrophages, or intestinal epithelial cells. Here, we investigated the effects of a trisulfated heparin DS (3S-DS) on two aspects of T cell function: secretion of proinflammatory cytokines and migration to an inflamed site. 3S-DS down-regulated nuclear factor-κB activity and reduced the secretion of TNF-α and interferon-γ (IFN-γ) by anti-CD3-activated T cells. In addition, 3S-DS inhibited CXC chemokine ligand 12 (CXCL12; stromal cell-derived factor-1α)-dependent migration in vitro and in vivo and decreased CXCL12-induced T cell adhesion to the extracellular matrix glycoprotein, fibronectin (FN). This inhibition was accompanied by attenuation of CXCL12-induced Pyk2 phosphorylation but did not involve internalization of the CXCL12 receptor, CXCR4, or phosphorylation of extracellular-regulated kinase. Despite inhibiting CXCL12-induced adhesion, 3S-DS, on its own, induced T cell adhesion to FN, which was accompanied by phosphorylation of Pyk2. A monosulfated DS showed no effect. Taken together, these data provide evidence that 3S-DS can regulate inflammation by inducing and modulating T cell-signaling events, desensitizing CXCR4, and modulating T cell receptor-induced responses.
Stage I and II Follicular Non-Hodgkin’s Lymphoma: Long-Term Follow-Up of No Initial Therapy
Authors: Advani Ranjana , Rosenberg Saul A. , Horning Sandra J.
Published: March 2004

Purpose

To analyze the outcome of no initial therapy in stage I and II follicular small-cleaved (FSC) and follicular mixed (FM) non-Hodgkin’s lymphoma (NHL) on overall survival, time to treatment, incidence and course of transformation, and cause of death.

Patients and Methods

This was a retrospective analysis. Criteria for selection were patients with stage I and IIA FSC and FM (grades 1 and 2) NHL with therapy deferred for at least 3 months after diagnosis and a minimum follow-up of 1 year.

Results

Forty-three patients were identified (11 stage I, 32 stage II), with a median age of 58 years. Reasons for no initial therapy included: physician choice (n = 20), large abdominal radiation field required (n = 10), advanced age (n = 7), concern for xerostomia (n = 4), or patient refusal (n = 2). At a median follow-up of 86 months, 27 patients (63%) had not been treated. The median time to treatment in the remaining 16 patients was 22 months. Four of 16 patients transformed to a higher-grade lymphoma. Nine patients died—six due to progressive lymphoma. Estimated survivals at 5, 10, and 20 years were 97%, 85%, and 22%, respectively.

Conclusion

In selected stage I and II follicular NHL patients, deferred therapy is an acceptable approach, as more than half of our patients remained untreated at a median of 6 or more years, and survival was comparable to that seen in reports with immediate treatment.
Effect of Ageing on Hormone Secretion and Follicular Dynamics in Sheep with and without the Booroola Gene
Authors: Gonzalez-Bulnes Antonio , Souza Carlos J. H. , Campbell Bruce K. , Baird David T.
Published: March 2004

It has been suggested that ewes carrying the Booroola gene (FecB) consistently ovulate more follicles because they recruit more primordial follicles and/or have a lower rate of atresia. If the former is correct, the pool of follicles would be depleted sooner in FecB animals. We have studied follicular dynamics and endocrine function during follicular and early luteal phases of the estrous cycle of older ewes with or without the fecundity gene and compared this data with data obtained 6 yr previously in the same animals. Older sheep carrying the Booroola gene maintained a significantly higher ovulation rate than noncarrier ewes [4.2 ± 0.8 vs. 2.2 ± 0.6 corpora lutea (CL), respectively; P < 0.05], and in keeping with data from young animals, both ovulatory follicles and CL (4.7 ± 0.3 vs. 6.9 ± 0.7 mm and 12.8 ± 0.5 vs. 16.7 ± 0.8 mm, respectively) were smaller than those of noncarrier ewes (P < 0.05). The interval from luteolysis to the onset of the LH surge increased with age in all the animals (from 52.0 ± 8.0 to 67.0 ± 7.5 h in gene carrier sheep and from 56.0 ± 2.0 to 79.5 ± 9.6 h in noncarrier sheep, P < 0.05). The concentration of estradiol and inhibin A in the early luteal phase was lower in older noncarrier ewes (P = 0.08 and P < 0.05, respectively), and the level of inhibin A was inversely related to the level of FSH in aged sheep of both genotypes (P < 0.0001). In contrast, the number of developing follicles in older ewes of both genotypes was similar to the number found in younger ewes, suggesting that increased ovulation rate in sheep carrying the FecB mutation is related to a reduced rate of atresia.
The flagella connector ofTrypanosoma brucei: an unusual mobile transmembrane junction
Authors: Briggs Laura J. , McKean Paul G. , Baines Andrea , Moreira-Leite Flavia , Davidge Jacqueline , Vaughan Sue , Gull Keith
Published: March 2004

Throughout its elongation, the new flagellum of the procyclic form of the African trypanosome Trypanosoma brucei is tethered at its tip to the lateral aspect of the old flagellum. This phenomenon provides a cytotactic mechanism for influencing inheritance of cellular pattern. Here, we show that this tethering is produced via a discrete, mobile transmembrane junction – the flagella connector. Light and electron microscopy reveal that the flagella connector links the extending microtubules at the tip of the new flagellum to the lateral aspect of three of the doublet microtubules in the old flagellar axoneme. Two sets of filaments connect the microtubules to three plates on the inner faces of the old and new flagellar membranes. Three differentiated areas of old and new flagellar membranes are then juxtaposed and connected by a central interstitial core of electron-dense material. The flagella connector is formed early in flagellum extension and is removed at the end of cytokinesis, but the exact timing of the latter event is slightly variable. The flagella connector represents a novel form of cellular junction that is both dynamic and mobile.
ATPase-deficient hVPS4 impairs formation of internal endosomal vesicles and stabilizes bilayered clathrin coats on endosomal vacuoles
Authors: Sachse Martin , Strous Ger J. , Klumperman Judith
Published: March 2004

Epidermal growth factor receptors (EGFRs) destined for lysosomal degradation are sorted in the early endosomal vacuole into small, lumenal vesicles that arise by inward budding of the limiting membrane. We have previously shown that, before their incorporation into internal vesicles, EGFRs are concentrated in flat bilayered-clathrin coats on the endosomal vacuole. Here, we show that an ATPase-deficient mutant of hVPS4 (hVPS4EQ) increases the association of bilayered coats with endosomal vacuoles. In addition, hVPS4EQ leads to a reduction in the number of internal vesicles in early and late endosomal vacuoles, and retention of EGFRs at the limiting membrane. Interestingly, hVPS4EQ was predominantly found on non-coated regions of endosomal vacuoles, often at the rim of a coated area. In line with published data on Vps4p function in yeast, these results suggest that hVPS4 is involved in the release of components of the bilayered coat from the endosomal membrane. Moreover, our data suggest that disassembly of the coat is required for the formation of internal vesicles.
The transcription factor Snail downregulates the tight junction components independently of E-cadherin downregulation
Authors: Ohkubo Tadashi , Ozawa Masayuki
Published: March 2004

Snail, a transcriptional repressor of E-cadherin expression, is involved in epithelial-mesenchymal transitions during development. We demonstrate that Snail activity is not restricted to E-cadherin downregulation. Expression of tight junction proteins, including claudin-1, occludin and ZO-1, was downregulated in MDCK cells exogenously expressing Snail protein. Although occludin mRNA levels were downregulated by Snail expression, the transcription of claudin-1 and ZO-1 were unaffected. Reporter assays using the claudin-1 promoter region revealed that promoter activity was not affected by Snail overexpression. Decreased synthesis of claudin-1 protein was observed, however, suggesting that Snail may act in translation initiation. Snail expression also altered the splicing pattern of p120. The levels of mRNA encoding the epithelial variant decreased, while the fibroblastic mRNA form increased. Although ectopic E-cadherin expression resulted in a downregulation of Snail-induced fibronectin expression, fibroblastic morphology was affected only minimally; the expression of tight junctional proteins remained at low levels. These results indicate that Snail is involved in both the direct transcriptional repression of genes, such as E-cadherin and occludin, and post-transcriptional events, including downregulation of claudin-1. These data support the idea that Snail is a transcription factor possessing pleiotropic activities.
Role of tau phosphorylation by glycogen synthase kinase-3β in the regulation of organelle transport
Authors: Tatebayashi Yoshitaka , Haque Niloufar , Tung Yunn-Chyn , Iqbal Khalid , Grundke-Iqbal Inge
Published: March 2004

Anterograde organelle transport is known to be inhibited by overexpression of the microtubule-associated protein tau in cultured cells. However, the molecular mechanism regulating this function of tau protein has not previously been understood. We found that in PC12 cells treated with NGF or fibroblast growth factor-2, glycogen synthase kinase-3β and tau were upregulated simultaneously from around day 2 of differentiation, with increasing glycogen synthase kinase-3-mediated tau phosphorylation. This phosphorylation did not alter tau's ability to bind to microtubules but appeared to be required for the maintenance of the anterograde organelle transport in differentiated cells. Lithium, alsterpaullone or valproate, three independent glycogen synthase kinase-3 inhibitors, but not butyrolactone 1, an inhibitor of cyclin-dependent protein kinases, induced mitochondrial clustering in association with tau dephosphorylation. In CHO cells transfected with human tau441, mitochondrial clustering was found in cells in which tau was unphosphorylated. These findings raise the possibility that the phosphorylation of tau by glycogen synthase kinase-3 might be involved in the regulation of organelle transport.
Active and specific recruitment of a soluble cargo protein for endoplasmic reticulum exit in the absence of functional COPII component Sec24p
Authors: Fatal Netta , Karhinen Leena , Jokitalo Eija , Makarow Marja
Published: March 2004

Exit of proteins from the yeast endoplasmic reticulum (ER) is thought to occur in vesicles coated by four proteins, Sec13p, Sec31p, Sec23p and Sec24p, which assemble at ER exit sites to form the COPII coat. Sec13p may serve a structural function, whereas Sec24p has been suggested to operate in selection of cargo proteins into COPII vesicles. We showed recently that the soluble glycoprotein Hsp150 exited the ER in the absence of Sec13p function. Here we show that its ER exit did not require functional Sec24p. Hsp150 was secreted to the medium in a sec24-1 mutant at restrictive temperature 37°C, while cell wall invertase and vacuolar carboxypeptidase Y remained in the ER. The determinant guiding Hsp150 to this transport route was mapped to the C-terminal domain of 114 amino acids by deletion analysis, and by an HRP fusion protein-based EM technology adapted here for yeast. This domain actively mediated ER exit of Sec24p-dependent invertase in the absence of Sec24p function. However, the domain was entirely dispensable for ER exit when Sec24p was functional. The Sec24p homolog Sfb2p was shown not to compensate for nonfunctional Sec24p in ER exit of Hsp150. Our data show that a soluble cargo protein, Hsp150, is selected actively and specifically to budding sites lacking normal Sec24p by a signature residing in its C-terminal domain.
αB-Crystallin-coated MAP microtubule resists nocodazole and calcium-induced disassembly
Authors: Fujita Yoshinobu , Ohto Eri , Katayama Eisaku , Atomi Yoriko
Published: March 2004

αB-Crystallin, one of the small heat-shock proteins, is constitutively expressed in various tissues including the lens of the eye. It has been suggested that αB-crystallin provides lens transparency but its function in nonlenticular tissues is unknown. It has been reported that αB-crystallin is involved in the stabilization and the regulation of cytoskeleton, such as intermediate filaments and actin. In this study, we investigate the possibility whether αB-crystallin interacts with the third cytoskeleton component, microtubules (MTs). First, we precisely observed the cellular localization of αB-crystallin and MT networks in L6E9 myoblast cells and found a striking coincidence between them. MTs reconstituted from cell lysate contained αB-crystallin. Electron micrographs clearly showed direct interactions of purified αB-crystallin with the surface of microtubule-associated proteins (MAPs) attached to MTs. Purified αB-crystallin bound to MAP-MTs in a concentration-dependent manner. However, αB-crystallin did not bind MTs reconstituted from purified tubulin. Finally, we observed that αB-crystallin increased the resistance of MTs to depolymerization in cells and in vitro. Taken together, these results suggest that one of the functions of αB-crystallin is to bind MTs via MAP(s) and to give the MTs resistance to disassembly.
Unconventional protein secretion: membrane translocation of FGF-2 does not require protein unfolding
Authors: Backhaus Rafael , Zehe Christoph , Wegehingel Sabine , Kehlenbach Angelika , Schwappach Blanche , Nickel Walter
Published: March 2004

Endoplasmic reticulum/Golgi-dependent protein secretion depends on signal peptides that mediate membrane translocation of nascent secretory proteins into the lumen of the endoplasmic reticulum. Classical secretory proteins are transported across the membrane of the endoplasmic reticulum in an unfolded conformation, which is similar to protein import into mitochondria. This process is mediated by Sec61, the protein-conducting channel of the endoplasmic reticulum. Employing both FACS-based in vivo transport assays and confocal microscopy, we now show that fibroblast growth factor 2 (FGF-2), a pro-angiogenic mediator exported from mammalian cells by an unconventional secretory pathway, does not need to be unfolded in order to be released into the extracellular space. These findings suggest that the molecular apparatus mediating export of FGF-2 is not only distinct from classical translocation machineries in terms of molecular identity but also operates in a mechanistically distinct manner that allows membrane translocation of FGF-2 in a folded conformation.
Partitioning of IGFBP-5 actions in myogenesis: IGF-independent anti-apoptotic function
Authors: Cobb Laura J. , Salih Dervis A. M. , Gonzalez Ivelisse , Tripathi Gyanendra , Carter Emma J. , Lovett Fiona , Holding Cathy , Pell Jennifer M.
Published: March 2004

Igfbp5 is upregulated during the differentiation of several key cell lineages and in some tumours; the function of IGFBP-5 in these physiological and pathological situations is unknown. Since IGFBP-5 contains sequence motifs consistent with IGF-independent actions, the aim of these studies was to distinguish between IGF-dependent and -independent actions of IGFBP-5. Myc-tagged wild-type (termed wtIGFBP-5) and non-IGF binding mouse Igfbp5 (termed mutIGFBP-5) cDNAs were generated and used to transfect C2 myoblasts, a cell line that undergoes differentiation to myotubes in an IGF- and IGFBP-5-regulated manner. WtIGFBP-5, but not mutIGFBP-5, inhibited myogenesis, as assessed by cell morphology, MHC immunocytochemistry and caveolin 3 expression. However, both wt- and mutIGFBP-5 increased cell survival and decreased apoptosis, as indicated by decreased caspase-3 activity and cell surface annexin V binding. Further examination of apoptotic pathways revealed that wt- and mutIGFBP-5 ameliorated the increase in caspase-9 but not the modest increase in caspase-8 during myogenesis, suggesting that IGFBP-5 increased cell survival via inhibition of intrinsic cell death pathways in an IGF-independent manner. The relationship between IGF-II and IGFBP-5 was examined further by cotransfecting C2 myoblasts with antisense Igf2 (previously established to induce increased cell death) and Igfbp5; both wt- and mutIGFBP-5 conferred equivalent protection against the decreased cell survival and increased apoptosis. In conclusion, we have partitioned IGFBP-5 action in myogenesis into IGF-dependent inhibition of differentiation and IGF-independent cell survival. Our findings suggest that, by regulation of cell survival, IGFBP-5 has an autonomous role in the regulation of cell fate in development and in tumourigenesis.
A study on the optimization of a mechanical press drive
Authors: Choi H J , Jang D H , Ko B D , Hwang B B
Published: March 2004

This paper is concerned with the optimization of the drive for a linear guide press, which is one of the mechanical presses. The design of a linear guide drive for a mechanical press is introduced, and the eccentric mechanism is optimized in order to improve the load and velocity characteristics. The optimized drive is compared with the existing one in terms of load, velocity, torque, etc. As a result of optimization, the load capacity during the stroke is increased and the slide velocity in the working region is reduced. The new design provides many applications for precision forming such as extrusion and the sheet metal forming processes.
Performance enhancement using an expert mechanism in a manufacturing simulator
Authors: Mebrahtu H , Walker R , Mileham T
Published: March 2004

The need to include a mechanism that could assist in analysis and performance enhancement of simulation models has been under discussion for a long time. Many simulation packages on the market offer powerful ‘What if evaluation techniques for production planning.’ However, most of them rely on the user's own experience to interpret the results after each simulation, and anyone without such experience would find it difficult to make reasonable sense of the results before deciding on the next simulation run. This paper describes the use of an expert mechanism that could be integrated into a simulation package to facilitate the process of interpreting and assessing simulation results and in improving performance. It also discusses the need for checking stability of the model before reporting the model as realistic.
Predicting winding stresses for wound coils of linear orthotropic material
Authors: de Hoog F R , Cozijnsen M , Yuen W Y D , Yuen W Y D , Huynh H-N
Published: March 2004

This paper examines centre winding of coils under the assumption that the material is linear and orthotropic. A radically different approach is taken in the analysis of residue stresses in the coils. Instead of the forward solution of determining the residue stresses from the given winding stress profile, as traditionally adopted in this field of research, an inverse solution is obtained in which the winding tension profile is determined from the prescribed residue stresses. This approach offers significant advantages in industrial applications, since the preferred residue stress distributions to prevent coiling problems, such as tight-bore collapses and coil slump, are often specified. Numerical results from the inverse solution are found to be in perfect agreement with the forward solution.
Dynamic instability characteristics of doubly curved panels subjected to partially distributed follower edge loading with damping
Authors: Kumar L Ravi , Datta P K , Prabhakara D L
Published: March 2004

The vibration and dynamic instability characteristics of doubly curved panels subjected to partially distributed non-conservative follower load are studied using finite element analysis. The first-order shear deformation theory is used to model the doubly curved panels, considering the effects of shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to Sander's first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. The modal transformation technique is applied to the resulting equilibrium equation for subsequent analysis. Structural damping is introduced into the system in terms of equivalent viscous damping. The effects of load bandwidth, boundary condition, load direction control parameter and damping are considered for the stability behaviour of the panels. The results show that the load bandwidth has a significant effect on the dynamic instability characteristics of the panels. The analysis also shows that, under follower loading, the system is susceptible to instability due to flutter alone or due to both flutter and divergence, depending upon the system parameters. Structural damping significantly affects the critical flutter loads of the panels.
Experimental buckling of a simple aerofoil under combined shear and in-plane bending
Authors: Featherston C A
Published: March 2004

The buckling loads and postbuckling behaviour of complex structures can only be determined analytically by simplifying them into a number of component parts and examining these individually using existing design rules. This approach does not consider the effect of geometric imperfections and large deflections or the interaction between overall and local buckling modes. Alternatively, finite element analysis can be used. This approach has the advantage of allowing geometry, boundary and loading conditions to be modelled more accurately. Large-scale deflections and material plasticity can be modelled, the effects of imperfections examined and all possible modes of failure considered.

This paper outlines a series of experiments carried out to determine the accuracy of these two alternative techniques in predicting the buckling loads and postbuckling behaviour for the case of a simple aerofoil under combined shear and in-plane bending.
Numerical modelling of atmospheric pool boiling by the coupled map lattice method
Authors: Ghoshdastidar P S , Kabelac S , Mohanty A
Published: March 2004

In the present paper, the characteristic atmospheric saturated pool boiling curve is qualitatively reproduced for water on a temperature-controlled long and thin copper strip using the coupled map lattice (CML) method known in non-linear spatio-temporal chaos dynamics. The pool height is 0.7 mm, indicating that the boiling is of the thin-film type. The work modifies the basic theoretical model proposed by Shoji in 1998 in terms of nucleation superheat distribution and mixing. The stirring action of the bubbles is modelled by increasing the fluid thermal diffusivity by an enhancement factor. It is assumed that boiling is governed by (a) nucleation from cavities on a heated surface, (b) thermal diffusion, (c) bubble rising motion and associated convection, (d) phase change and (e) Taylor instability. The effectiveness of the enhancement factor approach in the present model is clearly seen in its capability of reproducing the saturated pool boiling curve well and predicting the critical heat flux (CHF) in the same order of magnitude of the actual value.
Boiling heat transfer characteristics of binary magnetic fluid flow in a vertical circular pipe with a partly heated region
Authors: Shuchi S , Sakatani K , Yamaguchi H
Published: March 2004

An investigation was conducted for heat transfer characteristics of binary magnetic fluid flow in a partly heated circular pipe experimentally. The boiling heat transfer characteristics on the effects of the relative position of the magnetic field to the heated region were particularly considered in the present study. From the experimental verification, the Nusselt number, representing boiling heat transfer characteristics, was obtained for various flow and magnetic conditions which were represented by the non-dimensional parameters of the Reynolds number and the magnetic pressure number. Additionally, the rate of change of the Nusselt number found by applying the magnetic field was also estimated and the optimal position of the field to the partly heated region was discussed. The results indicated that the effect of the magnetic field to the heat transfer rate from the heated wall was mainly subjected to the effect of the vortices induced in the magnetic field region and the possibility of controlling the heat transfer rate by applying an outer magnetic field to utilize the effect.
Inertial liquid loading on the nozzle of a needle-free injection device
Authors: Symons D D
Published: March 2004

Needle-free injection devices allow delivery of liquid drugs without a hypodermic needle. Advantages include ease of use, patient preference, dose accuracy and elimination of the risk of ‘needle-stick’ injuries. All liquid needle-free devices use the same principle: the liquid drug is pressurized and delivered at high velocity through a small orifice in close proximity to the skin. The liquid jet penetrates the skin and the drug is delivered into the skin tissues. The high pressures within the drug capsule, together with pharmaceutical requirements that restrict material choice, provide a challenging design problem. This problem is further complicated by the possibility of bubbles within the drug liquid. Bubbles may significantly increase peak pressures and lead to capsule failure. In this paper a model is proposed for the inertial response of the liquid in an open conical nozzle. An equation of motion is derived for the liquid displacement, which is used to predict the pressure distribution. The equation for liquid flow in the nozzle is incorporated into a mathematical model of a needle-free injection device; this model is used in numerical simulations to predict the effect of a bubble at the orifice on the pressure in the nozzle.
A new perturbation estimator in a variable structure system with application to robot control
Authors: Choi S B , Ham J H
Published: March 2004

In this work, a new perturbation estimator using the theory of the variable structure system (VSS) is proposed to enhance control performance of non-linear systems subjected to perturbations such as parameter uncertainties and external disturbances. The proposed estimator is featured by an integrated average value of the imposed perturbation over a certain sampling period. By doing this, undesirable chattering phenomenon in the estimation process can be effectively alleviated. In addition, the proposed method offers a flexibility for tuning the ratio of the perturbation estimation sampling rate to the control input sampling rate. The benefits of the proposed control methodology are demonstrated on a planar robotic manipulator. The position tracking control performances of the manipulator are evaluated and compared between the proposed methodology and conventional scheme for perturbation estimation.
Multidimensional modelling of flow through piston-controlled ports using a multi-block, moving mesh algorithm
Authors: Bakshi S , Deshmukh D , Ravikrishna R V
Published: March 2004

In the present work, a complete algorithm is presented to simulate the gas exchange process across domains in a multi-block computation involving a piston-controlled port. The moving boundary scheme of Peric is used in conjunction with the zonal boundary scheme of Rai. The algorithm has been applied to two cases. The first case involves a typical air-filling process through the piston-operated port of a pneumatic pump, and the analysis shows that flowfield variable information is smoothly communicated across the zonal boundary using this algorithm. The second case involves modelling of the scavenging process in a loop-scavenged two-stroke internal combustion (IC) engine. In this case, the stepwise evolution of the scavenging flow in the engine cylinder is studied. Initiation of short circuiting at early stages of scavenging, tilting of the inlet flow in directions different from inlet port angles and the existence of a low-purity swirling loop in the exhaust-side top corner of the engine cylinder are observed from the flowfield computations.
Trends in acoustic properties of iron particle seeded auxetic polyurethane foam
Authors: Scarpa F , Bullough W A , Lumley P
Published: March 2004

The sound absorption characteristic of a clean, open-cell configuration, typical polyurethane flexible foam is shown against that of an auxetic foam made from it, and this same foam after it has been seeded with a magnetorheological fluid (then dried), having 2–5 μm carbonyl iron particles and subjected to zero, weak and concentrated magnetic fields in an acoustic impedance tube facility. The resultant foam indicates the capability of shifting the peak acoustic absorption coefficient within a given frequency bandwidth when constant intensity magnetic fields are applied.
Overstraining of flush plain cross-bored cylinders
Authors: Kihiu J M , Rading G O , Mutuli S M
Published: March 2004

A three-dimensional finite element method computer program was developed to establish the elastic-plastic, residual and service stress distributions in thick-walled cylinders with flush and non-protruding plain cross bores under internal pressure. The displacement formulation and eight-noded brick isoparametric elements were used. The incremental theory of plasticity with a 5 per cent yield condition (an element is assumed to have yielded when the effective stress is within 5 per cent of the material yield stress) and von Mises yield criterion were assumed. The frontal solution technique was used. The incipient yield pressure and the pressure resulting in a 0.3 per cent overstrain ratio were established for various cylinder thickness ratios and cross bore-main bore radius ratios. For a thickness ratio of 2.25 and a cross bore-main bore radius ratio of 0.1, the stresses were determined for varying overstrain and an optimum overstrain ratio of 37 per cent was established. To find the accuracy of the results, the more stringent yield condition of 0.5 per cent was also considered. The benefits of autofrettage were presented and alternative autofrettage and yield condition procedures proposed.
Shear stress tracking control of an electrorheological fluid considering hysteresis non-linearity
Authors: Han Y M , Choi S B
Published: March 2004

This paper presents shear stress tracking control of an electrorheological (ER) fluid actuator subjected to the hysteresis non-linearity. As a first step, polymethylaniline (PMA) particles are prepared and mixed with silicone oil to make an ER fluid. The Couette-type electroviscometer is employed to achieve the field-dependent shear stress. The Preisach model for the PMA-based ER fluid is identified using experimental first-order descending (FOD) curves. A compensation strategy is then formulated in a discrete manner through the Preisach model inversion to achieve the desired shear stress of the ER fluid. A proportional-intergal-derivative (PID) feedback controller is also integrated with the compensator in order to guarantee control robustness to uncertainty due to temperature-dependent hysteresis variation. The tracking performance of the control strategy is experimentally evaluated for two different desired shear stress trajectories.
Stress in V-section band clamps
Authors: Shoghi K , Barrans S M , Rao H V
Published: March 2004

This paper presents an analysis of the stresses in V-section band clamps by examining the correlation between experimental work and theoretical models. Theoretical models incorporating traditional beam-bending theories and allowing for friction were developed to calculate the stress distribution and displacements within the clamps. The theoretical models demonstrated that the normal manufacturing tolerances associated with this type of component, combined with the uncontrolled operating parameters, will produce a wide variation in working stresses.

These theoretical models were validated using strain and displacement measurements from a test with a V-section band clamp positioned around rigid flanges. The experimental results all fell within the range of stresses predicted by the theoretical models. The paper provides a knowledge base for the rational design of V-section band clamps.
On torsional stiffness and natural frequency of bellows
Authors: Lu C L , Wu T X , Yu J G , Ye Q T
Published: March 2004

Simplified formulae for torsional natural frequencies of bellows are developed using an equivalent thin-walled pipe model. To do this the torsional stiffness of bellows needs to be worked out. The torsional stiffness of bellows is determined using Chien's integration method. Accordingly, the Expansion Joint Manufactures Association (EJMA) formula for torsional stiffness calculation is modified using two different equivalent radii. The torsional natural frequencies of bellows are calculated using the simplified formulae based on the equivalent thin-walled pipe model and the modified formulae for torsional stiffness of bellows. The results from the simplified formuale are verified by those from a finite element (FE) model and good agreement is shown between the simplified formulae and the FE model.