bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of plasma membrane Ca2+ pump activity in normal human red blood cells
Authors: Lew Virgilio L. , Daw Nuala , Perdomo Deisy , Etzion Zipora , Bookchin Robert M. , Tiffert Teresa
Published: August 2003

The plasma membrane calcium pump (PMCA) is the only active Ca2+ transporter in human red blood cells (RBCs). Previous measurements of maximal Ca2+ extrusion rates (Vmax) reported only mean values in the RBC population. Despite early evidence for differences in Ca2+ extrusion capacity among RBCs, the precise Vmax distribution remained unknown. It was important to characterize this distribution to assess the range and modality (uni- or multimodal) of PMCA Vmax variation and the likelihood of RBCs with elevated [Ca2+]i in the circulation participating in physiologic and pathologic processes. We report here the application of a new method to investigate the detailed distribution of PMCA Vmax activity in RBCs. The migrating profile of osmotic lysis curves was used to identify and quantify the fraction of cells that extrude a uniform Ca2+ load at different rates. The results revealed that RBCs from single donors have large variations in PMCA activity that follow a unimodal, broad distribution pattern consistently skewed toward higher Vmax values, suggesting an excess of cells with Vmax higher than the mean value. The method applied may provide a way of evaluating whether the observed variation in PMCA Vmax is related to cell age. (Blood. 2003;102:4206-4213)
Allogeneic hematopoietic stem cell transplantation for myelofibrosis
Authors: Deeg H. Joachim , Gooley Theodore A. , Flowers Mary E. D. , Sale George E. , Slattery John T. , Anasetti Claudio , Chauncey Thomas R. , Doney Kristine , Georges George E. , Kiem Hans-Peter , Martin Paul J. , Petersdorf Effie W. , Radich Jerald , Sanders Jean E. , Sandmaier Brenda M. , Warren E. Houston , Witherspoon Robert P. , Storb Rainer , Appelbaum Frederick R.
Published: August 2003

Fifty-six patients, 10 to 66 years of age, with idiopathic myelofibrosis (IMF) or end-stage polycythemia vera or essential thrombocythemia received allogeneic hematopoietic cell transplants from related (n = 36) or unrelated (n = 20) donors. Forty-four patients were prepared with busulfan plus cyclophosphamide and 12 with total body irradiation plus chemotherapy. The source of stem cells was marrow in 33 and peripheral blood in 23 patients. All but 3 patients achieved engraftment. While 50 patients showed complete donor chimerism, 3 patients were found to be mixed chimeras at 26, 48, and 86 months after transplantation, respectively. Two patients died from relapse/progressive disease, and 18 died from other causes. There are 36 patients surviving at 0.5 to 11.6 (median, 2.8) years, for a 3-year Kaplan-Meier estimate of 58% (CI, 43%-73%). Dupriez score, cytogenetic abnormalities, and degree of marrow fibrosis were the most significant risk factors for posttransplantation mortality. Patients conditioned with a regimen of busulfan targeted to plasma levels of 800 to 900 ng/mL plus cyclophosphamide had a higher probability of survival (76% [CI, 62%-91%]) than other patients. Results with unrelated donors were comparable with those with HLA-identical sibling transplants. Thus, allogeneic hematopoietic cell transplantation offers long-term relapse-free survival for patients with myelofibrosis.
Inhibition of invariant chain expression in dendritic cells presenting endogenous antigens stimulates CD4+ T-cell responses and tumor immunity
Authors: Zhao Yangbing , Boczkowski David , Nair Smita K. , Gilboa Eli
Published: August 2003

Induction of potent and sustained antiviral or antitumor immunity is dependent on the efficient activation of CD8+ and CD4+ T cells. While dendritic cells constitute a powerful platform for stimulating cellular immunity, presentation of endogenous antigens by dendritic cells transfected with nucleic acid-encoded antigens favors the stimulation of CD8+ T cells over that of CD4+ T cells. A short incubation of mRNA-transfected dendritic cells with antisense oligonucleotides directed against the invariant chain enhances the presentation of mRNA-encoded class II epitopes and activation of CD4+ T-cell responses in vitro and in vivo. Immunization of mice with the antisense oligonucleotide-treated dendritic cells stimulates a more potent and longer lasting CD8+ cytotoxic T-cell (CTL) response and enhances the antitumor efficacy of dendritic cell-based tumor vaccination protocols. Transient inhibition of invariant chain expression represents a simple and general method to enhance the stimulation of CD4+ T-cell responses from endogenous antigens. (Blood. 2003;102:4137-4142)
The phosphoserine-585–dependent pathway of the GM-CSF/IL-3/IL-5 receptors mediates hematopoietic cell survival through activation of NF-κB and induction of bcl-2
Authors: Guthridge Mark A. , Barry Emma F. , Felquer Fernando A. , McClure Barbara J. , Stomski Frank C. , Ramshaw Hayley , Lopez Angel F.
Published: August 2003

We have recently identified a novel mechanism of hematopoietic cell survival that involves site-specific serine phosphorylation of the common beta subunit (βc) of the granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 receptors. However, the downstream components of this pathway are not known, nor is its relationship to survival signals triggered by tyrosine phosphorylation of the receptor clear. We have now found that phosphorylation of Ser585 of βc in response to GM-CSF recruited 14-3-3 and phosphatidyl inositol 3-OH kinase (PI 3-kinase) to the receptor, while phosphorylation of the neighboring Tyr577 within this “viability domain” promoted the activation of both Src homology and collagen (Shc) and Ras. These are independent processes as demonstrated by the intact reactivity of phosphospecific anti-Ser585 and anti-Tyr577 antibodies on the cytotoxic T-lymphocyte–ecotrophic retroviral receptor neomycin (CTL-EN) mutants βcTyr577Phe and βcSer585Gly, respectively. Importantly, while mutants in which either Ser585 (βcSer585Gly) or all tyrosines (βcF8) were substituted showed a defect in Akt phosphorylation, nuclear factor κB (NF-κB) activation, bcl-2 induction, and cell survival, the mutant βcTyr577Phe was defective in Shc, Ras, and extracellular signal-related kinase (ERK) activation, but supported CTL-EN cell survival in response to GM-CSF. These results demonstrate that both serine and tyrosine phosphorylation pathways play a role in hematopoietic cell survival, are initially independent of each other, and converge on NF-κB to promote bcl-2 expression.
The limited utility of electrocardiography variables used to predict arrhythmia in psychotropic drug overdose
Authors: Buckley Nicholas A , Chevalier Stephan , Leditschke I Anne , O'Connell Dianne L , Leitch James , Pond Susan M
Published: August 2003

Objective

The aim of the present study was to examine the relationship between serious arrhythmias in patients with psychotropic drug overdose and electrocardiography (ECG) findings that have been suggested previously to predict this complication.

Methods

Thirty-nine patients with serious arrhythmias (ventricular tachycardia, supraventricular tachycardia or cardiac arrest) after tricyclic antidepressant overdose or thioridazine overdose were compared with 117 controls with clinically significant overdose matched to each case for the drug ingested. These patients with psychotropic drug overdose had presented for treatment to the Department of Clinical Toxicology, Newcastle and to the Princess Alexandra Hospital, Brisbane. The heart rate, the QRS width, the QTc and QT intervals, the QT dispersion, and the R wave and R/S ratios in aVR on the initial ECGs were compared in cases and controls.

Results

The cases had taken dothiepin (16 patients), doxepin (six patients), thioridazine (five patients), amitriptyline (five patients), nortriptyline (three patients), imipramine (one patient) and a combination of dothiepin and thioridazine (three patients). In 20 of the 39 patients with arrhythmias, the arrhythmia had been a presumed ventricular tachycardia. Of the other 19 patients, 15 patients had a supraventricular tachycardia, two patients had cardiac arrests (one asystole, one without ECG monitoring) and two patients had insufficient data recorded to make classification of the arrhythmias possible. The QRS was ≥ 100 ms in 82% of cases but also in 76% of controls. QRS ≥ 160 ms had a sensitivity of only 13% and occurred in 2% of controls. QRS > 120 ms, QTc > 500 and the R/S ratio in aVR appeared to have a stronger association with the occurrence of arrhythmia: QRS > 120 ms (odds ratio [OR], 3.56; 95% confidence interval [CI], 1.46–8.68), QTc > 500 (OR, 3.07; 95% CI, 1.33–7.07), and R/S ratio in aVR > 0.7 (OR, 16; 95% CI, 3.47–74). Excluding thioridazine overdoses and performing the analysis for tricyclic antidepressant overdoses alone gave increased odds ratios for QRS > 120 ms (OR, 4.83; 95% CI, 1.73–13.5) and QTc > 500 (OR, 4.5; 95% CI, 1.56–13) but had little effect on that for the R/S ratio in aVR > 0.7 (OR, 14.5; 95% CI, 3.10–68).

Conclusion

ECG measurements were generally weakly related to the occurrence of arrhythmia and should not be used as the sole criteria for risk assessment in tricyclic antidepressant overdose. The frequently recommended practice of using either QRS ≥ 100 ms or QRS ≥ 160 ms to predict arrhythmias is not supported by our study. R/S ratio in aVR > 0.7 was most strongly related to arrhythmia but had estimated positive and negative predictive values of only 41% and 95%, respectively. The use of these specific predictors in other drug overdoses is not recommended without specific studies.
Estradiol Increases Pre- and Post-Synaptic Proteins in the CA1 Region of the Hippocampus in Female Rhesus Macaques (Macaca mulatta)
Authors: Choi Janet M. , Romeo Russell D. , Brake Wayne G. , Bethea Cynthia L. , Rosenwaks Zev , McEwen Bruce S.
Published: August 2003

The role of estrogen (E) in promoting learning and memory in females has been well studied in both rodent and primate models. In female rats, E increases dendritic spine number, synaptogenesis, and synaptic proteins in the CA1 region of the hippocampus, an area of the brain that mediates learning and memory. In the present study, we used radioimmunocytochemistry to examine whether E and progesterone were capable of modulating the levels of pre- and postsynaptic proteins in the CA1 region of the female nonhuman primate hippocampus. It was found that E increased syntaxin, synaptophysin (presynaptic), and spinophilin (postsynaptic) levels in the stratum oriens and radiatum of the CA1 region, whereas combined E and progesterone treatment decreased these synaptic proteins to the levels found in untreated, spayed controls. Furthermore, progesterone treatment alone significantly increased synaptophysin levels in the stratum oriens and radiatum of the CA1 region. The levels of these synaptic proteins were unaltered by hormone treatment in the dentate gyrus, suggesting that this steroid-induced plasticity is hippocampal region specific. As these synaptic proteins are important components of the synaptic apparatus and reliable markers of synaptogenesis, it appears that E-induced increases in cognitive function of higher order mammals may be mediated in part by the effect of E on hippocampal synaptogenesis and synaptic plasticity.
The Constitutively Active N111G-AT1 Receptor for Angiotensin II Maintains a High Affinity Conformation Despite Being Uncoupled from Its Cognate G Protein Gq/11α
Authors: Auger-Messier Mannix , Clement Martin , Lanctot Pascal M. , Leclerc Patrice C. , Leduc Richard , Escher Emanuel , Guillemette Gaetan
Published: August 2003

Asn111, localized in the third transmembrane domain of the AT1 receptor for angiotensin II, plays a critical role in stabilizing the inactive conformation of the receptor. We evaluated the functional and G protein-coupling properties of mutant AT1 receptors in which Asn111 was substituted with smaller (Ala or Gly) or larger residues (Gln or Trp). All four mutants were expressed at high levels in COS-7 cells and, except for N111W-AT1, recognized 125I-Ang II with high affinities comparable to that of the wild-type AT1 receptor. In phospholipase C assays, the four mutants encompassed the entire spectrum of functional states, ranging from constitutive activity (without agonist) for N111A-AT1 and N111G-AT1 to a significant loss of activity (upon maximal stimulation) for N111Q-AT1 and a major loss of activity for N111W-AT1. In Ca2+ mobilization studies, N111W-AT1 produced a weak Ca2+ transient and, unexpectedly, N111G-AT1 also produced a Ca2+ transient that was much weaker than that of the wild-type AT1. The agonist binding affinity of N111W-AT1 was not modified in the presence of GTPγ S, suggesting that this receptor is not basally coupled to a G protein. GTPγ S did not modify the high agonist-binding affinity of N111G-AT1 but abolished the coimmunoprecipitation of Gq/11α with this constitutively active mutant receptor. These results are a direct demonstration that the N111G-AT1 receptor maintains a high affinity conformation despite being uncoupled from the G protein Gq/11.
Steroidogenic Factor-1 and The Gonadotrope-Specific Element Enhance Basal and Pituitary Adenylate Cyclase-Activating Polypeptide-Stimulated Transcription of the Human Glycoprotein Hormone α-Subunit Gene in Gonadotropes
Authors: Fowkes Robert C. , Desclozeaux Marion , Patel Mayur V. , Aylwin Simon J. B. , King Peter , Ingraham Holly A. , Burrin Jacky M.
Published: August 2003

In the anterior pituitary, expression of the common glycoprotein hormone α-subunit (αGSU) is mediated in part by multiple response elements residing in the distal promoter (−435 bp). One such site is the gonadotrope-specific element (GSE), which is bound by the orphan nuclear receptor steroidogenic factor-1 (SF-1) and confers pituitary adenylate cyclase-activating polypeptide (PACAP)-stimulated αGSU expression. Here we investigated the functional importance of the GSE and SF-1 phosphorylation in both basal and stimulated αGSU transcription. Mutation of the GSE reduced basal and PACAP-stimulated αGSU promoter activity in the αT3-1 gonadotrope cell line. Overexpression of wild-type SF-1, but not an S203A mutant form of SF-1, enhanced basal and PACAP-stimulated αGSU promoter activity. The effect of PACAP on αGSU promoter activity was inhibited after overexpression of MAPK phosphatase. Helix assembly of the SF-1 ligand-binding domain was stimulated by PACAP in vitro via a MAPK-dependent pathway, as determined using a mammalian two-hybrid assay. PACAP quickly activated MAPK (within 5 min) and also resulted in elevated levels of phospho-cAMP response element-binding protein and phospho-SF-1, as judged by a specific antiphospho-S203 antibody; this effect was blocked by the MAPK kinase inhibitor, UO126. Collectively, these data demonstrate that SF-1 binds to the GSE and activates both basal and PACAP-stimulated αGSU transcription, which is further increased by phosphorylation at Ser203 via MAPK. These data suggest strongly that the induction of αGSU gene expression by peptide hormone signaling is coupled directly to the posttranslational status of SF-1.
Discovery in Silico and Characterization in Vitro of Novel Genes Exclusively Expressed in the Mouse Epididymis
Authors: Penttinen Jenni , Pujianto Dwi Ari , Sipilä Petra , Huhtaniemi Ilpo , Poutanen Matti
Published: August 2003

Epididymal proteins interact with sperm during their passage through the epididymis and thus contribute to the maturation and fertilizing capacity of the spermatozoa. In the present study we have discovered five novel epididymis-specific genes through in silico analysis of expressed sequence tags (ESTs) at the UniGene library collection. The strategy used is a powerful way to discover novel epididymis-specific genes. The full-length cDNA sequences were determined, and computational tools were used to characterize the genomic structures and to predict putative functions for the encoded proteins. In vitro analyses revealed that all five genes characterized were highly expressed in the defined areas of the epididymis, and they were not expressed at significant levels in any other tissue. Three of the genes were named on the basis of their putative functions: Spint4 (serine protease inhibitor, Kunitz type 4), and Rnase9 and Rnase10 (ribonuclease, Rnase A family 9 and 10), while for the ESTs AV381130 and AV381126 no putative functions could be predicted. The expression of Spint4, Rnase9, and AV381130 was found to be under a direct or indirect regulation by androgens, while the expression of Rnase10 is regulated by a testicular factor(s) other than androgen. None of the genes were expressed in the immature epididymis, while mRNAs were detected from d 17 onward, at the time of maturation of epididymal epithelium. However, the expression of AV381130 was not detected until d 30 after birth, indicating a close connection between gene expression and puberty.
Identification of a Novel Glucocorticoid Receptor Mutation in Budesonide-Resistant Human Bronchial Epithelial Cells
Authors: Kunz Susan , Sandoval Robert , Carlsson Peter , Carlstedt-Duke Jan , Bloom John W. , Miesfeld Roger L.
Published: August 2003

We developed a molecular genetic model to investigate glucocorticoid receptor (GR) signaling in human bronchial epithelial cells in response to the therapeutic steroid budesonide. Based on a genetic selection scheme using the human Chago K1 cell line and integrated copies of a glucocorticoid-responsive herpes simplex virus thymidine kinase gene and a green fluorescent protein gene, we isolated five Chago K1 variants that grew in media containing budesonide and ganciclovir. Three spontaneous budesonide-resistant subclones were found to express low levels of GR, whereas two mutants isolated from ethylmethane sulfonate-treated cultures contained normal levels of GR protein. Analysis of the GR coding sequence in the budesonide-resistant subclone Ch-BdE5 identified a novel Val to Met mutation at amino acid position 575 (GRV575M) which caused an 80% decrease in transcriptional regulatory functions with only a minimal effect on ligand binding activity. Homology modeling of the GR structure in this region of the hormone binding domain and molecular dynamic simulations suggested that the GRV575M mutation would have a decreased affinity for the LXXLL motif of p160 coactivators. To test this prediction, we performed transactivation and glutathione-S-transferase pull-down assays using the p160 coactivator glucocorticoid interacting protein 1 (GRIP1)/transcriptional intermediary factor 2 and found that GRV575M transcriptional activity was not enhanced by GRIP1 in transfected cells nor was it able to bind GRIP1 in vitro. Identification of the novel GRV575M variant in human bronchial epithelial cells using a molecular genetic selection scheme suggests that functional assays performed in relevant cell types could identify subtle defects in GR signaling that contribute to reduced steroid sensitivities in vivo.
The Lutropin/Choriogonadotropin Receptor-Induced Phosphorylation of the Extracellular Signal-Regulated Kinases in Leydig Cells Is Mediated by a Protein Kinase A-Dependent Activation of Ras
Authors: Hirakawa Takashi , Ascoli Mario
Published: August 2003

The pathways involved in activation of the ERK1/2 cascade in Leydig cells were examined in MA-10 cells expressing the recombinant human LH receptor (hLHR) and in primary cultures of rat Leydig cell precursors. In MA-10 cells expressing the recombinant hLHR, human choriogonadotropin-induced activation of ERK1/2 is effectively inhibited by overexpression of a cAMP phosphodiesterase (a manipulation that blunts the human choriogonadotropin-induced cAMP response), by addition of H89 (a selective inhibitor of protein kinase A), or by overexpression of the heat-stable protein kinase A inhibitor, but not by overexpression of an inactive mutant of this inhibitor. Stimulation of hLHR did not activate Rap1, but activated Ras in an H89-sensitive fashion. Addition of H89 to MA-10 cells that had been cotransfected with a guanosine triphosphatase-deficient mutant of Ras almost completely inhibited the hLHR-mediated activation of ERK1/2. We also show that 8-bromo-cAMP activates Ras and ERK1/2 in MA-10 cells and in primary cultures of rat Leydig cells precursors in an H89-sensitive fashion, whereas a cAMP analog 8-(4-chloro-phenylthio)-2′-O-methyl-cAMP (8CPT-2Me-cAMP) that is selective for cAMP-dependent guanine nucleotide exchange factor has no effect. Collectively, our results show that the hLHR-induced phosphorylation of ERK1/2 in Leydig cells is mediated by a protein kinase A-dependent activation of Ras.
Janus Kinase 2 Determinants for Growth Hormone Receptor Association, Surface Assembly, and Signaling
Authors: He Kai , Wang Xiangdong , Jiang Jing , Guan Ran , Bernstein Kenneth E. , Sayeski Peter P. , Frank Stuart J.
Published: August 2003

GH signaling depends on functional interaction of the GH receptor (GHR) and the cytoplasmic tyrosine kinase, Janus kinase 2 (JAK2), which possesses a C-terminal kinase domain, a catalytically inactive pseudokinase domain just N-terminal to the kinase domain, and an N-terminal half shown by us and others to harbor elements for GHR association. Computational analyses indicate that JAKs contain in their N termini (∼450 residues) divergent FERM domains. FERM domains (or subdomains within them) in JAKS may be important for associations with cytokine receptors. For some cytokine receptors, JAK interaction may be required for receptor surface expression. We previously demonstrated that a JAK2 mutant devoid of its N-terminal 239 residues (JAK2-Δ1–239) did not associate with GHR and could not mediate GH- induced signaling. In this report we employ a JAK2-deficient cell line to further define N-terminal JAK2 regions required for physical and functional association with the GHR. We also examine whether JAK2 expression affects cell surface expression of the GHR. Our results suggest that FERM motifs play an important role in the interaction of GHR and JAK2. While JAK2 expression is not required for detectable surface GHR expression, an increased JAK2 level increases the fraction of GHRs that achieves resistance to deglycosylation by endoglycosidase H, suggesting that the GHR-JAK2 association may enhance either the receptor’s efficiency of maturation or its stability. Further, we report evidence for the existence of a novel GH-inducible functional interaction between JAK2 molecules that may be important in the mechanism of GH-triggered JAK2 signaling.
ADAM12 induces actin cytoskeleton and extracellular matrix reorganization during early adipocyte differentiation by regulating β1 integrin function
Authors: Kawaguchi Nobuko , Sundberg Christina , Kveiborg Marie , Moghadaszadeh Behzad , Asmar Meena , Dietrich Nikolaj , Thodeti Charles K. , Nielsen Finn C. , Möller Peter , Mercurio Arthur M. , Albrechtsen Reidar , Wewer Ulla M.
Published: August 2003

Changes in cell shape are a morphological hallmark of differentiation. In this study we report that the expression of ADAM12, a disintegrin and metalloprotease, dramatically affects cell morphology in preadipocytes, changing them from a flattened, fibroblastic appearance to a more rounded shape. We showed that the highest levels of ADAM12 mRNA were detected in preadipocytes at the critical stage when preadipocytes become permissive for adipogenic differentiation. Furthermore, as assessed by immunostaining, ADAM12 was transiently expressed at the cell surface concomitant with the reduced activity of β1 integrin. Co-immunoprecipitation studies indicated the formation of ADAM12/β1 integrin complexes in these preadipocytes. Overexpression of ADAM12 at the cell surface of 3T3-L1 preadipocytes achieved by transient transfection or retroviral transduction led to the disappearance of the extensive network of actin stress fibers that are characteristic of these cells, and its reorganization into a cortical network located beneath the cell membrane. The cells became more rounded, exhibited fewer vinculin-positive focal adhesions, and adhered less efficiently to fibronectin in attachment assays. Moreover, ADAM12-expressing cells were more prone to apoptosis, which could be prevented by treating the cells with β1-activating antibodies. A reduced and re-organized fibronectin-rich extracellular matrix accompanied these changes. In addition, β1 integrin was more readily extracted with Triton X-100 from cells overexpressing ADAM12 than from control cells. Collectively, these results show that surface expression of ADAM12 impairs the function of β1 integrins and, consequently, alters the organization of the actin cytoskeleton and extracellular matrix. These events may be necessary for early adipocyte differentiation.
Talin loss-of-function uncovers roles in cell contractility and migration inC. elegans
Authors: Cram Erin J. , Clark Scott G. , Schwarzbauer Jean E.
Published: August 2003

Integrin receptors for extracellular matrix transmit mechanical and biochemical information through molecular connections to the actin cytoskeleton and to several intracellular signaling pathways. In Caenorhabditis elegans, integrins are essential for embryonic development, muscle cell adhesion and contraction, and migration of nerve cell axons and gonadal distal tip cells. To identify key components involved in distal tip cell migration, we are using an RNA interference (RNAi)-based genetic screen for deformities in gonad morphogenesis. We have found that talin, a cytoskeletal-associated protein and focal adhesion component, is expressed in the distal tip cell and plays a central role in regulating its migration. Reduction of talin expression caused severe defects in gonad formation because of aberrant distal tip cell migration and also disrupted oocyte maturation and gonad sheath cell structure. Contractile muscle cells showed disorganization of the actin cytoskeleton leading to complete paralysis, a phenotype that was also observed with depletion of pat-2 and pat-3 integrins. These in vivo analyses show that talin is required not only for strong adhesion and cytoskeletal organization by contractile cells, but also for dynamic regulation of integrin signals during cell migration. In addition, induction of distal tip cell migration defects by bacterial RNAi in C. elegans provides an effective screen to identify genes involved in integrin signaling and function.
Membrane type I-matrix metalloproteinase (MT1-MMP) is internalised by two different pathways and is recycled to the cell surface
Authors: Remacle Albert , Murphy Gillian , Roghi Christian
Published: August 2003

Membrane type 1-matrix metalloproteinase (MT1-MMP) is an integral type I transmembrane multidomain zinc-dependent endopeptidase involved in extracellular matrix remodelling in physiological as well as pathological processes. MT1-MMP participates in the regulated turnover of various extracellular matrix components as well as the activation of secreted metalloproteinases and the cleavage of various cell membrane components. MT1-MMP expression has been reported to correlate with the malignancy of various tumour types and is thought to be an important mediator of cell migration and invasion. Recently, it has been proposed that internalisation of the enzyme from the cell surface is a major short-term level of MT1-MMP regulation controlling the net amount of active enzyme present at the plasma membrane. In this paper we show that, in HT1080 fibrosarcoma cells, MT1-MMP is internalised from the cell surface and colocalises with various markers of the endocytic compartment. Interestingly, we observed that in these cells, internalisation occurs by a combination of both clathrin-mediated and -independent pathways, most probably involving caveolae. In addition, internalised MT1-MMP is recycled to the cell surface, which could, in addition to downregulation of the enzymatic activity, represent a rapid response mechanism used by the cell for relocalising active MT1-MMP at the leading edge during migration.
Cellular stress and DNA damage invoke temporally distinct Mdm2, p53 and PML complexes and damage-specific nuclear relocalization
Authors: Kurki Sari , Latonen Leena , Laiho Marikki
Published: August 2003

Mdm2 is a nucleoplasmic and nucleolar protein interacting with p53 and alternative reading frame (ARF) tumor suppressor proteins. Here we demonstrate relocalization and novel interactions of Mdm2 with the promyelocytic leukemia (PML) protein following cellular stress and DNA damage. We show that Mdm2 and PML interact directly in vivo and in vitro depending on the Mdm2 RING finger domain and the PML C-terminus, and that Mdm2 is recruited to the PML nuclear bodies by overexpression of PML. Cellular stress and DNA damage caused by UV-radiation, downregulation of the proteasome and arsenic trioxide promoted Mdm2 and PML damage-specific nuclear relocalization and interaction in a p53-independent manner. However, in vitro analyses showed that PML, Mdm2 and p53 form trimeric complexes. UV-radiation caused rapid rearrangements of PML nuclear bodies and promoted PML-p53 and PML-Mdm2 complex formation, coinciding with p53 stabilization and preceding p53-Mdm2 interaction suggesting temporally distinct complexes. The results demonstrate novel associations between Mdm2 and PML and show the capacity of PML to participate in the activation and stabilization of p53 in response to cellular stress through PML interaction with Mdm2.
Thermomechanical analysis through a pseudolinear equivalent constant stiffness system
Authors: Adak M , Mandal N R
Published: August 2003

A non-uniform heating and cooling cycle caused by a welding or line heating operation leads to deformation. To ascertain the extent of deformation calls for solving a complex thermal elastoplastic problem. In this investigation the concept of a pseudolinear constant stiffness system has been effectively implemented to solve this non-linear problem. The concept has been tested by solving a case of angular deformation of a beam model caused by bead-on-plate welding. The theoretical results compared well with those of the experimental ones.
A feasible study of fatigue life prediction for marine structures based on crack propagation analysis
Authors: Cui W-C
Published: August 2003

Marine structures such as ships and offshore platforms are designed with damage tolerance. This requires accurate prediction of fatigue crack growth under service conditions. Current fatigue strength assessment methods for marine structures are largely based on the cumulative fatigue damage (CFD) theory using stress-endurance (S-N) curves. The effects of initial defects and the load sequence have been neglected. The extent of final fatigue failure in real structures is also not specified. These result in a large scatter of the predicted fatigue lives. In the fatigue community, more and more researchers have realized that fatigue crack propagation (FCP) theory could overcome these deficiencies and has the potential to explain various fatigue phenomena observed. In this paper, a feasible study of fatigue life prediction for marine structures based on FCP theory is carried out. The basic requirements and the general procedure for such an analysis are addressed. The feasibility of this procedure and the capabilities of FCP theory for fatigue life prediction are demonstrated using a simple example of a finite width plate with a centre crack subjected to remote uniform fatigue loading. The key problems to be solved for a practical implementation are also discussed.
Reconfigurable control for ship steering
Authors: Omerdic E , Roberts G N , Vukic Z
Published: August 2003

This paper is concerned with the application of a heuristic approach in the design of a fault-tolerant control system for ship steering. It proposes an advanced reconfigurable control system (RCS) for ship course changing/keeping and track keeping, robust to faults in actuator, gyrocompass and global positioning system (GPS) in the presence of disturbances (waves and currents). The proposed control scheme uses a reference model for compensation of signals from fault sensors and a compensator for reducing the loss of the control performance produced by a fault in the steering machine. In the case of the occurrence of the fault in one or more components, this control system minimizes loss in the control performance and gives enough time for operators to take appropriate action in order to reduce the risk of safety hazards and avoid severe consequences of the fault. The unavoidable penalty of degradation in control performance was found to be acceptable.
Numerical simulation of ship propulsion transients and full-scale validation
Authors: Campora U , Figari M
Published: August 2003

The paper describes a mathematical model for the dynamics simulation of ship propulsion systems. The model, developed in a MATLAB-SIMULINK software environment, is structured in modular form; the various elements of the system are described as individuals blocks (hull, prime mover, gear, waterjet, etc.) and linked together to take their interactions into account. In this way it is possible to characterize the dynamic behaviour of both the single component and the whole propulsion plant.

The model may be used to analyse the system response at off-design and transient conditions. In particular, the developed computer simulation code may be considered as a useful tool to facilitate the correct matching of the prime mover (diesel or gas turbine) to the propulsor (waterjet or propeller) in a wide range of operating conditions. The paper shows the application of the methodology to a cruise ferry used to validate the model results through a full-scale test campaign conducted by the authors during normal operation of the ship.
Design and performance of an electric tip-driven thruster
Authors: Abu Sharkh S M , Turnock S R , Hughes A W
Published: August 2003

A 250 mm diameter demonstrator electromagnetic tip-driven propeller (ETDP) unit has been designed, built and tested in a towing tank at zero, advance speed and for a range of advance speeds. The aims have been to assess the performance, efficiency and general practicalities of such a propeller for use on underwater vehicles. An overview is given of the general design philosophy and practical design issues of the demonstrator. The testing procedure is described and performance results are presented.
A feasibility study of the use of biodiesel in recreational boats in the United Kingdom
Authors: Zhou P L , Fet A M , Michelsen O , Fet K
Published: August 2003

The paper presents a feasibility study for applying biodiesel in recreational boats in the United Kingdom for the purpose of rational utilization of energy resources and environmental protection. Biodiesel has been widely used to fuel diesel engines for onshore vehicles, particularly for agriculture machinery. Application of biodiesel for merchant ship propulsion on a large scale has been seen as not an option in the near future due to the lack of availability and supply chains of the fuel. However, there has been interest in the possibility of powering recreational boats with biodiesel in order to pursue marine environmental protection.

The study reviews the current status of using biodiesel in recreational boats and analyses the market in the United Kingdom. Results on fuel availability for the sector, economic aspects and environmental benefits are presented.
Interfacial Nanochemistry in Liquid–Liquid Extraction Systems
Authors: Watarai Hitoshi , Tsukahara Satoshi , Nagatani Hirohisa , Ohashi Akira
Published: August 2003

Recent development of the interfacial nanochemistry in the solvent extraction systems is reviewed, as well as the development of measurement methods for interfacial reactions. The studies on specific reactions at the interface of various metal extraction systems have elucidated essential modes of the interfacial reactions, including the interfacial adsorption, the interfacial complexation, and the interfacial aggregation. The catalytic role of the liquid-liquid interface in the solvent extraction kinetics and the molecular recognition ability of the self-assembled metal complexes at the interface were emphasized. Spectroscopic studies on the rotational and translational dynamics of fluorescent molecules, a single molecule in some cases, at the interface are also discussed. The utility of the molecular dynamics simulations is demonstrated in the discussions of the solvent structure in the interfacial region and of the stability of surface active molecules at the interface.
Recent Advances in Phenoxy-Based Catalysts for Olefin Polymerization
Authors: Suzuki Yasuhiko , Terao Hiroshi , Fujita Terunori
Published: August 2003

Olefiin polymerization behavior of phenoxy-based catalysts has been discussed. Phenoxy-based olefin polymerization catalysts are capable of showing high catalytic activities. Moreover, the phenoxy-based catalysts can display unique catalytic properties and thus have offered opportunities to make polyolefinic materials that are difficult or impossible to prepare using conventional catalysts. Therefore, the phenoxy-based catalysts have opened up a new dimension in the fields of olefin polymerization catalysis and polymer synthesis.
Magnetic Studies on Quaternary Iron Sulfides BaLn2FeS5 (Ln = Ce, Pr, Nd, Sm) by Magnetic Susceptibility, Specific Heat, 57Fe Mössbauer Spectrum, and Neutron Diffraction Measurements
Authors: Wakeshima Makoto , Ino Kentaro , Hinatsu Yukio , Ishii Yoshinobu
Published: August 2003

Magnetic properties of quaternary iron sulfides, BaLn2FeS5 (Ln = Ce, Pr, Nd, Sm), have been investigated through magnetic susceptibility, electrical resistivity, specific heat, 57Fe Mössbauer spectrum, and powder neutron diffraction measurements. In these compounds, the Fe2+ ion exhibits an antiferromagnetic ordering at around 40 K. In the Nd and Sm compounds, these lanthanide ions show an antiferromagnetic ordering at 6.5 K for Ln = Nd and at 28 K for Ln = Sm. The reduction of the Fe2+ magnetic moment is observed below 120–170 K for all the compounds. Their electrical conductivities show an Arrhenius temperature-dependence, and the activation energies change at around the moment-reduction temperatures. The 57Fe Mössbauer spectra for BaPr2FeS5 indicate that the FeS4 tetrahedron is distorted prominently below the temperature at which both the magnetic susceptibility and the electrical resistivity show an anomaly in their temperature dependence. The neutron diffraction data collected for BaPr2FeS5 at 10 K show that it has a collinear antiferromagnetic structure and that the magnetic moments of the Fe2+ ions are parallel to the c-axis.
Anodic Behaviour of Antimony and Antimony-Tin Alloys in Alkaline Solutions
Authors: El-Sayed Abd El-Rahman , Shaker Ali Mohamed , El-Kareem Hatem Gad
Published: August 2003

The electrochemical and corrosive behaviour of antimony and antimony-tin alloys (Alloy No./Sb(wt. %); I/90, II/80, III/65, IV/50) as anodes in various aqueous concentrations of KOH have been investigated using galvanostatic, potentiodynamic and potentiostatic techniques. Galvanostatic potential–time curves at 4 mA cm−2 revealed that passivation of both antimony and antimony tin alloys is inhibited by an increase in KOH concentration. The opposite effect was observed with an increase in Sn content in the alloy. At high Sn content and low [OH−] a pseudo passivation potential was observed. (Abnormal early passivation occurring in the active anodic region due to the formation of tin oxides, which dissolve in alkali. Then, potential decreases.) The alloy with 50% Sn exhibited immediate passivation. The potentiodynamic curves were swept from Eo.c up to +1000 mV vs SCE. The results showed an increase in the peak current (Ip) for antimony and its alloys with increasing [OH−] on the oxide film. The first three alloys showed two anodic peaks at −780 and −450 mV, but the forth traced a third peak at −940 mV. X-ray diffraction and SEM micrographs detailed the electrochemical results and morphology of the electrode surface.
Magnetizabilities of Ring-Structured Molecules, [8]-Cyclacene, [8]-BN-Cyclacene and [8]-Collarene, and their Effect on 3He Nuclear Shielding Tensor
Authors: Tonmunphean Somsak , Wijitkosoom Atchara , Tantirungrotechai Yuthana , Nuttavut Narin , Limtrakul Jumras
Published: August 2003

The magnetizabilities of three ring-structured molecules, [8]-cyclacene, [8]-BN-cyclacene, and [8]-collarene, were subsequently calculated at the B3LYP/6-31G* level with the CSGT gauge-origin treatment. The magnetizability of [8]-cyclacene shows a large diamagnetic nature in the direction parallel to the ring cylindrical axis, while the value of [8]-BN-cyclacene is nearly isotropic, and that of [8]-collarene is slightly more diamagnetic in the perpendicular direction than in the parallel direction. A large diamagnetic magnetizability in the parallel direction of [8]-cyclacene arises from the current flow around the ring circumference. The magnetic environment in the ring channel of these three molecules was investigated by calculating the nuclear shielding tensor of the 3He atom when the atom moves through the ring channel. The GIAO nuclear shielding tensor changes significantly toward a prolate shape in [8]-cyclacene, but becomes a slightly oblate shape in [8]-BN-cyclacene and [8]-collarene. The changes correlate well with the magnetizabilities of the ring-structured molecules.
Flotation and Spectrophotometry: Thorough Investigation and Application to the Determination of the Total Amounts of Lanthanum and Yttrium in Natural Samples
Authors: Akl Magda Ali , Kabil Mohammed Abdel Ghany , Abdallah Amin Mahmoud , Ismael Dalia Salah
Published: August 2003

The extraction and preconcentration of a metal complex via surfactant-mediated phase separation was studied. A sensitive, selective and low-cost methodology for the determination of microamounts of Lanthanum and Yttrium, using alizarin red sulfonate (ARS) with a flotation step prior to absorptiometric determination was developed. The precipitate in the scum layer was quantitatively collected, stripped with 10% HNO3 and measured by spectrophotometry at 650 nm. Stripping of La(III) and Y(III) from the scum layer was carried out in one step with different mineral acids. The stripping efficiency was found to be quantitative in the case of HNO3. Excess ARS was used to nullify the interfering effects of various foreign species. The proposed procedure has been applied to the determination of La and Y spiked in natural water samples and real ore samples. Additionally, the mechanism of flotation of the metal chelate was proposed to be due to a physical interaction between the metal chelate and the oleic acid surfactant through the van der Waal force.
Coordination of Amines to Palladium(II) Complexes of N21,N22-Bridged Porphyrins
Authors: Takao Yuko , Takeda Tokuji , Setsune Jun-ichiro
Published: August 2003

Pyridine and ethylenediamine reacted with Pd(II) complexes of N21,N22-bridged porphyrins to give mixed-ligand Pd(II) complexes. The UV-vis and 1H NMR spectral features of the porphyrin ligand provide information regarding the nature of the coexisting ligands and Pd(II) coordination geometry in the products. That is, the splitting pattern in the Soret region of the UV-vis spectra was dependent on whether porphyrinatopalladium(II) was coordinated by neutral ligands or anionic ligands. In the 1H NMR spectra of ethylenediamine complexes of porphyrinatopalladium(II), signal broadening of porphyrin β-pyrrole protons and a chemical shift change of ethylenediamine protons were seen in the dichloride in comparison with the bis(perchlorate). These phenomena indicate the equilibrium of the coordination and dissociation of chloride and amine at the apical and basal sites in the square pyramid. The H–D exchange in the ethylenediamine ligand was promoted by the presence of chloride.
Synthesis of Cross-Linked Chitosan Resin Possessing Leucine Moiety for the Column Collection/Concentration of Molybdenum and Determination of Molybdenum by ICP-MS, ICP-AES and GFAAS
Authors: Oshita Koji , Xu Jingsong , Gao Yun-Hua , Lee Kyue-Hyung , Oshima Mitsuko , Motomizu Shoji
Published: August 2003

A chitosan resin possessing the leucine moiety (leucine-type chitosan) was newly synthesized by using the chitosan cross-linked with ethylene glycol diglycidyl ether (EGDE) as a basic material. The adsorption behavior of trace amounts of metal ions on the leucine-type chitosan was systematically examined by packing it in a mini-column by ICP-MS (inductively coupled plasma mass spectrometry). Molybdenum was adsorbed on the resin quantitatively and was easily eluted with 1 M nitric acid. The optimized pH range was from 1 to 5, and Mo was collected by the chelation mechanism and/or the anion-exchange mechanism. The method was applied to the determination of Mo in sea and river water samples. A pretreatment with the resin could remove the matrix components in seawater. Preconcentration by 100-fold was accomplished by a column treatment, which had a sufficient concentration to measure trace Mo in river water samples by ICP-AES (inductively coupled plasma atomic emission spectrometry) and GFAAS (graphite furnace atomic absorption spectrometry): LODs with a 100-fold preconcentration by ICP-AES and GFAAS were 0.007 ng mL−1 and 0.009 ng mL−1, respectively, and the RSDs were both within 4.0%.
Conformation and Packing of Odd-Numbered α-Oligothiophenes in Single Crystals
Authors: Azumi Reiko , Goto Midori , Honda Kazumasa , Matsumoto Mutsuyoshi
Published: August 2003

X-ray single crystal analyses revealed the molecular geometry and molecular packing of odd-numbered α-oligothiophenes (septithiophene, quinquethiophene and terthiophene) in single crystals prepared by sublimation. Septithiophene crystallizes into triclinic, which is in contrast to the monoclinic packing of even-numbered oligomers. The molecular arrangement of septithiophene in a single crystal resembles that reported for even-numbered oligomers, while the molecules take a more random conformation: only one of the two terminal thienyl rings exhibits disorder and significant torsion from the conjugated plane. The X-ray diffraction data of a quinquethiophene single crystal suggest that the molecule with one of the two different orientations randomly occupies each site.
Kinetic Study of Fast Complexation of Zinc(II) with 8-Quinolinol and 5-Octyloxymethyl-8-Quinolinol at 1-Butanol/Water Interface by Two-Phase Sheath Flow/Laser-Induced Fluorescence Microscopy
Authors: Tokimoto Takahira , Tsukahara Satoshi , Watarai Hitoshi
Published: August 2003

The kinetics of the fast complexation of zinc(II) with 8-quinolinol (Hqn) and 5-octyloxymethyl-8-quinolinol (Hocqn) at the 1-butanol/water interface was investigated with two-phase sheath flow/laser-induced fluorescence microscopy. The micrometer-sized two-phase sheath flow system was constructed in a flow cell, in which the 1-butanol phase was introduced as an inner flow and the aqueous phase as an outer flow. The fluorescence emitted from the zinc(II) complex was corrected by an objective lens, and detected with a CCD camera. It was revealed that the fluorescence intensity had a maximum value at the interfacial region, and increased with the reaction time up to 2 ms after the formation of the interface. The complexation rate increased with the increase of the initial ligand concentration in the organic phase, giving a saturation curve. The complexation rate of Hqn with zinc(II) was three times faster than that of Hocqn at equivalent conditions. A digital simulation taking into account the interfacial formation rate of 1:1 complex, the interfacial adsorption of the ligand and complex, and the diffusion of each species reproduced accurately the observed results. It was suggested that the interfacial adsorption of ligands was delayed and depressed by the preferential occupancy of 1-butanol molecules at the interface.