bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron‐dependent regulation of the divalent metal ion transporter
Authors: Gunshin Hiromi , Allerson Charles R. , Polycarpou-Schwarz Maria , Rofts Andreas , Rogers Jack T. , Kishi Fumio , Hentze Matthias W. , Rouault Tracey A. , Andrews Nancy C. , Hediger Matthias A.
Published: October 2002

The first step in intestinal iron absorption is mediated by the H+‐coupled Fe2+ transporter called divalent cation transporter 1/divalent metal ion transporter 1 (DCT1/DMT1) (also known as natural resistance‐associated macrophage protein 2). DCT1/DMT1 mRNA levels in the duodenum strongly increase in response to iron depletion. To study the mechanism of iron‐dependent DCT1/DMT1 mRNA regulation, we investigated the endogenous expression of DCT1/DMT1 mRNA in various cell types. We found that only the iron responsive element (IRE)‐containing form, which corresponds to one of two splice forms of DCT1/DMT1, is responsive to iron treatment and this responsiveness was cell type specific. We also examined the interaction of the putative 3′‐UTR IRE with iron responsive binding proteins (IRP1 and IRP2), and found that IRP1 binds to the DCT1/DMT1‐IRE with higher affinity compared to IRP2. This differential binding of IRP1 and IRP2 was also reported for the IREs of transferrin receptors, erythroid 5‐aminolevulinate synthase and mitochondrial aconitase. We propose that regulation of DCT1/DMT1 mRNA by iron involves post‐transcriptional regulation through the binding of IRP1 to the transporter's IRE, as well as other as yet unknown factors.
Identification of (E)‐4‐hydroxy‐3‐methyl‐but‐2‐enyl pyrophosphate as a major activator for human γδ T cells in Escherichia coli
Authors: Hintz Martin , Reichenberg Armin , Altincicek Boran , Bahr Ute , Gschwind Ruth M. , Kollas Ann-Kristin , Beck Ewald , Wiesner Jochen , Eberl Matthias , Jomaa Hassan
Published: October 2002

The gcpE and lytB gene products control the terminal steps of isoprenoid biosynthesis via the 2‐C‐methyl‐D‐erythritol 4‐phosphate pathway in Escherichia coli. In lytB‐deficient mutants, a highly immunogenic compound accumulates significantly, compared to wild‐type E. coli, but is apparently absent in gcpE‐deficient mutants. Here, this compound was purified from E. coli ΔlytB mutants by preparative anion exchange chromatography, and identified by mass spectrometry, 1H, 13C and 31P NMR spectroscopy, and NOESY analysis as (E)‐4‐hydroxy‐3‐methyl‐but‐2‐enyl pyrophosphate (HMB‐PP). HMB‐PP is 104 times more potent in activating human Vγ9/Vδ2 T cells than isopentenyl pyrophosphate.
Photoswitching of peroxidase activity by position‐specific incorporation of a photoisomerizable non‐natural amino acid into horseradish peroxidase
Authors: Muranaka Norihito , Hohsaka Takahiro , Sisido Masahiko
Published: October 2002

Horseradish peroxidase mutants containing L‐p‐phenylazophenylalanine (azoAla) at various positions were synthesized by using an Escherichia coli in vitro translation system. Among the 15 mutants examined, four mutants containing a single azoAla unit at the 6th, 68th, 142nd, and 179th positions, respectively, retained the peroxidase activity. The activity of the Phe68azoAla mutant was higher when the azobenzene group was in the cis form than in the trans form. On the contrary, the activity of the Phe179azoAla mutant disappeared when the azobenzene group was photoisomerized to the cis form, but recovered in the trans form. In the latter mutant, therefore, an on/off photoswitching of the peroxidase activity was attained.
The short splice form of Casper/c‐FLIP is a major cellular inhibitor of TRAIL‐induced apoptosis
Authors: Bin Lianghua , Li Xiaoyan , Xu Liang-Guo , Shu Hong-Bing
Published: October 2002

TRAIL (tumor necrosis factor‐related apoptosis‐inducing ligand) is a member of the tumor necrosis factor family that selectively induces apoptosis of cancer cells. However, some cancer cells or subpopulations within cancer cell lines are resistant to TRAIL‐induced apoptosis. We developed a retroviral cDNA library‐based functional cloning approach to unambiguously identify putative inhibitory genes of TRAIL‐induced apoptosis. This effort identified the short splice form of Casper/c‐FLIP, Casper‐S/c‐FLIPs, as a major cellular protein that confers resistance to TRAIL‐induced apoptosis. Furthermore, we found that Casper deficient embryonic fibroblasts (EFs) were highly sensitive while their wild‐type counterparts were completely resistant to TRAIL‐induced apoptosis. Retroviral‐mediated transduction of Casper‐S/c‐FLIPs into Casper(−/−) EFs restored resistance to TRAIL. These data suggest that Casper‐S/c‐FLIPs is a major cellular inhibitor of TRAIL‐induced apoptosis.
Rapid regulation of divalent metal transporter (DMT1) protein but not mRNA expression by non‐haem iron in human intestinal Caco‐2 cells
Authors: Sharp Paul , Tandy Sarah , Yamaji Sachie , Tennant Jason , Williams Mark , Singh Srai Surjit Kaila
Published: October 2002

A divalent metal transporter, DMT1, located on the apical membrane of intestinal enterocytes is the major pathway for the absorption of dietary non‐haem iron. Using human intestinal Caco‐2 TC7 cells, we have shown that iron uptake and DMT1 protein in the plasma membrane were significantly decreased by exposure to high iron for 24 h, in a concentration‐dependent manner, whereas whole cell DMT1 protein abundance was unaltered. This suggests that part of the response to high iron involved redistribution of DMT1 between the cytosol and cell membrane. These events preceded changes in DMT1 mRNA, which was only decreased following 72 h exposure to high iron.
Apigenin and LY294002 prolong EGF‐stimulated ERK1/2 activation in PC12 cells but are unable to induce full differentiation
Authors: Llorens Franc , Garcia Lourdes , Itarte Emilio , Gómez Néstor
Published: October 2002

In rat pheochromocytoma cell line (PC12) cells, initial epidermal growth factor (EGF)‐stimulated extracellular signal‐regulated protein kinases 1/2 (ERK1/2) phosphorylation was similar to that promoted by nerve growth factor (NGF), but declined rapidly. Pre‐treatment with apigenin or LY294002 sustained EGF‐stimulated ERK1/2 phosphorylation whereas wortmannin partially blocked initial ERK1/2 phosphorylation. Changes in ERK1/2 phosphorylation correlated with alterations in p90 ribosomal S6 kinase activity. Wortmannin, LY294002 and apigenin totally blocked growth factor‐induced protein kinase B phosphorylation. However, none of them potentiated Raf activation, which was in fact decreased by LY290042 and wortmannin. The sustained EGF‐induced ERK1/2 activation promoted by apigenin was not sufficient to commit PC12 cells to differentiate, which was achieved by stimulation with NGF, either alone or in the presence of apigenin.
Expression and regulation of the nuclear receptor RORα in human vascular cells
Authors: Besnard Sandrine , Heymes Christophe , Merval Régine , Rodriguez Marianne , Galizzi Jean-Pierre , Boutin Jean A , Mariani Jean , Tedgui Alain
Published: October 2002

Retinoic acid receptor‐related orphan receptor α (RORα) is a member of the nuclear receptor superfamily. Using RT‐PCR, RORα mRNA was identified in human aortic smooth muscle cells (hASMC), endothelial cells (EC), as well as in human mammary arteries and atherosclerotic plaques. We found a predominant expression of RORα1 in hASMC, and RORα4 in EC. RORα2 and RORα3 were not detected. In arteries, RORα4 was predominant compared with RORα1. In atherosclerotic plaques, RORα expression was significantly decreased. In hASMC stimulated with cytokines, RORα expression was increased by 2.5‐fold. RORα mRNA was also significantly increased (∼2‐fold) in hASMC and EC cultured under hypoxia.
The role of protein nitration in the inhibition of platelet activation by peroxynitrite
Authors: Low Sylvia Y , Sabetkar Mojhgan , Bruckdorfer K.Richard , Naseem Khalid M
Published: October 2002

Peroxynitrite at low concentrations (3–10 μM) inhibited agonist‐induced platelet aggregation by a mechanism not dependent on the formation of cyclic guanosine monophosphate. Platelets recovered completely from peroxynitrite‐induced inhibition within 30 min. Peroxynitrite induced nitration of cytosolic proteins, but this diminished to near basal levels within 60 min of exposure to the oxidant. During this period there was a reduction in tyrosine phosphorylation of specific proteins such as syk, but this was not due to direct nitration of these same proteins. The inhibition of phosphorylation was reversible with platelet proteins recovering the ability to be phosphorylated within 15 min of exposure to peroxynitrite. Conversely, peroxynitrite increased phosphorylation of other proteins, but again these events were not directly linked to nitration. Nitration may affect the phosphorylation of tyrosine residues in a number of proteins, but by an indirect route, possibly by acting on proteins upstream in the signalling cascades. We suggest that low concentrations of peroxynitrite reversibly inhibit platelet aggregation by preventing the phosphorylation of key signalling proteins.
The FHA domain
Authors: Durocher Daniel , Jackson Stephen P.
Published: October 2002

The forkhead‐associated (FHA) domain is a small protein module recently shown to recognize phosphothreonine epitopes on proteins. It is present in a diverse range of proteins in eukaryotic cells, such as kinases, phosphatases, kinesins, transcription factors, RNA‐binding proteins, and metabolic enzymes. It is also found in a number of bacterial proteins. This suggests that FHA domain‐mediated phospho‐dependent assembly of protein complexes is an ancient and widespread regulatory mechanism.
Can we infer peptide recognition specificity mediated by SH3 domains?
Authors: Cesareni Gianni , Panni Simona , Nardelli Giuliano , Castagnoli Luisa
Published: October 2002

Protein interaction domain families that modulate the formation of macromolecular complexes recognize specific sequence or structural motifs. For instance SH3 and WW domains bind to polyproline peptides while SH2 and FHA domains bind to peptides phosphorylated in Tyr and Thr respectively. Within each family, variations in the chemical characteristics of the domain binding pocket modulate a finer peptide recognition specificity and, as a consequence, determine the selection of functional protein partners in vivo. In the proteomic era there is the need for reliable inference methods to help restricting the sequence space of the putative targets to be confirmed experimentally by more laborious experimental approaches. Here we will review the published data about the peptide recognition specificity of the SH3 domain family and we will propose a classification of SH3 domains into eight classes. Finally, we will discuss whether the available information is sufficient to infer the recognition specificity of any uncharacterized SH3 domain.
Chickens’ Cry2: molecular analysis of an avian cryptochrome in retinal and pineal photoreceptors
Authors: Bailey Michael J , Chong Nelson W , Xiong Jin , Cassone Vincent M
Published: October 2002

We have identified and characterized an ortholog of the putative mammalian clock gene cryptochrome 2 (Cry2) in the chicken, Gallus domesticus. Northern blot analysis of gCry2 mRNA indicates widespread distribution in central nervous and peripheral tissues, with very high expression in pineal and retina. In situ hybridization of chick brain and retina reveals expression in photoreceptors and in visual and circadian system structures. Expression is rhythmic; mRNA levels predominate in late subjective night. The present data suggests that gCry2 is a candidate avian clock gene and/or photopigment and set the stage for functional studies of gCry2.
Curcumin induces apoptosis in human breast cancer cells through p53‐dependent Bax induction
Authors: Choudhuri Tathagata , Pal Suman , Agwarwal Munna L , Das Tanya , Sa Gaurisankar
Published: October 2002

The aim of this study was to determine the mechanisms of curcumin‐induced human breast cancer cell apoptosis. From quantitative image analysis data showing an increase in the percentage of cells with a sub‐G0/G1 DNA content, we demonstrated curcumin‐induced apoptosis in the breast cancer cell line MCF‐7, in which expression of wild‐type p53 could be induced. Apoptosis was accompanied by an increase in p53 level as well as its DNA‐binding activity followed by Bax expression at the protein level. Further experiments using p53‐null MDAH041 cell as well as low and high p53‐expressing TR9‐7 cell, in which p53 expression is under tight control of tetracycline, established that curcumin induced apoptosis in tumor cells via a p53‐dependent pathway in which Bax is the downstream effector of p53. This property of curcumin suggests that this molecule could have a possible therapeutic potential in breast cancer patients.
A bilayer cell‐free protein synthesis system for high‐throughput screening of gene products
Authors: Sawasaki Tatsuya , Hasegawa Yoshinori , Tsuchimochi Masateru , Kamura Nami , Ogasawara Tomio , Kuroita Toshihiro , Endo Yaeta
Published: October 2002

A high‐throughput cell‐free protein synthesis method has been described. The methodology is based on a bilayer diffusion system that enables the continuous supply of substrates, together with the continuous removal of small byproducts, through a phase between the translation mixture and substrate mixture. With the use of a multititer plate the system was functional for a prolonged time, and as a consequence yielded more than 10 times that of the similar batch‐mode reaction. Combining this method with a wheat germ cell‐free translation system developed by us, the system could produce a large amount of protein sufficient for carrying out functional analyses. This novel bilayer‐based cell‐free protein synthesis system with its simplicity, minimum time and low cost may be useful practical methodology in the post‐genome era.
Noladin ether, a putative novel endocannabinoid: inactivation mechanisms and a sensitive method for its quantification in rat tissues
Authors: Fezza Filomena , Bisogno Tiziana , Minassi Alberto , Appendino Giovanni , Mechoulam Raphael , Di Marzo Vincenzo
Published: October 2002

The occurrence of the novel proposed endocannabinoid, noladin ether (2‐arachidonyl glyceryl ether, 2‐AGE) in various rat organs and brain regions, and its inactivation by intact C6 glioma cells, were studied. 2‐AGE was measured by isotope dilution liquid chromatography‐atmospheric pressure chemical ionization‐mass spectrometry, with a detection limit of 100 fmol. A compound with the same mass and chromatographic/chemical properties as 2‐AGE was found in whole brain, with the highest amounts in the thalamus and hippocampus. Synthetic [3H]2‐AGE was inactivated by intact rat C6 glioma cells by a time‐ and temperature‐dependent process consisting of cellular uptake and partial incorporation into phospholipids. Further data suggested that 2‐AGE is taken up by cells via the anandamide/2‐arachidonoyl glycerol (2‐AG) membrane transporter(s), and biosynthesized in a different way as compared to 2‐AG.
Thyroid hormone increases transcription of GA‐binding protein/nuclear respiratory factor‐2 α‐subunit in rat liver
Authors: Rodrı́guez-Peña Angeles , Escrivá Héctor , Handler Ana C , Vallejo Carmen G
Published: October 2002

Thyroid hormone (TH) regulates mitochondrial respiratory rate by activating coordinated transcription in the nucleus and mitochondria. Whereas TH activates transcription of mitochondrial genes directly, the activation of nuclear‐encoded mitochondrial genes is probably executed by indirect unknown mechanisms. Nuclear respiratory factors (NRF)‐1 and GA‐binding protein (BP)/NRF‐2 may function as transacting genes, but regulation of these genes by TH is not demonstrated. We show that TH administration to hypothyroid rats promptly increases GABP/NRF‐2 α‐subunit mRNA levels in the liver, without significant changes in β, γ subunits. In run‐on and time‐course experiments, the transcription rate and protein levels increased three‐fold in response to TH, indicating GABP/NRF‐2 transcriptional regulation. The results also support the notion that ATP synthase β‐subunit is regulated by TH through the indirect activation of GABP/NRF‐2.
Phosphorylation of microtubule‐associated protein tau by stress‐activated protein kinases in intact cells
Authors: Buée-Scherrer Valérie , Goedert Michel
Published: October 2002

Tau is a microtubule‐associated protein that is abnormally hyperphosphorylated in the filamentous lesions that define a number of neurodegenerative diseases collectively referred to as tauopathies. We previously showed that stress‐activated protein (SAP) kinases phosphorylate tau protein at many of the hyperphosphorylated sites in vitro. Here we have developed a system to study the effects of five SAP kinases (SAPK1c/JNK1, SAPK2a/p38α, SAPK2b/p38β, SAPK3/p38γ and SAPK4/p38δ) on tau phosphorylation in intact cells. All kinases phosphorylated tau, albeit at different efficiencies. Tau was a good substrate for SAPK3/p38γ and SAPK4/p38δ, a reasonable substrate for SAPK2b/p38β and a relatively poor substrate for SAPK2a/p38α and SAPK1c/JNK1. These findings indicate that the aberrant activation of SAP kinases, especially SAPK3/p38γ and SAPK4/p38δ, could play an important role in the abnormal hyperphosphorylation of tau that is an invariant feature of the tauopathies.
Targeted cytosolic delivery of hydrogel nanoparticles into HepG2 cells through engineered Sendai viral envelopes
Authors: Jana Siddhartha S , Bharali Dhruba J , Mani Prashant , Maitra Amarnath , Gupta Chhitar M , Sarkar Debi P
Published: October 2002

Hydrogel nanoparticles of cross‐linked polyvinylpyrrolidone (PVP‐NP) (35–50 nm in diameter) containing fluoresceinated dextran (FITC‐Dx) were encapsulated in reconstituted Sendai viral envelopes containing only the fusion (F) protein (F‐virosomes1). Incubation of these loaded F‐virosomes with human hepatoblastoma cells (HepG2) in culture resulted in membrane‐fusion‐mediated delivery of NPs to the cell cytoplasm, as inferred from the ability of cells to internalize FITC‐Dx loaded PVP‐NP (PVPf‐NP) in the presence of azide (an inhibitor of the endocytotic process). Introduction of PVPf‐NP into the HepG2 cells was assured by selective accumulation of FITC fluorescence in the cytosolic compartment. The structural integrity of the internalized PVPf‐NP was also confirmed by fluorescence microscopy and ultracentrifugation analysis. The potential usefulness of PVP‐NP‐mediated cytosolic release of water soluble drugs both in vitro and in vivo has been established for the first time.
Identification of ten exon deleted ERβ mRNAs in human ovary, breast, uterus and bone tissues: alternate splicing pattern of estrogen receptor β mRNA is distinct from that of estrogen receptor α
Authors: Poola Indra , Abraham Jessy , Baldwin Kate
Published: October 2002

Four different human tissues and breast cancer cell lines were screened to identify exon deletion variant transcripts of estrogen receptor β (ERβ) by reverse transcription‐polymerase chain reaction using the ‘splice targeted primer approach’ that amplifies each category of exon deleted variants as a separate gene population. A total of 10 different variant mRNAs that have deletions in various combination of exons were identified by sequence analysis. They were exon 2Δ; exons 2 and 5–6Δ; exon 3Δ; exon 4Δ; exon 5Δ; exons 5 and 2Δ; exon 6Δ; exons 6 and 2Δ; exons 6, 2–3Δ; and exons 5–6Δ. In some cases, deletion of an exon appears to be associated with a mutation of a specific base. Although ERα and ERβ are highly homologous, have identical exon and functional domain organization, exhibit similar ligand‐binding profiles and interact with identical DNA response elements, the sequence of exon skipping in ERβ pre‐mRNA appears to be distinct from that of ERα mRNA. Furthermore, results described here also suggest that alternate splicing of ERβ mRNA is tissue specific. The presence of a ERβ variant profile together with other ER isoforms in a tissue may have functional implications in binding and response to a particular ligand.
Effect of calcium channel antagonist diltiazem and calcium ionophore A23187 on cyclosporine A‐induced apoptosis of renal tubular cells
Authors: Cheng Chi-Hung , Hsieh Chin-Ling , Shu Kuo-Hsiung , Chen Yen-Ling , Chen Hong-Chen
Published: October 2002

Calcium channel antagonists have been reported to have a favorable impact on cyclosporin A (CsA)‐treated kidney transplant recipients. However, it is not clear whether this is because of their direct effect on antagonizing the toxicity of CsA to renal tubular cells. In this study, we have used Madin–Darby canine kidney tubular cells as a model to examine the effect of diltiazem, a calcium channel antagonist, on CsA‐induced apoptosis. Moreover, to investigate the possible regulation of CsA cytotoxicity by intracellular calcium level, the effect of the calcium ionophore A23187 on CsA‐induced apoptosis was also examined. We found that treatment of CsA (20 μM) alone caused 20–30% cell death, which was apparently (30–40%) enhanced by diltiazem at 100 μg/ml, accompanied by more severe DNA fragmentation, activation of caspases, and a decreased level of Bcl‐2. The caspase inhibitor ZVAD‐fmk or Bcl‐2 overexpression was capable of suppressing apoptosis induced by the synergistic effect of diltiazem and CsA. Moreover, the survival rate of cells treated with CsA (30 μM) alone remained only 30%, however, it was markedly (∼40%) elevated by co‐treatment with A23187 (75 ng/ml). The rescue of cells from CsA‐induced apoptosis by A23187 was correlated with AKT activation, BAD phosphorylation, and caspase‐3 inactivation. Taken together, our results suggest that the reported favorable impact of diltiazem on kidney grafts is likely not because of its direct protection on renal tubular cells. Instead, it enhances the toxicity of CsA to renal tubular cells. In addition, our findings raise a possibility that the intracellular calcium level and the AKT pathway may participate in the regulation of CsA cytotoxicity.
Overexpression of sTnC polypeptide in muscle cells is controlled by its rapid degradation
Authors: Yin Xingping , Choudhury Monideepa , Bag Jnanankur
Published: October 2002

The check‐points that maintain stoichiometric synthesis of muscle proteins were examined by misexpression of slow troponin C (sTnC) in mouse C2 myotubes. The sTnC mRNA was overexpressed in myotubes by transfecting these cells with a plasmid construct containing the constitutive CMV promoter‐driven sTnC cDNA. An approximately four‐fold increase of sTnC mRNA level in the transfected cells was observed. However, the increased mRNA level did not produce a corresponding increase of the sTnC polypeptide level in transfected cells. Only a modest 1.5‐fold increase of the sTnC polypeptide level in the transfected cells was observed. The excess sTnC polypeptide in transfected cells was found in the soluble form which was not complexed with other thin filament proteins. The difference between the increase of sTnC mRNA and the polypeptide levels in transfected cells was not due to inefficient translation of the overexpressed sTnC mRNA. Analyses of the stability of the sTnC polypeptide in the thin filament and in the unassembled soluble forms showed that the excess soluble sTnC polypeptide was degraded more rapidly than the sTnC polypeptide of the thin filament. Analyses of the mRNA and polypeptide levels of several thin filament complements showed no effect of overexpression of the sTnC mRNA.
Helicobacter pylori in North and South America before Columbus
Authors: Yamaoka Yoshio , Orito Etsuro , Mizokami Masashi , Gutierrez Oscar , Saitou Naruya , Kodama Tadashi , Osato Michael S , Kim Jong G , Ramirez Francisco C , Mahachai Varocha , Graham David Y
Published: October 2002

We present a molecular epidemiologic study, based on an analysis of vacA, cagA and cag right end junction genotypes from 1042 Helicobacter pylori isolates, suggesting that H. pylori was present in the New World before Columbus. Eight Native Colombian and Alaskan strains possessed novel vacA and/or cagA gene structures and were more closely related to East Asian than to non‐Asian H. pylori. Some Native Alaskan strains appear to have originated in Central Asia and to have arrived after strains found in South America suggesting that H. pylori crossed the Bering Strait from Asia to the New World at different times.
Mouse cone arrestin gene characterization: promoter targets expression to cone photoreceptors
Authors: Zhu Xuemei , Ma Bo , Babu Sudha , Murage Jaji , Knox Barry E , Craft Cheryl M
Published: October 2002

Cone arrestin (CAR) is a novel member of the arrestin superfamily expressed in retinal cone photoreceptors and the pineal gland. To understand the regulatory mechanisms controlling its cone‐ and pineal‐specific expression, and to facilitate further functional studies using gene knockout approaches, we characterized the genomic organization and the 5′‐flanking region of the mouse CAR (mCAR) gene. The mCAR gene is comprised of 17 exons and 16 introns, encoding five alternatively spliced transcripts. A 215‐bp proximal promoter fragment containing a TATA box, an Sp1 site and four cone‐rod homeobox‐binding sites is sufficient to direct expression in cultured retinoblastoma cells and in cone photoreceptors and the pineal gland in transgenic Xenopus laevis.
Transient interaction of cpSRP54 with elongating nascent chains of the chloroplast‐encoded D1 protein; ‘cpSRP54 caught in the act’
Authors: Nilsson Robert , van Wijk Klaas Jan
Published: October 2002

The signal recognition particle (SRP) in bacteria and endoplasmic reticulum is involved in co‐translational targeting. Plastids contain cpSRP54 and cpSRP43, unique to plants, but lack a SRP RNA molecule. A role for cpSRP in biogenesis of plastid‐encoded membrane proteins has not been firmly established yet. In this study, a transient interaction between cpSRP54 and elongating D1 protein was observed using a homologous chloroplast translation system. Using the novel approach of cross‐linking at different time points during elongation of full‐length D1 protein, we showed that cpSRP54 interacts strongly with the elongating nascent chain forming two distinct cross‐linked products. However, this interaction did not lead to an elongation arrest and cpSRP54 was released from the nascent chains, once they were longer than ∼14 kDa. Detailed mutant analysis showed that the cpSRP54 interaction occurred via the first transmembrane domain, which could be replaced by other hydrophobic domains of more than 10 amino acids.
Molecular identification and characterisation of the human eag2 potassium channel
Authors: Ju M , Wray D
Published: October 2002

We report the molecular cloning from foetal brain of the human potassium channel heag2. The cDNA encodes a protein of 988 amino acids, 73% identical to heag1. Heag2 is expressed in the brain, but is also found in a range of tissues including skeletal muscle. In oocytes, the channel is a non‐inactivating outward rectifier, with dependence of activation rate on holding potential. Compared with heag1, the conductance–voltage curve for heag2 was shifted to the left, the voltage sensitivity was less, activation kinetics were different, and the sensitivity to terfenadine was lower. The heag2 channel may have important physiological roles.
GLUT2 is a high affinity glucosamine transporter
Authors: Uldry Marc , Ibberson Mark , Hosokawa Masaya , Thorens Bernard
Published: October 2002

When expressed in Xenopus oocytes, GLUT1, 2 and 4 transport glucosamine with V
max values that are three‐ to four‐fold lower than for glucose. The K
ms for glucosamine and glucose of GLUT1 and GLUT4 were similar. In contrast, GLUT2 had a much higher apparent affinity for glucosamine than for glucose (K
m=0.8±0.1 mM vs. ∼17–20 mM). Glucosamine transport by GLUT2 was confirmed in mammalian cells and, using hepatocytes from control or GLUT2‐null mice, HgCl2‐inhibitable glucosamine uptake by liver was shown to be exclusively through GLUT2. These data have implications for glucosamine effects on impaired glucose metabolism and for structure–function studies of transporter sugar binding sites.
Serum creatine phosphokinase elevation in patients treated with intravenous magnesium sulfate
Authors: Kuno N , Ishikawa K
Published: October 2002

Objective: During the treatment of pre‐term labor with magnesium sulfate, we noted an abnormal elevation of maternal serum creatine phosphokinase. This study was aimed at evaluating the relationship between tocolysis with MgSO4 and maternal serum CPK elevation, which represents the possible damage of muscles by magnesium sulfate. Methods: Clinical records of 45 women treated with magnesium sulfate and beta‐sympathomimetics for the treatment of pre‐term labor were retrospectively examined. Results: Serum CPK was abnormally elevated in 32 out of 45 cases (71.1%), but in only one out of 21 in the control group. In three cases, the decrease of serum creatine phosphokinase after cessation of magnesium sulfate was demonstrated, despite the continuous infusion of beta‐sympathomimetics. Conclusions: Magnesium sulfate may cause muscular damage and abnormal elevation of maternal serum creatine phosphokinase. Special attention must be paid to patients when drugs acting on muscle cells, for example succinyl choline, are going to be used.
A case study of batching in a mass service operation
Authors: Simons Jacob V , Russell Gregory R
Published: October 2002

Job batching is used extensively in manufacturing and the relevant theoretical considerations have been well‐researched. However, while batching is also employed in mass services, it is not clear to what extent the manufacturing theory may be transferred. A single case study of a court scheduling service system with imbedded instances of batching was studied to address this question. The findings and analysis of the case indicate that while the factors that affect batching in manufacturing still apply, so do additional factors. The net effect is a broader set of considerations which influence the determination of when batching is desired in mass services and how big batches should be. Definitions of these factors, their relationships with batch size, and testable hypotheses are offered.
Multiple case studies of team effectiveness in manufacturing organizations
Authors: Pagell Mark , LePine Jeffrey A
Published: October 2002

The use of teams in manufacturing contexts is increasing. Researchers have responded with a great deal of theoretical and empirical work aimed at identifying factors that influence the performance of these teams. Scholars, however, have tended to focus their research on variables human resource managers can readily control (e.g. the composition of teams relative to members’ characteristics, team goals) and little emphasis has been placed on factors inherent to production systems. Identifying factors in the production system that influence team effectiveness is crucial because many of these factors are not changeable in the short term. Accordingly, these production system factors are likely to be a crucial factor when deciding whether or not to organize a production system around teams. In a departure from past research, this article reports a qualitative study aimed at identifying factors in operational systems that influence team effectiveness. Our qualitative results suggest that four characteristics of the operational system influence team effectiveness: work organized around the team’s output, opportunities for informal communication, work that includes novel problems to solve, and management trust in teams.
Elliptic equations with critical Sobolev exponents in dimension 3
Authors: Druet Olivier
Published: October 2002

We study the existence of minimizing solutions for an elliptic equation with critical Sobolev growth on a smooth bounded domain of

\mathbf R^{3}

. We answer in particular two questions of Haı̈m Brezis. Higher dimensions

n⩾4

are completely understood thanks to previous works by H. Brezis and L. Nirenberg.

On étudie l'existence de solutions minimisantes à une EDP elliptique à croissance de Sobolev critique sur des domaines de l'espace euclidien de dimension 3. On résout en particulier une conjecture de H. Brezis sur le sujet. Les questions analogues en dimensions plus grandes étaient parfaitement comprises depuis des travaux de H. Brezis et L. Nirenberg.
Isoperimetric inequalities for parametric variational problems
Authors: Clarenz Ulrich , von der Mosel Heiko
Published: October 2002

We prove isoperimetric inequalities for general parametric variational double integrals

\mathcal F

, whose Lagrangians

F

depend on the position vector

X

and on the surface normal 

N

. As an essential tool we introduce Sauvigny's

F

-conformal parameters adapted to the parametric integrand and use the notion of generalized mean and Gaussian curvature. The special cases of minimal surfaces, surfaces of bounded mean curvature and -minimizing surfaces are also discussed.

Nous démontrerons des inégalités isopérimétriques pour les intégrales doubles variationnelles paramétriques générales

\mathcal F

dont la fonction de Lagrange

F

dépend du vecteur de position

X

et de la surface normal 

N

. Comme outil essentiel, nous introduiserons des paramètres

F

-conformes de Sauvigny adaptés l'intégrand paramétrique et nous employerons la notion de la courbure moyenne généralisée et gaussienne généralisée. Nous discuterons également les cas particuliers des surfaces minimales, des surfaces de courbure moyenne limitée et des surfaces minimalisant .
Monotonicity and separation for the Mumford–Shah problem
Authors: David Guy , Léger Jean-Christophe
Published: October 2002

We prove some monotonicity properties of the global Mumford–Shah minimizers as defined by Bonnet in [4]. The main consequence is that the only solutions for which the complement in the plane of the singular set is not connected correspond to lines and propellers. We also get a boundary version of the Mumford–Shah conjecture.

Nous prouvons des propriétés de monotonie des solutions du problème de Mumford–Shah global défini par Bonnet dans [4]. La conséquence principale en est que les seules solutions dont le complémentaire de l'ensemble singulier n'est pas connexe correspondent à des droites et des propulseurs. Nous obtenons aussi une version à la frontière de la conjecture de Mumford–Shah.
Accuracy and precision of radiostereometric analysis in the measurement of THR femoral component translations: human and canine in vitro models
Authors: Önsten Ingemar , Berzins Aivars , Shott Susan , Sumner Dale R.
Published: October 2002

Radiostereometric analysis (RSA) is used to measure translations of joint replacement components with respect to the host bone in vivo. We used two cadaveric models of hip arthroplasty, one human and one canine, to evaluate the accuracy and precision of RSA‐based estimates of translations of the femoral component with respect to the femur under ideal conditions. The femoral components were attached rigidly to a micrometer stage that provided standard displacements in increments of 25 and 50 μm in the interval from zero to 500 μm along three orthogonal axes. Radiostereometric examinations were performed for each increment. Accuracy was calculated as the 95% prediction intervals from regression analyses between the measured and actual displacements. Precision was evaluated as the standard deviation of five repeated measurements of a 200 μm displacement along each axis. Both accuracy and precision were best along the longitudinal axis, with a prediction interval of ±47 μm in the human model and ±45 μm in the canine model and a standard deviation of 30 μm in the human model and 40 μm in the canine model. The use of only the prosthetic head as a landmark (as opposed to three markers placed on the femoral stem) led to a 3‐fold larger prediction interval in the human model and a 2‐fold greater prediction interval in the canine model. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
A new device to measure knee laxity during weightbearing and non‐weightbearing conditions
Authors: Un Benjamin S. , Beynnon Bruce D. , Churchill David L. , Haugh Larry D. , Risberg May Arna , Fleming Braden C.
Published: October 2002

The Vermont knee laxity device (VKLD) was developed to evaluate anterior—posterior (A—P) displacement of the tibia relative to the femur (A—P laxity) during weightbearing and non‐weightbearing conditions. The purposes of this study were to determine the repeatability and reliability of the VKLD measurements of A—P laxity and to compare them with two devices currently in clinical use: the KT‐1000 knee arthrometer and planar stress radiography. Two independent examiners tested six subjects with no history of knee injury. A—P laxity was measured on three separate days with the KT‐1000 and the VKLD. With the VKLD, A—P laxity was measured in the weightbearing and non‐weightbearing conditions. In addition, one examiner measured A—P laxity in each subject on each day using a planar stress radiography technique. Similar A—P laxity values were obtained with the KT‐1000 and the VKLD; however, the planar stress radiography technique measured less A—P laxity compared to the VKLD (9.2 ± 2.2 mm versus 13.3 ± 2.9 mm, P = 0.0004). None of the three devices showed significant differences in measuring A—P laxity between days. During weightbearing, A—P laxity was reduced by 65–70% compared to the non‐weightbearing condition (P = 0.0001). Future investigations will use the VKLD to study subjects that have suffered injury to the anterior and posterior cruciate ligaments. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Significance of lesion size and location in the prediction of collapse of osteonecrosis of the femoral head: a new three‐dimensional quantification using magnetic resonance imaging
Authors: Nishii Takashi , Sugano Nobuhiko , Ohzono Kenji , Sakai Takashi , Sato Yoshinobu , Yoshikawa Hideki
Published: October 2002

Size and location of a necrotic lesion are considered important factors predicting collapse of the femoral head in the early stages of osteonecrosis. However, few analytical studies have performed a three‐dimensional quantification of lesions to clarify how these two morphological factors are related to the occurrence of collapse. We evaluated the relevance of lesion size and location for prediction of collapse quantitatively using new three‐dimensional indexes. Magnetic resonance (MR) imaging was performed in 65 hips in a consecutive series of 47 patients with osteonecrosis without radiological evidence of collapse. Lesion volume as well as latitude and longitude of the center of gravity of the lesion within the femoral head were calculated. Thirty‐three hips developed radiological collapse, while in the remaining 32 hips collapse did not occur over 2 years. Multiple logistic regression analysis showed a significant relationship between lesion volume and radiological collapse. In 35 hips in which the lesion volume was less than 30% of the femoral head, only 9 collapsed. In comparison with non‐collapsed hips, collapsed hips had a significantly higher combined value for latitude and longitude of the lesion, corresponding to the anterosuperior portion of the femoral head. Quantitative analysis of lesion morphology demonstrated that lesion volume is strongly correlated with risk of collapse, and that lesion location is an important prognostic indicator of collapse in small necrotic lesions. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
In situ cell nucleus deformation in tendons under tensile load; a morphological analysis using confocal laser microscopy
Authors: Arnoczky Steven P. , Lavagnino Michael , Whallon Joanne H. , Hoonjan Amardeep
Published: October 2002

Cell and cell nucleus deformations have been implicated in the mechanotransduction of mechanical loads acting on tissues. While in situ cell nucleus deformation in response to increasing tissue strains has been examined in articular cartilage this phenomenon has not been investigated in tendons. To examine in situ cell nuclei deformation in tendons undergoing tensile strain rat tail tendons were harvested from adult Sprague–Dawley rats and stained with acridine orange to highlight the cell nuclei. The tendons were mounted on a custom‐designed, low‐load, tensile testing device affixed to the mechanical stage of a confocal laser microscope. Cells within the tendons were isolated for analysis. Images of individual cells were captured at 0% strain as well as sequentially at 2%, 4% and 6% grip‐to‐grip tendon strain. Digital images of the cell nuclei were then measured in the x (length) and y (height) axis and deformation expressed as a percentage of cell nuclei strain. In addition, centroid‐to‐centroid distances of adjacent cell nuclei within each image were measured and used to calculate local tissue strain. There was a weak (r2 = 0.34) but significant (p < 0.01) correlation between local tissue strain and cell nucleus strain in the x axis. The results of this study support the hypothesis that in situ cell nucleus deformation does occur during tensile loading of tendons. This deformation may play a significant role in the mechanical signal transduction pathway of this tissue. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
A new animal model of femoral head osteonecrosis: one that progresses to human‐like mechanical failure
Authors: Conzemius Michael G. , Brown Thomas D. , Zhang Yongde , Robinson Robert A.
Published: October 2002

Existing animal models of femoral head osteonecrosis, while displaying varying levels of concordance with early histopathologic features of the human disorder, generally fail to progress to end‐stage mechanical collapse. A new animal model of osteonecrosis is here introduced, utilizing the emu (Dromaius novaehollandie). These animals' bipedality and their high activity level represent a much more challenging biomechanical environment to the hip than seen in quadrupedal models of this disorder. Femoral head osteonecrosis was induced surgically, using a combination of ischemic (vessel ligation) and cryogenic (liquid nitrogen) insults. Of nineteen emus allowed free‐roaming pen activity to study the natural history of such lesions, eighteen progressed to an osseous structural failure, sixteen of them developing incapacitating lameness at an average time point 11.75 weeks after the surgical insult. Histologically, the animals showed close concordance with both the early‐ and late‐stage human pathology, in six cases even to the point of developing a crescent sign. Because of its large physical size and its consistent progression to mechanical collapse, the emu appears to offer a unique opportunity for the near‐human‐scale study of surgical interventions to forestall femoral head collapse. Toward this end, various directions for model refinement are outlined. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Chronic anterior cruciate ligament deficiency is associated with increased anterior translation of the tibia during the transition from non‐weightbearing to weightbearing
Authors: Beynnon Bruce D. , Fleming Braden C. , Labovitch Ryan , Parsons Bradford
Published: October 2002

Translation of the tibia relative to the femur was measured while a group of subjects with normal knees and group with anterior cruciate ligament (ACL) tears underwent transition from non‐weightbearing to weightbearing stance. Subjects were positioned in the Vermont knee laxity device (VKLD) with muscles relaxed and the limb segment and compressive joint load offset (non‐weightbearing). A lateral radiograph of the knee, with the posterior aspects of the femoral condyles superimposed, was obtained to document the position of the tibia relative to the femur. Immediately after, a compressive load equal to 40% of bodyweight was applied to each foot, and a second radiograph was obtained to document the change in position of the tibia relative to the femur. The transition from non‐weightbearing to weightbearing produced a significant increase of anterior translation of the tibia relative to the femur (mean; 3.4 mm) for the subjects with ACL tears compared with the contralateral normal knees (0.8 mm). Similarly, there was a significant increase in anterior translation of the tibia for the subjects with ACL tears compared to the group of subjects with normal knees (1.2 mm). The fourfold increase in anterior translation of the tibia for the knees with ACL tears compared to the contralateral side is a concern because it is substantially greater than the 95% confidence limits of the side‐to‐side differences in anterior–posterior knee laxity measured from subjects with normal knees. This observation could explain, at least in part, one of the mechanisms that initiates damage to the meniscus and articular cartilage in subjects that have suffered an ACL tear. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Effects of hyaluronan on proteoglycan content of osteoarthritic chondrocytes in vitro
Authors: Stöve Johannes , Gerlach Christina , Huch Klaus , Günther Klaus‐Peter , Puhl Wolfhart , Scharf Hanns‐Peter
Published: October 2002

Purpose: To investigate the effect of hyaluronic acid (HA) on proteoglycan (PG) concentration in alginate cultures of human osteoarthritic chondrocytes and to analyze whether HA exhibit anti‐degradative effects in the presence of the cytokine IL‐1β.

Methods: Cartilage samples from ten patients with osteoarthritis of the knee were harvested and chondrocytes were cultivated in alginate beads. Four groups were cultured: control group with and without IL‐1β (500 pg/ml) and HA group (100 μg/ml) with and without IL‐1β (500 pg/ml). PG concentration was estimated by a dimethylmethylene blue assay. To assess cell proliferation, we measured DNA content fluorometrically.

Results: The proliferation rate (DNA) was unchanged in all culture groups. In the control‐group PG/DNA (ng/ng) concentration was 27.1 ± 7.2. Supplementation of the medium with HA decreased PG concentration to 25.3 ± 6.9 (p < 0.05). After administration of IL‐1β PG/DNA concentration dropped to 23.1 ± 6.0 (p < 0.01). By contrast HA treatment of IL‐1β stimulated chondrocytes did not further decrease PG concentration (23.9 ± 6.1). In fact the negative effect of isolated HA application was inverted if HA was given with IL‐1β (p < 0.05).

Conclusions: In osteoarthritic chondrocytes cultured phenotypically stable, HA could exhibit protective effects only in the presence of the degradative cytokine IL‐1β. Thus, the reported anti‐inflammatory effects of HA to cartilage matrix seem to be more indirect by blocking degradative effects of cytokines to the matrix. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.