bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphocyte glutathione status in relation to their Con A proliferative response
Authors: Lacombe Philippe , Kraus Laurence , Fay Michel , Pocidalo Jean-Jacques
Published: July 2002

We studied the intracellular total, oxidized and reduced glutathione levels in thymus and spleen rat lymphocytes cultured with or without Con A and 2‐mercaptoethanol (2‐ME). After 48 h culture, the total glutathione level decreased and the oxidized glutathione level increased in the two types of unstimulated and stimulated cells. In the presence of 2‐ME, the tritiated thymidine incorporation increased in splenocytes but not in thymocytes; on the other hand, the two types of stimulated cells increased their total and oxidized glutathione content. The enhancement of the GSSG/GSH + GSSG ratio, irrespective of culture conditions, indicates a severely disturbed redox state of the cells. 2‐ME acts on the glutathione synthesis of stimulated lymphocytes but is unable to maintain a normal redox state of these cells.
Mefloquine: an antimalarial drug interacting with the b/c region of bacterial respiratory chains
Authors: Zannoni D.
Published: July 2002

The effects of mefloquine, a quinoline‐4‐methanol antimalarial drug, on respiration by various bacterial strains endowed with branched electron transport pathways, have been examined. It is concluded that mefloquine strongly interacts with cytochrome b in the b/c segment of the chain. Unlike myxothiazol, mefloquine does not inhibit oxidant‐induced b‐type reduction but does induce an extra cytochrome b reduction when used in combination with antimycin A. The data reported are interpreted as evidence that mefloquine inhibits a ubiquinol oxidase site in common to both the alternative oxidase and the b/c oxidoreductase complex of the chain.
The role of fibrinogen αC‐domains in the fibrin assembly process
Authors: Medved' L.V. , Gorkun O.V. , Manyakov V.F. , Belitser V.A.
Published: July 2002

Turbidity development registration and electron microscopic observation of the assembly process of the fibrin monomer and its derivative lacking in intact αC‐domains (monomeric X1 fragment) have shown that these domains participate in fibrin polymerization, not as structural components, but as a factor promoting the ordered process of fibrin assembly.
Poliovirus‐encoded proteinase 3C: a possible evolutionary link between cellular serine and cysteine proteinase families
Authors: Gorbalenya A.E. , Blinov V.M. , Donchenko A.P.
Published: July 2002

Here we demonstrate significant similarities between the amino acid sequences of trypsin (a serine protease) and the N‐terminal piece of a specific fragment of the poliovirus polyprotein encompassing the sequence of the viral proteinase 3C, and also between cathepsin H (a cysteine protease) and the C‐terminal piece of the same fragment. A coherent alignment of the sequences of the 3 proteases was obtained, in which the principal catalytically active residues occupy identical positions. A hypothesis is proposed that the viral enzyme may provide an evolutionary link between serine and cysteine protease families.
Ciguatoxin and brevetoxins share a common receptor site on the neuronal voltage‐dependent Na+ channel
Authors: Lombet Alain , Bidard Jean-Noël , Lazdunski Michel
Published: July 2002

Binding studies indicate that ciguatoxin and brevetoxin allosterically enhance in a very similar way the binding of [3H]batrachotoxinin A 20‐α‐benzoate to the neuronal Na+ channel protein. Moreovr ciguatoxin competitively inhibits the binding of [3H]brevetoxin‐3 to rat brain membranes. The affinity of ciguatoxin for the Na+ channel is at least 20–50‐times higher than that of brevetoxin. These results indicate that ciguatoxin and brevetoxins act at the same binding site on the sodium channel.
Brain 14‐3‐3 protein is an activator protein that activates tryptophan 5‐monooxygenase and tyrosine 3‐monooxygenase in the presence of Ca2+,calmodulin‐dependent protein kinase II
Authors: Ichimura Tohru , Isobe Toshiaki , Okuyama Tsueno , Yamauchi Takashi , Fujisawa Hitoshi
Published: July 2002

We have found that the 14‐3‐3 protein, an acidic neuronal protein, is substantially identical to the ‘activator’ protein [(1981) J. Biol. Chem. 256, 5404–5409] that activates tryptophan 5‐monooxygenase and tyrosine 3‐monooxygenase in the presence of Ca2+,calmodulin dependent protein kinase II. This finding is based on the remarkable similarity of both these proteins in physicochemical, biochemical and immunochemical properties, as well as on detection for the 14‐3‐3 protein of an activator activity towards tryptophan 5‐monooxygenase. The result suggests that the 14‐3‐3 protein plays a role in the regulation of serotonin and noradrenaline biosynthesis in brain.
Regulation of mitochondrial proteolysis
Authors: Duque-Magalhães M.C. , Gualberto J.M.
Published: July 2002

The in vitro degradation of respiratory chain polypeptide components by a proteinase associated with the intermembrane space fraction was studied in rat liver mitochondria. Differences in susceptibility to proteolysis were detected by gel analysis after electrophoretic separation of the degraded polypeptides. A 55 kDa subunit is protected from proteolysis by the ATP molecule.
Calcium channel blockers inhibit bacterial chemotaxis
Authors: Matsushita Taku , Hirata Hajime , Kusaka Iwao
Published: July 2002

The effect of several Ca2+ channel blockers, which inhibit the voltage‐dependent Ca2+ uptake in Bacillus subtilis, on chemotactic behaviour of the bacterium was studied. Nitrendipine, verapamil, LACl3 and ω‐conotoxin were tested and these blockers inhibited chemotactic behaviour in the bacterium toward L‐alanine. Among these blockers, ω‐conotoxin was the most effective inhibitor of chemotaxis. EGTA was also as effective as ω‐conotoxin. In contrast, these blockers, did not inhibit the motility and the growth of the bacterium. These results suggest that internal Ca2+ plays an important role in the sensory system of bacterial chemotaxis.
Cloning and sequence analysis of a cDNA encoding the β‐subunit of mouse β‐hexosaminidase
Authors: Bapat Bharati , Ethier Marguerite , Neote Kuldeep , Mahuran Don , Gravel Roy A.
Published: July 2002

A cDNA encoding the prepro‐β‐polypeptide of mouse β‐hexosaminidase (Hex) was isolated from a mouse lymphoblast cDNA library. The cDNA contains an open reading frame corresponding to a polypeptide of 536 amino acids which shows 74% homology with the human prepro‐β‐polypeptide. An examination of the amino acid sequence identifies a putative signal peptide and five possible glycosylation sites, two of which are identical to the confirmed glycosylation sites of the human β‐chain. The amino acid sequence also shows a structurally similar though not identical site for internal cleavage responsible for the generation of mature βa‐ and βb‐polypeptides.
The herbicidally active experimental compound Hoe 704 is a potent inhibitor of the enzyme acetolactate reductoisomerase
Authors: Schulz Arno , Spönemann Petra , Köcher Helmut , Wengenmayer Friedrich
Published: July 2002

Growth inhibition of plants and bacteria by the experimental herbicide Hoe 704 (2‐methylphosphinoyl‐2‐hydroxyacetic acid) was alleviated by the addition of the branched‐chain amino acids to growth media. Hoe 704 caused a massive accumulation of acetoin and acetolactate, indicating its direct interference with the branched‐chain amino acid biosynthetic pathway. The second enzyme of this pathway, acetolactate reductoisomerase (EC 1.1.1.86), was found to be subject to strong inhibition by Hoe 704. The inhibition was time‐dependent and competitive with the enzyme's substrate, acetolactate. This report establishes acetolactate reductoisomerase as a new target for a herbicidal compound.
Recombinant human interleukin‐6 (IL‐6/BSF‐2/HSF) regulates the synthesis of acute phase proteins in human hepatocytes
Authors: Castell José V. , Gómez-Lechón Maria J. , David Martina , Hirano Toshio , Kishimoto Tadamitsu , Heinrich Peter C.
Published: July 2002

Recombinant human IL‐6 (rhIL‐6) is a potent inducer of the synthesis of acute phase proteins in adult human hepatocytes. A wide spectrum of acute phase proteins is regulated by this mediator. After labeling of rhIL‐6 stimulated human hepatocytes with [35S]methionine acute phase protein synthesis was measured by immunoprecipitation. Serum amyloid A, C‐reactive protein, haptoglobin, α1‐antichymotrypsin and fibrinogen were strongly induced (26‐, 23‐, 8.6‐, 4.6‐ and 3.8‐fold increases, respectively). Moderate increases were found for α1‐antitrypsin (2.7‐fold) and α1‐acid glycoprotein (2.7‐fold). RhIL‐6 had no effect on α1‐macroglobulin, whereas fibronectin, albumin and transferrin decreased to 64, 56 and 55% of controls. In the cases of serum amyloid A, haptoglobin, α1‐antichymotrypsin, α1‐antitrypsin and α1‐acid glycoprotein, dexamethasone enhanced the action of rhIL‐6. We conclude that rhIL‐6 controls the acute phase response in human liver cells.
Developmental regulation of five subunit specific mRNAs encoding acetylcholine receptor subtypes in rat muscle
Authors: Witzemann Veit , Barg Brigitte , Criado Manuel , Stein Elke , Sakmann Bert
Published: July 2002

The muscular content of the mRNAs encoding the five subunits of the nicotinic acetylcholine receptor was measured during postnatal development in the rat. Subunit specific mRNAs show differential regulation. The levels of the α‐, γ‐ and δ‐subunit specific mRNAs decrease steadily after birth, while the β and ε‐subunit mRNAs increase transiently and then decrease. The adult pattern of subunit specific mRNA levels is reached at 4–6 weeks postnatally. The content of γ‐ and ε‐subunit mRNA changes in a reciprocal fashion during the first 2 postnatal weeks, supporting the view that differential regulation of γ‐ and ε‐subunit mRNA during development is one mechanism mediating the appearance of the adult, ε‐subunit containing, subtype of end‐plate channel. Denervation of neonatal muscle increases the levels of all subunit‐specific mRNAs during further development. It prevents the postnatal decrease in γ‐subunit mRNA and enhances the initial increase in ε‐subunit mRNA. This makes it appear that the ε‐subunit gene is less sensitive to regulation by the nerve in the postnatal period than the γ‐subunit gene.
Monoclonal antibody to galactosylceramide: discrimination of structural difference in the ceramide moiety
Authors: Nakakuma Hideki , Arai Mitsuhiro , Kawaguchi Tatsuya , Horikawa Kentaro , Hidaka Michihiro , Sakamoto Kiyoshi , Iwamori Masao , Nagai Yoshitaka , Takatsuki Kiyoshi
Published: July 2002

A mouse monoclonal antibody (mAb) was developed against monohexaosylceramide. This mAb differentially reacted on thin‐layer chromatograms with 3 types of galactosylceramide (GalCer) obtained from bovine brain. Structural analysis of the 3 glycolipids revealed that they consisted of the same galactose and sphingosine but of apparently different fatty acids. Among the 3 GalCers, the mAb reacted with two GalCers which contained α‐hydroxy fatty acids, but not with GalCer composed of nonhydroxy fatty acids. These findings suggest not only that the mAb discriminated the fatty acid composition in the ceramide moiety of GalCer, but also that the ceramide structure defines the immunological epitope as it is known to do for the carbohydrate moiety of glycosphingolipid.
Identification of a Gs‐protein coupling domain to the β‐aderenoceptor using site‐specific synthetic peptides
Authors: Palm Dieter , Münch Gerald , Malek Daria , Dees Christian , Hekman Mirko
Published: July 2002

Competition between Gs‐protein and the synthetic peptide, GSA 379‐394, derived from the carboxyl‐terminal region of the αs‐subunit, led to complete inhibition of receptor‐mediated adenylate cyclase activation in turkey erythrocyte membranes. Related peptides corresponding to the homologous carboxyl‐terminal region of αt‐,αil‐ or αo‐subunits did not interfere with β‐receptor‐Gs coupling. The direct coupling between Gs and adenylate cyclase was not influenced by any of these peptides. These results emphasize the important role of the carboxyl‐terminus of G‐protein α‐subunits for the specific recognition of their corresponding receptors and for signal transduction.
Human galanin: Primary structure and indentification of two molecular forms
Authors: Bersani Maurizio , Johnsen Anders H. , Højrup Peter , Dunning Beth E. , Andreasen Jan J. , Holst Jens J.
Published: July 2002

From acid/ethanol extracts of surgical specimens of human large intestine we isolated two peptides, in approximately equal amounts, that reacted with an antiserum against porcine galanin. By amino acid analysis, sequence analysis and mass spectrometry, the larger of the two peptides was found to consist of 30 amino acid residues, the sequence of which was identical to that of porcine galanin except for the following substitutions: Val16, Asn17, Asn36, Thr20 and Scr30. Unlike porcine galanin, the caboxy‐terminus was not amidated. The smaller peptide corresponded to the first 19 amino acid residues counted from the N‐terminus of the 30 residue peptide (again without amidation). The structural analysis was repeated on another batch of tissue with identical results. By HPLC analysis of extracts of specimens from a further 4 patients, the same peptides were identified. Thus, human galanin includes two peptides of 19 and 30 amino acids that share the sequence of the N‐terminal 15 residues with other mammalian galanins, but exhibit characteristic differences in the remaining part of the molecules.
Binding of HIV‐1 gp120 to the nicotinic receptor
Authors: Bracci Luisa , Lozzi Luisa , Rustici Mauro , Neri Paolo
Published: July 2002

We previously described a significant sequence homology between HIV‐1 gp120 and the functional sites responsible for the specific binding of snake curare‐mimetic neurotoxins and rabies virus glycoprotein to the nicotinic acetylcholine receptor. Here we report findings about the existence of a mechanism of functional molecular mimicry which could enable the binding of HIV‐1 gp120 to nicotinic acetylcholine receptors in muscle cells and neurons.
Side chain and backbone assignments in isotopically labeled proteins from two heteronuclear triple resonance experiments
Authors: Logan Timothy M. , Olejniczak Edward T. , Xu Robert X. , Fesik Stephen W.
Published: July 2002

Two multidimensional heteronuclear NMR experiments are described for assigning the resonances in uniformly 15N‐ and 13C‐labeled proteins. In one experiment (HCNH‐TOCSY), the amide nitrogen and proton are correlated to the side‐chain protons and carbons of the same and preceding residue. In a second triple resonance experiment (HC(CO)NH‐TOCSY), the amide nitrogen and proton of one residue is correlated exclusively with the side‐chain proton and carbon resonances of the preceding residue by transferring magnetization through the intervening carbonyl. The utility of these two experiments for making sequential resonance assignments in proteins is illustrated for [U‐15N, 13C]FKBP (107 residues) complexed to the immunosuppressant, ascomycin.
Sunlight‐induced mutagenicity of a common sunscreen ingredient
Authors: Knowland John , McKenzie Edward A , McHugh Peter J , Cridland Nigel A
Published: July 2002

We have tested the mutagenicity of a UV‐B sunscreen ingredient called Padimate‐O or octyl dimethyl PABA, which, chemically speaking, is identical to an industrial chemical that generates free radicals when illuminated. It is harmless in the dark but mutagenic in sunlight, attacking DNA directly. A commercial sunscreen containing Padimate‐O behaves in the same way. UV‐A in sunlight also excites Padimate‐O, although less than UV‐B. Some related compounds, including a known carcinogen, behave similarly. As mutagens may be carcinogenic, our results suggest that some sunscreens could, while preventing sunburn, contribute to sunlight‐related cancers.
Mercury inhibition at the donor side of photosystem II is reversed by chloride
Authors: Bernier Michelle , Popovic Radovan , Carpentier Robert
Published: July 2002

Mercury is an environmental contaminant that strongly inhibits photosynthetic electron transport, photosystem II being the most sensitive target. We investigated in greater detail the effect of mercury using photosystem II submembrane fractions of higher plants. Oxygen evolution was strongly inhibited and variable chlorophyll fluorescence was severely quenched by mercury. Chloride, an inorganic cofactor known to be essential for the optimal function of photosystem II, significantly reversed the inhibitory effect of mercury. However, calcium, another essential cofactor, showed no reversal capacity. It is concluded that on the donor side of PSII, mercury exerts its action by perturbing chloride binding and/or function. Considering the exceptional affinity of mercury for sulfhydryl groups of proteins, the results suggest the implication of cystein residue(s) in maintaining structural and functional integrity of photosystem II.
Redox control of transcription: sensors, response regulators, activators and repressers
Authors: Allen John F.
Published: July 2002

In a growing number of cases, transcription of specific genes is known to be governed by oxidation or reduction of electron carriers with which the gene products interact. The biological function of such control is to activate synthesis of appropriate redox proteins, and to repress synthesis of inappropriate ones, in response to altered availability of specific electron sources and sinks. In prokaryotic systems this control appears to operate by two general classes of mechanism: by two‐component regulation involving protein phosphorylation on histidine and aspartate; and by direct oxidation‐reduction of gene repressors or activators. For the first class, termed ‘two‐component redox regulation’, the term ‘redox sensor’ is proposed for any electron carrier that becomes phosphorylated upon oxidation or reduction and thereby controls phosphorylation of specific response regulators, while the term ‘redox response regulator’ is proposed for the corresponding sequence‐specific DNA‐binding protein that controls transcription as a result of its phosphorylation by one or more redox sensors. For the second class of redox regulatory mechanism, the terms ‘redox activator protein’ and ‘redox repressor protein’ are proposed for single proteins containing both electron transfer and sequence‐specific DNA‐binding domains. The structure, function and biological distribution of these components are discussed.
Dephosphorylation of tau protein and Alzheimer paired helical filaments by calcmeurin and phosphatase‐2A
Authors: Drewes G. , Mandelkow E.-M. , Baumann K. , Goris J. , Merlevede W. , Mandelkow E.
Published: July 2002

We have shown previously that brain tissue contains protein kinases which can phosphorylate tau protein to a state reminiscent of the pathological state of Alzheimer paired helical filaments (PHFs); these include proline‐directed kinases which phosphorylate SP or TP motifs (such as MAP kinase and GSK‐3) [Drewes et al. (1992); Mandelkow et al. (1992)], as well as a novel kinase which phosphorylates S262 of tau protein and thereby strongly reduces the binding of tau to imcrotubules [Biernat et al. (1993)]. Here we report on the corresponding phosphatases in brain which normally keep the ‘pathological’ sites free of phosphate. The major phosphatases acting on tau are calcineurin and PP‐2A, but not PP‐1. Both are present and active in brain extracts, they can dephosphorylate recombinant tau after prior phosphorylation with either MAP kinase, GSK‐3, or brain extract, and the course of dephosphorylation can be monitored with antibodies diagnostic of the pathological state of tau. Both phosphatases also act directly on PHF tau isolated from Alzheimer brains.
Free radical activation of acetaldehyde and its role in protein alkylation
Authors: Albanoa Emanuele , Clot Paolo , Comoglio Adriana , Dianzani Mario U. , Tomasi Aldo
Published: July 2002

The formation of carbon centered free radicals, identified as methylcarbonyl species, was observed using ESR spectroscopy and the spin trapping agent 4‐pyridyl‐1‐oxide‐N‐t‐butyl nitrone (4‐POBN) during the oxidation of acetaldehyde by xanthine oxidase. The reaction was dependent upon the presence of OH• radicals and was inhibited by the addition of superoxide dismutase, catalase or OH• radical scavengers. The generation of methylcarbonyl radicals was associated with a doubling of stable acetaldehyde adducts with serum albumin, and 4‐POBN or superoxide dismutase and catalase, completely blocked this effect. Thus, methylcarbonyl radicals contributed to acetaldehyde‐mediated protein alkylation which is involved in causing toxic as well as immunological reactions ascribed to acetaldehyde.
Directed mutagenesis of pig renal membrane dipeptidase His219 is critical but the DHXXH motif is not essential for zinc binding or catalytic activity
Authors: Keynan Shoshana , Hooper Nigel M. , Turner Anthony J.
Published: July 2002

Pig renal membrane dipeptidase cDNA has been expressed in COS‐1 cells. Directed mutagenesis was used to investigate the roles of some conserved histidyl and aspartyl residues. Mutation of His219 to Arg, Lys or Leu results in complete abolition of enzyme activity, although the mutants are expressed at the cell‐surface. Residues in a proposed motif (DHXDH; residues 269−273) for zinc binding have been mutated individually. Each retained activity comparable to that of the wild‐type, excluding an essential role for components of this motif. The zinc‐binding ligands in membrane dipeptidase therefore represent a novel domain for a metallopeptidase with His219 being one candidate.
Cloning and functional characterization of the human 5‐HT2B serotonin receptor
Authors: Schmuck Karin , Ullmer Christoph , Engels Peter , Lübbert Hermann
Published: July 2002

Recently, we have reported the cloning of the rat 5‐HT2B receptor cDNA. This receptor is particularly interesting since it may be involved in diseases such as migraine. Here, we describe the isolation of a human 5‐HT2B receptor clone from a cDNA library derived from SH‐SY5Y cells. Although the receptor sequence was only 80% homologous to the rat sequence, the exon‐intron distribution was conserved between the two species. In the human body, the receptor mRNA was detected in most peripheral organs. Only low expression levels were found in the brain. After expression in HEK 293 cells, activation of the receptor stimulated the production of phosphatidylinositol. The pharmacology of this functional response correlated well with that of the rodent receptor.
4‐O‐Phosphoryl‐l‐threonine, a substrate of the pdxC(serC) gene product involved in vitamin B6 biosynthesis
Authors: Drewke Christel , Klein Matthias , Clade Dorothee , Arenz Ansgar , Müller Rolf , Leistner Eckhard
Published: July 2002

The Escherichia coli pdxC(serC) gene codes for a transaminase (EC 2.6.1.52). The gene is involved in both pyridoxine (vitamin B6) and serine biosynthesis and was over‐expressed as a MalE/PdxC(SerC) fusion protein. The fusion protein was purified by affinity chromatography on an amylose resin and hydrolyzed in the presence of protease factor Xa. Both the fusion protein and the PdxC(SerC) protein were characterized (K
M value, turnover number, optimum pH). Both enzymes used 4‐O‐phosphoryl‐l‐threonine rather than 4‐hydroxy‐l‐threonine as a substrate indicating that the phosphorylated rather than the non‐phosphorylated amino acid is involved in pyridoxine biosynthesis. Pyridoxal phosphate was shown to be the cofactor for both enzymes and therefore seems to be involved in its own biosynthesis.
Structural and functional similarities between HIV‐1 reverse transcriptase and the Escherichia coli RNA polymerase β′ subunit
Authors: Szilvay Anne Marie , Stern Beate , Blichenberg Arne , Helland Dag E.
Published: July 2002

Four monoclonal antibodies (MAbs) recognizing HIV‐1 reverse transcriptase (RT) were shown here to cross‐react with the β′ subunit of Escherichia coli RNA polymerase (RNAP). The anti‐RT MAbs bind to a peptide comprising residues 294–305 of the RT amino acid sequence. Computer analyses revealed sequence similarity between this peptide and two regions of the RNAP β′ subunit. MAb‐binding studies using RT mutants suggested that the epitope is located to amino acids 652–663 of the β′ sequence. One of the MAbs which inhibited the polymerase activity of RT also mediated a dose dependent inhibition of the RNAP activity.
Cytomegalovirus infection increases the expression and activity of ecto‐ATPase (CD39) and ecto‐5′nucleotidase (CD73) on endothelial cells
Authors: Kas-Deelen A.M. , Bakker W.W. , Olinga P. , Visser J. , de Maar E.F. , van Son W.J. , The T.H. , Harmsen M.C.
Published: July 2002

We describe enhanced expression and enzymatic activity of ecto‐ATPase and ecto‐5′nucleotidase on CMV infected endothelial cells as compared to uninfected cells. These ectoenzymes play a major role in modulation of platelet activation and aggregation. Furthermore, adenosine has a modulatory effect upon inflammation. Addition of ATP, ADP or AMP to cultures of CMV infected or uninfected endothelial cells revealed increased turnover of AMP in CMV infected endothelial cells. In addition, the superoxide production by stimulated polymorphonuclear cells was inhibited in the presence of CMV infected endothelial cells as compared to uninfected cells, probably due to the enhanced activity of ecto‐5′nucleotidase and associated to production of adenosine.
Analysis of the reaction mechanism of the non‐specific endonuclease of Serratia marcescens using an artificial minimal substrate
Authors: Kolmes Bettina , Franke Ingo , Friedhoff Peter , Pingoud Alfred
Published: July 2002

We have studied the mechanism of action of the Serratia nuclease using deoxythymidine 3′,5′‐bis‐(p‐nitrophenyl‐phosphate) as a substrate. A comparison of the activity with which the wild‐type enzyme and several mutant enzymes attack this artificial substrate and herring sperm DNA, respectively, supports the suggestion that His89 is the general base and a Mg2+ ion bound to Glu127 the general acid in the mechanism of phosphodiester bond hydrolysis by the Serratia nuclease, and that Asn119 directly participates in catalysis, for example by transition state stabilisation. Arg57, Arg87 and Arg131, essential for nuclease activity, are not needed for cleavage of the artificial substrate, suggesting that they are involved in binding and positioning of nucleic acid substrates.
Interaction between the fission yeast nim1/cdr1 protein kinase and a dynamin‐related protein
Authors: Pelloquin Laetitia , Ducommun Bernard , Belenguer Pascale
Published: July 2002

The nim1/cdr1 protein kinase is required for an efficient adaptation of cell cycle parameters to changes in nutritional conditions. We have isolated msp1, a new fission yeast member of the dynamin‐related large GTPase family, in a two‐hybrid screen designed to identify proteins interacting with the nim1 kinase. Msp1 has been shown to be essential for the maintenance of mtDNA and hence for the inheritance of functional mitochondria. We present evidence indicating that nim1 and msp1 proteins physically interact both in vitro and in vivo in fission yeast. These interactions occur through the amino‐terminal catalytic domain of nim1 and the carboxy‐terminal putative regulatory domain of msp1. These results provide new evidence for the existence of a connection between mitochondrial function and the cell cycle machinery.
Purification, characterization and crystallization of ERA, an essential GTPase from Escherichia coli1
Authors: Chen Xin , Chen Su-Min , S. Powell Bradford , Court Donald L , Ji Xinhua
Published: July 2002

ERA is an essential GTPase widely conserved in bacteria. Homologues of ERA are also present in higher eukaryotic cells. ERA is involved in bacterial cell cycle control at a point preceding cell division. In order to aid the functional investigation of ERA and to facilitate structure‐function studies, we have undertaken the X‐ray crystallographic analysis of this protein. Here, we report the purification and crystallization procedures and results. The purified ERA exhibits nucleotide‐binding activity and GTP‐hydrolytic activity. ERA is one of the very few multi‐domain GTPases crystallized to date.
The α‐isoform of class II phosphoinositide 3‐kinase is more effectively activated by insulin receptors than IGF receptors, and activation requires receptor NPEY motifs
Authors: Ursø B. , Brown R.A. , O'Rahilly S. , Shepherd P.R. , Siddle K.
Published: July 2002

Little is known about the physiological role and mechanism of activation of class II phosphoinositide 3‐kinases (PI3Ks), although it has been shown that the PI3K‐C2α isoform is activated by insulin. Using chimaeric receptor constructs which can be activated independently of endogenous receptors in transfected cells, we found that PI3K‐C2α activity was stimulated to a greater extent by insulin receptors than IGF receptors in 3T3‐L1 adipocytes. Activation of PI3K‐C2α required an intact NPEY motif in the receptor juxtamembrane domain. We conclude that PI3K‐C2α is a candidate for participation in insulin‐specific intracellular signalling.
Ozone potentiates vitamin E depletion by ultraviolet radiation in the murine stratum corneum
Authors: Valacchi Giuseppe , Weber Stefan U. , Luu Chate , Cross Carroll E. , Packer Lester
Published: July 2002

As the outermost layer of the skin, the stratum corneum is exposed to environmental oxidants. To investigate putative synergisms of environmental oxidative stressors in stratum corneum, hairless mice were exposed to ultraviolet radiation (UV) and ozone (O3) alone and in combination. Whereas a significant depletion of α‐tocopherol was observed after individual exposure to either a 0.5 minimal erythemal dose of UV or 1 ppm O3 for 2 h, the combination did not increase the effect of UV alone. However, a dose of 0.5 ppm O3×2 h, which had no effect when used alone, significantly enhanced the UV‐induced depletion of vitamin E. We conclude that concomitant exposure to low doses of UV and O3 at levels near those that humans can be exposed to causes additive oxidative stress in the stratum corneum.
An assessment of survey research in POM: from constructs to theory
Authors: Malhotra Manoj K , Grover Varun
Published: July 2002

The use of field‐based empirical methodologies in the production and operations management (POM) area has been steadily increasing over the past several years. One of the most prominent among these is the survey research methodology which has often been used to capture data from business organizations. However, to effectively contribute to theory development in the POM field, this methodology must be carefully implemented. Poorly designed and executed survey research is of little or no value. This paper attempts to provide a normative perspective on ‘good survey research practices’. In doing so, it attempts to bridge the gap between survey research and theory development. The paper liberally draws from work in other social science disciplines like psychology, marketing, organizational behavior, and other related fields that are more mature in the use of surveys, and applies it to the POM area. A set of ideal survey research attributes are identified, and existing POM survey work in four prestigious academic journals is evaluated with respect to these attributes. Results of assessing 25 survey‐based articles published in these journals between 1990 and 1995 indicate that both exploratory as well as explanatory survey research is being conducted, with current emphasis being more on explanatory kind of research. In order to move the field forward, greater attention will need to be focused on employing multi‐item constructs, assessing them for content validity, and purifying them through field‐based pretesting. More sophisticated POM studies in the future would have to aim for testing theory with reliable and valid scales that are relatively free of measurement related errors. It is hoped that this work will act as a catalyst in compressing the learning curve with respect to survey research practices in POM, and also accelerate the use of greater methodological rigor in future empirical studies in the field.
Testing a model of pull production: a paradigm for manufacturing research using structural equation modeling
Authors: Koufteros Xenophon A
Published: July 2002

The measurement of unobservable (latent) variables has been a recent phenomenon in the manufacturing research area. Most available empirical research in manufacturing has been exploratory in nature and has borrowed its methods extensively from other fields such as psychology, sociology, and marketing. Traditional exploratory techniques have been used to provide preliminary scales and assess measurement properties. Manufacturing researchers have, however, overlooked the assessment of unidimensionality, an essential measurement property and a basic assumption of measurement theory. An explicit evaluation of unidimensionality can be accomplished with a confirmatory factor analysis (CFA) of individual measures as specified by a multiple‐indicator measurement model. A paradigm for scale evaluation incorporating CFA for the assessment of unidimensionality is outlined here along with methodology to assess other measurement properties such as convergent validity, discriminant validity, composite reliability, and average variance extracted. A measurement model is tested first followed by a structural model of interest. The hypothesized structural model relates pull production with two of its antecedents, setup improvement and preventive maintenance practices. It further relates pull production to one of its consequences, delivery dependability. Responses from 244 firms are used to test the measurement and structural model.
BMP signaling stimulates chondrocyte maturation and the expression of Indian hedgehog
Authors: Grimsrud Christopher D. , Romano Paul R. , D'Souza Mary , Puzas J. Edward , Schwarz Edward M. , Reynolds Paul R. , Roiser Randy N. , O'Keefe Regis J.
Published: July 2002

Mutant BMP receptors were transfected into cultured embryonic upper sternal chrondrocytes using retroviral vectors to determine if BMP signaling is required for chondrocyte maturation and the expression of a key regulatory molecule, Indian hedgehog (Ihh). Chondrocytes infected with replication competent avian retroviruses (RCAS) viruses carrying constitutive active (CA) BMPR‐IA and BMPR‐IB had enhanced expression of type X collagen and Ihh mRNA. Addition of PTHrP, a known inhibitor of chondrocyte maturation, abolished the expression of type X collagen, BMP‐6, and Ihh mRNAs in control cells. In contrast, PTHrP treated cultures infected with of CA BMPR‐IA or CA BMPR‐IB had low levels of BMP‐6 and type X collagen, but high levels of Ihh expression. Although dominant negative (DN) BMPR‐IA had no effect, DN BMPR‐IB inhibited the expression of type X collagen and BMP‐6, and decreased alkaline phosphatase activity, even in the presence of exogenously added BMP‐2 and BMP‐6. DN BMPR‐IB also completely blocked Ihh expression. Overall, the effect of DN BMPR‐IB mimicked the effects of PTHrP. To determine if there is an autocrine role for the BMPs in chondrocyte maturation, the cultures were treated with noggin and follistatin, molecules that bind BMP‐2/‐4 and BMP‐6/‐7, respectively. While noggin and follistatin inhibited the effects of recombinant BMP‐2 and BMP‐6, respectively, they had only minimal effects on the spontaneous maturation of chondrocytes in culture, suggesting that more than one subgroup of BMPs regulates chondrocyte maturation. The results demonstrate that: (i) BMP signaling stimulates chondrocyte maturation; (ii) BMP signaling increases Ihh expression independent of maturational effects; and (iii) BMP signaling can partially overcome the inhibitory effects of PTHrP on maturation. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Ankle ligament injury risk factors: a prospective study of college athletes
Authors: Beynnon Bruce D. , Renström Per A. , Alosa Denise M. , Baumhauer Judith F. , Vacek Pamela M.
Published: July 2002

Over two million individuals suffer ankle ligament trauma each year in the United States, more than half of these injuries are severe ligament sprains; however, very little is known about the factors that predispose individuals to these injuries. The purpose of this study was to determine the risk factors associated with ankle injury. We performed a prospective study of 118 Division I collegiate athletes who participated in soccer, lacrosse, or field hockey. Prior to the start of the athletic season, potential ankle injury risk factors were measured, subjects were monitored during the athletic season, and injuries documented. The number of ankle injuries per 1000 person‐days of exposure to sports was 1.6 for the men and 2.2 for the women. There were 13 injuries among the 68 women (19%) and seven injuries among the 50 men (13%), but these proportions were not significantly different. Women who played soccer had a higher incidence of ankle injury than those who played field hockey or lacrosse. Among men, there was no relationship between type of sport and incidence of injury. Factors associated with ankle ligament injury differ for men relative to women. Women with increased tibial varum and calcaneal eversion range of motion are at greater risk of suffering ankle ligament trauma, while men with increased talar tilt are at greater risk. Generalized joint laxity, strength, postural stability, and muscle reaction time were unrelated to injury. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Amyloid β peptide is not a candidate for the neurotrophic activities released from chromaffin cells
Authors: Legutko Beata , Staufenbiel Matthias , Krieglstein Kerstin
Published: July 2002

We have previously shown that chromaffin cells, the neuron‐like cells of the adrenal medulla, release proteins, which promote in vitro survival of a large number of peripheral and central nervous system neurons (cf. Lachmund, A., Gehrke, D., Krieglstein, K. and Unsicker, K, Trophic factors from chromaffin granules promote survival of peripheral and central nervous system neurons. Neuroscience, 1994, 62, 361–370). In a search for the active molecules we are testing compounds that are known to be synthesized and released by chromaffin cells. Amyloid precursor protein (βAPP) is one of these factors (Bieger, S., Klafki, H.‐W. and Unsicker, K., Synthesis and release of the β‐amyloid precursor protein by bovine chromaffin cells. Neurosci. Lett., 1993, 162, 173–175). In the present study we have investigated the possibility that amyloid β peptide (AβP) generated from βAPP may have survival supporting effects for neurons from embryonic chick ciliary (CG) and dorsal root ganglia (DRG). Embryonic rat hippocampal neurons, for which promotion of short‐term survival by AβP has been reported (Whitson, J. S., Selkoe, D. J. and Cotman, C. W., Amyloid β protein enhances the survival of hippocampal neurons in vitro. Science, 1989, 243, 1488–1490), were employed as a reference. AβP fragment 1–40, administered over a wide range of concentrations (1.5–100 μmg\ml) did not promote the survival of CG and DRG neurons isolated from embryonic day (E) 8 chick embryos. The peptide also failed to toxically suppress survival of these neuron populations in the presence of survival promoting factors. In confirmation of previous reports, the 1–40 peptide, in comparison to the reverse 40–1 peptide, significantly enhanced survival of hippocampal neurons. These results suggest that AβP is not a trophic factor for the peripheral neuron populations tested and, most likely, not a neurotrophic component among the neurotrophic factors released by chromaffin cells.
Founding family controlled firms: Efficiency and value
Authors: McConaughy Daniel L. , Walker Michael C. , Henderson Glenn V. , Mishra Chandra S.
Published: July 2002

We examine the efficiency and value of founding family controlled firms (FFCFs), firms whose CEOs are either the founder or a descendant of the founder. We find that FFCFs are more efficient and valuable than non‐FFCFs that are similar with respect to industry, size, and managerial ownership. We also observe that descendant‐controlled firms are more efficient than founder‐controlled firms. Finally, we show that younger founder‐controlled firms are more efficient than older ones. These results are robust after controlling for the age of the firm and a variety of investment opportunity measures. Our results are consistent with the notions that managerial ownership is endogenous to the firm and that family relationships improve monitoring while providing incentives that are associated with better firm performance.
Cyclosporine pharmacokinetics and pharmacodynamics in African American and white subjects
Authors: Stein C. Michael , Sadeque Abu J. , Murray John J. , Wandel Christoph , Kim Richard B. , Wood Alastair J. J.
Published: July 2002

Background

Renal allograft survival is lower in African American patients compared with white patients. Interethnic differences in cyclosporine (INN, ciclosporin) pharmacokinetics in renal transplant recipients have been described but have not been well characterized. Pharmacodynamic responses to cyclosporine have not been compared among ethnic groups.

Methods

Healthy men were studied after 5 days on a controlled diet. Cyclosporine concentrations were determined in whole blood drawn at intervals over 24 hours after administration of a microemulsion cyclosporine formulation (4 mg/kg; 9 African American subjects and 9 white subjects) and after a standard cyclosporine formulation (4 mg/kg; 10 African American subjects and 10 white subjects). Inhibition of phytohemagglutinin‐P–stimulated interleukin‐2 production in whole blood drawn 4 hours after cyclosporine was used as a pharmacodynamic measure to compare the effect of cyclosporine in African American and white subjects.

Results

The microemulsion cyclosporine formulation (area under the cyclosporine concentration‐time curve, 7432 ± 560 ng · h/mL in African American subjects and 7043 ± 454 ng · h/mL in white subjects) was more bioavailable than the standard formulation (area under the cyclosporine concentration‐time curve, 4828 ± 319 ng · h/mL in African American subjects and 4538 ± 301 ng · h/mL in white subjects); this resulted in an approximately 50% greater area under the cyclosporine concentration‐time curve (P < .001 in both ethnic groups). There were no differences between African American subjects and white subjects in any pharmacokinetic measurement, with both the standard and the microemulsion cyclosporine formulations. Inhibition of phytohemagglutinin‐P–stimulated interleukin‐2 production 4 hours after the administration of cyclosporine was similar in African American subjects (70% ± 5% inhibition) and white subjects (64% ± 7% inhibition; P = .5).

Conclusions

The pharmacokinetics and pharmacodynamics of cyclosporine were similar in a matched group of African American and white subjects studied under controlled conditions. Environmental factors may contribute more than genetic variability to the lower bioavailability of cyclosporine reported in African American renal transplant recipients.

Clinical Pharmacology & Therapeutics (2001) 69, 317–323; doi: 10.1067/mcp.2001.115073
Lung disorders induced by respirable organic chemicals
Authors: Morimoto Yasuo , Nishida Chinatsu , Tomonaga Taisuke , Izumi Hiroto , Yatera Kazuhiro , Sakurai Kazuo , Kim Yangho
Published: June 2021

Respirable organic chemicals were originally thought to cause allergic respiratory diseases, such as bronchial asthma and hypersensitivity pneumonitis, and believed not to cause lung disorders derived from inflammatory or fibrotic processes such as pulmonary fibrosis and interstitial pneumonitis. It has recently been reported, however, that exposure to organic chemicals can cause interstitial lung diseases. In this review, we discuss the clinical features of occupational asthma and hypersensitivity pneumonitis, as well as other lung disorders, including interstitial pneumonitis, caused by humidifier disinfectants in Korea and by a cross-linked acrylic acid-based polymer (CL-PAA) in Japan.
Bird community recovery following removal of an invasive tree
Authors: O'Leary Benjamin A. , Burd Martin , Venn Susanna E. , Gleadow Roslyn M.
Published: June 2021

Faunal responses to plant invasions and their managed removal can expand our understanding of the nature of disturbance and the success of restored plant communities.

We examined how bird communities responded to the presence and removal of the invasive understorey tree Pittosporum undulatum Vent. (sweet pittosporum) in matched woodland areas in temperate south‐eastern Australia that were free of P. undulatum invasion, were invaded, or had been cleared up to 14 years prior to our sampling.

Overall bird species richness and individual abundance were insensitive indicators, as neither were significantly affected by the presence or removal of P. undulatum. However, richness and abundance were sharply lower in and beneath the P. undulatum canopies compared to the forest overstorey, pointing to a large structural modification by the invader. Bird community composition changed in fairly consistent ways at multiple sites upon invasion by P. undulatum, changes that were partly but not completely reversed by removal of P. undulatum. The suite of functional traits of the birds present at the sites was disrupted in idiosyncratic ways at sites invaded by P. undulatum and only very weakly restored upon clearing of P. undulatum. Functional and diversity indices are dependent on the type of management implemented.

We propose that a more nuanced approach to management such that some of the invaded forest in neighbouring areas is retained while new trees become established in the cleared areas, providing access to suitable habitat for birds during the transition phase. Such measures are challenging in terms of management and funding but are necessary to maintain avian diversity during and after restoration processes.
Anisotropically Fatigue‐Resistant Hydrogels
Authors: Liang Xiangyu , Chen Guangda , Lin Shaoting , Zhang Jiajun , Wang Liu , Zhang Pei , Wang Zeyu , Wang Zongbao , Lan Yang , Ge Qi , Liu Ji
Published: June 2021

Nature builds biological materials from limited ingredients, however, with unparalleled mechanical performances compared to artificial materials, by harnessing inherent structures across multi‐length‐scales. In contrast, synthetic material design overwhelmingly focuses on developing new compounds, and fails to reproduce the mechanical properties of natural counterparts, such as fatigue resistance. Here, a simple yet general strategy to engineer conventional hydrogels with a more than 100‐fold increase in fatigue thresholds is reported. This strategy is proven to be universally applicable to various species of hydrogel materials, including polysaccharides (i.e., alginate, cellulose), proteins (i.e., gelatin), synthetic polymers (i.e., poly(vinyl alcohol)s), as well as corresponding polymer composites. These fatigue‐resistant hydrogels exhibit a record‐high fatigue threshold over most synthetic soft materials, making them low‐cost, high‐performance, and durable alternatives to soft materials used in those circumstances including robotics, artificial muscles, etc.