bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPLETE LOCAL CHARACTERIZATION OF STRONG 26-SURFACES: CONTINUOUS ANALOGS FOR STRONG 26-SURFACES
Authors: MALGOUYRES RÉMY , BERTRAND GILLES
Published: April 2003

In Ref. 6, two similar characterizations of discrete surfaces of ℤ3 are proposed which are called strong 18-surfaces and strong 26-surfaces. The proposed characterizations consist in some natural global properties of surfaces. In this paper, we first give local necessary conditions for an object to be a strong 26-surface. An object satisfying these local properties is called a near strong 26-surface. Then we construct continuous analogs for near strong 26-surfaces and, using the continuous Jordan Theorem, we prove that the necessary local conditions previously introduced in fact give a complete local characterization of strong 26-surfaces: the class of near strong 26-surfaces coincides with the class of strong 26-surfaces.
ON THE RECOVERY OF MOTION AND STRUCTURE WHEN CAMERAS ARE NOT CALIBRATED
Authors: BOUFAMA BOUBAKEUR S.
Published: April 2003

This paper addresses the problem of computing the camera motion and the Euclidean 3D structure of an observed scene using uncalibrated images. Given at least two images with pixel correspondences, the motion of the camera (translation and rotation) and the 3D structure of the scene are calculated simultaneously. We do not assume the knowledge of the intrinsic parameters of the camera. However, an approximation of these parameters is required. Such an approximation is all the time available, either from the camera manufacturer's data or from former experiments. Classical methods based on the essential matrix are highly sensitive to image noise. This sensitivity is amplified when the intrinsic parameters of the cameras contain errors. To overcome such instability, we propose here a method where a particular choice of a 3D Euclidean coordinate system with a different parameterization of the motion/structure problem allowed us to reduce significantly the total number of unknowns. In addition, the simultaneous calculation of the camera motion and the 3D structure has made the computation of the motion and structure less sensitive to the errors in the values of the intrinsic parameters of the camera. All steps of our method are linear. However, a final nonlinear optimal step might be added to improve the accuracy of the results and to allow the orthogonality of the rotation matrix to be taken into account.

Experiments with real images validated our method and showed that a good quality motion/structure can be recovered from a pair of uncalibrated images. Intensive experiments with simulated images have shown the relationship between the errors on the intrinsic parameters and the accuracy of the recovered 3D structure.
INNOVATION AND FOREIGN INVESTMENT IN A DYNAMIC OLIGOPOLY
Authors: PETIT MARIA-LUISA , SANNA-RANDACCIO FRANCESCA , TOLWINSKI BOLESLAW
Published: April 2003

The paper examines the impact of the firms' choice between export and foreign direct investment on the incentive to innovate, as well as the effects of innovation and technological spillovers on the firms' international strategy and on its changes over time. The innovation process is analysed in the context of a two-country imperfect competition market, modelled as an infinite horizon, non-linear dynamic game, for which Markov perfect equilibria are computed. Where the models are not tractable by analytical techniques, equilibria are calculated by using a computational procedure based on a policy iteration method.
DOES NOISE UNDERMINE THE FIRST-MOVER ADVANTAGE? AN EVOLUTIONARY ANALYSIS OF BAGWELL'S EXAMPLE
Authors: OECHSSLER JÖRG , SCHLAG KARL H.
Published: April 2003

Bagwell (1995) considered a simple Stackelberg-type game in which one player benefits from the other's ability to observe his move, assuming they play the unique subgame perfect equilibrium. He showed that introducing noise in the observability of the move eliminates that equilibrium, and thus the advantage. Van Damme and Hurkens (1997) objected that the noisy game also has a mixed strategy equilibrium close to the pure strategy one Bagwell had eliminated. However, we analyse the noisy game with a wide variety of evolutionary and learning dynamics, and find that almost all admit the no-first-mover-advantage equilibrium as a possible outcome, and often they select it uniquely.
VON NEUMANN AND MORGENSTERN STABLE SETS IN A COURNOT MERGER SYSTEM
Authors: ESPINOSA M. P. , INARRA E.
Published: April 2003

We address the problem of endogenous coalition formation in Cournot oligopoly markets. The formation of coalitions is formalised as an abstract system where the elements of the abstract set are derived from a valuation function and the dominance relation specifies the rules of coalition formation. We focus on a particular instance of this approach: Market structure determination under Cournot competition, and in the resulting Cournot merger system we find von Neumann and Morgenstern stable sets.
EVOLUTIONARY AND DYNAMIC STABILITY IN SYMMETRIC EVOLUTIONARY GAMES WITH TWO INDEPENDENT DECISIONS
Authors: CRESSMAN ROSS , GAUNERSDORFER ANDREA , WEN JEAN-FRANÇOIS
Published: April 2003

A two-decision competition model is developed where players may choose different strategies at different decisions knowing that their payoff at one decision is not affected by their performance at the other. It is shown that both static solution concepts of Nash and evolutionarily stable equilibria for the two-decision model are directly related to those of the separate decisions. Furthermore, if there are at most two pure strategies at each decision, dynamic stability can also be characterised through a separate analysis of each decision. However, when there are more than two strategies, this last statement is not always true.
CLASSICAL TO QUANTUM CROSSOVER IN HIGH-CURRENT NOISE OF ONE-DIMENSIONAL BALLISTIC WIRES
Authors: GREEN FREDERICK , DAS MUKUNDA P.
Published: April 2003

Microscopic current fluctuations and conductance are inseparable. We present a unified kinetic theory of both quantized conductance and nonequilibrium noise in one-dimensional ballistic wires. We show that high-current ballistic fluctuations depend, directly and robustly, on carrier statistics. This is dramatically evident in the large noise peaks predicted to coincide with the quantized steps in the two-probe conductance. The outstanding features of nonlinear ballistic fluctuations are: (i) their observability by standard experimental techniques; (ii) their strong suppression by electron degenercy; (iii) their divergence in any model that ignores the explicit dynamics of dissipative scattering in the macroscopic leads; (iv) their numerical dominance over the noise predictions of the Landauer-Büttiker model. The nonequilibrium noise of hot ballistic carriers is strikingly sensitive to their inelastic energy loss on entering the leads. Uniquely and quantitatively, it characterizes the observed nonideality of quantized conductance.
Imipramine-Associated Hyperpigmentation
Authors: Dean Charles E , Grund Frank M
Published: April 2003

OBJECTIVE:

To inform clinicians of the potential for severe and persistent facial hyperpigmentation with the long-term use of imipramine.

CASE SUMMARY:

A 65-year-old white male veteran with a history of paranoid schizophrenia was referred to the psychiatry service by a dentist who thought that the patient was both cyanotic and psychotic. The history and biopsy results indicated the possibility of imipramine-associated hyperpigmentation, only the second reported case in a male patient. The presentation was complex, with a history of neuroleptic exposure and multiple signs of parkinsonism. A brain single photon-emission computed tomography scan demonstrated frontal lobe hypermetabolism and bilateral caudate hypermetabolism, which normalized 14 months later. Despite discontinuation of imipramine, the patient continued to appear cyanotic, leading to worsening social isolation. He became known as “the man with the purple face.” On his rare ventures outside the home, he was embarrassed by sporadic calls to 911 by persons fearing he was ill.

DISCUSSION:

Although facial hyperpigmentation secondary to the use of phenothiazines has been reported frequently, it is much less common with imipramine, and is very rare in males. Failure to recognize this adverse reaction led to continuing treatment with imipramine and to an apparently irreversible condition. The brain imaging findings have no link with the hyperpigmenting process, but raise questions about neuroleptic-induced metabolic changes in the brain.

CONCLUSIONS:

Clinicians need to be aware of rare adverse reactions such as hyperpigmentation, and be prepared to take appropriate and early action to prevent such reactions from becoming irreversible.
Sub‐regional seasonal precipitation linkages to SOI and PDO in the Southwest United States
Authors: Brown David P. , Comrie Andrew C.
Published: April 2003

This paper highlights the relationship between precipitation variability at the sub‐regional level in the Southwest United States and the SOI and PDO climate teleconnection indices during the period 1950–2000. Statistical correlations at α = 0.05 and 0.01 levels are calculated for fall, winter, and spring precipitation in the Southwest, and contemporaneous and antecedent seasonal SOI and PDO index values. A strong SOI‐winter precipitation signal is seen to progress across Arizona and New Mexico from southwest to northeast over a three‐season lagged period. The PDO also exhibits a strong relationship with winter and spring precipitation in New Mexico; however, the PDO is not well correlated with precipitation in Arizona. The results underscore the non‐uniform spatio‐temporal relationships of the SOI and PDO indices as they relate to the precipitation regime of the Southwest, and provide a framework for future diagnostic analyses of these relationships. Copyright © 2003 Royal Meteorological Society.
Holocene Vegetation and Paleoclimatic and Paleomagnetic History from Lake Johnston, Tasmania
Authors: Anker Sharon A. , Colhoun Eric A. , Barton Charles E. , Peterson Mike , Barbetti Mike
Published: April 2003

Lake Johnston cirque contains some of the best subalpine rainforest in Tasmania. Pollen from the sediments showsLagarostrobos franklinii, which presently reaches 1040 m, may be a glacial relict.Nothofagus cunninghamii–Nothofagus gunniisubalpine rainforest developed between 9000 and 600014C yr B.P., with a maximum at 870014C yr B.P. After 600014C yr B.P.Nothofagus gunniibecame more important, and from 360014C yr B.P. sclerophyll and heath components increased. Partial burning of the catchment occurred periodically. Early Holocene climate was warmer and wetter than late Holocene climate. The vegetation and climate changes are similar to those recorded from western South Island New Zealand and Chile. Radiocarbon dates give a sedimentation rate of 0.43 mm/yr. Cores are correlated by magnetic susceptibility. Magnetic ages are assigned by matching with the14C-dated secular variation master curve for southeastern Australia. Magnetic ages are consistent with the14C chronology when the former are adjusted by 350 years.
Identification of Disseminated Trego Hot Springs Tephra in the Palouse, Washington State
Authors: King Matthew , Busacca Alan J. , Foit Franklin F. , Kemp Rob A.
Published: April 2003

Tephra layers form important chronostratigraphic marker horizons within the Wisconsinan loess-paleosol stratigraphy of the Palouse, Washington State. This paper details the presence of disseminated glass shards of the Trego Hot Springs tephra that has not previously been recognized within the Palouse or environs. The tephra provides additional chronological control for the regional Late Wisconsinan stratigraphy and raises the possibility of correlating the paleoclimatic proxy record contained within the Palouse to those of lake sequences in Oregon, California, and Nevada.
The Magnitude and Proximate Cause of Ice-Sheet Growth Since 35,000 yr B.P.
Authors: Winograd Isaac J.
Published: April 2003

The magnitude of late Wisconsinan (post-35,000 yr B.P.) ice-sheet growth in the Northern Hemisphere is not well known. Ice volume at ∼35,000 yr B.P. may have been as little as 20% or as much as 70% of the volume present at the last glacial maximum (LGM). A conservative evaluation of glacial–geologic, sea level, and benthic δ18O data indicates that ice volume at ∼35,000 yr B.P. was approximately 50% of that extant at the LGM (∼20,000 yr B.P.); that is, it doubled in about 15,000 yr. On the basis of literature for the North Atlantic and a sea-surface temperature (SST) data compilation, it appears that this rapid growth may have been forced by low-to-mid-latitude SST warming in both the Atlantic and Pacific Oceans, with attendant increased moisture transport to high latitudes. The SST ice-sheet growth notion also explains the apparent synchroneity of late Wisconsinan mountain glaciation in both hemispheres.
The cation‐independent mannose‐6‐phosphate receptor binds to soluble GPI‐linked proteins via mannose‐6‐phosphate
Authors: Green Paula J. , Ferguson Michael A.J. , Robinson Peter J. , Feizi Ten
Published: April 2003

The cation‐independent mannose‐6‐phosphate/insulin‐like growth factor II receptor has been observed to bind to soluble forms of glycosyl‐phosphatidylinositol‐linked molecules, one of mammalian origin (rat Thy‐1) and two of protozoan origins. Of the two phosphate groups found on the soluble forms of the protozoan glycosyl‐phosphatidylinositol‐linked molecules: (i) the internal mannose‐6‐phosphate diester (which forms a part of the ethanolamine bridge) and (ii) the inositol‐1,2 cyclic phosphate group (which arises after cleavage of the membrane associated form with phosphatidylinositol‐specific phospholipase C), only the former appears to be recognized by the mannose‐6‐phosphate/insulin‐like growth factor II receptor, as mild acid hydrolysis which destroys the latter has been observed not to affect the receptor binding site.
Cytokine‐mediated production of nitric oxide in isolated rat hepatocytes is dependent on cytochrome P‐450III activity
Authors: Kuo Paul C. , Abe Keith Y.
Published: April 2003

To investigate the role of the cytochrome P‐450 system in NO synthesis, cytochrome P‐450IIIA, IIE and IA activities were specifically inhibited by cimetidine (IIIA), clotrimazole (IIIA), benzoflavone (IA) and disulfiram (IIE) in a model of cultured rat hepatocytes. Cytokine‐induced NO synthesis was significantly decreased in the presence of cimetidine and clotrimazole. Kinetic analysis revealed a non‐competitive mode of inhibition (K
i = 21 mM, cimetidine; K
i = 13 μM, clotrimazole). Reverse transcriptase‐PCR and immunoblot analysis revealed no significant change in steady state levels of iNOS mRNA and protein expression with P‐450IIIA inhibition. Purified iNOS enzyme activity was not altered. These data suggest that cytokinemediated hepatocyte synthesis of NO is dependent upon P‐450IIIA activity, which functions in a post‐translational capacity.
Synthesis and refolding of human TIMP‐2 from E. coli, with specific activity for MMP‐2
Authors: Negro Alessandro , Onisto Maurizio , Masiero Laura , Garbisa Spiridione
Published: April 2003

Tissue inhibitors of metalloproteinase (TIMPs) are inhibitory counterparts of collagenases, containing 12 cysteine residues paired to six internal disulphide bridges. TIMP‐2, an inhibitory protein of 72 kDa gelatinase/type IV collagenase (MMP‐2), was expressed in Escherichia coli as a fusion protein with a 34 amino acid NH2‐linked tail containing six consecutive histidine residues. The protein was purified in a single‐step using an ion metal affinity column (IMAC) in denaturing conditions. The immobilized fusion TIMP‐2 protein was refolded at a high concentration in the column, producing about 5 mg of protein per litre of bacterial cells. It shows specific binding and inhibitory activity against MMP‐2, but has no effect against 92 and 45 kDa gelatinases.
GZ coupling to the rat κ‐opioid receptor
Authors: Lai Helen W.L. , Minami Masabumi , Satoh Masamichi , Wong Yung H.
Published: April 2003

We have expressed the cloned rat κ‐opioid receptor in human embryonic kidney 293 cells and studied the ability of κ‐selective ligands to inhibit adenylyl cyclase. In transfected 293 cells, activation of the κ‐opioid receptor by U50,488 and the dynorphins resulted in the inhibition of cAMP accumulation. The inhibitory response was sensitive to pertussis toxin and highly selective for κ‐agonists; neither μ‐ nor θ‐opioids were able to activate the κ‐opioid receptor. Upon co‐transfection with the α subunit of Gz, inhibition of cAMP accumulation by κ‐agonist became refractory to pertussis toxin, indicating that the κ‐opioid receptor can couple to both Gi and Gz proteins.
Extreme thermostability of tarantula hemocyanin
Authors: Sterner Reinhard , Vogl Thomas , Hinz Hans-Jürgen , Penz Franz , Hoff Rainer , Föll Roman , Decker Heinz
Published: April 2003

Biotops with extreme temperatures such as deserts force animals to avoid or escape high temperatures by biochemical, behavioural or morphological adaptation. In this context we tested the resistance to heat of the oxygen carrier hemocyanin from the ancient tarantula Eurypelma californicum, which is found in arid zones of North America. Differential scanning calorimetry, light scattering, crossed immunogelelectrophoresis and oxygen binding experiments show that the 24‐meric hemocyanin is conformationally stable and fully functioning at temperatures up to 90°C. Our results demonstrate that the cation‐mediated state of oligomerization is not only crucial for the high cooperativity of oxygen binding of this hemocyanin, but also for its extreme stability in the physiological temperature and pH range.
Relevance of histidine‐84 in the elongation factor Tu GTPase activity and in poly(Phe) synthesis: Its substitution by glutamine and alanine
Authors: Scarano Giuliana , Krab Ivo M. , Bocchini Vincenzo , Parmeggiani Andrea
Published: April 2003

Substitution of His‐84 (→ Gln and → Ala), a residue of the switch II region of E. coli elongation factor (EF) Tu, hardly affected the binding of GTP or GDP. The activity in poly(Phe) synthesis and GTP hydrolysis of EF‐Tu H84Q were both reduced to about 35%, as compared to EF‐Tu wt, whereas EF‐Tu H84A was inactive in poly(Phe) synthesis but still showed a 10% residual GTPase activity. Phe‐tRNAPhe exerted a similar inhibitory effect on the GTPase activity of EF‐Tu wt and EF‐Tu H84Q while abolishing that of EF‐Tu H84A. Ribosomes enhanced the GTPase activity of EF‐Tu H84Q, but not that of EF‐Tu H84A, on which they even seemed to exert an inhibitory effect. The one‐round GTP hydrolysis associated with the EF‐TuH84Q‐dependent binding of Phe‐tRNAPhe to poly(U)‐programmed ribosomes was less efficient than with EF‐Tu wt. Kirromycin stimulated the GTPase activities of both mutants less than EF‐Tu wt. The results of this work do not support a catalytic role of His‐84 in the intrinsic GTPase of EF‐Tu, but they emphasize the importance of its side‐chain for polypeptide synthesis and GTP hydrolysis.
Identification of Rab3‐, Rab5a‐ and synaptobrevin II‐like proteins in a preparation of rat kidney vesicles containing the vasopressin‐regulated water channel
Authors: Liebenhoff Ursula , Rosenthal Walter
Published: April 2003

According to the ‘shuttle hypothesis’, vasopressin increases the water permeability of renal epithelial cells by exocytotic fusion of vesicles containing the water channel AQP‐CD with the apical plasma membrane, whereas withdrawal of vasopressin results in endocytotic uptake of AQP‐CD. The proteins involved in the redistribution of AQP‐CD have not been identified. With a panel of monoclonal antibodies, we detected Rab3‐, Rab5a‐ and synaptobrevin II‐like proteins in a kidney preparation enriched in AQP‐CD‐containing vesicles. The synaptobrevin II‐like protein is not identical with the ubiquitous cellubrevin. Rab3‐ and synaptobrevin II‐ but not Rab5a‐like proteins were co‐enriched with AQP‐CD. The data suggest that the proteins involved in hormonal regulation of water permeability in kidney epithelial cells are identical or similar to those involved in regulated exocytosis in secretory cells.
Interaction between cardiolipin and the mitochondrial presequence of cytochrome c oxidase subunit IV favours lipid mixing without destabilizing the bilayer structure
Authors: Mandieau V. , Martin I. , Ruysschaert J.-M.
Published: April 2003

We demonstrate the ability of a peptide corresponding to the presequence of the cytochrome c oxidase subunit IV to induce lipid mixing between large unilamellar liposomes. This lipid mixing requires the presence of CL or PE, lipids able to form non‐bilayer structures, and is not observed with other negatively charged lipids. However, the fact that this mixing occurs without mixing of the liposome aqueous phases and without destabilizing the lipid organisation is unusual and has not been observed for other amphiphilic peptides. This observation supports the idea that the presequence could play a role in the formation of translocation contact sites between the two mitochondrial membranes and facilitate the structural rearrangements of the outer and inner membrane proteins involved in the two import machineries in a way to permit the formation of a continuous import channel through the two mitochondrial membranes without mixing the cytoplasmic and mitochondrial aqueous contents.
Fluorescence‐detected interactions of oligonucleotides in RecA complexes
Authors: Wittung Pernilla , Funk Mario , Jernström Bengt , Nordén Bengt , Takahashi Masayuki
Published: April 2003

A technique has been developed to probe directly RecA‐DNA interactions by the use of the fluorescent chromophore, (+)anti‐benzo(a)pyrene‐7,8‐dihydrodiol‐9,10‐epoxide (BPDE), covalently attached to DNA. The 24‐mer oligonucleotide 5′‐d(CTACTAAACATTACAAATCATCC) was specifically modified on the exocyclic nitrogen of the central guanine, to yield a trans‐adduct. Upon interaction of the modified oligonucleotide with RecA we find an increase in BPDE fluorescence and a rather high fluorescence anisotropy, suggesting a restricted motion of the BPDE‐oligonucleotide in the protein filament. In the presence of the cofactor ATPγS, binding of two oligonuclotides, identical or complementary in sequence, in the RecA filament is possible. The RecA‐DNA complex is, however, more stable when the sequences are complementary; in addition, a shift in the BPDE emission peaks is observed. In the presence of ATP (and an ATP regeneration system), the RecA‐DNA interaction between two complementary oligonucleotides is changed, and we now find protein‐mediated renaturation to occur.
ID ‐ A dominant negative regulator of skeletal muscle differentiation — is not involved in maturation or differentiation of vascular smooth muscle cells
Authors: Kemp Paul R. , Metcalfe James C. , Grainger David J.
Published: April 2003

Rat aortic vascular smooth muscle cells (VSMCs) expressing the MyoD gene formed myotubes at a low frequency in the presence of serum but at a high frequency in the absence of serum. Expression of an antisense Id gene increased myotube formation in the presence of serum indicating that a reduction in Id levels is a major mechanism by which serum withdrawal promotes myotube formation. The role of Id in the development of VSMCs was investigated by expressing an antisense Id gene in neonatal VSMCs. No evidence was found for the conversion of neonatal VSMCs to adult VSMCs in the presence of the antisense Id gene. Similarly reduction in Id by serum withdrawal also failed to cause conversion of the neonatal VSMCs to the adult phenotype. These data suggest that the maturation of neonatal smooth muscle cells is not controlled by a VSMC homologue of the skeletal muscle basic‐helix‐loop‐helix proteins.
The effect of residue 1106 on the thioester‐mediated covalent binding reaction of human complement protein C4 and the monomeric rat α‐macroglobulin α1I3
Authors: Ren Xiang-Dong , Dodds Alister W. , Enghild Jan J. , Chu Charleen T. , Alex Law S.K.
Published: April 2003

The histidine at position 1106 of the C4B isotype of human complement is involved in catalyzing the covalent binding of the thioester to glycerol and water. By replacing the histidine with other residues, it was found that tyrosine is also capable of mediating the reaction. We propose that they act as nucleophiles by first attacking the thioester, upon activation, to form acyl intermediates, which subsequently react with the hydroxyl groups of glycerol or water. The monomeric α‐macroglobulin, α1I3 of the rat, was also studied. Unlike α2‐macroglobulin, which is a tetramer, α1I3 has binding properties similar to those of C4A.
High affinity interaction of mammalian DNA topoisomerase I with short single‐ and double‐stranded oligonucleotides
Authors: Nevinsky Georgy A. , Bugreev Dmitry V. , Buneva Valentina N. , Yasui Yoshihiro , Nishizawa Miwako , Andoh Toshiwo
Published: April 2003

The interaction of DNA topoisomerase I (topo I) with a set of single‐ and double‐stranded oligonucleotides containing 5–27 mononucleotides was investigated. All single‐ and double‐stranded oligonucleotides were found to inhibit competitively the supercoiled DNA relaxation reaction catalyzed by topo I. The enzyme affinity for specific sequence pentanucleotides of the scissile (GACTT, K
i = 2 μM) and non‐cleaved chain (AAGTC, K
i = 110 μM) is about 2–4 orders of magnitude higher than that for non‐specific oligonucleotides. This specific sequence affinity increases in several cases: lengthening of single‐stranded oligonucleotides, formation of stable duplexes between complementary oligonucleotides and preincubation of the enzyme with ligands before addition of supercoiled DNA. We assume that oligonucleotides having a high affinity to the enzyme can offer a unique opportunity for rational design of topoisomerase‐targeting drugs.
Apolipoprotein E increases the fibrillogenic potential of synthetic peptides derived from Alzheimer's, Gelsolin and AA amyloids
Authors: Soto Claudio , Castaño Eduardo M. , Prelli Frances , Asok Kumar R. , Baumann Marc
Published: April 2003

Apolipoprotein E (apoE) has been found in association with several differents types of systemic and cerebral amyloid deposits and the presence of the ϵ4 allele constitutes a risk factor for Alzheimer's disease. It has been shown that apoE binds and promotes the fibrillogenesis in vitro of Alzheimer's amyloid β‐peptide, suggesting an important role for apoE in the modulation of amyloidogenesis. Due to the co‐localization of apoE with several biochemically distinct amyloid deposits, it has been proposed that apoE plays a general role modulating and/or participating in amyloidosis. In the present study, we show for the first time that apoE, isolated from human plasma, increases fibril formation of synthetic peptides comprising the amyloidogenic sequences of gelsolin amyloid related to familial amyloidosis Finnish type, and amyloid A found in secondary amyloidosis and familial Mediterranean fever. Our results suggest that apoE acts as a general pathological chaperone in various amyloidoses by enhancing the transition from soluble peptides into amyloid‐forming, pathological molecules.
Interleukin‐4 induces endothelial vascular cell adhesion molecule‐1 (VCAM‐1) by an NF‐κb‐independent mechanism
Authors: McCarty John M. , Yee Esther K. , Deisher Theresa A. , Harlan John M. , Kaushansky Kenneth
Published: April 2003

While all features of the inflammatory response induced by IL‐1 are not observed following IL‐4 stimulation, suboptimal concentrations both cytokines result in synergistic VCAM‐1 expression in HUVEC. We have shown that, while IL‐1 stimulated HUVEC express GM‐CSF, tissue factor and VCAM‐1, only VCAM‐1 is detectable after exposure to IL‐4. While kB was found essential for both basal and IL‐1‐mediated activity of VCAM‐1, IL‐4 induction was kB‐independent. Inducible kB‐binding proteins were identified in IL‐1‐, but not IL‐4‐stimulated nuclear extracts. Our results indicate that IL‐4 exerts its transcriptional effects on the VCAM‐1 gene through element(s) which do not require kB.
Novel disulfide‐constrained pentapeptides as models for β‐VIa turns in proteins
Authors: Weißhoff Hardy , Frost Klaus , Brandt Wolfgang , Henklein Peter , Mügge Clemens , Frömmel Cornelius
Published: April 2003

The conformational behavior of cyclic peptides of the amino acid sequence Cys‐Phe/Ala‐Pro‐Ala‐Cys has been investigated through the combined use of molecular simulation methods and NMR experiments to find models for β‐VIa turns of proteins. Both oxidized (cyclic) peptides and reduced (linear) forms were investigated. At least 95% of the cyclic peptides show a cis conformation of the Xaa‐Pro bond in solution in DMSO or water, whereas all other peptide bonds are trans. Furthermore, we observed a hydrogen bond between the NH group of residue Ala4 and the C = O group of residue Cys1. Both properties are indicative of β‐VIa turns. After reduction of the disulfide bridge, the all‐trans form of the peptide bonds predominates.
The functioning of the SRP receptor FtsY in protein‐targeting in E. coli is correlated with its ability to bind and hydrolyse GTP
Authors: Kusters Ron , Lentzen Georg , Eppens Elaine , van Geel Anton , van der Weijden Coen C. , Wintermeyer Wolfgang , Luirink Joen
Published: April 2003

In this study, we have established that FtsY, the E. coli homolog of the mammalian signal recognition particle (SRP) receptor, is a GTP‐binding protein which displays intrinsic GTPase activity. GTP was found to influence the protease sensitivity of FtsY indicative of a conformational change. FtsY mutated in the 4th GTP‐binding consensus element displayed reduced GTP‐binding and ‐hydrolysis which correlated with a reduced ability to interact with SRP. Overexpression of the mutant proteins had a stronger inhibitory effect on protein translocation than overexpression of wild‐type FtsY. These observations suggest that in E. coli GTP is important for proper functioning of FtsY in protein‐targeting.
Effect of iC3b binding to immune complexes upon the phagocytic response of human neutrophils: synergistic functions between FcγR and CR3
Authors: Ohkuro Masayoshi , Ogura-Masaki Michiko , Kobayashi Katsuya , Sakai Masatoshi , Takahashi Kazuhiko , Nagasawa Shigeharu
Published: April 2003

We compared the phagocytosis of immune complexes (IC) and iC3b‐opsonized derivatives (iC3b‐IC) by human neutrophils. The phagocytosis of iC3b‐IC via FcγR and CR3 was much greater than that of IC via FcγR alone. Adding ethanol to the cells decreased iC3b‐IC phagocytosis to that of IC, which was not affected by these reagents, suggesting that the enhanced phagocytosis is attributable to CR3‐mediated phospholipase D activation. The IC phagocytosis was inhibited more effectively by anti‐FcγIIIB, whereas the iC3b‐IC phagocytosis was partly inhibited only by anti‐FcγRII. The main FcγR might differ in IC and iC3b‐IC phagocytosis.
Direct evidence for the presence of two external NAD(P)H dehydrogenases coupled to the electron transport chain in plant mitochondria
Authors: Roberts Thomas H. , Fredlund Kenneth M. , Møller Ian M.
Published: April 2003

Exogenous NADPH oxidation by purified mitochondria from both potato tuber and Arum maculatum spadix was completely and irreversibly inhibited by sub‐micromolar diphenyleneiodonium (DPI), while exogenous NADH oxidation was inhibited to only a small degree. Addition of DPI caused the collapse of the membrane potential generated by NADPH oxidation, while the potential generated by NADH was unaffected. We conclude that there are two distint enzymes on the outer surface of the inner membrane of plant mitochondria, one specific for NADH, the other relatively specific for NADPH, with both enzymes linked to the electron transport chain.
GCAP‐II: Isolation and characterization of the circulating form of human uroguanylin
Authors: Hess Rüdiger , Kuhn Michaela , Schulz-Knappe Peter , Raida Manfred , Fuchs Martin , Klodt Joachim , Adermann Knut , Kaever Volkhard , Cetin Yalcin , Forssmann Wolf-Georg
Published: April 2003

The systematic isolation of circulating regulatory peptides which generate cGMP as second messenger resulted in the identification of a novel member of the guanylin family. In the present study we describe the purification and amino acid sequence of a new guanylate cyclase C activating peptide (GCAP‐II). GCAP‐II contains 24 amino acids in the following sequence: FKTLRTIANDDCELCVNVACTGCL. Its molecular mass is 2597.7 Da. The 16 C‐terminal amino acids are identical to uroguanylin from human urine. Native and synthetic GCAP‐II activate GC‐C, the specific guanylate cyclase receptor, of cultured human colon carcinoma (T84) cells. GCAP‐II stimulates chloride secretion in isolated human intestinal mucosa mediated by intracellular cGMP increase. GCAP‐II specific antibodies were used to localize the peptide by immunohistochemistry in entero‐endocrine cells of the colonic mucosa.
Reconstitution of the metal‐tetracycline/H+ antiporter of Escherichia coli in proteoliposomes including F0F1‐ATPase
Authors: Someya Yuichi , Moriyama Yoshinori , Futai Masamitsu , Sawai Tetsuo , Yamaguchi Akihito
Published: April 2003

The tetracycline resistance gene (tetA) was cloned downstream of the lac promoter. When expression of the tetA gene in E. coli cells carrying the lac Iq gene was induced with isopropyl β‐d‐thiogalactopyranoside, the tetracycline resistance protein (TetA) was overproduced, amounting to about 30% of the integral cytoplasmic membrane protein. Essentially pure TetA protein could be obtained by solubilization with 1.25% and one‐step purification by DEAE Sepharose CL‐6B column chromatography. The TetA protein was incorporated into proteoliposomes with F0F1‐ATPase. The proteoliposomes exhibited [3H]tetracycline transport dependent on ATP hydrolysis. The specific activity was about 2 nmol/mg protein/min. The proteoliposomes also showed H+ efflux coupled with tetracycline influx. Tetracycline/H+ antiport by proteoliposomes reconstituted with the Ser‐65 → Cys mutant TetA protein was inhibited by N‐ethylmaleimide. These results proved for the first time that the tetracycline/H+ antiport is only mediated by the TetA protein.
Protease inhibitors block apoptosis at intermediate stages: a compared analysis of DNA fragmentation and apoptotic nuclear morphology
Authors: Ghibelli L. , Maresca V. , Coppola S. , Gualandi G.
Published: April 2003

The possible correlation between DNA digestion and changes in nuclear morphology in apoptosis was studied by blocking the apoptotic process at intermediate stages. The apoptogenic action of three drugs: etoposide, puromycin, tributyltin, was contrasted with protease inhibitors with different specificity on U937 cells. The inhibitors interfered with the development of the apoptotic features without shifting cell death to necrosis: treated cells showed abnormal morphologies, which could be recognized as intermediate stages of apoptosis; accordingly, DNA analysis showed an inhibitor‐dependent block of the apoptotic DNA digestion. The comparison between size of DNA fragments and nuclear morphology suggested the following correlations: loss of normal nuclear shape with the appearence of a ≥ 2 Mb DNA band; ongoing chromatin condensation with the progressive DNA digestion up to 50 kb; nuclear fragmentation with DNA laddering. Protease inhibitors in etoposide‐treated cells did not allow the formation of 700‐300 kb fragments, suggesting that they possibly derive from a cell‐mediated effect.
Thapsigargin discriminates strongly between Ca2+‐ATPase phosphorylated intermediates with different subcellular distributions in bovine adrenal chromaffin cells
Authors: Caspersen Casper , Treiman Marek
Published: April 2003

We studied the effects of thapsigargin on the formation of the phosphorylated intermediates (E∼Ps) of endoplasmic reticulum Ca2+‐ATPases in microsomes from bovine adrenal medulla. When submicrosomal fractions were separated on a sucrose gradient, two components of 100 kDa Ca2+‐ATPase E∼P displaying distinct subcellular distributions were resolved. The first component was defined by Ca2+‐induced protection against thapsigargin inhibition. The second component did not display such protection, with a 3 orders of magnitude difference in thapsigargin inhibitory potency towards the 2 components. In the absence of Ca2+, both E∼P components were highly sensitive to thapsigargin inhibition, revealing the presence of high‐affinity thapsigargin‐binding sites characteristic of SERCA ATPases. These data demonstrate a new level of molecular heterogeneity among Ca2+‐ATPases of endoplasmic reticulum, and provide the first evidence of differential subcellular localization of individual Ca2+ pump subtypes in cells of neural origin.
A rainbow trout SRY‐type gene expressed in pituitary glands
Authors: Ito Michihiko , Ishikawa Masako , Suzuki Shin , Takamatsu Nobuhiko , Shiba Tadayoshi
Published: April 2003

A Sox (SRY‐type HMG box) gene, designated SoxP1, was isolated from a cDNA library made from pituitaries of immature rainbow trout. Sequence analysis indicated that the cDNA had an open reading frame encoding 467 amino acid residues containing a DNA binding motif, known as the high mobility group (HMG) box. Northern blot analysis showed trout SoxP1 mRNA was detected in pituitaries and gonadal tissues, but not in liver, spleen, and heart. In pituitaries, trout SoxP1 mRNA was more abundant in immature fish than in mature fish. Gel shift retardation analysis indicated that the recombinant HMG box protein of SoxP1 produced in E. coli had a DNA binding property for an AACAAT or AACAAAG sequence. These findings suggest that the trout SoxP1 protein may play certain roles in growth or maturation in pituitaries as a transcription factor.
Blockage of urokinase receptor reduces in vitro the motility and the deformability of endothelial cells
Authors: Lu He , Mabilat Christelle , Yeh Patrice , Guitton Jean-Dominique , Li Hong , Pouchelet Marcel , Shoevaert Damien , Legrand Yves , Soria Jeannette , Soria Claudine
Published: April 2003

The binding of urokinase (u‐PA) to its cell surface receptor (u‐PAR) is critical for tumor cell invasion. Here, we report that the disruption of this binding by an u‐PAR antagonist ATF‐HSA inhibits in vitro the motility of endothelial cells in a dose‐dependent manner. This inhibition was also observed when the cells were first stimulated with potent angiogenic factors, including bFGF or VEGF. [3H]thymidine incorporation assay demonstrated that ATF‐HSA did not affect the cell proliferation. ATF‐HSA was more potent than plasmin inhibitors, suggesting that it exerts its effects not solely by inhibiting the remodeling of the extracellular matrix. In fact, analysis of the cell shape change during migration revealed for the first time that its effect is related to a decrease in cell deformability. These results suggest that u‐PAR antagonist may be a new approach to control angiogenesis.
Effect of genistein on amylase release and protein tyrosine phosphorylation in parotid acinar cells
Authors: Takuma Taishin , Tajima Yoshifumi , Ichida Tokuro
Published: April 2003

We evaluated the role of protein tyrosine phosphorylation in amylase exocytosis from parotid acinar cells by using genistein, a tyrosine kinase inhibitor. Amylase release stimulated by isoproterenol was dose‐dependently inhibited by genistein. Genistein also inhibited the exocytosis evoked by dibutyryl‐ or 8‐chlorophenylthio‐cAMP. Daidzein, a negative control agent of genistein, elicited no inhibitory effect. Isoproterenol had dual effects on protein tyrosine phosphorylation; it increased the phosphorylation of 190‐ and 210‐kDa proteins and decreased that of a 90‐kDa one. The phosphorylation was dose‐dependently inhibited by genistein but not by daidzein. These results suggest that protein tyrosine phosphorylation plays a role in the process of amylase exocytosis from parotid acinar cells.
Cloning of rat GADD45 gene and induction analysis following ionizing radiation in vivo
Authors: Yoshida Toru , Okazaki Takashi , Hughes Paul E. , Schneider Edward L. , Mori Nozomu
Published: April 2003

A gene encoded GADD45 was isolated from rat and revealed four exons along with a p53 binding consensus sequence and a putative AP‐1 site in the third intron. This suggests that the rat GADD45 gene is also involved in the p53 signal pathway related to the G1 cell cycle checkpoint. The rat GADD45 mRNA was induced within 30 min in liver and increased as a function of γ‐irradiation. We found that mRNA expression differed substantially in a variety of tissues (brain, liver, kidney, and spleen). The finding of in vivo induction of GADD45 gene may provide insight into the role of GADD45 gene in DNA repair.
Double long‐chain amidine liposome‐mediated self replicating DNA transfection
Authors: El Ouahabi A. , Pector V. , Fuks R. , Vandenbranden M. , Ruysschaert J.M.
Published: April 2003

We present experimental evidence that a complex made of a double long chain cationic amphiphile and recombinant mRNA facilitates the entry and expression of genetic material into cells. Combining the properties of the self replicating recombinant mRNA driven by the Semliki Forest Virus (SFV) replicon and the transfection potentialities of a new cationic amphiphile (N‐t‐butyl‐N′‐tetradecyl‐3‐tetradecylaminopropionamidine) yields a highly efficient mRNA transfection system conferring up to 100% infectivity. The preparation and characterization of the long chain amidine cationic amphiphile‐mRNA complex as well as the influence of the diC14‐amidine/RNA ratio on the infective activity are described.
Role of mitochondria and C‐terminal membrane anchor of Bcl‐2 in Bax induced growth arrest and mortality in Saccharomyces cerevisiae
Authors: Greenhalf William , Stephan Christine , Chaudhuri Bhabatosh
Published: April 2003

In mammalian cells, the Bcl‐2 and Bcl‐x(L) proteins suppress programmed cell death whereas the topographically similar Bax protein accelerates the apoptotic process. Recently published data suggest that expression of the human Bax‐α gene is lethal for the yeast can be overcome by co‐expressing Bcl‐2 or Bcl‐x(L). Our findings corroborate these results. However, we find that although Bax induction invariably stops cell growth under all circumstances, it does not lead to death in ‘petite’ cell. Petites cannot respire because they lack functional mitochondria. It seems that in ‘grande’ cells, which do possess normal mitochondrial DNA, nutritional limitation is critical for increased mortality. Surprisingly, murine Bcl‐2 lacking the membrane anchor of human Bcl‐2 has no effect on grande cells, but can efficiently rescue petites in rich medium. It has been suggested that the C‐terminal membrane anchor of human Bcl‐2 may have a crucial role in rescuing apoptosis in mammalian cells. When murine Bcl‐2 is fused to the membrane anchor of yeast mitochondrial Mas70 protein, the Bcl‐2 variant mBcl‐2‐mma rescues not only petites but also grandes, just like human Bcl‐x(L). The rescuing ability of Bcl‐x(L), which contains its own membrane anchor, surpasses that of mBcl‐2‐mma. Our results indicate that the process involving Bax‐induced growth inhibition followed by possible lethality, and the rescuing effect of Bcl‐2 or Bcl‐x(L) is linked to yeast mitochondrial function. We propose a model which is consistent with these observations.
Role of the mitochondrial DnaJ homologue, Mdj1p, in the prevention of heat‐induced protein aggregation
Authors: Prip-Buus Carina , Westermann Benedikt , Schmitt Matthias , Langer Thomas , Neupert Walter , Schwarz Elisabeth
Published: April 2003

The role of the mitochondrial Hsp70 system in the prevention of heat‐induced protein aggregation was studied in isolated mitochondria from Saccharomyces cerevisiae. Firefly luciferase was employed as a thermolabile tester protein. After shift to 40°C a transient increase of mt‐Hsp70/luciferase complex was observed, which required functional Mdj1p and Mge1p, the mitochondrial homologues of DnaJ and GrpE. The kinetics of luciferase aggregation, however, were not influenced by mutations in either mt‐Hsp70 or Mge1p. Only the absence of Mdj1p led to enhanced protein aggregation. Thus, a central role in the transient protection against heat stress is attributed to this mitochondrial DnaJ homologue.
Chemical modification of porcine kidney aminopeptidase P indicates the involvement of two critical histidine residues
Authors: Lim Jaeseung , Turner Anthony J.
Published: April 2003

Aminopeptidase P (AP‐P), purified to homogeneity from porcine kidney membranes, was completely inactivated by treatment with 0.2 mM diethylpyrocarbonate (DEP) at pH 7.0. Treatment of the modified enzyme with 20 mM hydroxylamine resulted in recovery of AP‐P activity. The differential absorption of native and modified AP‐P at 240 nm showed that DEP modified two histidyl residues per mol of AP‐P. The substrates, bradykinin(1–5) and Gly‐Pro‐Hyp, and also the inhibitor, apstatin, could protect against DEP inactivation. These results suggest that histidine residues are critical for AP‐P activity.
Mitochondrial import of a yeast cytoplasmic tRNALys: possible roles of aminoacylation and modified nucleosides in subcellular partitioning
Authors: Entelis Nina S. , Krasheninnikov Igor A. , Martin Robert P. , Tarassov Ivan A.
Published: April 2003

The yeast tRNACUU
Lys is transcribed from a nuclear gene and then unequally redistributed between the cytosol (97–98%) and mitochondria (2–3%). We have optimized the conditions for its specific import into isolated mitochondria. However, only a minor fraction (about 0.5%) of the added tRNA was translocated into the organelles. An in vitro transcript, once aminoacylated, appeared to be a better import substrate than the natural tRNA which carries modified nucleosides. The tRNA is translocated across mitochondrial membranes in its aminoacylated form and remains relatively stable inside the organelle. Possible roles of aminoacylation, tRNA‐protein interactions and nucleoside modification in subcellular partitioning of the tRNA are discussed.
Cloning and chromosomal localization of a cDNA encoding a mitochondrial porin from Drosophila melanogaster
Authors: Messina Angela , Neri Mariangela , Perosa Federico , Caggese Corrado , Marino Mario , Caizzi Ruggiero , De Pinto Vito
Published: April 2003

We have raised polyclonal antibodies against purified the Drosphila melanogaster mitochondrial porin. They showed high titre and specificity and were thus used as a tool for screening an expression library. The isolated clone 1T1 showed 74% sequence identity in the last 19 residues at the C‐terminus of human porin. A subclone of 1T1, containing the porin‐like sequence, was thus used as a probe for re‐screening a cDNA library and several positive clones were plaque‐purified. We present here the sequence of a 1363 bp cDNA encoding a protein of 279 amino acids. Its identity with porin was also confirmed by N‐terminal Edman degradation of the purified protein. The D. melanogaster porin shows an overall 51.8% identity with human porin isoform 1 (porin 31HL or HVDAC1) and an overall 55.7% identity with human porin isoform 2 (HVDAC2). Hydrophobicity plots and secondary structure predictions showed a very high similarity with data obtained from known porin sequences. The D. melanogaster porin cDNA was used as a probe for in situ hybridization to polytenic salivar gland chromosomes. It hybridizes with different intensities in two sites, in chromosome 2L, at region 31E and in chromosome 3L at region 79D. Thus, also in Drosophila melanogaster porin polypeptide(s) belong(s) to a multigene family.