bluuebunny/crossref_metadata_2025 huggingface dataset:
ANALYSIS AND COMPUTATION OF PROJECTIVE INVARIANTS FROM MULTIPLE VIEWS IN THE GEOMETRIC ALGEBRA FRAMEWORKS
Authors: LASENBY JOAN , BAYRO-CORROCHANO EDUARDO
Published: April 2003

A central task of computer vision is to automatically recognize objects in real-world scenes. The parameters defining image and object spaces can vary due to lighting conditions, camera calibration and viewing positions. It is therefore desirable to look for geometric properties of the object which remain invariant under such changes. In this paper we present geometric algebra as a complete framework for the theory and computation of projective invariants formed from points and lines in computer vision. We will look at the formation of 3D projective invariants from multiple images, show how they can be formed from image coordinates and estimated tensors (F, fundamental matrix and T, trilinear tensor) and give results on simulated and real data.
HISTORY OF A "PARADOX" FOR THIN-WALLED MEMBERS WITH VARIABLE, OPEN CROSS-SECTIONS
Authors: CYWIŃSKI Z.
Published: April 2003

This paper describes the development of research conducted in the theory of thin-walled members with variable, open cross-sections. Special attention is paid to the torsional stability of centrally compressed I-columns with some references to the closely related problem of torsional vibration. The particular contributions of the author in those fields are highlighted. He discovered that in the case of variable, bisymmetric I-sections, the critical torsional buckling loads (and, recognized even earlier in the context of the frequencies of torsional vibration) fell outside the range determined by values relevant for similar enveloping constant, minimum and maximum, cross-sections — thus becoming "paradoxical". Later investigations of different scholars concentrated more on the torsional buckling aspect alone. They confirmed that "paradox" but, until now, no convincing reasoning was produced. The author recalls the problems and issues in order to activate further discussion.
DISTRIBUTED TRANSFER FUNCTION ANALYSIS OF MULTI-BODY PRISMATIC ELASTIC SOLIDS
Authors: PARK D.-H. , YANG B.
Published: April 2003

A semi-analytical method is developed for static and dynamic analyses of three-dimensional elastic solids composed of prismatic subregions. Based on a prism distributed transfer function formulation, the method is capable of synthesizing multi-body continua, and at the same time maintains the high accuracy and efficiency of analytical solutions. The proposed method is unique in that it systematically generates closed-form, semi-analytical regional solutions that can be used for multi-body assembly. Unlike many analytical approaches, the method does not depend on any series expansion, and is valid for arbitrary external loads and boundary conditions. Numerical examples are provided to justify the advantages of the proposed method.
DESIGNING AND SIMULATING CLOTHES
Authors: MAGNENAT-THALMANN NADIA , VOLINO PASCAL , MOCCOZET LAURENT
Published: April 2003

The most intuitive and natural approach for building garments takes its inspiration from the traditional garment industry where garments are created from two-dimensional patterns and then seamed together. MIRACloth uses this approach. Working with 2D patterns is the simplest way of keeping an accurate, precise and measurable description and representation for a cloth surface. In the traditional garment and fashion design approach, garments are usually described as a collection of cloth surfaces, tailored in fabric material, along with the description of how these patterns should be seamed together to obtain the final garment. Our virtual garment design system reproduces this approach by providing a framework for accurately designing the patterns with the information necessary for their correct seaming and assembly. Subsequently, these are placed on the 3D virtual bodies and animated along with the virtual actor's motion. In the following sections, we describe the different components — mechanical model, numerical resolution, collision detection and collision response — to develop for the simulation of clothes, then, we provide the different steps and tasks involved in dressing virtual actors, constructing and animating garments on them.
iFACE: A 3D SYNTHETIC TALKING FACE
Authors: HONG PENGYU , WEN ZHEN , HUANG THOMAS S.
Published: April 2003

We present the iFACE system, a visual speech synthesizer that provides a form of virtual face-to-face communication. The system provides an interactive tool for the user to customize a graphic head model for the virtual agent of a person based on his/her range data. The texture is mapped onto the customized model to achieve a realistic appearance. Face animations are produced by using text stream or speech stream to drive the model. A set of basic facial shapes and head action is manually built and used to synthesize expressive visual speech based on rules.
RECENT ADVANCES IN VIDEO CONTENT ANALYSIS: FROM VISUAL FEATURES TO SEMANTIC VIDEO SEGMENTS
Authors: HANJALIC ALAN , LAGENDIJK REGINALD L. , BIEMOND JAN
Published: April 2003

This paper addresses the problem of automatically partitioning a video into semantic segments using visual low-level features only. Semantic segments may be understood as building content blocks of a video with a clear sequential content structure. Examples are reports in a news program, episodes in a movie, scenes of a situation comedy or topic segments of a documentary. In some video genres like news programs or documentaries, the usage of different media (visual, audio, speech, text) may be beneficial or is even unavoidable for reliably detecting the boundaries between semantic segments. In many other genres, however, the pay-off in using different media for the purpose of high-level segmentation is not high. On the one hand, relating the audio, speech or text to the semantic temporal structure of video content is generally very difficult. This is especially so in "acting" video genres like movies and situation comedies. On the other hand, the information contained in the visual stream of these video genres often seems to provide the major clue about the position of semantic segments boundaries. Partitioning a video into semantic segments can be performed by measuring the coherence of the content along neighboring video shots of a sequence. The segment boundaries are then found at places (e.g., shot boundaries) where the values of content coherence are sufficiently low. On the basis of two state-of-the-art techniques for content coherence modeling, we illustrate in this paper the current possibilities for detecting the boundaries of semantic segments using visual low-level features only.
AUTOMATIC PALMPRINT VERIFICATION
Authors: SHU WEI , RONG GANG , BIAN ZHAOQI , ZHANG DAVID
Published: April 2003

Automic palmprint verification is an important complement of biometric authentication. As the first attempt of personal identification by palmprint, this paper explores different methods for three main processing stages in palmprint verification including datum point registration, line feature extraction and palmprint classification. The datum points of palmprint which have the remarkable advantage of invariable location are defined and their determination method using the directional projection algorithm is improved. Then, line feature extraction and line matching method is described to detect whether a couple of palmprints are from the same palm. In addition, palmprint classification method based on the orientation property of the ridges is discussed to distinguish six typical cases. Various palmprint images have been tested to illustrate the effectiveness of the proposed methods.
Models of the predictability of a simple nonlinear dynamical system
Authors: James I. N.
Published: April 2003

Chaotic nonlinear low order systems are often regarded as paradigms of the atmospheric behaviour, not least because of their limited predictability. In this paper, the predictability of a forced nonlinear system proposed by Lorenz is examined. The system is a compelling heuristic model of the mid‐latitude global circulation; it exhibits limited predictability. While weak error growth takes place throughout most of the phase space of the system, strong error growth is confined to very limited regions of phase space. A “discrete scattering” model of error growth is proposed. Copyright © 2003 Royal Meteorological Society.
Episodic Emergence in the Past 3000 Years at the Akkeshi Estuary, Hokkaido, Northern Japan
Authors: Sawai Yuki
Published: April 2003

At the Akkeshi estuary, rapid emergence interrupted Holocene submergence at least four times in the past 3000 years. Each emergence event produced an upward change from estuarine mud to freshwater peat. While the estuarine mud abounds in brackish and marine diatoms, freshwater taxa dominate the peat. Emergence events occurred from 1700 to 2300, 1000 to 1300, and 500 to 700 cal yr B.P. An additional emergence event predated by several decades a volcanic ash that erupted in A.D. 1694. At least three of the events produced contacts abrupt enough to represent uplift during earthquakes. Such uplift may reconcile seemingly conflicting records of vertical crustal movement in eastern Hokkaido. This tectonically active area, which is being subducted by the Pacific plate at 8 cm/yr, contains marine terraces that imply 0.1–0.5 mm/yr of net uplift in the late Quaternary. However, these terraces adjoin tide gages that recorded 8–9 mm/yr of steady submergence in the 20th century. The terrace uplift need not conflict with the gaged submergence if the region is subject to occasional coseismic uplift, as during the emergence events implied by Holocene geology near Akkeshi.
Holocene Monsoon Changes Inferred from Lake Sediment Pollen and Carbonate Records, Northeastern Cambodia
Authors: Maxwell Andrew Lee
Published: April 2003

Major Holocene monsoon changes in continental Southeast Asia are reconstructed from analysis of14C-dated changes in pollen and organic/inorganic carbon in sediment cores taken from permanent, closed-basin, volcanic lakes in Ratanakiri Province, northeastern Cambodia. Analysis focuses on the nature and timing of monsoon changes, inferred from changes in vegetation and lake conditions. These data provide the first well-dated palynological record, covering most of the Holocene and continuous up to the present, from a terrestrial site in mainland Southeast Asia. The record from a 15-m core retrieved from Kara Lake, representing the last 9300 years, shows that the late Glacial conditions ended about 850014C yr B.P., more than 1000 years later than sites in southwest China. Summer monsoon intensity increased over the period ca. 8400–530014C yr B.P., similar to most other sites in the Asian monsoon region. A subsequent expansion of secondary forests at the expense of dense semievergreen forests suggest a drier climate leading to more frequent fire disturbance. After ca. 350014C yr B.P. disturbance frequency may have increased further with increasing seasonality. From ca. 250014C yr B.P. to the present, dense forest has recovered in a mosaic with annually burned dry forest, but climate may not be the main control on local vegetation dynamics in the late Holocene.
Photosensitized decomposition of S‐nitrosothiols and 2‐methyl‐2‐nitrosopropane Possible use for site‐directed nitric oxide production
Authors: Singh Ravinder Jit , Hogg Neil , Joseph Joy , Kalyanaraman B.
Published: April 2003

Irradiation of S‐nitrosoglutathione (GSNO) with light (λ = 550 nm) resulted in the homolytic decomposition of GSNO to generate glutathionyl radical (GS ·) and nitric oxide (·NO), which were monitored by ESR spectrometry. Inclusion of Rose Bengal (RB) resulted in a 9‐fold increase in the quantum yield for ·NO production and also an increase in the rate of thiyl radical formation. The bimolecular rate constant for the interaction of triplet RB with GSNO has been estimated to be approximately 1.2 × 109 M−1s−1 by competition with oxygen. Hematoporphyrin (HP) also enhanced the rate of ·NO and tert‐butyl radical. Aluminum 2‐Methyl‐2‐nitrosopropane (MNP) decomposed on irradiation (λ = 660 nm) to form ·NO and tert‐butyl radical. Aluminum phthalocyanine tetrasulphonate enhanced the rate of decomposition of MNP by 10‐fold. These studies show that photosensitizers enhance the release of ·NO from donor compounds.
Cyclooxygenase inhibitors augment the production of pro‐matrix metalloproteinase 9 (progelatinase B) in rabbit articular chondrocytes
Authors: Ito Akira , Nose Takashi , Takahashi Shuya , Mori Yo
Published: April 2003

Matrix metalloproteinase 9 (MMP‐9/gelatinase B) has recently been proposed to participate in the destruction of articular cartilage. Here, we report that interleukin 1 (IL‐1) enhances the production of the precursor of MMP‐9 in rabbit articular chondrocytes in primary culture, and this IL‐1‐mediated production of proMMP‐9 is greatly augmented by cyclooxygenase inhibitors such as diclofenac and indomethacin, whereas the constitutive production of proMMP‐2 (progelatinase A) is not modulated by IL‐1 and/or cyclooxygenase inhibitors. Exogenous prostaglandin (PG) E1 and PGE2 suppress the proMMP‐9 production in a dose‐dependent manner. Similar results are also obtained with cultured rabbit synoviocytes. These results provide the first evidence that PGE down‐regulates the production of proMMP‐9 in chondrocytes and synoviocytes. Thus, cyclooxygenase inhibitors probably exert undesirable catabolic actions on the maintenance of articular cartilage under inflammatory conditions.
Characterization and ultrastructural localization of annexin VI from mitochondria
Authors: Rainteau Dominique , Mansuelle Pascal , Rochat Hervé , Weinman Serge
Published: April 2003

Annexin VI, a member of a family of related intracellular proteins that associate reversibly with membrane phospholipids in a Ca2+‐dependent manner, has been purified from bovine liver mitochondria and characterized. Moreover, biochemical and immunocytochemical lines of evidence are presented which strongly suggest that annexin VI is closely associated with the cristae in the inner membrane of mitochondria. These findings are consistent with a calcium channel activity of annexin VI in mitochondria.
Protein histidine phosphatase activity in rat liver and spinach leaves
Authors: Matthews Harry R. , MacKintosh Carol
Published: April 2003

Whole cell extracts from rat liver or spinach leaves contain divalent ion‐independent protein histidine phosphatase activity due to phosphatases of the PP1/PP2A family. In the rat liver extract, almost all the activity was found in the PP1, PP2A1and PP22peaks. In the spinach leaf extract, four phosphorylase phosphatase activity peaks were resolved — three containing PP1 and one containing PP2A — and all showed histidine phosphatase activity. Thus, protein histidine phosphatase activity is expressed in the cytosolic forms of protein phosphatases of the PP1/PP2A family in mammalian and plant cells.
DARPP‐32 (dopamine and cAMP‐regulated phosphoprotein, Mr 32,000) is a membrane protein in the bovine parathyroid
Authors: Matovcik Lisa M. , Hemmings Hugh C. , Kinder Barbara K.
Published: April 2003

A distinct form of DARPP‐32, a protein phosphatase‐1 inhibitor, has been identified in bovine calf parathyroid glands. Immunoblot analysis of parathyroid tissue revealed a 32 kDa protein present predominantly in a particulate fraction; it remained particulate after treatment with 1.0 M NaCl or 0.1 M Na2CO3. Metabolic labeling of parathyroid cells with mevalonolactone demonstrated that DARPP‐32 is isoprenylated. Immunocytochemical localization studies demonstrated that DARPP‐32 is present in vesicles throughout the cytoplasm of parathyroid cells, and that protein phosphatase‐1γ is concentrated in the region of the plasma membrane. Thus, in contrast to the predominately soluble form of DARPP‐32 that has been characterized in selected areas of the central nervous system, the parathyroid form is tightly associated with intracellular membranes.
1H and 13C NMR assignment and secondary structure of Chlorobium limicola f. thiosulfatophilum ferrocytochrome c555
Authors: Morelle Nathalie , Simorre Jean-Pierre , Caffrey Michael , Meyer Terrance , Cusanovich Michael , Marion Dominique
Published: April 2003

The 1H resonances of the ferrocytochrome c
555 from the anaerobic green sulfur bacterium Chlorobium limicola f thiosulfatophilum (strain Tassajara) have been assigned. Identification of spin systems and sequential assignment of 1H was accomplished by automated assignment computer programs followed by manual verification. In addition, 13C resonances have been extensively assigned by HSQC experiments at natural abundance. As determined by short‐range NOE connectivities, 13Cα chemical shifts, and HN exchange experiments, the secondary structure consists of 3 helices ranging from residues 3–13, 43–53 and 70–86. Interestingly, the second helix is significantly longer than observed by X‐ray crystallography [1977, Proc. Natl. Acad. Sci. USA 74, 5244–5247]. A topological model of the cytochrome c
555 is presented based on a small number of long‐range NOE contacts. The helices are shown to pack onto the heme according to the pattern common to all class I cytochromes c.
Glucose responsiveness of a reporter gene transduced into hepatocytic cells using a retroviral vector
Authors: Chen Ruihuan , Doiron Bruno , Kahn Axel
Published: April 2003

An MMLV‐based retroviral vector containing the chloramphenicol acetyl transferase reporter gene under the control of a glucose‐dependent internal promoter derived from the L‐type pyruvate kinase gene was constructed. After transfection into psi‐CRIP packaging cells, clones producing recombinant retrovirus were selected. These retroviruses were used to infect cultured established hepatocytic cells whose endogenous L‐type pyruvate kinase gene is transcriptionally regulated by glucose. In the infected cells, the reporter gene was as responsive to glucose as the endogenous L‐type pyruvate kinase gene, and the glucose gene activation was time‐ and concentration‐dependent. The possibility to confer a glucose responsiveness on a transgene carried by a retroviral vector provides a powerful tool in the prospect of gene therapy for diabetes mellitus.
Differential sensitivity to proteolysis by brain calpain of adult human tau, fetal human tau and PHF‐tau
Authors: Mercken M. , Grynspan F. , Nixon R.A.
Published: April 2003

Reduced turn‐over of tau by calpains is a possible mechanism to facilitate the incorporation into paired helical filaments (PHFs) in Alzheimer's disease. The present study shows that the differently phosphorylated fetal tau isoforms are all rapidly proteolysed to an equal extent by human brain m‐calpain. This result argues against the hypothesis that this type of fetal phosphorylation is involved in reducing tau turn‐over by calpain in Alzheimer's disease. Adult and fetal tau fragments in vitro generated by m‐calpain, but not trypsin, cathepsin D or chymotrypsin resemble the post‐mortem in situ degradation patterns, suggesting a possible role for calpains in tau metabolism in vivo. Tau incorporated into PHFs was considerably more resistant to proteolysis by calpain which can help to explain the persistence of these structures in Alzheimer's disease.
Effects of the anaesthetic propofol on the calcium‐induced permeability transition of rat heart mitochondria: direct pore inhibition and shift of the gating potential
Authors: Sztark François , Ichas François , Ouhabi Rachid , Dabadie Philippe , Mazat Jean-Pierre
Published: April 2003

Mitochondrial calcium exchanges are involved in intracellular calcium homeostasis and in the contraction‐relaxation process in myocytes. The calcium‐induced permeability transition of the heart mitochondria inner membrane appears to be an important calcium efflux mechanism involved in some physiological and pathological situations. The negative inotropic effect of the anaesthetic propofol results in part from a decrease in intracellular calcium availability. Thus, this study evaluates the effects of propofol on calcium transport and permeability transition of heart mitochondria. The propofol‐inhibition of the permeability transition of liver mitochondria was previously investigated [Eriksson, O. (1991) FEBS Lett. 279, 45–48] in such conditions that its uncoupling effect was not taken into account. We show here that propofol uncoupling results in a decrease in calcium uptake rate which could in part explain the decreased permeability transition rate. However, comparison of equipotent uncoupling concentrations of propofol and carbonylcyanide m‐chlorophenylhydrazone reveals that beyond this uncoupling effect, propofol has a direct inhibitory action on the permeability transition pore, concomittant with a shift of its gating potential.
Roles of the phosphorylation of human interleukin 1α in proteolytic processing
Authors: Watanabe Naoko , Kobayashi Yoshiro
Published: April 2003

To investigate the role of phosphorylation of a precursor form of interleukin‐1α (pre‐IL‐1α), we obtained cells producing either phosphorylated or unphosphorylated pre‐IL‐1α. Although calcium‐dependent proteolytic processing of unphosphorylated pre‐IL‐1α could be observed in cell lysates, proteolytic processing was not induced by treatment with calcium ionophore in intact cells producing the unphosphorylated pre‐IL‐1α. Further, unphosphorylated pre‐IL‐1α showed no calcium‐dependent binding to acidic phospholipids at concentrations below 5 × 10−6 M. These results suggested that phosphorylated pre‐IL‐1α became susceptible to proteolytic processing by association with the cell membrane in a calcium‐dependent manner.
The 60‐kDa precursor to the dithiothreitol‐sensitive tetrameric protease of spinach thylakoids: structural similarities between the protease and polyphenol oxidase
Authors: Kuwabara Tomohiko
Published: April 2003

The 60‐kDa precursor to the 39‐kDa dithiothreitolsensitive protease was purified from photosystem II membranes of spinach. When partially purified 60‐kDa protein was stored at 4°C, the protein was degraded to fragments of 39 and 21 kDa. The 39‐kDa fragment was suggested to be identical to the 39‐kDa protease from effects of dithiothreitol on these polypeptides. The N‐terminal amino acid sequences of the 60‐kDa protein and the 39‐kDa protease were the same, APILPDVEK‐, suggesting that the latter was derived from the N‐terminal portion of the former. Immunostaining with polyclonal antibodies against the 60‐kDa protein indicated that the 60‐kDa protein represents the species that occurs in the native thylakoids. These and other structural properties suggest that the protein might be identical to polyphenol oxidase.
α‐Crystallin quaternary structure: molecular basis for its chaperone activity
Authors: Singh Kamalendra , Groth-Vasselli Barbara , Kumosinski Thomas F. , Farnsworth Patricia N.
Published: April 2003

α‐Crystallin, the major protein in all vertebrate lenses, functions as a chaperone. In the present analysis, an ‘open’ micellar structure composed of αA subunits is used to simulate chaperoning of partially heat denatured soluble γ‐crystallin. The interaction is both electrostatic and hydrophobic and satisfies experimental evidence for a 1:1 α/γ molar ratio, a doubling of molecular mass and a minimal increase in the dimensions of the complex [J. Biol. Chem. (1994) 269, 13601–13608; Invest. Opthalmol. Vis. Sci. (1995) 36, 311–321]. These data are also in accord with Farahbaksh et al. [Biochemistry (1995) 34, 509–516]; i.e. the bound γ‐crystallin monomers are not in a central cavity, but are separated by αA subunits.
Interaction of peptides derived from the Fas ligand with the Fyn‐SH3 domain
Authors: Hane Michael , Lowin Bente , Peitsch Manuel , Becker Karin , Tschopp Jürg
Published: April 2003

Interaction of the widely expressed Fas with its membrane‐bound ligand (FasL) leads to rapid cell death via apoptosis. To avoid pathological tissue damage, the activity of FasL requires tight regulation. Here, we report that the Src homology 3 (SH3) domain of Fyn binds to the proline‐rich cytoplasmic region of FasL. Binding of the SH3 domain occurs between amino acid residues 44–71 which contains several potential SH3 interaction sites. This binding is specific, as SH3 domains of Lck, Grb2 and ras‐GAP bind only weakly or not at all. We suggest that FasL activity may be modulated by SH3 domains of the src‐like Fyn kinase.
Cardiolipin modulates the secondary structure of the presequence peptide of cytochrome oxidase subunit IV: a 2D 1H‐NMR study
Authors: Chupin Vladimir , Leenhouts Johanna M. , de Kroon Anton I.P.M. , de Kruijff Ben
Published: April 2003

The secondary structure of the presequence of cytochrome oxidase subunit IV (p25) was studied by circular dichroism and 2D nuclear magnetic resonance in micelles of dodecylphosphocholine (DPC) and mixed micelles of DPC and mitochondrial cardiolipin (CL). In both systems, α‐helix formation was observed. The α‐helix stretches from the N‐ to the C‐terminus with a break at the proline residue at position 13. Upon introduction of CL in the DPC micellar system, an increased stability of the helix was observed around proline13 and in the C‐terminal half. This observation, together with reported results on specific interactions between CL and p25, led to the proposal of a two‐state equilibrium of the α‐helical conformation of p25, modulated by CL.
Detection of β‐1,2‐mannosyltransferase in Candida albicans cells
Authors: Suzuki Akifumi , Takata Yuka , Oshie Asayo , Tezuka Atsuko , Shibata Nobuyuki , Kobayashi Hidemitsu , Okawa Yoshio , Suzuki Shigeo
Published: April 2003

A particulate insoluble fraction from Candida albicans J‐1012 (serotype A) strain cells was obtained as the residue after extracting a 105,000 × g pellet of cell homogenate with 1% Triton X‐100. Incubation of this fraction with a mannopentaose, Manβ1 → 2Manα1 → (2Manα1 →)22Man (αβMan5), in the presence of GDP‐mannose followed by high performance liquid chromatography showed the formation of a mannohexaose. Analysis of the product by 1H NMR indicates that αβMan5 was changed to Manβ1 → 2Manβ1 → 2Manα1 → (2Manα1 →)22Man (αβMan6). This β‐1,2‐mannosyltransferase (ManTase) II activity was completely inhibited by Zn2+ and was not restored by the addition of EDTA. The corresponding enzyme fraction from C. albicans NIH B‐792 (serotype B) strain cells, the mannan of which does not possess both the αβMan5 and αβMan6 side chains, also exhibited the same β‐1,2‐ManTase II activity.
Thermal stability of the polyheme cytochrome c3 superfamily
Authors: Florens L. , Bianco P. , Haladjian J. , Bruschi M. , Protasevich I. , Makarov A.
Published: April 2003

The cytochrome c
3 superfamily includes Desulfovibrio polyheme cytochromes c. We report the characteristic thermal stability parameters of the Desulfovibrio desulfuricans Norway (D.d.N.) cytochromes c
3 (M
r 13,000 and M
r 26,000) and the Desulfovibrio vulgaris Hildenborough (D.v.H.) cytochrome c
3 (M
r 13,000) and high molecular mass cytochrome c (Hmc), as obtained with the help of electronic spectroscopy, voltammetric techniques and differential scanning calorimetry. The polyheme cytochromes are denatured over a wide range of temperatures: the D.v.H. cytochrome c
3 is highly thermostable (T
d = 1°C) contrary to the D.d.N. protein (T
d = 73 C). The thermostability of the polyheme cytochromes is redox state dependent. The results are discussed in the light of the structural and functional relationships within the cytochrome c
3 superfamily.
Marked depletion of GLUT4 glucose transporters in transverse tubules of skeletal muscle from streptozotocin‐induced diabetic rats
Authors: Dombrowski Luce , Marette André
Published: April 2003

The principal goal of the present study was to determine the subcellular content of GLUT4 in diabetic rat muscle, and to test the hypothesis that a reduced abundance of the transporter protein in transverse tubules is responsible for impaired glucose utilization in that tissue. GLUT4 protein levels were measured in hindlimb muscle homogenates as well as in subcellular membrane fractions enriched with either plasma membranes, transverse tubules, or GLUT4‐containing intracellular membranes from control and diabetic (streptozotocin‐induced) rats. GLUT4 protein contents in diabetic muscle homogenates was reduced by 30% as compared to control rats. Subcellular fractionation experiments revealed that GLUT4 contents in transverse tubules‐enriched fractions was markedly decreased (by 55–60%) in skeletal muscle of diabetic animals whereas no significant reductions in GLUT4 abundance was observed in the plasma membrane fraction. Moreover, GLUT4 was markedly depleted (by 45%) in the GLUT4‐enriched intracellular membrane fraction. These results indicate that GLUT4 is markedly depleted in both the intracellular pool and in the cell surface membranes in muscle of STZ‐diabetic rats. Most strikingly, this study demonstrates that transverse tubules and not the plasma membrane are the main sites of cell surface GLUT4 depletion in diabetic muscle.
Down‐modulation of c‐kit mRNA and protein expression by erythroid differentiation factor/activin A
Authors: Hino Masayuki , Nishizawa Yoshiki , Tatsumi Noriyuki , Tojo Arinobu , Morii Hirotoshi
Published: April 2003

We examined the effects of erythroid differentiation factor (EDF)/activin A on the expression of c‐kit mRNA and protein in murine erythroleukemia (MEL) cells. EDF/activin A induced MEL cells to benzidine positive cells. Northern blot analysis showed that the c‐kit mRNA expression was reduced synchronously with increase of β‐globin and uroporphyrinogen decarboxylase gene expression during EDF/activin A induced erythroid differentiation. Scatchard analysis indicated that the cell surface receptor number was reduced without change of affinity during differentiation. Our results suggest that EDF/activin A may act as a natural regulator of erythropoiesis with modulation of c‐kit gene expression.
Distribution of mRNA encoding the inwardly rectifying K+ channel, BIR1 in rat tissues
Authors: Dixon A.K. , Gubitz A.K. , Ashford M.L.J. , Richardson P.J. , Freeman T.C.
Published: April 2003

The distribution of mRNA encoding the inwardly rectifying K+ channel, BIR1 [1] was investigated in rat tissues, and a comparison made with the expression of related genes rcKATP and GIRK1 using the reverse transcription‐polymerase chain reaction (RT‐PCR). This showed BIR1 to be expressed in all areas of the brain examined, in the eye but not in any other peripheral tissue. This pattern was distinct from rcKATP and GIRK1. Additional in situ hybridisation studies of the central expression of BIR1 demonstrated high levels of BIR1 mRNA in the hippocampus dentate gyrus, taenia tecta and cerebellum and at lower levels in the cortex, habenular nucleus, olfactory bulb, primary olfactory cortex, thalamus, pontine nucleus and amygdaloid nucleus.
Identification of disulfide bonds in the ninth component (C9) of human complement
Authors: Lengweiler Stephan , Schaller Johann , Rickli Egon E.
Published: April 2003

C9 is the most abundant protein of the membrane attack complex of complement. By means of limited proteolysis, different chromatographic techniques, a thiol‐specific fluorescence assay, amino acid analysis, and Edman degradation, 9 out of 12 disulfide bridges are definitely assigned (Cys22Cys57, Cys33Cys36, Cys67Cys73, Cys121Cys160, Cys233Cys234, Cys359Cys384, Cys489Cys505, Cys492Cys507, Cys509Cys518). Weaker evidence permits to reduce the number of possible configurations for the remaining 3 cystines (Cys80Cys91, Cys86Cys104, Cys98Cys113, or Cys80Cys91, Cys86Cys113, Cys98Cys104). These findings are discussed in comparison with the strongly related components C6, C7, C8α, and C8β.
Chloroplast fructose‐1,6‐bisphosphatase: Modification of non‐covalent interactions promote the activation by chimeric Escherichia coli thioredoxins
Authors: Mora-García Santiago , Ballícora Miguel A. , Wolosiuk Ricardo A.
Published: April 2003

Although all thioredoxins contain a highly conserved amino acid sequence responsible for thiol/disulfide exchanges, only chloroplast thioredoxin‐f is effective in the reductive stimulation of chloroplast fructose‐ 1,6‐bisphosphatase. We set out to determine whether Escherichia coli thioredoxin becomes functional when selected modulators alter the conformation of the target enzyme. Wild type and chimeric Escherichia coli thioredoxins match the chloroplast counterpart when the activation of chloroplast fructose‐ 1,6‐bssphosphatase is performed in the presence of fructose 1,6‐bisphosphate, Ca2+, and either trichloroacetate or 2‐propanol. These modulators of enzyme activity do change the conformation of chloroplast fructose‐1,6‐bisphosphatase whereas bacterial thioredoxins remain unaltered. Given that fructose 1,6‐bisphosphate, Ca2+, and non‐physiological perturbants modify non‐covalent interactions of the protein but do not participate in redox reactions, these results strongly suggest that the conformation of the target enzyme regulates the rate of thiol/disulfide exchanges catalyzed by protein disulfide oxidoreductases.
Allelic forms of the knob associated histidine‐rich protein gene of Plasmodium falciparum
Authors: Kant Rajiv , Sharma Yagya D.
Published: April 2003

The knob associated histidine‐rich protein (KAHRP) gene was cloned and sequenced from two Indian isolates of Plasmodium falciparum, Pf3‐92 and Pf29‐92. These isolates showed major sequence differences in the C‐terminal repeat domain of KAHRP. However, the biologically important domains such as spectrin‐actin binding region remained highly conserved. The PCR amplification of a variable C‐terminal repeat domain from the clinical isolates of P. falciparum, from Rajasthan epidemic, showed the presence of multiple alleles of KAHRP gene. The presence of multiple alleles indicates the existence of several P. falciparum strains in India. This should be taken into account for future malaria control strategies such as molecular therapy and vaccines.
Characterization of topoisomerase II‐DNA interaction and identification of a DNA‐binding domain by ultraviolet laser crosslinking
Authors: Hung Franki , Luo Dan , Sauvé Debra M. , Muller Mark T. , Roberge Michel
Published: April 2003

We have used ultraviolet laser crosslinking to characterize the DNA‐binding properties of highly purified yeast topoisomerase II in the absence of ATP. A single 5 ns, 20 mJ pulse of 266 nm light produced optimal crosslinking to a short DNA duplex, with an efficiency of 0.25%. An equilibrium binding constant (K
eq) of 1.2 +‐ 0.5 × 108 M
−1 was determined from kinetic analysis. Topoisomerase II showed highest affinity for supercoiled DNA. Limited proteolysis of crosslinked topoisomerase II‐DNA complexes showed a site of crosslinking to be within a 29‐kDa fragment with Leu‐681 at its amino‐terminal end. This region contains the active Tyr‐783 and is homologous to the amino‐terminal region of the DNA‐binding bacterial gyrase GyrA subunit, suggesting a conserved DNA‐binding mechanism.
Expression of Zm13, a pollen specific maize protein, in Escherichia coli reveals IgE‐binding capacity and allergenic potential
Authors: Heiss Susanne , Flicker Sabine , Hamilton Douglas A. , Kraft Dietrich , Mascarenhas Joseph P. , Valenta Rudolf
Published: April 2003

Plant proteins belong to the most frequent elicitors of type I allergic symptoms in industrialized countries. Several relevant plant allergens have been found to be either specifically expressed or highly upregulated in mature pollen. The cDNA coding for a pollen specific maize protein, Zm13, shows significant sequence homology with a number of pollen or anther specific proteins from monocot and dicot plants as well as with recently described allergens from olive and rye grass. To test whether the Zm13 protein might possess IgE‐binding capacity, Zm13 was expressed in E coli. The coding region of Zm13 was PCR amplified from a genomic clone and expressed as as a glutathione‐S‐transferase fusion protein. The recombinant Zm13 fusion protein bound a Zm13 specific rabbit antiserum and reacted with serum IgE from grass pollen allergic patients indicating that Zm13 and homologous proteins represent a family of conserved plant allergens.
Existence of Na+‐translocating NADH‐quinone reductase in Haemophilus influenzae
Authors: Hayashi Maki , Nakayama Yuji , Unemoto Tsutomu
Published: April 2003

We previously cloned and sequenced nqr operon encoding the Na+‐translocating NADH‐quinone reductase (NQR) from the marine bacterium Vibrio alginolyticus. A gene cluster very similar to nqr operon was found to exist in the genome of Haemophilus influenzae Rd. We examined the membrane fraction from H. influenzae, and the respiratory chain of H. influenzae was found to contain a Na+‐dependent NQR that is essentially identical to those found in the marine V. alginoltyticus. These results indicate that quite similar to the salt‐loving marine bacteria, the blood‐loving H. influenzae has a redox‐driven Na+ pump and utilizes Na+ circulation for energy coupling.
Early expression of D3dopamine receptors in murine embryonic development
Authors: Fishburn C.Simone , Bedford Mark , Lonai Peter , Fuchs Sara
Published: April 2003

In order to determine whether the D2and D3dopamine receptors may have a role in prenatal development, we have studied the mRNA expression and distribution of these receptors during murine embryonic development. Using RT‐PCR on RNA from embryos taken at progressive stages of development, we have shown that the D3receptor is expressed significantly earlier than the D2receptor, being detectable at day 9.5 post‐conception (p.c.), compared with day 13.5 p.c. for the D2subtype. We have also examined the mRNA distribution of the two receptors by whole mount in situ hybridisation. In agreement with the PCR assays, the D3receptor was expressed earlier than the D2subtype. D3receptor transcripts were first detected at day 9.5 p.c. in the ventral aspect of the anterior neural tube, whereas D2receptor transcripts first appeared a day later. By day 10.5–11.5 p.c. both D3and D2receptor transcripts were present in the developing forebrain, and later also in the branchial arches and along the prospective vertebral column. The early appearance of the D3subtype in murine development and its predominance over the D2subtype suggest that the D3receptor may have a functional role in prenatal development.
Infrared evidence of a β‐hairpin peptide structure in solution
Authors: Arrondo JoséLuis R. , Blanco Francisco J. , Serrano Luis , Goñi Félix M.
Published: April 2003

The IR spectrum of an 16‐amino acid peptide corresponding, according to NMR studies, to a β‐hairpin has been analysed. Two characteristic features distinguish its spectrum from that of an antiparallel β‐sheet: the low‐frequency band that in a β‐sheet structure is located at 2 ∼ 1632 cm−1 appears here at 2∼ 1620 cm−1, and the high‐frequency component does not undergo the isotopic shift typical of β‐sheet from 1690 to 1675 cm−1 when transferred to D2O. The infrared characteristics associated with β‐hairpins have been described so far in two proteins, in one of which, whose three‐dimensional structure is known from X‐ray diffraction, a β‐hairpin has actually been detected.
Phosphatidylcholine synthesis‐related enzyme activities of bovine brain microvessels exhibit susceptibility to peroxidation
Authors: Sipione Simonetta , Lupo Gabriella , Anfuso Carmelina D. , Albanese Vincenzo , Alberghina Mario
Published: April 2003

In microvessels isolated from bovine brain, microsomal enzyme activities involved in phosphatidylcholine biosynthesis and degradation were determined. The microvessels possessed acyl‐CoA:1‐acyl‐sn‐glycero‐3‐phosphocholine (AT) and glycerophosphocholine phosphodiesterase (GroPChoPDE) activity at a higher level compared with bovine and rat brain or rat liver microsomes whereas they expressed CTP: phosphocholine cytidylyltransferase (CT) and choline phosphotransferase (CPT) activity at a lower level. Each enzyme has been characterized in terms of response to inhibitors or activators revealing properties very similar to those in brain and liver microsomes. In the homogenate prepared from t‐butylhydroperoxide‐treated microvessels (10 min exposure to 10 μM up to 1 mM concentrations), AT and CPT activities exhibited a significant dose‐dependent inhibition. In contrast, GroPChoPDE activity was unaffected. CT was inhibited only at 1 mM concentration. Short treatment of microvessels with Fe2+ (20 μM)‐ascorbate (0.25 mM) or 100 μM linoleate hydroperoxide did not have any effect on the activity of the four enzymes. Strong inhibition of all enzymes was noted when the linoleate hydroperoxide system was fortified by Fe2+ ions (100 μM). AT inactivation was also found when oxidized low density lipoprotein was preincubated with microvessels. On the other hand, oxidized LDL left unchanged CPT and GroPChoPDE activities whereas it promoted a slight stimulation of cytidylyltransferase activity. Overall, the results suggest a link between oxygen radical generation and the perturbation of the microvessel membrane structure in which the four enzymes are incorporated, coupled to a direct sulfhydryl protein modification.
The spatial distribution of phospholipids and glycolipids in the membrane of the bacterium Micrococcus luteus varies during the cell cycle
Authors: Welby Michèle , Poquet Yannick , Tocanne Jean-François
Published: April 2003

Recently, we have developed a photocrosslinking approach which uses anthracene as a photoactivatable group and which allows us to determine the lateral distribution of lipids in membranes quantitatively. In synchronous cultures of the gram‐positive bacterium Micrococcus luteus, this approach shows that the spatial distribution of phosphatidylglycerol and diamnnosyldiacylglycerol, the two major lipids in the bacterial membrane, varies greatly during the cell cycle. Minimum heterogeneity was observed during cell growth while maximum heterogeneity was detected during cell division.
The structural origin of the color differences in the bioluminescence of firefly luciferase
Authors: Yoshihiro Ohmiya  , Takashi Hirano  , Mamoru Ohashi
Published: April 2003

Six chimeric mutants between Hotaria parvula (λmax=568 nm) and Pyrocoelia miyako (λmax=550 nm) luciferases were reconstructed to determine the structural origin of the color differences in firefly luciferase. Based on light‐emitting color, five chimeric luciferases could be divided into two groups: the three green‐emitting mutants, classified as P. miyako luciferase, and the two yellow‐emitting mutants, classified as H. parvula luciferase. Their common fragments between Val‐209 and Ala‐318 within each group contain the active site for the color differences.
C‐terminal region contributes to muscle acylphosphatase three‐dimensional structure stabilisation
Authors: Taddei Niccolò , Magherini Francesca , Chiti Fabrizio , Bucciantini Monica , Raugei giovanni , Stefani Massimo , Ramponi Giampietro
Published: April 2003

Ser‐Ala and Ser‐Ala‐Ser‐Ala C‐terminus elongated (Δ+2 and Δ+4, respectively) and two C‐terminus deleted (Δ−2 and Δ−3) muscle acylphosphatase mutants were investigated to assess the catalytic and structural roles of the C‐terminal region. The kinetic analysis of these mutants shows that the removal of two or three C‐terminal residues reduces the catalytic activity to 7% and 4% of the value measured for the wild‐type enzyme, respectively; instead, the elongation of the C‐terminus does not significantly change the enzyme behaviour.1H Nuclear magnetic resonance spectroscopy indicates that all mutants display a native‐like fold though they appear less stable, particularly Δ−2 and Δ−3 mutants, as compared to the wild‐type enzyme. Such destabilisation of the C‐terminal modified mutants is further confirmed by urea inactivation experiments. The results here presented account for an involvement of the C‐terminal region in the stabilisation of the three‐dimensional structure of acylphosphatase, particularly at the active‐site level. Moreover, a participation of the C‐terminal carboxyl group to the catalytic mechanism can be excluded.
Ultraviolet‐A induces activation of AP‐1 in cultured human keratinocytes
Authors: Djavaheri-Mergny Mojgan , Mergny Jean-Louis , Bertrand France , Santus René , Mazière Cécile , Dubertret Louis , Mazière Jean-Claude
Published: April 2003

UV‐A irradiation induces a time‐dependent activation of AP‐1 in NCTC 2544 human keratinocytes. 4 h after irradiation, a 2–3‐fold increase in AP‐1 activity is observed in human keratinocytes and fibroblasts. Activation is still detectable 24 h later. The UV‐A induced AP‐1 binding complex is shown to contain c‐Fos and c‐Jun proteins. Lipophilic vitamin E impedes UV‐A induced lipid peroxidation but does not prevent AP‐1 activation which is inhibited by N‐acetylcysteine, a hydrophilic antioxidant. This finding suggests that UV‐A‐dependent AP‐1 activation is sensitive to the cellular redox state but is not related to membrane lipid peroxidation.
Biochemical evidence for the interaction of regulatory subunit of cAMP‐dependent protein kinase with IDA (Inter‐DFG‐APE) region of catalytic subunit
Authors: Sahara Setsuko , Sato Ken-ichi , Kaise Hiroshi , Mori Kiyotoshi , Sato Ayako , Aoto Mamoru , Tokmakov Alexander A. , Fukami Yasuo
Published: April 2003

To explore the structural basis required for the holoenzyme formation of cAMP‐dependent protein kinase, we have prepared rabbit anti‐peptide antibodies that can block the holoenzyme formation without affecting the catalytic activity of the enzyme. The antibodies were raised against a specific site in the catalytic (C)‐subunit, termed IDA (Inter‐DFG‐APE) region, which lies between the kinase subdomains VII and VIII. Although the C‐subunit immunoprecipitated with anti‐IDA antibodies could not form a stable complex with regulatory (R)‐subunit, it was still susceptible to inhibition by the R‐subunit or by PKI, a specific inhibitor peptide containing a pseudosubstrate site. These results indicate that there exists an IDA regionmediated interaction between the R‐ and C‐subunits, which is distinct from that mediated through the substrate site and substrate binding site. In accordance with this idea, association of synthetic IDA peptides with the R‐subunit was directly demonstrated by resonance mirror analysis. The calculated association constants of IDA peptides were high enough to suggest a possible involvement of the IDA region in the initial step of holoenzyme formation.
Modulation of microtubule shape in vitro by high molecular weight microtubule associated proteins MAP1A, MAP1B, and MAP2
Authors: Pedrotti Barbara , Francolini Maura , Cotelli Franco , Islam Khalid
Published: April 2003

The effect of microtubule associated proteins on microtubule shape has been investigated in reconstitution experiments using purified tubulin and purified MAP1A, MAP1B, and MAP2. Microtubules assembled in the presence of these MAPs were fixed with 0.1% glutaraldehyde and, after negative staining, were examined by electron microscopy. The results show that MAP1A microtubules were generally short and ‘straight’ while those assembled with MAP1B were longer and ‘bendy’. MAP2 microtubules showed both types of morphologies even though straight microtubules were more abundant. These data suggest that MAPs may modulate not only microtubule dynamics but also microtubule shape which may be important in their spatial distribution and/or role in specific neuronal areas.
Decreased l‐arginine‐nitric oxide pathway in cultured myoblasts from spontaneously hypertensive versus normotensive Wistar‐Kyoto rats
Authors: Dubois G.
Published: April 2003

The hypertrophy of the arterial media exhibited by spontaneously hypertensive rats is related to the hyperproliferation of their smooth muscle cells in culture. Using two methods to assay nitric oxide synthase activity, we showed that this abnormal proliferation results from a decreased activity of the inducible NOS II and less modulation of this enzymatic activity by these cells compared to control Wistar Kyoto cells.