bluuebunny/crossref_metadata_2025 huggingface dataset:
Polar Effect on the Stacking Interaction between a Zinc Complex of an Anionic Porphyrin and Anionic Aromatics
Authors: Kano Koji , Kobayashi Shiho
Published: October 2003

Although 2-anthracenesulfonate did not interact with a zinc complex of 5,10,15,20-tetrakis(p-sulfonatophenyl)porphyrin (ZnTPPS), anthraquinone-2-sulfonate (AQS) and -2,6-disulfonate (AQDS) formed stable molecular complexes with ZnTPPS in aqueous solution. Such results suggest the polar effect on the stacking interaction between aromatic compounds. Molecular complexation of ZnTPPS was further studied using mono-substituted benzoate anions as the partners by means of 1H NMR spectroscopy. The electron-withdrawing groups of the benzoates stabilized the complexes, while the electron-donating groups restrained the complexation. These results suggest that a reduction of the electrostatic repulsion by electron-withdrawing group(s) is important to form stable molecular complexes of ZnTPPS and anionic aromatics via the London dispersion force. A similar mechanism could be applied to the formation of the AQS dimer, which takes a slipped edge-to-edge arrangement.
Structures of deacylated tRNA mimics bound to the E site of the large ribosomal subunit
Authors: SCHMEING T. MARTIN , MOORE PETER B. , STEITZ THOMAS A.
Published: October 2003

During translation, tRNAs cycle through three binding sites on the ribosome: the A, the P, and the E sites. We have determined the structures of complexes between the Haloarcula marismortui large ribosomal subunit and two different E site substrates: a deacylated tRNA acceptor stem minihelix and a CCA-acceptor end. Both of these tRNA mimics contain analogs of adenosine 76, the component responsible for a large proportion of E site binding affinity. They bind in the center of the loop-extension of protein L44e, and make specific contacts with both L44e and 23S rRNA including bases that are conserved in all three kingdoms of life. These contacts are consistent with the footprinting, protection, and cross-linking data that have identified the E site biochemically. These structures explain the specificity of the E site for deacylated tRNAs, as it is too small to accommodate any relevant aminoacyl-tRNA. The orientation of the minihelix suggests that it may mimic the P/E hybrid state. It appears that the E site on the 50S subunit was formed by only RNA in the last common ancestor of the three kingdoms, since the proteins at the E sites of H. marismortui and Deinucoccus radiodurans large subunits are not homologous.
Visualization of membrane RNAs
Authors: JANAS TADEUSZ , YARUS MICHAEL
Published: October 2003

Using fluorescence microscopy, we show that previously isolated membrane-binding RNAs coat artificial phospholipid membranes relatively uniformly, except for a frequent tendency to concentrate at bends, membrane junctions, and other unusual sites. Membrane RNAs can also be visualized as single molecules or isolated complexes by atomic force microscopy (AFM) of free RNAs on mica. Finally, RNAs can be seen within membranes by AFM of RNA-liposomes immobilized on hydrophobic mica surfaces. Monomer RNAs appear globular, as expected for small RNAs. When mixed under conditions in which RNAs bind bilayers, RNA 9 and RNA 10 combine to yield about 80% of RNAs as mainly linear oligomers of ≈2–8 molecules. Once inserted in membranes, the RNAs oligomerize further, yielding larger, irregular ropelike structures that prefer the edges of altered lipid patches. These properties can be interpreted in terms of RNA–RNA loop interactions, and the RNA effects on membranes can be explained in terms of an RNA preference for irregular lipid conformations. The RNA-bilayer system poses new opportunities for combining the properties of membranes and RNA in contemporary cells, and also in the ribocytes of an RNA world.
A template-proximal RNA paired element contributes to Saccharomyces cerevisiae telomerase activity
Authors: SETO ANITA G. , UMANSKY KFIR , TZFATI YEHUDA , ZAUG ARTHUR J. , BLACKBURN ELIZABETH H. , CECH THOMAS R.
Published: October 2003

The ribonucleoprotein complex telomerase is critical for replenishing chromosome-end sequence during eukaryotic DNA replication. The template for the addition of telomeric repeats is provided by the RNA component of telomerase. However, in budding yeast, little is known about the structure and function of most of the remainder of the telomerase RNA. Here, we report the identification of a paired element located immediately 5′ of the template region in the Saccharomyces cerevisiae telomerase RNA. Mutations disrupting or replacing the helical element showed that this structure, but not its exact nucleotide sequence, is important for telomerase function in vivo and in vitro. Biochemical characterization of a paired element mutant showed that the mutant generated longer products and incorporated noncognate nucleotides. Sequencing of in vivo synthesized telomeres from this mutant showed that DNA synthesis proceeded beyond the normal template. Thus, the S. cerevisiae element resembles a similar element found in Kluyveromyces budding yeasts with respect to a function in template boundary specification. In addition, the in vitro activity of the paired element mutant indicates that the RNA element has additional functions in enzyme processivity and in directing template usage by telomerase.
Substantive intumescence from phosphorylated 1,3‐propanediol derivatives substituted on to cellulose
Authors: Zhang Sheng , Horrocks A. Richard
Published: October 2003

Cellulose flame retarded with an ammonia‐cured, polycondensed tetrakis(hydroxymethyl)phosphonium–urea derivative (as Proban CC®, Rhodia) phosphorylated by cyclic 1,3‐propanediol phosphoryl chloride and cyclic 2,2‐diethyl‐1,3‐propanediol phosphoryl chloride can give phosphorus levels up to 6.9% (w/w). Such high levels suggest up to 35.5% yields of reaction if the free secondary amine groups present in the crosslinked flame retardant and the C(6) primary hydroxyl groups are the assumed phosphorylation sites. The presence of substituted propanediol phosphonate moieties in the fibers significantly increases char formation above 400©C and scanning electron microscopy indicates that the char has an intumescent structure. The influence of the chemical structure of the propanyl moeity to the reaction extent of the possible phosphorylation sites and the char formation mechanism during thermal pyrolysis of the modified samples are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3165–3172, 2003
Pervaporation separation of a water/ethanol mixture by a sodium sulfonate polysulfone membrane
Authors: Hung Mu‐Ya , Chen Shih‐Hsiung , Liou Rey‐May , Hsu Chin‐Shan , Lai Juin‐Yih
Published: October 2003

A sodium sulfonate polysulfone membrane was prepared for the dehydration of a water/ethanol mixture by pervaporation. The separation performances of water and ethanol were examined by the testing of the ethanol/water mixture under operating conditions. The permselectivity of the sodium sulfonate polysulfone membrane was found to strongly depend on the sodium content in the membrane. The sodium sulfonate ratio showed a significant influence on the hydrophilicity and diffusion behavior of the polysulfone membrane. Moreover, the difference in the diffusion of the permeates played an important role in the sulfonate polysulfone membrane. It was found that a high‐performance pervaporation membrane could be achieved with a sodium sulfonate polysulfone membrane. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3374–3383, 2003
High performance nanocomposites of polyurethane elastomer and organically modified layered silicate
Authors: Song M. , Hourston D. J. , Yao K. J. , Tay J. K. H. , Ansarifar M. A.
Published: October 2003

High performance nanocomposites comprising a polyurethane elastomer (PUE) and an organically modified layered silicate are prepared. These nanocomposites are based on poly(propylene glycol), 4,4′‐methylene bis(cyclohexyl isocyanate), 1,4‐butandiol, and organoclay. The tensile strength and strain at break for these novel PUE nanocomposites increases more than 150%, but the hardness remains unchanged. The fatigue properties are significantly improved. With 3 wt % organoclay, the fatigue properties are improved the most, which is important for the PU industry. The effects of the isocyanate index on the mechanical properties of the PUE nanocomposites are investigated. It is found that an isoyanate index of 1.10 results in the best improvement in stress and elongation at break. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3239–3243, 2003
Study on characterization of pyrolysis and hydrolysis products of poly(vinyl chloride) waste
Authors: Lu Jun , Ma Shibai , Gao Jinsheng , Freitas Jair C. C. , Bonagamba Tito J.
Published: October 2003

Poly(vinyl chloride) PVC pyrolysis and hydrolysis are conducted in a fixed bed reactor and in an autoclave, respectively, under different operating conditions such as the temperature and time. The product distribution is studied. For the PVC pyrolysis process, the main gas product is HCl (55% at 340°C), there is 9% hydrocarbon gas (C1–C5), the liquid product fraction is about 5% (at 340°C), and the solid residue fraction is about 31% (at 340°C). For the hydrolysis process, the main gas product is HCl (55.8% at 240°C) and the solid residue is about 49.6% (at 240°C). The pyrolysis liquid product is analyzed by using gas chromatography with magic‐angle spinning. Aromatic hydrocarbons are the main class (90%), of which the major part is benzene (33%). The residue produced through pyrolysis and hydrolysis is investigated by high‐resolution solid‐state 13C‐NMR. These details revealed by the high‐field NMR spectra provide importmant information about the chemical changes in the PVC pyrolysis and hydrolysis process. The mechanism of PVC hydrolysis dechlorination is also discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3252–3259, 2003
Spectroelectrochemical investigations of aniline–thiophene copolymers in acetonitrile
Authors: Özçiçek Nuran Pekmez , Pekmez Kadir , Holze Rudolf , Yıldız Attila
Published: October 2003

The copolymerization of aniline and thiophene with varying concentration ratios was studied in acetonitrile/tetrabutylammonium tetrafloroborate. In situ UV‐vis and in situ surface resonance Raman spectroscopic studies revealed that polythiophene and polyaniline units of different lengths enter into the electropolymerization products. The copolymers deposited were either polyaniline‐based or polythiophene‐based polymeric structures depending on the initial concentration of the monomers used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3417–3423, 2003
Graft copolymerization of oleic acid onto low‐density polyethylene in the molten state
Authors: Liu Mingzhu , Liu Zaiman , Ding Shenglong , Li Sheqing , Zhang Liji
Published: October 2003

A graft copolymer of oleic acid (OA) onto low‐density polyethylene (LDPE) was prepared using dicumyl peroxide (DCP) as an initiator in the molten state. The grafting was carried out in a Haake rheometer. The effects of the reaction time and the amount of DCP and the monomer on the percentage of grafting were studied. The rheological behavior and the melt‐flow rate of the graft copolymer (LDPE‐g‐OA) were also investigated. FTIR spectroscopy and a mass spectrum were used to characterize the structure of LDPE‐g‐OA. The experimental results showed that when the OA amount was 10 wt % and the DCP amount was 0.4 wt % based on the LDPE the percentage of grafting of LDPE‐g‐OA, prepared by maintaining the temperature at 170°C and the roller speed at 80 rpm, was about 6 wt %. It was found that both LDPE and LDPE‐g‐OA were pseudoplastic fluids. OA was grafted onto LDPE in the form of a monomer and a dimer. The grafted LDPE is expected to act as a compatibilizer between starch and polyethylene. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3299–3304, 2003
Effect of plasticizers on mechanical, electrical, permanence, and thermal properties of poly(vinyl chloride)
Authors: Shah B. L. , Shertukde V. V.
Published: October 2003

Effects of three different plasticizers and their blends with dioctyl phthalate (DOP) on thermal stability, flammability, mechanical, electrical, and permanence properties of poly(vinyl chloride) (PVC) compound were studied. Various plasticizers used were DOP, butyl benzyl phthalate (BBP), isodecyl diphenyl phosphate (IDDP), and polybutylene adipate (PBA) at concentrations of up to 40 phr level. Studies showed that processability and softness were improved by addition of BBP. An increase in the content of IDDP increased the electrical and flammability properties, whereas compositions with PBA exhibited the best permanence properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3278–3284, 2003
Miniature permanent magnet for table‐top NMR
Authors: Moresi Giorgio , Magin Richard
Published: October 2003

The multi‐infinity dipole magnet is a new design capable of generating a relatively high and homogeneous permanent magnetic field (0.1–3 Tesla and homogeneity 20 ppm for 3 mm) that is suitable for nuclear magnetic resonance (NMR) or electron spin resonance (ESR) studies of small volume chemical or biological samples. The theoretical design and practical aspects involved in the construction of a prototype tabletop NMR system (0.6 T and homogeneity of 10 ppm in a ellipsoidal region of 3 × 3 × 5 mm3) are described. A simple NMR relaxation time experiment was performed on a water sample doped with 40 mM of CuSO4. This system in its current configuration is suitable for relaxation time studies of materials or for educational use. The introduction of shim coils would increase the homogeneity of the magnet by a factor of 100, allowing the system to be used as a portable NMR spectrometer. In addition the introduction of gradient coils between the poles would transform the spectrometer to a MRI portable system for tissue analysis or simple MR microimaging at fields up to 3 T. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 19B: 35–43, 2003.
Nuclear magnetic resonance in pulsed high‐field magnets
Authors: Haase Jürgen , Eckert Dieter , Siegel Hartmut , Eschrig Helmut , Müller Karl‐Hartmut , Steglich Frank
Published: October 2003

NMR has benefited tremendously from superconducting magnet technology providing stable, ever increasing magnetic fields over the last few decades. However, since superconductors expel magnetic field and with no suitable material in sight this trend has come to a halt at ∼20 T, and resistive magnet designs are being used again for high‐field applications. Outside NMR, much higher magnetic fields (∼85 T) can be achieved with pulsed, resistive magnets. A low duty cycle and a small magnet volume cut down on the average losses and make these systems affordable. Here, we show for the first time that NMR can be accomplished even in pulsed high‐field magnets, and we discuss why this technique is able to become a promising research tool. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 19B: 9–13, 2003
Common mode signal rejection methods for MRI: Reduction of cable shield currents for high static magnetic field systems
Authors: Peterson David M. , Beck Barbara L. , Duensing G. Randy , Fitzsimmons Jeffrey R.
Published: October 2003

This experiment was conducted to identify common mode currents that flow on the shield of a coaxial cable and to investigate techniques that reduce their effects at high fields of ≥3 Tesla. It will be shown that there are two different methods of common mode interference for two different coil types. First, is the transceive case, where common mode cable shield currents flow as a result of unbalanced loop voltages that couple to the cable shield. In the second case, unwanted common mode signals are induced from the field of the transmission coil onto the cable shield of the receive‐only coil. Two important factors relating to the investigation of common mode signals are danger to the patient from an RF burn and the reduction of the signal‐to‐noise ratio (SNR) because of extra noise being introduced into the MRI environment. It will be shown that through the use of cable shield traps and balun matching circuits, common mode signals can be reduced significantly, increasing patient safety and SNR. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 19B: 1–8, 2003.
Crossed and uncrossed retinal projections to the hamster circadian system
Authors: Muscat Louise , Huberman Andrew D. , Jordan Cynthia L. , Morin Lawrence P.
Published: October 2003

The hamster suprachiasmatic nucleus (SCN), site of the circadian clock, has been thought to be equally and completely innervated by each retina. This issue was studied in animals that had received an injection of the tracer cholera toxin subunit B (CTb) conjugated to Alexa 488 into the vitreous of one eye, with CTb‐Alexa 594 injected into the other. Retinal projections to the SCN and other nuclei of the circadian system were simultaneously evaluated by using confocal laser microscopy. Each retina provides completely overlapping terminal fields throughout each SCN. Although SCN innervation by the contralateral retina is slightly denser than that from the ipsilateral retina, there are distinct SCN regions where input from one side is predominant, but not exclusive. A dense terminal field from the contralateral retina encompasses, and extends dorsally beyond, the central SCN subnucleus identified by calbindin‐immunoreactive neurons. Surrounding the dense terminal field, innervation is largely derived from the ipsilateral retina. The densest terminal field in the intergeniculate leaflet is from the contralateral retina, which completely overlaps the ipsilateral projection. Most nuclei of the pretectum receive innervation largely, but not solely, from the contralateral retina, although the olivary pretectal nucleus has very dense patches of innervation derived exclusively from one retina or the other. Retina‐dependent variation in terminal field density within the three closely examined nuclei may indicate areas of specialized function not previously appreciated. This issue is discussed in the context of the melanopsin‐containing retinal ganglion cell projections to several nuclei in the circadian visual system. J. Comp. Neurol. 466:513–524, 2003. © 2003 Wiley‐Liss, Inc.
Paleocortex is specified in mice in which dorsal telencephalic patterning is severely disrupted
Authors: Vyas Aditee , Saha Bhaskar , Lai Eseng , Tole Shubha
Published: October 2003

The patterning of the telencephalon is regulated by the concerted action of distinct mechanisms operating in different portions of this structure. Although much progress has been made in understanding the mechanisms underlying the specification of dorsal and ventral structures, little is known about the specification of the paleocortex, the olfactory cortex located at the interface of the dorsal and ventral telencephalon. The paleocortex is thought to be a dorsal, cortical structure, derived from the lateral extreme of the dorsal telencephalon. We examined mutant mice in which dorsal telencephalic patterning is severely disrupted, to ask how these perturbations affect the paleocortex. In the Lhx2−/− telencephalon, where the cortex is greatly shrunken such that medial and dorsal cortical tissue is undetectable, normal expression of several paleocortical markers is observed. The Gli3−/− telencephalon, where the dorsal telencephalon is ventralized, also displays paleocortical markers. In contrast, when the ventral telencephalon is almost completely deleted, such as in the BF1−/− brain, paleocortical markers are undetectable. These results indicate that the specification of the paleocortex can occur in spite of drastic perturbations of dorsal patterning. Furthermore, in the Lhx2 mutant, the paleocortex is juxtaposed to an expanded and mislocated source of Wnt and Bmp signaling, the cortical hem, whereas, in the Gli3 mutant, paleocortical markers arise even though the cortical hem is missing. This indicates that an increase or decrease in cues from this dorsal signaling center does not disrupt the specification of the paleocortex. Finally, by using an in vitro assay, we found that isolated explants of lateral telencephalon up‐regulate normal expression of paleocortical markers when maintained in vitro, from as early as embryonic day (E) 10.5. Together, the results reveal that, although the paleocortex is considered to be a cortical structure, it is specified even when dorsal telencephalic patterning is grossly perturbed. Furthermore, our in vitro data reveal that, if mechanisms outside the lateral telencephalon are involved in the specification of the paleocortex, they must act extremely early, prior to E10.5. J. Comp. Neurol. 466:545–553, 2003. © 2003 Wiley‐Liss, Inc.
A hybrid 3D watershed algorithm incorporating gradient cues and object models for automatic segmentation of nuclei in confocal image stacks
Authors: Lin Gang , Adiga Umesh , Olson Kathy , Guzowski John F. , Barnes Carol A. , Roysam Badrinath
Published: October 2003

Background

Automated segmentation of fluorescently‐labeled cell nuclei in 3D confocal microscope images is essential to many studies involving morphological and functional analysis. A common source of segmentation error is tight clustering of nuclei. There is a compelling need to minimize these errors for constructing highly automated scoring systems.

Methods

A combination of two approaches is presented. First, an improved distance transform combining intensity gradients and geometric distance is used for the watershed step. Second, an explicit mathematical model for the anatomic characteristics of cell nuclei such as size and shape measures is incorporated. This model is constructed automatically from the data. Deliberate initial over‐segmentation of the image data is performed, followed by statistical model‐based merging. A confidence score is computed for each detected nucleus, measuring how well the nucleus fits the model. This is used in combination with the intensity gradient to control the merge decisions.

Results

Experimental validation on a set of rodent brain cell images showed 97% concordance with the human observer and significant improvement over prior methods.

Conclusions

Combining a gradient‐weighted distance transform with a richer morphometric model significantly improves the accuracy of automated segmentation and FISH analysis. Cytometry Part A 56A:23–36, 2003. © 2003 Wiley‐Liss, Inc.
Relative efficacy of a 4‐day versus a 5‐day day hospital program
Authors: Olmsted Marion P. , Kaplan Allan S. , Rockert Wendi
Published: October 2003

Objective

Day hospital treatment has demonstrated effectiveness in the treatment of eating disorders, but no information regarding the required intensity of treatment is currently available. The purpose of this study was to compare the short‐term effectiveness of a 4‐day versus a 5‐day day hospital program.

Methods

The study followed a sequential cohort design. Four hundred sixty‐eight patients attended a 5‐day program between 1985 and 1994 and 288 patients attended a 4‐day program between 1995 and 2000. Weight, binging, and vomiting frequencies and psychological functioning were assessed at the beginning and at the end of treatment.

Results

The two programs were equally effective in helping underweight patients to gain weight. However, the 5‐day program was associated with higher abstinence rates for binging and vomiting and with better psychological functioning at the end of treatment. The 4‐day program was more cost‐effective when symptom change was considered as a percentage reduction per treatment day.

Discussion

Overall, the 5‐day program was both more effective and more costly. The relative long‐term outcome of the two programs is a critical question and these data are currently being collected. © 2003 by Wiley Periodicals, Inc. Int J Eat Disord 34: 441–449, 2003.
Risk factors for anorexia nervosa: A national cohort study
Authors: Lindberg Lene , Hjern Anders
Published: October 2003

Objective

To identify possible risk factors for anorexia nervosa through national registers.

Method

The study includes the entire Swedish population of 989,871 individuals born between 1973 and 1982. Patients with anorexia nervosa were identified through the Swedish Hospital Discharge Register from November 1990 to December 1999. Information about sociodemographic, perinatal, and psychosocial variables was obtained from different national registers. Attributable risk (AR) was calculated for potential risk factors.

Results

Females had the highest AR for hospital admission because of anorexia nervosa (89.2%). Another important risk factor was having parents born in northern, central, or eastern Europe (AR: 49.3%). Psychosocial risk factors also were associated with an increased risk for anorexia nervosa (AR: 7.6%), whereas perinatal complications had an AR of only 3.6%.

Discussion

The most important risk factors were related to the sociocultural context of the individual, thus supporting hypotheses of a sociocultural etiology of anorexia nervosa. © 2003 by Wiley Periodicals, Inc. Int J Eat Disord 34: 397–408, 2003.
Review of the prevalence and incidence of eating disorders
Authors: Hoek Hans Wijbrand , van Hoeken Daphne
Published: October 2003

Objective

To review the literature on the incidence and prevalence of eating disorders.

Methods

We searched Medline using several key terms relating to epidemiology and eating disorders and we checked the reference lists of the articles that we found. Special attention has been paid to methodologic problems affecting the selection of populations under study and the identification of cases.

Results

An average prevalence rate for anorexia nervosa of 0.3% was found for young females. The prevalence rates for bulimia nervosa were 1% and 0.1% for young women and young men, respectively. The estimated prevalence of binge eating disorder is at least 1%. The incidence of anorexia nervosa is 8 cases per 100,000 population per year and the incidence of bulimia nervosa is 12 cases per 100,000 population per year. The incidence of anorexia nervosa increased over the past century, until the 1970s.

Discussion

Only a minority of people who meet stringent diagnostic criteria for eating disorders are seen in mental health care. © 2003 by Wiley Periodicals, Inc. Int J Eat Disord 34: 383–396, 2003.
Fractal image coding with a multiscaling‐domain
Authors: Furusawa Ryuji , Nakagawa Masahiro
Published: October 2003

In order to improve the approximation capability of fractal coding, a fractal coding method using multiple domains is proposed in which an approximation is carried out by superposition of contracted images from multiple domain blocks. By combining the multidomain method with the multiscaling procedure of dividing blocks into regions and individually providing the scaling coefficients of brightness, a contraction transform with even better degrees of approximation is obtained and edge reconstruction is improved. As a result, excellent reconstructed images are obtained even for complicated images for which high reproducibility cannot be realized with the conventional fractal coding. Also, it is possible to reproduce contour regions containing edges. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(2): 79–87, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10081
Convergence analysis and a synchronized learning algorithm for a joint lattice predictor and FIR adaptive filter
Authors: Tokui Naoki , Nakayama Kenji , Hirano Akihiro
Published: October 2003

Since the transfer function of a two‐stage adaptive filter combining a lattice predictor and a FIR filter includes the reflection coefficients and the filter coefficients, a conventional learning algorithm does not integrate the updates of the reflection coefficients and the filter coefficients. Therefore, error reduction could not be guaranteed. To solve this problem, we proposed a learning algorithm that corrects the coefficients of the adaptive filter synchronized to updating the reflection coefficients. The filter coefficientsw(n+ 1) are corrected so that the transfer function based on the filter coefficientsw(n+ 1) updated by using the reflection coefficientsk(n) updated at sample timenis identical for the reflection coefficientsk(n+ 1) updated at sample timen+ 1, and the filter coefficientsw(n+ 1) are used in the output calculation for samplen+ 1. The computational complexity required for updating is 2 (prediction order × filter order). We conducted a simulation to estimate an unknown system by using white noise, colored noise, and speech as the input signal and compared the performance to a conventional method. We verified the following. The conventional method that does not correct the filter coefficients in response to fluctuations in the reflection coefficients cannot adequately reduce the estimation errors. The proposed method converges 4 to 5 times faster than NLMS for speech input, and its errors are equivalent to those of RLS. When the prediction order ≪ the filter order, the computational complexity can be substantially less than RLS. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(2): 67–78, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10088
Design of Chebyshev‐type IIR filters with approximately linear phase characteristics
Authors: Takeuchi Ryousuke , Zhang Xi , Yoshikawa Toshinori , Takei Yoshinori
Published: October 2003

Digital filters with a linear phase characteristic are needed in many applications for signal processing. In this paper, design of a Chebyshev‐type IIR filter with approximate linear phase characteristics in the passband is described. First, it is shown that a flat stopband can easily be realized by placing multiple zeros at the specified frequency points in the stopband. Next, the complex Remez exchange algorithm is applied to the passband so that the filter design problem is formulated as an eigenvalue problem. Hence, by solving the eigenvalue problem, the filter coefficients can be derived easily. Further, by means of iterative calculations, an equiripple characteristic of the error function in the passband is obtained. Finally, it is shown that a reverse Chebyshev‐type IIR filter with an approximate linear phase characteristic can also be obtained by parallel connection of the proposed Chebyshev‐type filter and a delay line. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(2): 1–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10133
Poly(ADP‐ribose) and carcinogenesis
Authors: Masutani Mitsuko , Nakagama Hitoshi , Sugimura Takashi
Published: October 2003

Poly(ADP‐ribose) and poly(ADP‐ribose) polymerase (PARP) were discovered about 40 years ago, but their significance was not well elucidated until recently. In the early stage of the history of PARP, the presence of antibodies in the sera of human patients with lupus erythematosus indicated its natural occurrence. PARP, as well as the degrading enzyme, poly(ADP‐ribose) glycohydrolase (PARG), are present in most eukaryotes except for yeasts. Studies that used inhibitors of PARP indicated the involvement of PARP and poly(ADP‐ribose) in DNA damage repair, and eventually PARP was purified and the gene was cloned. Molecular analysis then revealed various functional domains, such as the one for binding to strand breaks of DNA. Parp‐1–deficient and Parg‐deficient cells showed, in general, enhanced sensitivity to the lethal effects of ionizing radiation and alkylating agents. Parp‐1 knockout mouse embryonic stem cells developed into teratocarcinoma‐like tumors when injected subcutaneously into nude mice, these tumors featuring giant cells similar to syncytiotrophoblastic giant cells with hyperploidy. Parp‐1 was also found in centrosomes, suggesting that poly(ADP‐ribose) and PARP‐1 are functionally involved in the maintenance of chromatin structure and the equal distribution of chromosomes into daughter cells. Intriguing findings on the real biological significance continue to be generated, with new light shed on mechanisms of carcinogenesis and pointing to novel cancer treatments. Highlights during the last four decades of studies by laboratories focusing on poly(ADP‐ribose)/PARP, including our own, are condensed and summarized in this review. © 2003 Wiley‐Liss, Inc.
Multiple roles of the tuberous sclerosis complex genes
Authors: Yeung Raymond S.
Published: October 2003

Soon after proposing the “two‐hit” hypothesis for tumorigenesis, Knudson pursued further experimental validation of the concept by using a rat model of dominantly inherited renal tumor. Today, the Eker rat is one of the best characterized models of tuberous sclerosis complex (TSC) and has been used extensively for study of the function of the TSC2 tumor suppressor gene. Along with TSC1, these two genes behave as expected for tumor suppressor genes with evidence for loss of heterozygosity in tumors and suppression of growth when expressed in proliferating cells. Despite much experimental work, the mechanisms of these genes have remained elusive until recently. This review summarizes some of the current concepts in our understanding of the biological and biochemical function of the TSC genes. © 2003 Wiley‐Liss, Inc.
Sustained calpain activation associated with lysosomal rupture executes necrosis of the postischemic CA1 neurons in primates
Authors: Yamashima Tetsumori , Tonchev Anton B. , Tsukada Toshiyuki , Saido Takaomi C. , Imajoh‐Ohmi Shinobu , Momoi Takashi , Kominami Eiki
Published: October 2003

Because of the paucity of primate experimental models, the precise molecular mechanism of ischemic neuronal death remains unknown in humans. This study focused on nonhuman primates to determine which cascade necrosis or apoptosis is predominantly involved in the development of delayed (day 5) neuronal death in the hippocampal CA1 sector undergoing 20 min ischemia. We investigated expression, activation, and/or translocation of μ‐calpain, lysosome‐associated membrane protein‐1 (LAMP‐1), caspase‐3, and caspase‐activated DNase (CAD), as well as morphology of the postischemic CA1 neurons and DNA electrophoresis pattern. Immunoblotting showed sustained (immediately after ischemia until day 5) and maximal (day 3) activation of μ‐calpain. The immunoreactivity of activated μ‐calpain became remarkable as coarse granules at lysosomes on day 2, while it translocated throughout the perikarya on day 3. The immunoreactivity of LAMP‐1 also showed a dynamic and concomitant translocation that was maximal on days 2–3, indicating calpain‐mediated disruption of the lysosomal membrane after ischemia. In contrast, immunoblotting demonstrated essentially no increase in the activated caspase‐3 at any time points after ischemia, despite upregulation of pro‐caspase‐3. Although expression of CAD was slightly upregulated on day 1 or 2, or both, it was much less compared with lymph node or intestine tissues. Furthermore, light and electron microscopy showed eosinophilic coagulation necrosis and membrane disruption without apoptotic body formation, while DNA electrophoresis did not show a ladder pattern, but rather a smear pattern. Sustained calpain activation and the resultant lysosomal rupture, rather than CAD‐mediated apoptosis, may cause ischemic neuronal necrosis in primates. © 2003 Wiley‐Liss, Inc.
Intracellular correlate of EPSP‐spike potentiation in CA1 pyramidal neurons is controlled by GABAergic modulation
Authors: Staff Nathan P. , Spruston Nelson
Published: October 2003

The hippocampus has been used extensively as a model to study plastic changes in the brain's neural circuitry. Immediately after high‐frequency stimulation to hippocampal Schaffer collateral axons, a dramatic change occurs in the relationship between the presynaptic CA3 and the postsynaptic CA1 pyramidal neurons. For a fixed excitatory postsynaptic potential (EPSP), there arises an increased likelihood of action potential generation in the CA1 pyramidal neuron. This phenomenon is called EPSP‐spike (E‐S) potentiation. We explored E‐S potentiation, using patch‐clamp techniques in the hippocampal slice preparation. A specific protocol was developed to measure the action potential probability for a given synaptic strength, which allowed us to quantify the amount of E‐S potentiation for a single neuron. E‐S potentiation was greatest when γ‐aminobutyric acid (GABA)ergic inhibition was intact, suggesting that modulation of inhibition is a major aspect of E‐S potentiation. Expression of E‐S potentiation also correlated with a reduced action‐potential threshold, which was greatest when GABAergic inhibition was intact. Conditioning stimuli produced a smaller threshold reduction when inhibition was blocked, but some reduction also occurred in the absence of a conditioning stimulus. Together, these results suggest that E‐S potentiation is caused primarily through a reduction of GABAergic inhibition, leading to larger EPSPs and reduced action potential threshold. Our findings do not rule out, however, the possibility that modulation of voltage‐gated conductances also contributes to E‐S potentiation. © 2003 Wiley‐Liss, Inc.
Expression of plasma membrane GABA transporters but not of the vesicular GABA transporter in dentate granule cells after kainic acid seizures
Authors: Sperk Günther , Schwarzer Christoph , Heilman Jutta , Furtinger Sabine , Reimer Richard J. , Edwards Robert H. , Nelson Nathan
Published: October 2003

Kainic acid‐induced seizures cause a marked increase in the expression of glutamate decarboxylase 67 (GAD67) in granule cells of the dentate gyrus. To determine the possible modes of sequestration of newly formed γ‐aminobutyric acid (GABA), we used in situ hybridization and immunocytochemistry to investigate the expression of several proteins related to GABA in dentate granule cells of rats 4 h to 60 days after kainic acid‐induced status epilepticus and in controls. GAD67 and GAD65 mRNA levels were increased by up to 300% and 800%, respectively, in the granule cell layer 6–24 h after kainate injection. Subsequently, increased GAD and GABA immunoreactivity was observed in the terminal field of mossy fibers and in presumed dendrites of granule cells. mRNA of both known plasma membrane GABA transporters (GAT‐1 and GAT‐3) was expressed in granule cells of control rats. GAT‐1 mRNA levels increased (by 30%) 9 h after kainate injection but were reduced by about 25% at later intervals. GAT‐3 mRNA was reduced (by 35–75%) in granule cells 4 h to 30 days after kainic acid injection. In contrast, no expression of the mRNA or immunoreactivity of the vesicular GABA transporter was detected in granule cells or in mossy fibers, respectively. GABA transaminase mRNA was only faintly expressed in granule cells, and its levels were reduced (by 60–65%) 12 h to 30 days after kainate treatment. The results indicate that GABA can be taken up and synthesized in granule cells. No evidence for the expression of the vesicular GABA transporter (VGAT) in granule cells was obtained. After sustained epileptic seizures, the markedly increased expression of glutamate decarboxylase and the reduced expression of GABA transaminase may result in increased cytoplasmic GABA concentrations in granule cells. It is suggested that, during epileptic seizures, elevated intracellular GABA and sodium concentration could then result in nonvesicular release of GABA from granule cell dendrites. GABA could then act on GABA‐A receptors, protecting granule cells from overexcitation. © 2003 Wiley‐Liss, Inc.
Increased levels of acidic calponin during dendritic spine plasticity after pilocarpine‐induced seizures
Authors: Ferhat Lotfi , Esclapez Monique , Represa Alfonso , Fattoum Abdellatif , Shirao Tomoaki , Ben‐Ari Yezekiel
Published: October 2003

We have previously shown that, in HEK 293 cells, overexpression of acidic calponin, an actin‐binding protein, induces remodeling of actin filaments, leading to a change in cell morphology. In addition, this protein is found in dendritic spines of adult hippocampal neurons. We hypothesized that this protein plays a role in regulating actin‐based filaments during dendritic spine plasticity. To assess this hypothesis, the pilocarpine model of temporal lobe epilepsy was selected because an important reorganization of the glutamatergic network, which includes an aberrant sprouting of granule cell axons, neo‐synaptogenesis, and dendritic spine remodeling, is well established in the dentate gyrus. This reorganization begins after the initial period of status epilepticus after pilocarpine injection, during the silent period when animals display a normal behavior, and reaches a plateau at the chronic stage when the animals have developed spontaneous recurrent seizures. Our data show that the intensity of immunolabeling for acidic calponin was clearly increased in the inner one‐third of the molecular layer of the dentate gyrus, the site of mossy fiber sprouting, and neo‐synaptogenesis, at 1 and 2 weeks after pilocarpine injection (silent period) when the reorganization was taking place. In contrast, in chronic pilocarpine‐treated animals, when the reorganization was established, the levels of labeling for acidic calponin in the inner molecular layer were similar to those observed in control rats. In addition, double immunostaining studies suggested that the increase in acidic calponin levels occurred within the dendritic spines. Altogether, these results are consistent with an involvement of acidic calponin in dendritic spine plasticity. © 2003 Wiley‐Liss, Inc.
Nitric oxide synthase and arginase in the rat hippocampus and the entorhinal, perirhinal, postrhinal, and temporal cortices: Regional variations and age‐related changes
Authors: Liu Ping , Smith Paul F. , Appleton Ian , Darlington Cynthia L. , Bilkey David K.
Published: October 2003

Increasing evidence suggests that nitric oxide synthase (NOS)/nitric oxide (NO) contributes to the aging process. By contrast, the role of arginase, which shares a common substrate with NOS, has not been determined. In the present study, regional variations and age‐related changes in NOS and arginase in the hippocampus and its neighboring structures were investigated for the first time. In young adult rats, high levels of NOS activity were found in the entorhinal, perirhinal, and postrhinal cortices, whereas low values were located in the hippocampus and the temporal cortex. Interestingly, arginase activity showed an overall inverse pattern with the lowest levels in the entorhinal and perirhinal cortices. When a comparison was carried out between young (4‐month‐old) and aged (24‐month‐old) rats, significant increases in total NOS activity were found in the aged entorhinal and temporal cortices, and a significant decrease in arginase activity was observed in the aged postrhinal cortex. Western blotting demonstrated significant decreases in both neuronal and endothelial NOS expression in the aged hippocampus and postrhinal cortex, whereas arginase I and II expression did not show age‐related changes in any region examined. Activity and protein expression of inducible NOS were not detected in any tissue from either group. The present findings of region‐specific changes in NOS and arginase appear to support the potential involvement of NOS/NO in the aging process and raise the issue of a possible contribution of arginase to aging. © 2003 Wiley‐Liss, Inc.
Reversal of breast cancer resistance protein–mediated drug resistance by tryprostatin A
Authors: Woehlecke Holger , Osada Hiroyuki , Herrmann Andreas , Lage Hermann
Published: October 2003

MDR in human cancers is one of the major causes of failure of chemotherapy. A member of the superfamily of ABC transporters, BCRP, was demonstrated to confer an atypical MDR phenotype to tumor cells. To overcome the BCRP‐mediated drug resistance, the fungal secondary metabolite TPS‐A, a diketopiperazine, was analyzed with regard to its potency to reverse the BCRP‐mediated drug‐resistant phenotype. At concentrations of 10–50 μM, TPS‐A reversed a mitoxantrone‐resistant phenotype and inhibited the cellular BCRP‐dependent mitoxantrone accumulation in the human gastric carcinoma cell line EPG85‐257RNOV, the human breast cancer cell line MCF7/AdrVp (both exhibiting acquired BCRP‐mediated MDR) and the BCRP cDNA‐transfected breast cancer cell line MCF‐7/BCRP clone 8. No cytotoxicity was seen at effective concentrations. These data indicate that TPS‐A is a novel BCRP inhibitor. © 2003 Wiley‐Liss, Inc.
15‐hydroxy‐eicosatetraenoic acid arrests growth of colorectal cancer cells via a peroxisome proliferator‐activated receptor gamma‐dependent pathway
Authors: Chen George G. , Xu Hu , Lee Janet F.Y. , Subramaniam Malayannan , Leung Ka L. , Wang Su H. , Chan Ursula P.F. , Spelsberg Thomas C.
Published: October 2003

Peroxisome proliferator‐activated receptor gamma (PPARγ) inhibits cell growth via promoting apoptosis. Human colorectal cancer tissues had abundant PPARγ but the incidence of apoptosis was very low, suggesting a defect in the PPARγ pathway. Here, we found that 15‐hydroxy‐eicosatetraenoic acid (15S‐HETE), an endogenous ligand for PPARγ, was significantly decreased in the serum of patients with colorectal cancer. Treatment of colon cancer cells with 15S‐HETE inhibited cell proliferation and induced apoptosis, which was preceded by an increase in TGF‐β‐inducible early gene (TIEG) and a decrease in Bcl‐2. The action of 15S‐HETE could be blocked when PPARγ was suppressed. Overexpression of Bcl‐2 prevented the apoptosis. The levels of TIEG and 15‐lipoxygenase (15‐LOX), the enzyme responsible for 15S‐HETE production, was decreased in colorectal cancer. Therefore, colorectal cancer is associated with decreased 15S‐HETE. Treatment of colon cancer cells with 15S‐HETE inhibits cell proliferation and induces apoptosis in a PPARγ‐dependent pathway involving augmentation of TIEG and reduction of Bcl‐2 expression. © 2003 Wiley‐Liss, Inc.
Autocrine motility factor signaling induces tumor apoptotic resistance by regulations Apaf‐1 and Caspase‐9 apoptosome expression
Authors: Haga Arayo , Funasaka Tatsuyoshi , Niinaka Yasufumi , Raz Avraham , Nagase Hisamitsu
Published: October 2003

Autocrine motility factor (AMF) is a cytokine that regulates locomotion and metastasis of tumor cells. It is well known that expression levels of AMF secretion and its receptor (AMF R) are closely related to tumor malignancy and rheumatoid arthritis. We have established that AMF signaling induced anti‐apoptotic activity and that human fibrosarcoma HT‐1080 line that secreted high levels of AMF were resistant to drug‐induced apoptosis. These cells did not express the apoptotic protease activating factor‐1 (Apaf‐1) and Caspase‐9 genes that encode for the proteins that form the “apoptosome” complex. The disappearance of the Apaf‐1 and Caspase‐9 gene was recovered by a cellular signaling inhibitor of protein kinase C, phosphatidylinositol 3‐phosphate kinase and mitogen‐activated protein kinase of the in vitro cultured human fibrosarcoma HT‐1080 line. Treatment with these inhibitors favored apoptotic cell death induced by anti‐cancer drugs of the murine ascites Ehrlich line. Apoptotic resistance of tumor cells allows them to escape death from cancer chemotherapy, so an understanding of malignant anti‐apoptotic activities is important. Antibodies against AMF induced Ehrlich ascites apoptosis in vitro, and effectively aided in vivo apoptosis induced by anti‐cancer drugs. The results might indicate a novel route by which tumor cells protect themselves with products, such as AMF, and proliferate despite various stresses and chemical insults; AMF regulates expression of Apaf‐1 and caspase‐9 genes via a complex signaling pathway and indirectly regulates formation of the apoptosome. © 2003 Wiley‐Liss, Inc.