bluuebunny/crossref_metadata_2025 huggingface dataset:
Photonic Crystal Composites with Reversible High‐Frequency Stop Band Shifts
Authors: Foulger S.H. , Jiang P. , Lattam A. , Smith D.W. , Ballato J. , Dausch D.E. , Grego S. , Stoner B.R.
Published: April 2003

The fabrication of photonic crystal composites composed of encapsulated electrostatically stabilized colloidal arrays with tailorable thermomechanical properties is introduced. Composites with sub‐ambient Tg exhibited reversible mechanochromic characteristics and a 172 nm stop‐band tuning range, and could be modulated up to frequencies of 200 Hz. The Figure shows reflective characteristics of the composites at different strain levels (see also inside front cover).
Vulcanization kinetics of natural rubber–organoclay nanocomposites
Authors: López‐Manchado M. A. , Arroyo M. , Herrero B. , Biagiotti J.
Published: April 2003

The effect of the incorporation of a bentonite on the vulcanization kinetics of natural rubber was investigated by means of both cure‐meter testing and differential scanning calorimetry (DSC) under dynamic and isothermal conditions. The vulcanization curves showed that the modified clay behaved as an effective vulcanizing agent, accelerating the vulcanization reaction of the elastomer. A marked decrease in the induction time and optimum cure time of the elastomer were observed in the presence of the organoclay. Although the octadecylamine itself accelerated the vulcanization process, the octadecylamine‐modified clay gave rise to a further noticeable increase in the vulcanization rate, which could be attributed to a synergetic effect between the filler and the amine. Moreover, in the presence of the organoclay, a dramatic increase in the torque value was obtained because of the formation of a higher number of crosslinks, which could be attributed to the confinement of the elastomer chains within the silicate galleries and, consequently, to better interactions between the filler and the rubber. However, no significant changes were observed in the unmodified clay composite. These results were in concordance with those obtained by DSC. In addition, the activation energy of the vulcanization process was also calculated by means of both techniques. A clear decrease in the activation energy was observed when the organoclay was added to the nanocomposite, which indicated that the layered silicate favored the processing of the elastomer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1–15, 2003
Development of a toughened DGEBS/DDS system toward improved thermal and mechanical properties by the addition of a tetrafunctional epoxy resin and a novel thermoplastic
Authors: Blanco Ignazio , Cicala Gianluca , Faro Carmelo Lo , Recca Antonio
Published: April 2003

It was the object of the present article to discuss the effect of the addition of a tetrafunctional resin, namely, tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM), and of a novel 40:60 polyethersulfone:polyetherethersulfone (PES:PEES) copolymer on a blend constituted by a difunctional resin, diglycidyl ether of bisphenol S (DGEBS), and an aromatic ammine, 4,4′‐diaminodiphenylsulfone (4,4′DDS). The formulated blends were fully characterized in terms of the morphology and the viscoelastic and mechanical properties. The modification by the tetrafunctional resin was proved to be a useful means to improve the glass transition temperature and, therefore, to widen the range of the working temperature. The addition of the novel copolymer resulted in a marked increase in toughness without negatively affecting the thermal and elastic properties of the blend. TEM analysis, despite the high amount of thermoplastic used, showed a homogeneous morphology that would lead to the conclusion of the existence of a full‐IPN network. Moisture‐uptake experiments were conducted both on the blend and on the resins on their own. It was shown that the combination of the difunctional resin with the tetrafunctional led to a decrease of the percent of the water absorbed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 268–273, 2003
Study on adsorption behavior between Cr(VI) and crosslinked amphoteric starch
Authors: Xu Shi‐Mei , Zhang Shu‐Fen , Lu Rong‐Wen , Yang Jin‐Zong , Cui Chang‐Xi
Published: April 2003

Crosslinked amphoteric starches (CASs) with quaternary ammonium cationic and carboxymethyl anionic groups were prepared by a hemidry reaction. Their adsorption behavior for Cr(VI) was investigated, and was found to follow the Langmuir isotherm. The adsorption process was found to be dependent on initial pH, concentration of Cr(VI), dose of CAS, and temperature. The adsorption capacity decreased with increasing degree of substitution of anionic groups. The thermodynamic study indicated that the adsorption process was exothermic, and the enthalpy changes (ΔHθ), the entropy changes (ΔSθ), and free energy changes (ΔGθ) for CASs were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 263–267, 2003
Development of a maize molecular evolutionary genomic database
Authors: Du Chunguang , Buckler Edward , Muse Spencer
Published: April 2003

PANZEA is the first public database for studying maize genomic diversity. It was initiated as a repository of genomic diversity for an NSF Plant Genome project on ‘Maize Evolutionary Genomics’. PANZEA is hosted at the Bioinformatics Research Center, North Carolina State University, and is open to the public (http://statgen.ncsu.edu/panzea). PANZEA is designed to capture the interrelationships between germplasm, molecular diversity, phenotypic diversity and genome structure. It has the ability to store, integrate and visualize DNA sequence, enzymatic, SSR (simple sequence repeat) marker, germplasm and phenotypic data. The relational data model is selected and implemented in Oracle. An automated DNA sequence data submission tool has been created that allows project researchers to remotely submit their DNA sequence data directly to PANZEA. On‐line database search forms and reports have been created to allow users to search or download germplasm, DNA sequence, gene/locus data and much more, directly from the web. Copyright © 2003 John Wiley & Sons, Ltd.
Dlx‐1 and Dlx‐2 expression in the adult mouse brain: Relationship to dopaminergic phenotypic regulation
Authors: Saino‐Saito Sachiko , Berlin Roseann , Baker Harriet
Published: April 2003

Expression of the homeodomain‐containing transcription factors Dlx‐1 and Dlx‐2 in the lateral (LGE) and medial (MGE) ganglionic eminences, subpallial embryonic structures, is required for generation of telencephalic interneurons. LGE‐ and MGE‐derived progenitors migrate and populate a number of forebrain structures, including the cortex, hippocampus, and olfactory bulb (OB). Previous reports focusing on embryogenesis of telencephalic neurons in Dlx‐1 and Dlx‐2 null mice suggested a specific role for these genes in expression of the OB dopamine (DA) phenotype. We have investigated whether these genes also are expressed in adult brain, especially in those pallial derivatives, such as the OB, hippocampus, and possibly cortex, where neurogenesis continues in adults. With a highly sensitive, nonradioactive in situ hybridization technique and both DLX‐2 and pan DLX antisera, widespread expression of both genes was found in adult mouse fore‐ but not mid‐ or hindbrain. The adult unilateral naris closure paradigm was employed to establish a causative role for Dlx in regulating tyrosine hydroxylase (TH) expression; TH is the first enzyme in DA biosynthesis. TH mRNA, but not Dlx expression, was significantly down‐regulated in the OB ipsilateral to closure. These findings suggest that Dlx‐1 and ‐2 do not play a direct role in DA phenotypic differentiation and TH gene regulation in adult OB. The widespread expression of Dlx mRNA and protein in the adult brain suggests that these genes may have additional roles in mature animals. J. Comp. Neurol. 461:18–30, 2003. © 2003 Wiley‐Liss, Inc.
Topological charge of the real periodic finite‐gap Sine‐Gordon solutions
Authors: Grinevich P. G. , Novikov S. P.
Published: April 2003

An effective description of the inverse spectral data corresponding to the real periodic and quasi‐periodic finite‐gap (algebro‐geometrical) solutions for the sine‐Gordon equation is obtained. In particular, the explicit formula for the so‐called topological charge of the solutions is found and proven. As was already understood 20 years ago, it is very hard to extract any formula for this quantity from the Θ‐functional expressions. A new method was developed by the authors for this goal. In Appendix C an analogue of the Fourier‐Laurent integral transform on the Riemann surface is defined, based on the constructions of soliton theory. It is a natural continuous analogue of the discrete Krichever‐Novikov bases developed in the late 1980s for the needs of the operator quantization of string theory. © 2003 Wiley Periodicals, Inc.
Effect of pulsatile administration of levodopa on dyskinesia induction in drug‐naïve MPTP‐treated common marmosets: Effect of dose, frequency of administration, and brain exposure
Authors: Smith Lance A. , Jackson Michael J. , Hansard Matthew J. , Maratos Eleni , Jenner Peter
Published: April 2003

Levodopa (L‐dopa) consistently primes basal ganglia for the appearance of dyskinesia in parkinsonian patients and 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine hydrochloride (MPTP) ‐treated primates. This finding may reflect its relatively short duration of effects resulting in pulsatile stimulation of postsynaptic dopamine receptors in the striatum. We have compared the relationship between L‐dopa dose and frequency of administration on dyskinesia initiation in drug‐naïve, MPTP‐treated common marmosets. We have also studied the effect of increased brain exposure to pulsatile administration by combining a low‐dose of L‐dopa with the peripheral catechol‐O‐methyltransferase inhibitor (COMT‐I), entacapone. Pulsatile administration of a low (dose range, 5.0–7.5 mg/kg p.o.) or a high (12.5 mg/kg) dose of L‐dopa plus carbidopa b.i.d. produced a dose‐related reversal of motor deficits. Repeated administration of low and high doses of L‐dopa for 26 days to drug‐naïve, MPTP‐treated animals also caused a dose‐related induction of peak‐dose dyskinesia. Repeated administration of high‐dose L‐dopa b.i.d. compared to once daily caused a frequency‐related improvement of motor symptoms, resulting in a more rapid and initially more intense appearance of peak‐dose dyskinesia. Administration of low‐dose L‐dopa b.i.d. for 26 days in combination with entacapone enhanced the increase in locomotor activity and reversal of disability produced by L‐dopa alone, but with no obvious change in duration of L‐dopa's effect. However, combining entacapone with L‐dopa resulted in the more rapid appearance of dyskinesia, which was initially more severe than occurred with L‐dopa alone. Importantly, increasing pulsatile exposure of brain to L‐dopa by preventing its peripheral breakdown also increases dyskinesia induction. © 2003 Movement Disorder Society
Effect of short glass fiber on structure and viscoelastic behavior of olefinic polymers synthesized with metallocene catalyst
Authors: Martínez‐Burgos J. M. , Benavente R. , Pérez E. , Cerrada M. L.
Published: April 2003

Several composites were prepared on the basis of an ethylene homopolymer and different copolymers of ethylene and 1‐hexene, synthesized with a metallocene catalyst, as matrices and a content of a 5 wt % of short glass fiber. The effect of the fiber incorporation on the structure and mechanical and viscoelastic behaviors was analyzed for the different samples. The glass fibers induced a slightly higher crystallinity, and the crystallite morphology significantly changed (long spacings and crystal orientation). The incorporation of fibers did not reinforce the different matrices under study at this low content; consequently, the mechanical parameters, such as Young's modulus, yielding stress, and microhardness, were lower in the composites as compared with those values found in the neat polyolefins. The location and apparent activation energies of distinct relaxation processes are also discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1244–1255, 2003
DNA degradation by water extract of green tea in the presence of copper ions: implications for anticancer properties
Authors: Malik Arshi , Azam Sonish , Hadi Naghma , Hadi S. M.
Published: April 2003

In recent years a number of reports have documented the chemopreventive effect of green tea consumption on various types of cancers such as those of bladder, prostate, esophagus and stomach. This property is attributed to the presence in green tea of polyphenols known as catechins. These include epigallocatechin‐3‐gallate, epigallocatechin and epicatechin. In addition to their antioxidant properties plant derived polyphenolics are also capable of oxidative DNA damage particularly in the presence of transition metal ions. We have recently proposed a mechanism for cytotoxic action of plant‐derived polyphenols against cancer cells that involves mobilization of endogenous copper and consequent prooxidant action. In partial support of the idea, in the present paper we show that water extract of green tea is considerably more efﬁcient than black tea extract in DNA cleavage in the presence of copper ions. Green tea extract also shows a higher rate of Cu(II) reduction and consequent hydroxyl radical formation. Cu(II) reduction is presumably accompanied by the formation of ‘oxidized species’ of tea polyphenols, which in turn also appear to catalyze the reduction of Cu(II) leading to redox cycling of copper ions. The results are discussed in relation to the structural differences between polyphenols of green and black tea. Copyright © 2003 John Wiley & Sons, Ltd.
Antinociceptive, antiinﬂammatory and acute toxicity effects of Salvia leriifolia Benth. seed extract in mice and rats
Authors: Hosseinzadeh Hossein , Haddadkhodaparast Mohammad H. , Arash Ali R.
Published: April 2003

The antinociceptive and antiinﬂammatory effects as well as the acute toxicity of Salvia leriifolia aqueous seed extract were studied in mice and rats. Antinociceptive activity was assessed using the hot‐plate and tail ﬂick tests. The effect on acute inﬂammation was studied using vascular permeability increased by acetic acid and xylene‐induced ear oedema in mice. The activity against chronic inﬂammation was assessed using the cotton pellet test in rats. The LD50 of the extract was found to be 19.5 g/kg (i.p.) in mice. The aqueous seed extract showed signiﬁcant and dose‐dependent (1.25–10 g/kg) antinociceptive activity over 7 h, and was inhibited by naloxone pretreatment. Signiﬁcant and dose‐dependent (2.5–10 g/kg) activity was observed against acute inﬂammation induced by acetic acid and in the xylene ear oedema test. In the chronic inﬂammation test the extract (2.5–5 g/kg) showed signiﬁcant and dose‐dependent antiinﬂammatory activity. The aqueous seed extract of S. leriifolia may therefore have supraspinal antinociceptive effects which may be mediated by opioid receptors, and showed considerable effects against acute and chronic inﬂammation. Copyright © 2003 John Wiley & Sons, Ltd.
The protein fold of the von Willebrand factor type A domain is predicted to be similar to the open twisted β‐sheet flanked by α‐helices found in human ras‐p21
Authors: Edwards Yvonne J.K. , Perkins Stephen J.
Published: April 2003

The von Willebrand Factor type A domain is the prototype for a protein superfamily. It possesses no significant sequence similarity to any known protein structure. Secondary structure predictions indicate a largely alternating pattern of six α‐helices and six β‐strands. A protein fold for this domain is proposed to correspond to a doubly‐wound open twisted β‐sheet structure flanked by α‐helices. Close agreement was found with the GTP‐binding domain of human ras‐p21, provided that an extra α‐helix was inserted. The structure of the predicted fold showed high compatibility with the proximate location of two Mg2+‐binding Asp residues, two disulphide‐bridged Cys residues, and other known functional attributes of this domain.
The effect of iron status on glyceraldehyde 3‐phosphate dehydrogenase expression in rat liver
Authors: Quail Elizabeth A. , Yeoh George C.T.
Published: April 2003

The influence of iron status on glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) gene transcription, mRNA levels and distribution was determined in whole liver samples from adult Wistar rats. While iron loading did not alter GAPDH expression, iron deficiency evoked a 2.3‐fold increase in the steady‐state level of liver GAPDH mRNA, but did not affect gene transcription or intracellular localisation of the message. Therefore, the over‐expression of GAPDH mRNA in iron deficiency is probably due to increased message stability.
The proteasome from Thermoplasma acidophilum is neither a cysteine nor a serine protease
Authors: Seemüller Erika , Lupas Andrei , Zühl Frank , Zwickl Peter , Baumeister Wolfgang
Published: April 2003

The 20 S proteasome, found in eukaryotes and in the archaebacterium Thermoplasma acidophilum, forms the proteolytic core of the 26 S proteasome which is the central protease of the non‐lysosomal protein degradation pathway. Inhibitor studies have indicated that the 20 S proteasome may be an unusual type of cysteine or serine protease and a recent study of the Thermoplasma β subunit has indicated that it carries the proteolytic activity. We have attempted to obtain information on the nature of the active site by mutating the only cysteine, both histidines and two completely conserved aspartates in the archaebacterial complex as well as all serines of the β subunit, without decreasing the catalytic activity of the enzyme to any significant extent. Indeed, mutation of the conserved aspartate in the β subunit increased the activity of the proteasome threefold. We conclude that the proteasome is not a cysteine or serine protease.
Purification, crystallisation and preliminary X‐ray analysis of the vanadium‐dependent haloperoxidase from Corallina officinalis
Authors: Rush Cliff , Willetts Andrew , Davies Gideon , Dauter Zbigniew , Watson Herman , Littlechild Jennifer
Published: April 2003

The vanadium‐dependent haloperoxidase from the seaweed Corallina officinalis has been purified to homogeneity and crystallised. The protein is reported to be a hexamer of 12 × 64,000 Da, contains no haem, and is dependent on vanadium for activity. The crystals are grown from polyethylene glycol (PEG) 6,000 and 0.4 M potassium chloride. They are stable and diffract to better than 2 Å resolution. They are of a cubic space group I23 (or I2,3) with cell dimensions .
Association of high molecular weight DNA fragmentation with apoptotic or non‐apoptotic cell death induced by calcium ionophore
Authors: Kataoka Akihiro , Kubota Masaru , Wakazono Yoshihiro , Okuda Akiro , Bessho Rikimaru , Ying Wei Lin  , Usami Ikuya , Akiyama Yuichi , Furusho Kenshi
Published: April 2003

Calcium ionophore (A23187)‐induced high molecular weight (HMW) and internucleosomal DNA fragmentation were investigated in human leukemia cell lines. An apoptosis‐sensitive cell line, HL‐60, showed HMW, internucleosomal DNA fragmentation and morphological changes of apoptosis by A23187. MOLT‐4, which is resistant to apoptosis, exhibited only HMW DNA fragmentation and died of necrosis under the same conditions. Autodigestion experiments suggested the endonucleolytic activity to cause HMW fragmentation in the cytoplasm of both cell lines. The activity was more dependent on Mg2+ than Ca2+ in HL‐60, whereas it was Ca2+‐dependent in MOLT‐4. These results suggest that HMW DNA fragmentation is not specific to apoptosis.
Thermostable chimeric PQQ glucose dehydrogenase
Authors: Sode Koji , Watanabe Kazumoto , Ito Shunsuke , Matsumura Kazunori , Kikuchi Tomoko
Published: April 2003

The thermal stability of PQQ glucose dehydrogenases (PQQGDHs) which were chimeras with more than 95% made up of the N‐terminal region of Escherichia coli PQQGDH and the rest made up of the C‐terminal region of Acinetobacter calcoaceticus PQQGDHswas investigated. Among the chimeric PQQGDHs, E97A3 (E. coli 97% and A. calcoaceticus 3%) and E9545 were found to possess higher thermal stability than parental E. coli PQQGDH. Further detailed characterization of the thermal stability was carried out, focusing on E97A3. E97A3 showed a more than 3‐fold and 12‐fold increase in half life time at 40°C, compared with the PQQGDHs of E. coli and A. calcoaceticus, respectively. Using transition state theory, the increase in the free energy of inactivation observed in E97A3 was compared with those of the E. coli and A. calcoaceticus parental enzymes. The region responsible for this stabilization was also discussed.
Cloning of a Syrian hamster cDNA related to sexual dimorphism: establishment of a new family of proteins
Authors: Domínguez Pedro
Published: April 2003

The clone FHG22, isolated from a female minus male subtracted cDNA library obtained from the sexually dimorphic Syrian hamster Harderian glands (HG) is 440 bp long with a 95 amino acids ORF, and hybridizes to a female HG‐specific 0.6 kb mRNA. The FHG22 nucleotide and amino acid sequences are similar to the subunits from prostatein, uteroglobin, major cat allergen Fel dI (chain 1) and mouse salivary androgen binding proteins (subunit α). Therefore I propose that all those polypeptides belong to a common new family. The hamster genome has a single copy of the FHG22 gene, without homologous genes. FHG22 mRNA is also found in male and female parotid (higher levels in females) and submandibular glands, indicating a tissue and sex‐dependent control of expression.
Nitric oxide synthase in chick embryo retina during development
Authors: Ientile Riccardo , Malecka Bozena , Picciurro Vincenzo , Naso Antonio , Pedale Santa , Macaione Salvatore
Published: April 2003

High levels of nitric oxide synthase were found in the early stages of developing chick embryo retina. The enzyme activity sharply decreased up to 13‐day‐old chick embryo retina, when the level of the last embryonic day was reached. The results show that nitric oxide is synthesized in chick embryo retina prior to synaptogenesis. The incubation of chick embryo retinas in presence of NMDA increased the synthesis of nitric oxide, thus, the appearance of nitric oxide production before the synaptogenesis in the retina as well as in the brain may be considered as signal for the development and shaping of neuronal and non‐neuronal cells.
Protein tyrosine kinase inhibitors prevent didemnin B‐induced apoptosis in HL‐60 cells
Authors: Johnson Karina L. , Vaillant François , Alfons Lawen
Published: April 2003

Didemnin B induces rapid apoptosis in human promyeloid HL‐60 cells with an optimal concentration of 1 μM (Grubb et al. (1995) Biochem. Biophys. Res. Commun. 215, 1130–1136), but little is known about how it does so. In order to determine whether protein tyrosine phosphorylation is involved in this rapid induction of apoptosis, HL‐60 cells were pre‐treated with tyrosine kinase inhibitors for 1 h before didemnin B treatment. Genistein, 2,5‐dihydroxycinnamic acid methyl ester, and a range of tyrphostins inhibit didemnin B‐induced apoptotic morphology in a concentration‐dependent manner. DNA fragmentation induced by didemnin B is also inhibited by genistein, 2,5‐dihydroxycinnamic acid methyl ester, and tyrphostins.
Met‐enkephalin induces cytolytic processes of apoptotic type in K562 human erythroid leukemia cells
Authors: Mernenko Olga A. , Blishchenko Elena Yu. , Mirkina Irina I. , Karelin Andrey A.
Published: April 2003

Cytolytic activity of Met‐enkephalin, an endogenous opioid peptide, was studied within the 10−7−10−17 M concentration range in K562 human erythroid leukemia cells. Cytolytic activity was determined by the trypan blue inclusion method after 13, 15 and 18 h of Met‐enkephalin co‐incubation with target cells. Discrete maxima of cytolytic activity were detected at concentrations of 10−9−10−10, 10−13 and 10−15 M. Cytolysis was accompanied by internucleosomal DNA fragmentation which is indicative of the mechanism of cell death being apoptosis.
Hyaluronan‐binding properties of human serum hemopexin
Authors: Hrkal Z. , Kuzelová K. , Muller-Eberhard U. , Stern R.
Published: April 2003

Hemopexin, the heme‐binding serum glycoprotein, exhibits a complex electrophoretic pattern on two‐dimensional immunoelectrophoresis on agarose gels into which hyaluronic acid is incorporated in the first and monospecific anti‐hemopexin in the second dimension. This heterogeneity reflects a range of interactions of hemopexin isoforms with hyaluronic acid. Electrophoretic patterns of individual human sera greatly differ in their contents of hyaluronan‐interacting hemopexin species. Hemopexin itself has no hyaluronidase activity.
Induction of β‐methylcrotonyl‐coenzyme A carboxylase in higher plant cells during carbohydrate starvation: evidence for a role of MCCase in leucine catabolism
Authors: Aubert Serge , Alban Claude , Bligny Richard , Douce Roland
Published: April 2003

Induction of β‐methylcrotonyl‐coenzyme A carboxylase (MCCase) activity was observed during carbohydrate starvation in sycamore cells. In mitochondria isolated from starved cells, we noticed a marked accumulation of the biotinylated subunit of MCCase, of which the apparent molecular weight of 74 000 was similar to that of the polypeptide from mitochondria of potato tubers. Our results provide evidence for a role of MCCase in the catabolic pathway of leucine, a branched‐chain amino acid which transiently accumulates in carbon‐starved cells in relation to a massive breakdown of proteins. Furthermore, when control sycamore cells were incubated in the presence of exogenous leucine, this amino acid accumulated in the cells and no induction or accumulation of MCCase was observed, indicating that leucine is not responsible for the induction of its catabolic machinery. Finally, MCCase is proposed as a new biochemical marker of the autophagic process triggered by carbohydrate starvation.
Cholecystokinin receptor antagonist, loxiglumide, inhibits invasiveness of human pancreatic cancer cell lines
Authors: Hirata Manabu , Itoh Masaki , Tsuchida Akira , Ooishi Hideo , Hanada Keiji , Kajiyama Goro
Published: April 2003

Recently, cholecystokinin has been reported to be important in regulating the growth of pancreatic cancer. We investigated the effect of loxiglumide (LXG), a cholecytskinin receptor antagonist, on the invasiveness of two human pancreatic cancer cell lines. Cells were treated with LXG for 24 h, and examined in the invasion assay. The expression and activity of MMP‐9 in supernatants from cancer cells were analyzed by Western blotting and zymogram. Interestingly, the invasiveness of cancer cells and expression of MMP‐9 were decreased by LXG in a dose‐dependent manner. LXG may be a useful therapeutic agent against pancreatic cancer.
Ion channel properties of a protein complex with characteristics of a glutamate/N‐methyl‐d‐aspartate receptor
Authors: Aistrup Gary L. , Szentirmay Marilyn , Kumar Keshava N. , Babcock Kent K. , Schowen Richard L. , Michaelis Elias K.
Published: April 2003

The functional reconstitution of glutamate receptor proteins purified from mammalian brain has been difficult to accomplish. However, channels activated by l‐glutamate (L‐Glu) and N‐methyl‐d‐aspartate (NMDA) were detected in planar lipid bilayer membranes (PLMs) following the reconstitution of a complex of proteins with binding sites for NMDA receptor (NMDAR) ligands. The presence of glycine was necessary for optimal activation. A linear current‐voltage relationship was observed with the reversal potential being zero. Channels activated by L‐Glu had conductances of 23, 47 and 65 pS, and were suppressed partially by competitive and fully by non‐competitive inhibitors of NMDARs. Magnesium had little effect on the reconstituted channels.
Tamoxifen retards glycosphingolipid metabolism in human cancer cells
Authors: Cabot Myles C. , Giuliano Armando E. , Volner Alon , Han Tie-Yan
Published: April 2003

In this study we provide evidence that tamoxifen, the widely used breast cancer drug, is a potent antagonist of glycolipid metabolism. When added to the medium of cultured multidrug resistant (MDR) KB‐V‐1 carcinoma cells, tamoxifen, at 5.0 μM, drastically lowered the levels of glucosylceramide (glc‐cer), as evidenced by a reduction in glc‐cer mass. In a similar fashion, in cultured human melanoma cells grown with [3H]galactose, tamoxifen inhibited formation of glc‐cer by 44%, and retarded lactosylceramide and ganglioside formation by 50 and 35%, respectively. When glc‐cer synthase of melanoma was assayed in cell‐free incubations, the inclusion of tamoxifen, at a 1:10 molar ratio with ceramide, inhibited glc‐cer synthesis by 50%. These results clearly reveal a new action of tamoxifen and thereby pose intriguing questions regarding mechanisms of action in the realm of estrogen receptor‐independent modalities, including effects on MDR.
Acrosome membrane associated protein kinase activity in hamster spermatozoa
Authors: Devi K.Uma , Ahmad M.Basheer , Shivaji S.
Published: April 2003

Acrosomal membranes isolated from the caput and cauda epididymal spermatozoa of hamster exhibited protein kinase activity and the endogenous protein substrates that were phosphorylated in the acrosomal membranes of caput and cauda spermatozoa were not all the same. The kinase activity was identified as a cAMP independent type and the use of specific stimulators and inhibitors indicated that the activity was not due to casein kinase, protein kinase A or protein kinase C but due to a tyrosine specific protein kinase that was not inhibited by Genistein. Phosphotyrosine was identified as the predominant phosphorylated residue in the proteins.
Sodium nitroprusside inhibits proliferation and putrescine synthesis in human colon carcinoma cells
Authors: Blachier F. , Robert V. , Selamnia M. , Mayeur C. , Duee P.H.
Published: April 2003

In human colon carcinoma HT‐29 Glc−/+ cells, l‐arginine is the common precursor of polyamines which are absolutely necessary for cellular proliferation and nitric oxide (NO) with reported anti‐proliferative activity. The aim of the present work was to test the effect of the NO donor sodium nitroprusside (SNP) on polyamine synthesis and cellular growth in HT‐29 cells. SNP in the micromolar range inhibits cellular putrescine synthesis and this effect is greatly reversed by haemoglobin, supporting the view that the effect of SNP is related to the generation of NO. This corresponds to the inhibition by SNP of ornithine decarboxylase activity. Furthermore, SNP inhibits cellular proliferation. The effect of SNP is reversed by haemoglobin after 2 days of treatment but not after 4 days. Although no acute toxic effect of SNP was detected after 90 min incubation, it greatly enhanced the cellular death rate after several days in culture as estimated by the LDH leakage test. In conclusion, our data raise the possibility of an inhibitory interrelationship between NO and polyamine metabolic pathways. NO induced inhibition of putrescine synthesis and growth in HT‐29 cells is discussed from a causal perspective.
Strategic operations management decisions and professional performance in U.S. HMOs
Authors: Heineke Janelle
Published: April 2003

Professional service organizations are becoming an increasingly important segment of the service sector in the U.S. but little attention has been paid to the management of these organizations, particularly in relation to technical performance. This paper reports the findings of a survey of managers of Health Maintenance Organizations (HMOs) which related operations management decisions about organization, workforce management, quality management and planning and control, to clinical process and outcome performance.

This research demonstrates that managerial decisions do affect clinical performance in HMOs. These findings have implications for both researchers and practitioners. For researchers, the study provides a framework for future research on the important link between management decisions and technical performance in professional service organizations. For practitioners, this study suggests that technical performance will be enhanced when professional work is appropriately managed.
Synapse selection based on differences in synapse turnover
Authors: Thompson Jeffrey M. , Eisenbarth George S. , Ruffolo Robert R. , Nirenberg Marshall
Published: April 2003

Rat retinal neurons formed transient synapses with rat muscle cells in culture only during a discrete period in development, from the 20th day of embryonic development to the 7th neonatal day. In contrast, chick embryo spinal cord neurons formed synapses at all developmental stages tested, from the 2nd to the 18th day of embryonic development. The percentage of cells from the spinal cord that formed synapses with muscle cells was maximum at 4 days of embryonic development and decreased thereafter. However, the number of synapses with muscle formed by cells from 8‐day embryonic spinal cord did not decrease during 14 days of culture. Under identical conditions, all synapses formed between rat retinal neurons and muscle cells were terminated during 7 days of culture. These results show that differences in the rates of turnover of two populations of cholinergic synapses can result in the selective retention of one population of synapses and the loss of the other, and thereby alter the specificity of synaptic connections.
Serotonin as a stimulator of hippocampal cell differentiation in tissue culture
Authors: Gromova H. A. , Chubakov A. R. , Chumasov E. I. , Konovalov H. V.
Published: April 2003

The effects of serotonin (5‐HT) on morphofunctional development of hippocampal cultures derived from newborn rats were studied. It was established that systematic addition of 5‐HT to nutrient medium during cultivation stimulates neuropil development, axon myelination and synaptogenesis. Electrophysiological studies of hippocampal cells in 5‐HT treated cultures showed earlier exhibition of spontaneous activity and an increased number of spontaneously firing neurons and prevalence of periodic (bursting) type of discharges. These results indicate that 5‐HT stimulates the differentiation of hippocampal cells in tissue culture.
Immunohistochemical and biochemical approaches to the development of neuroglia in the CNS, with special reference to cerebellum
Authors: Ghandour M. S. , Langley O. K. , Clos J.
Published: April 2003

Immunocytochemical methods have in recent years played a more important role in investigations of the development and function of glial cells in the nervous system because of their potential to distinguish between different cell populations. This short review attempts to highlight the value of this approach and summarizes the major cell‐type markers currently available. These include, for the astrocyte, GFA protein, S‐100 protein, vimentin, αα‐enolase and α‐2 glycoprotein. For the oligodendrocyte, myelin basic protein, the Wolfgram proteins, 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase, myelin associated glycoprotein, proteolipid protein, galactocerebroside, carbonic anhydrase and glycerol 3‐phosphate dehydrogenase and other glial cell markers recognized by monoclonal antibodies are discussed. The application of these techniques to the study of the developing brain (and in particular the rodent cerebellum) are reviewed. It has proved possible to follow the development of distinct populations of astrocytes and oligodendrocytes from a very precocious age to the adult situation, thus providing new insight on the relationship between glial cells and neurons during normal and abnormal histogenesis.
GABA influences the ultrastructure composition of cerebellar granule cells during development in culture
Authors: Hansen Gert H. , Meier Eddi , Schousboe Arne
Published: April 2003

The influence of GABA on cerebellar granule cells in culture was followed morphometrically during in vitro development by growing the cells in the absence or presence of 50 μM GABA. The presence of GABA in the culture media increased the number of neurite‐extending cells by 50% after 7 days in culture. At the ultrastructural level GABA treatment led to an increased density of neurotubules, rough endoplasmic reticulum, Golgi apparatus, coated vesicles and other vesicles, whereas structures such as mitochondria and smooth endoplasmic reticulum were not affected by GABA. The density of free ribosomes showed a more pronounced tendency to decrease as a function of the culture period (1–7 days) when the cells were grown in the presence of GABA as compared to control cultures. The results strongly indicate that GABA in addition to being an important neurotransmitter serves as a trophic factor in the development of at least certain types of neurons.
Monosialoganglioside internal ester stimulates the dopaminergic reinnervation of the striatum after unilateral hemitransection in rat
Authors: Aldinio Caterina , Valenti Giacomina , Savoini Gian Enrico , Kirschner Guenter , Agnati Luigi F. , Toffano Gino
Published: April 2003

The effects of the administration of GM1 monosialoganglioside internal ester, AGF2, on the dopaminergic reinnervation of the striatum in rats with unilateral hemitransection has been studied. AGF2 increases the apparent Vmax and the density of tyrosine‐hydroxylase‐positive nerve terminals in the striatum of the lesioned side, without modification of the tyrosine‐hydroxylase activity in the unlesioned side. AGF2, at lower doses, is more active than its parent natural molecule GM1. AGF2 has a larger half‐life and a higher distribution volume than GM1, and undergoes a slow hydrolysis in the serum releasing the original natural compound GM1. Mannitol and dexamethazone, often used to prevent swelling of the brain after injury, or isoaxonine, proposed to stimulate neurite growth are unable to reproduce the effects of AGF2 on the recovery of striatal tyrosine‐hydroxylase activity after hemitransection. The data are compatible with the view that AGF2, through its conversion into GM1, facilitates the collateral sprouting of the nigro‐striatal dopaminergic neurons.
Modification of taurine and hypotaurine uptake systems in cultured primary astrocytes by serum‐free medium and dibutyryl cyclic AMP treatment
Authors: Holopainen I.
Published: April 2003

The characteristics of taurine and hypotaurine uptake were studied during astrocyte maturation in cultures grown in normal, serum‐containing medium or in serum‐free medium in the presence of 0.1 mmol/l dibutyryl cyclic AMP (dBcAMP). The uptake of both amino acids consisted of one saturable high‐affinity component in both control and treated cultures. The dBcAMP treatment produced no marked modification of the transport systems. In the treated cultures the kinetic parameters of taurine and hypotaurine uptake remained unaltered during maturation. In the control cells the transport constant and maximal velocity of taurine uptake were greater in 21‐day‐old than in 16‐day‐old cultures, while the changes in hypotaurine transport were the opposite. The uptakes were strictly sodium‐dependent and also considerably decreased when potassium ions were omitted from incubation medium. The uptake of both amino acids was affected more by potassium omission in the dBcAMP‐treated than in the control cultures. Also the results with metabolic poisons suggest that physiological ion gradients sustained by an active Na+, K+‐pump are essential for the normal uptake of taurine and hypotaurine.
Comparison of embryonic and adult torpedo acetylcholine receptor by sedimentation characteristics and antigenicity
Authors: Holton Beatrice , Tzartos Socrates J. , Changeux Jean‐Pierre
Published: April 2003

The acetylcholine receptor (AChR) from Torpedo marmorata electric organ exists in a light form (α2βγδ) of apparent molecular weight 250,000. The association of two light forms via an intermolecular δ‐δ disulfide bridge results in the AChR heavy form. In adult Torpedo electric organ extracts the heavy form constitutes about 70% of the AChR. We report that, in contrast, embryonic electric organ extracts contain only about 30% of the heavy form, the rest being light form. In addition, amongst a library of 38 monoclonal antibodies (mAbs), all of those that distinguished between embryonic and adult AChR did so only because they precipitated the heavy form of the AChR better than the light form.
Effect of hydrocortisone on the number of small intensely fluorescent cells in the rat superior cervical ganglion during pre‐ and postnatal development
Authors: Päivärinta H. , Soinila S. , Eränkö O.
Published: April 2003

During the first postnatal week hydrocortisone causes a massive increase in the number of small intensely fluorescent (SIF) cells. The purpose of the present study was to investigate whether the number of SIF cells can be increased with hydrocortisone also prenatally and after the first postnatal week.

Because it was desirable to apply the same kind of treatment before and after birth, the embryos and neonatal rats were injected only once and were studied 4 days later. Pregnant rats were injected daily during the last 7 days of pregnancy and the superior cervical ganglia of their embryos were studied thereafter. After birth, the effect of 7 daily injections of hydrocortisone was also studied.

The number of embryonal brightly fluorescent cells, the probable prenatal precursors of the SIF cells. could not be increased either with a single injection into the embryos, or in embryos of pregnant rats treated with hydrocortisone. A single injection of hydrocortisone into newborn and 4‐day‐old rats caused a massive increase in the number of SIF cells as studied in 4‐ and 8‐day‐old rats, respectively. The increase in the number of SIF cells was smaller but still statistically significant in 12‐day‐old rats injected with hydrocortisone on postnatal day 8. Daily injections of hydrocortisone for 7 days caused on the second, but not on the third postnatal week, a statistically significant increase in the number of SIF cells.

After 7 injections of hydrocortisone. on postnatal days 3–9 or 40–46. no increase in the number of SIF cells was observed in 47‐day‐old rats, as compared with saline‐treated controls of the same age, but 7 injections of hydrocortisone both on days 3–9 and 40–46 resulted in a significant increase in the number of small intensely fluorescent cells on day 47.

It is concluded that hydrocortisone‐induced increase in the number of SIF cells is limited in vivo to the first two postnatal weeks, while exposure to hydrocortisone at birth restores the responsiveness of these cells to increase in number even later after a second exposure to hydrocortisone.
Differentiation of neurons and radial glia in the spinal cord of the teleost Brachydanio rerio (the zebrafish): An immunocytochemical study
Authors: van Raamsdonk W. , Heyting C. , Pool C.W. , Smit‐Onel M.J. , Groen J.L.
Published: April 2003

The differentiation of neurons and glial cells in the spinal cord of the zebrafish was studied by means of immunohistochemistry, using antisera against the 68 kD subunit of neurofilament (anti‐NFP68) and against glial fibrillary acidic protein (anti‐GFAP), both isolated from the bovine brain. Anti‐NFP68 and anti‐GFAP reactivity appear in the spinal cord at about 60 h after fertilization. At that time the anti‐NFP68 reactivity is detectable in the dorsal Rohon‐Beard neurons. About 12 h later, NFP68 positive neurons appear in the prospective motor column. In this respect the differentiation of the primary sensory system precedes that of the spinal motor system. During development the configuration of the glial cell processes changes from a horizontal arrangement in embryos to a radial frame work in larvae and in adults. From these observations together with data on the organization of the adult spinal motor column28 we conclude that the motoneurons of the white and those of the red myotomal muscle fibers may have different origins in the neuroepithelial germinal layer. The anti‐NFP68 serum recognizes a 120 and a 94 kD component of fish neurofilaments. Thus the subunit composition of neurofilament in fishes differs from that in mammals.
Association of laminin and other basement membrane components with regions of high acetylcholine receptor density on cultured myotubes
Authors: Daniels Mathew P. , Vigny Marc , Sonderegger Peter , Bauer Hans‐Christian , Vogel Zvi
Published: April 2003

The distribution of immunoreactivity to basement membrane components in cultures of rat skeletal myotubes was compared to acetylcholine receptor distribution by fluorescence microscopy. Laminin occurred in patches on the myotube surface, and most laminin patches coincided or overlapped with acetylcholine receptor aggregates. Almost all receptor aggregates coincided with laminin patches. Most of the heparan sulfate proteoglycan and fibronectin was associated with non‐muscle cells, but some patches coincided with receptor aggregates on myotubes. In cultures treated with l‐ascorbate, collagen types IV and V covered much of the myotube surface and receptor aggregates often coincided with intense collagen patches. When receptor aggregation was induced by treatment of cultures with soluble neural factors, the newly formed receptor aggregates coincided with laminin patches.

The results suggest that each of the basement membrane components studied has a distinct distribution pattern in primary rat muscle cell cultures. The striking association of laminin immunoreactivity with receptor aggregates, together with the enhancement of receptor aggregation by laminin reported previously (Vogel et al., J. Neurosci. 3, 1058–1068, 1983) suggests that laminin could have a role in the organization of acetylcholine receptors on developing muscle fibers.
Immunohistochemical analysis of the ontogeny of neuropeptide Y immunoreactive neurons in foetal rat brain
Authors: Foster G.A. , Schultzberg M.
Published: April 2003

The development of neuropeptide Y‐like immunoreactive structures in the foetal rat brain was investigated by means of the indirect immunohistofluorescence technique.

Neuropeptide Y‐like immunoreactive cells and fibres first appeared on day 13 of gestation, in the solitary tract nucleus, lateral reticular nucleus and nucleus ambiguus in the medulla oblongata, and in the primordial inferior colliculus and deep mesencephalic nucleus. Thereafter, neuropeptide Y‐like immunoreactive cells and fibres increased in number in many areas including the primary olfactory cortex, the frontoparietal, somatosensory cortex, caudate putamen, lateral hypothalamus, ventrolateral thalamus, amygdala and parafascicular nucleus. The maximum number of cells over the age range studied, namely day 12 of gestation to birth day, occurred at around day 21. On the day of birth, accordingly, there were significantly fewer neuropeptide Y‐like immunoreactive cell bodies in a number of brain areas, the most striking deficit being in the ventrolateral thalamus.

The present study demonstrates the very early appearance of neuropeptide Y‐like immunoreactive structures during foetal brain development. The functional role of the peptide during this period remains, however, to be determined.
Postnatal development of rat cerebellum: Glycosaminoglycan changes related to variation in water content, cell formation and organ growth
Authors: Normand G. , Clos J. , Vincendon G. , Gombos G.
Published: April 2003

Modifications of glycosaminoglycans were studied during rat cerebellum ontogenesis. Levels of both hyaluronic acid and sulphated glycosaminoglycans increase during development but not at the same rate as cerebellar size or proteins. As in the rest of the brain, cerebellar hyaluronic acid concentration decreases during development but not, as expected, in parallel with the loss of tissue water content. In contrast to forebrain, the concentration of cerebellar sulphated glycosaminoglycans decreases at a slow rate. The correlation, suggested by several authors, between glycosaminoglycans concentration and tissue hydratation, cell migration and myelination were not confirmed in developing rat cerebellum.