bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tracheal length changes during zebra finch song and their possible role in upper vocal tract filtering
Authors: Daley Monica , Goller Franz 
Published: April 2004

AbstractSounds produced in the avian vocal organ may be modified by filter properties of the upper vocal tract. Possible mechanisms to actively control filter characteristics include movements of the beak, tongue, and larynx and adjustments of tracheal length. We investigated whether length changes of the trachea are a likely mechanism for adjusting upper vocal tract filter properties during song in the zebra finch (Taeniopygia guttata). Tracheal length was monitored at the basal end using sonomicrometry and was recorded together with subsyringeal air sac pressure and acoustic output. Tracheal shortening occurred at the onset of song bouts, and during each motif the tracheal length decreased during expiratory pressure pulses and increased during the short inspirations. A bilateral tracheal syringeal nerve cut confirmed that the initial shortening at the onset of the song bout is an active shortening of the trachea (i.e., mediated by syringeal muscle activity). The modulation of length during the motif was not affected by the denervation and is most likely driven by the pressurization of the interclavicular air sac. The absolute length change during the motif was small (<0.2 mm) and not clearly related to acoustic features of the song. For example, some high‐frequency syllables, which are generated during inspiration, were accompanied by tracheal elongation. Because this elongation shifts tube resonances to lower frequencies, it is inconsistent with an active adjustment of length to enhance high frequency sounds. The small magnitude and inconsistent nature of dynamic tracheal length changes during song make it unlikely that they significantly affect vocal tract filter properties if the trachea is modeled as a rigid tube. © 2004 Wiley Periodicals, Inc. J Neurobiol 59: 319–330, 2004
Reassessing popular participation in Uganda
Authors: Golooba‐Mutebi Frederick 
Published: April 2004

AbstractThe 1980s saw the emergence of popular participation as a mechanism for promoting good governance in developing countries Good governance was seen as crucial to efforts to improve the welfare of poor people in countries where elites had hitherto benefited disproportionately from policies conceived at the top without reference to ordinary citizens at the bottom. Donor pressure helped accelerate the change. In Uganda these developments coincided with the rise to power of a government that sought to democratise the country's politics. A major plank in the democratisation agenda was the establishment of a participatory system of local administration in which ordinary citizens, facilitated by local councils, would participate in public affairs and influence the way government functioned. These aspirations coincided with those of the donor community and enthusiasts of popular participation. This article is an account of the evolution of village councils and popular participation from 1986, when the National Resistance Movement came to power in Uganda, to 1996. It shows that while at the beginning the introduction of local councils seized the public's imagination leading to high levels of participation, with time, public meetings as consultative fora succumbed to atrophy due to participation fatigue and unwarranted assumptions about the feasibility and utility of popular participation as an administrative and policy‐making devise. It calls for political history and the socio‐cultural context to be taken into account in efforts to promote participation. Copyright © 2004 John Wiley & Sons, Ltd.
Loss of Smad4 correlates with loss of the invasion suppressor E‐cadherin in advanced colorectal carcinomas
Authors: Reinacher‐Schick Anke , Baldus Stephan E , Romdhana Bashra , Landsberg Stephanie , Zapatka Marc , Mönig Stefan P , Hölscher Arnulf H , Dienes Hans P , Schmiegel Wolff , Schwarte‐Waldhoff Irmgard 
Published: April 2004

AbstractSmad4 is a tumour suppressor gene predominantly involved in gastrointestinal carcinogenesis. Loss of Smad4 is considered to be a genetically late step and occurs in up to 30% of metastatic colorectal carcinomas. Smad4, originally characterized as an intracellular transmitter of transforming growth factor‐β (TGF‐β) signals, is a transcriptional co‐modulator capable of integrating cellular responses to multiple signalling cascades. Thus, there are many Smad4 target genes and they are presumably strongly context‐dependent. It was recently shown that re‐expression of Smad4 in Smad4‐deficient SW480 human colon carcinoma cells restored epithelioid morphology and induced P‐cadherin and E‐cadherin transcription. The cadherins are key players in cell–cell adhesion connecting adjacent cells via the cadherin–catenin adhesion complex. Frequent loss of E‐cadherin expression in human cancers has been a long‐standing observation, but the underlying mechanisms are not yet fully understood. To assess the role of Smad4 in E‐cadherin regulation in colorectal carcinogenesis further, the present study has analysed Smad4 and E‐cadherin RNA and protein expression in colorectal carcinoma cell lines and in 51 late‐stage colorectal carcinomas. In primary tumours, loss of Smad4 expression correlated highly significantly with loss of E‐cadherin expression, thus providing further evidence for involvement of the tumour suppressor Smad4 in the control of expression of the tumour and invasion suppressor E‐cadherin. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Endothelial nitric oxide synthase in the control of osteoblastic mineralizing activity and bone integrity
Authors: Afzal Faiza , Polak Julia , Buttery Lee 
Published: April 2004

AbstractIt has been shown previously that osteoblast differentiation and maintenance of bone mass are impaired in endothelial nitric oxide synthase gene knockout mice. The present study shows by analysis of messenger RNA expression that the transcription factor Cbfa‐1/Runx‐2 and the bone matrix protein osteocalcin, which are fundamental to osteoblast differentiation, are significantly reduced in neonatal calvarial osteoblasts from these gene knockout mice. Expression of these genes could be restored to wild‐type levels by exogenous supply of the photoactivatable nitric oxide donor potassium nitrosylpentachlorouthenate, but this was dependent on the timing of its activation and recovery in gene expression was only evident during the latter stages of osteoblast differentiation associated with its mineralizing activity. Calvarial, femoral/pelvic, spinal, and total bone mineral density, together with bone microhardness and expression of osteocalcin in whole femurs, were all reduced significantly in gene knockout mice at 8 weeks of age, but not at 12 weeks, where all of these indices of bone integrity were comparable to wild type. In accordance with these temporal effects, reduced bone mineral density, bone microhardness, and osteocalcin expression could be restored to normal, wild‐type values after 21 days in vivo administration of the nitric oxide donor glyceryl trinitrate to 4‐week‐old endothelial nitric oxide synthase knockout mice, but there was no significant effect in older animals. Taken together, these results further demonstrate the importance of endothelial nitric oxide synthase in the regulation of osteoblast metabolism. In particular, they show that nitric oxide is involved in co‐ordinating specific phases of osteoblast differentiation and bone formation: this could be relevant to its therapeutic actions on bone turnover. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Site‐independent prognostic value of chromosome 9q loss in primary gastrointestinal stromal tumours
Authors: Gunawan Bastian , Schulten Hans‐Jürgen , von Heydebreck Anja , Schmidt Bettina , Enders Christina , Höer Jörg , Langer Claus , Schüler Phillip , Schindler Christian G , Kuhlgatz Jens , Füzesi László 
Published: April 2004

AbstractAlthough the significance of tumour site for estimating malignant potential in gastrointestinal stromal tumours (GISTs) has recently been recognized, site‐specific genetic patterns have not to date been defined. This study examined 52 c‐kit‐positive primary GISTs (with a mean follow‐up of 42.3 months in 51 cases) from three different locations (35 gastric, 12 small intestinal, and five colorectal) using comparative genomic hybridization (CGH). In general, tumour site correlated with key prognostic factors, including tumour size, mitotic rate, proliferative activity, and probable malignant potential. Furthermore, several DNA copy number changes showed a site‐dependent pattern. These included losses at 14q (gastric 83%, intestinal 35%; p = 0.001), losses at 22q (gastric 46%, intestinal 82%; p = 0.02), losses at 1p (gastric 23%, intestinal 88%; p = 1 × 10−5), losses at 15q (gastric 14%, intestinal 59%; p = 0.002), losses at 9q (gastric 14%, intestinal 53%; p = 0.006), and gains at 5p (gastric 11%, intestinal 53%; p = 0.002). These data demonstrate strong site‐dependent genetic heterogeneity in GISTs that may form a basis for subclassification. Prognostic evaluation of DNA copy number changes identified losses at 9q as a site‐independent prognostic marker associated with shorter disease‐free survival (p = 0.03) and overall survival (p = 0.002). Furthermore, 9q loss also appeared to carry prognostic value in predicting overall survival for patients with advanced or progressive GISTs (p = 0.003). Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Mechanisms underlying the dysfunction of melanocytes in vitiligo epidermis: role of SCF/KIT protein interactions and the downstream effector, MITF‐M
Authors: Kitamura Reiko , Tsukamoto Katsuhiko , Harada Kazutoshi , Shimizu Akira , Shimada Shinji , Kobayashi Takeshi , Imokawa Genji 
Published: April 2004

AbstractLittle is known about the mechanisms involved in the dysfunction of melanocytes in vitiligo epidermis. It is hypothesized that some cytokine/receptor interactions may be affected, resulting in dysfunction and/or loss of melanocytes. This study has compared the expression of endothelin (ET)‐1, the ET‐1 receptor (ETBR), granulocyte macrophage colony stimulating factor (GM‐CSF), stem cell factor (SCF), the SCF receptor (KIT protein), tyrosinase, and S100α between lesional and non‐lesional vitiligo epidermis. Analysis by reverse transcription‐polymerase chain reaction (RT‐PCR) and by western blotting for ET‐1 and SCF unexpectedly demonstrated up‐regulated expression of these cytokines in lesional vitiligo epidermis. Immunohistochemistry with antibodies to melanocyte markers revealed that at the edge of the lesional epidermis, melanocytes remain and express tyrosinase, S100α and ETBR, but not KIT protein or melanocyte‐specific microphthalmia‐associated transcription factor (MITF‐M). Quantitation of the staining revealed a slight or moderate decrease in the number of S100α, tyrosinase, and ETBR‐positive cells at the edge of the lesional epidermis. In contrast, the number of cells expressing KIT protein was markedly decreased at the edge of the lesional epidermis compared with the non‐lesional epidermis. At the centre of the lesional epidermis, there was complete loss of melanocytes expressing KIT protein, S100α, ETBR, and/or tyrosinase. Western blotting revealed down‐regulated expression of c‐kit and MITF‐M proteins at the edge of the lesional epidermis in vitiligo. These findings suggest that reduction in the expression of KIT protein by melanocytes and its downstream effectors, including MITF‐M, may be associated with the dysfunction and/or loss of melanocytes in vitiligo epidermis. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Activation of pro‐MMP‐2 mediated by MT1‐MMP in human salivary gland carcinomas: possible regulation of pro‐MMP‐2 activation by TIMP‐2
Authors: Kayano Kaori , Shimada Taketoshi , Shinomiya Takashi , Nakai Shigeru , Hisa Yasuo , Aoki Takanori , Seiki Motoharu , Okada Yasunori 
Published: April 2004

AbstractMatrix metalloproteinases (MMPs), a family of extracellular matrix‐degrading enzymes, are considered to play important roles in cancer invasion and metastasis. The present study examined the production levels of eight different MMPs (MMP‐1, 2, 3, 7, 8, 9 and 13, and MT1‐MMP) and two tissue inhibitors of metalloproteinases (TIMP‐1 and 2) in homogenates of human salivary gland carcinomas [mucoepidermoid carcinomas (MECs), adenoid cystic carcinomas (ACCs), and adenocarcinomas (ADEs)] and non‐neoplastic control salivary glands using sandwich enzyme immunoassay systems. The levels of MMP‐1, MMP‐2, MMP‐13, MT1‐MMP, and TIMP‐1 were significantly higher in the carcinoma samples than in the controls (p < 0.05). Gelatin zymography demonstrated that the activation ratio of the MMP‐2 zymogen (pro‐MMP‐2) was significantly higher in the carcinomas than in the controls (p < 0.05). In addition, the activation ratio in MECs was significantly higher than that in ACCs or ADEs (p < 0.01) and also correlated with histological grade and lymph node metastasis in MECs (p < 0.05), whereas the ratio showed no such correlation in ACCs or ADEs. Although the production levels of pro‐MMP‐2 and MT1‐MMP were similar among these carcinoma groups, TIMP‐2 levels were significantly higher in ACCs and ADEs than in MECs (p < 0.01). In carcinoma samples, the pro‐MMP‐2 activation ratio correlated directly with the MT1‐MMP/TIMP‐2 ratio (r = 0.736, n = 23; p < 0.01). Immunohistochemistry and in situ zymography demonstrated localization of MMP‐2, MT1‐MMP, and TIMP‐2 to carcinoma cells, but only in MECs did carcinoma cell nests exhibit gelatinolytic activity, which was inhibited by 1,10‐phenanthroline. These results suggest that enhanced activation of pro‐MMP‐2 mediated by MT1‐MMP is implicated in the invasion and metastasis of MECs and that TIMP‐2 may regulate pro‐MMP‐2 activation in salivary gland carcinomas. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Reversible addition fragmentation chain transfer polymerization of sterically hindered monomers: Toward well‐defined rod/coil architectures
Authors: Szablan Zachary , Toy Andrew Ah , Davis Thomas P. , Hao Xiaojuan , Stenzel Martina H. , Barner‐Kowollik Christopher 
Published: April 2004

AbstractThe sterically hindered monomers dibutyl itaconate (DBI) and dicyclohexyl itaconate (DCHI) were polymerized via reversible addition fragmentation chain transfer (RAFT) free‐radical polymerization. S,S′‐Bis(α,α′‐dimethyl‐α″‐acetic acid) trithiocarbonate, cumyl dithiobenzoate, and cumyl phenyldithioacetate have been used as RAFT agents to mediate a series of polymerizations at 65 °C yielding rod polymers ranging in number average molecular weight from 9000 to 92,000 g mol−1. The progress of the polymerization was followed via online Fourier transform–near infrared spectroscopy. The polydispersity indices of the obtained rod polymers were relatively high at 1.4–1.7. The RAFT polymerizations of the hindered monomers used in the present study displayed both ideal living and hybrid behavior between conventional and living polymerization, depending on the RAFT agent used. DCHI rod polymers generated via the RAFT process were subsequently reinitiated in the presence of styrene to produce a range of BAAB and A‐B rod‐coil block copolymers of molecular weights up to 164,000 g mol−1. The chain extension yields molecular weight distributions that progressively shift to higher molecular weights and are unimodal. Thermogravimetric analysis of the pDCHI‐block‐pStyrene copolymers indicates thermal degradation in two separate steps for the pDCHI and pStyrene blocks. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2432–2443, 2004
Ion‐exchange resins. III. Functionalization–morphology correlations in the synthesis of some macroporous, strong basic anion exchangers and uranium‐sorption properties evaluation
Authors: Dragan Ecaterina Stela , Avram Ecaterina , Axente Damian , Marcu Cristina 
Published: April 2004

AbstractThe synthesis and characterization of a series of macroporous, strong basic anion exchangers (SBAEs), with an average pore radius higher than 50 nm, and the evaluation of their sorption properties for uranyl chlorocomplexes from HCl solutions are reported. Finely divided macroporous styrene–divinylbenzene (S–DVB) copolymers with a narrow distribution of beads sizes, diameters within the range of 90–200 μm, were prepared for this purpose with 2‐ethyl‐1‐hexanol as a porogen, at a high dilution of monomers (D ≥ 0.55 mL/mL). Chloromethyl groups were introduced with (CH2O)n/Me3SiCl as a chloromethylation agent in the presence of a Lewis acid as a catalyst (TiCl4, SnCl4, and FeCl3) in CHCl3 as a reaction medium. SnCl4 and FeCl3 gave comparable chloromethylation degrees in the same reaction conditions. TiCl4 was not efficient as a catalyst in the chloromethylation with this reagent. Diethyl‐2‐hydroxyethylamine was used as a tertiary amine to prepare SBAEs. Structural and morphological characteristics were determined after every functionalization step of the macroporous network. Both the chloromethylation, in the presence of FeCl3 as a catalyst, and the amination reactions determined a significant decrease of the pore volume, in the whole range of the nominal crosslinking degree, comparative with the starting copolymer. The specific surface area and the average pore radius varied in a different way as a function of the nominal crosslinking degree. Thus, the specific surface area increased and the average pore radius decreased after chloromethylation and amination for copolymers with a DVB content lower than 10 wt %. Small decreases of the specific surface area and the average pore radius were observed after chloromethylation and amination reactions for copolymers with a DVB content higher than 10 wt %. SBAEs were also characterized by thermogravimetric analysis and sorption capacity for uranyl chlorocomplexes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2451–2461, 2004
Synthesis, complex formation, and dilute‐solution associative behavior of linear poly(methacrylic acid)‐graft‐poly(2‐ethyl‐2‐oxazoline)*
Authors: Poe Garrett D. , McCormick Charles L. 
Published: April 2004

AbstractPoly(methacrylic acid) (PMA) and poly(2‐ethyl‐2‐oxazoline) (PEOZO) are a polyacid/polybase pair capable of forming reversible, pH‐responsive, hydrogen‐bonding complexes stabilized by hydrophobic effects in aqueous media. Linear PMA was modified with long‐chain (number‐average molecular weight: 10,000) PEOZO via statistical coupling reactions in organic media to prepare a series of PMA‐graft‐PEOZO copolymers. Potentiometric titrations revealed that the presence of tethered PEOZO markedly increases the pKa values for PMA‐g‐PEOZO copolymers as compared with simple PMA/PEOZO mixtures at degrees of ionization, α, between 0.0 and 0.1. The dilute‐solution PMA–PEOZO intramolecular association has been probed by monitoring the PEOZO NMR spin–spin (T2) relaxation as a function of pH. Covalently attached PEOZO side chains participate in complexation at higher values of α than untethered PEOZO. Surprisingly, most PEOZO side chains did not take part in hydrogen bonding at low α, and the highest level of PEOZO incorporation induced a decrease in the number of PMA/PEOZO hydrogen bonds. The polymer self‐diffusion as a function of α was measured with dynamic light scattering. At low pH, the copolymers had no charge and they were in a collapsed form. At high pH, the expected conformational expansion of the PMA units was enhanced at moderate levels of PEOZO incorporation. However, the highest PEOZO incorporation induced the onset of intramolecular associations between PEOZO units along the copolymer chains. Low shear rheometry and light scattering measurements were used in conjunction with the T2 NMR measurements to propose a model consistent with the aforementioned behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2520–2533, 2004
Novel, organosoluble, light‐colored fluorinated polyimides based on 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl or 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐1,1′‐binaphthyl
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Tsai Che‐Yu , Liou Guey‐Sheng 
Published: April 2004

AbstractTwo series of fluorinated polyimides were prepared from 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl (2) and 2,2′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐1,1′‐binaphthyl (4) with various aromatic dianhydrides via a conventional, two‐step procedure that included a ring‐opening polyaddition to give poly(amic acid)s, followed by chemical or thermal cyclodehydration. The inherent viscosities of the polyimides ranged from 0.54 to 0.73 and 0.19 to 0.36 dL/g, respectively. All the fluorinated polyimides were soluble in many polar organic solvents, such as N,N‐dimethylacetamide and N‐methylpyrrolidone, and afforded transparent and light‐colored films via solution‐casting. These polyimides showed glass‐transition temperatures in the ranges of 222–280 and 257–351 °C by DSC, softening temperatures in the range of 264–301 °C by thermomechanical analysis, and a decomposition temperature for 10% weight loss above 520 °C both in nitrogen and air atmospheres. The polyimides had low moisture absorptions of 0.23–0.58%, low dielectric constants of 2.84–3.61 at 10 kHz, and an ultraviolet–visible absorption cutoff wavelength at 351–434 nm. Copolyimides derived from the same dianhydrides with an equimolar mixture of 4,4′‐oxydianiline and diamine 2 or 4 were also prepared and characterized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2416–2431, 2004
Metal‐induced optical sensing and optical switching in poly(pyridyl phenylene)
Authors: Na Jongho , Kim Young‐Shin , Park Won Ho , Lee Taek Seung 
Published: April 2004

AbstractThe synthesis of a conjugated polymer containing pyridyl units in the polymer backbone was successfully carried out with 2,6‐dibromopyridine and a diboronic acid derivative via the Suzuki coupling reaction. This polymer had a number‐average molecular weight of 4000 and excellent solubility in conventional organic solvents; this suggested the effect of the incorporation of dialkoxy side chains. A metallochromic phenomenon with ferric ions was clearly observed in spin‐coated films and solutions of the polymer. The response of the absorption and the fluorescence changes of the polymer films were rapid and were reproduced more than 15 times. A lightly bound intermolecular interaction between the pyridine ligand and cation was presumed to be responsible for the facile optical switching property of the polymer films. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2444–2450, 2004
Melting behavior in blends of isotactic polypropylene and a liquid crystalline polymer
Authors: Torre J. , Cortázar M. , Gómez M. , Ellis G. , Marco C. 
Published: April 2004

AbstractThe influence of low contents of a liquid crystalline polymer on the crystallization and melting behavior of isotactic polypropylene (iPP) was investigated using electron and optical microscopy, differential scanning calorimetry, and X‐ray diffraction. In pure iPP, the α modification was found, whereas for iPP/Vectra blends at Vectra concentration <5%, both α and β forms were observed. The amount of β phase varied from 0.23 to 0.16. Optical microscopy showed that Vectra was able to nucleate both α and β forms. Non‐isothermal crystallization produces a material with a strong tendency for recrystallization of the α and β forms (αα′ and ββ′ recrystallization) leading to double endotherms for both crystalline forms in DSC thermograms. Melting thermograms after isothermal crystallization at low temperatures showed a similar behavior. At values of Tc > 119 °C for the α form and Tc > 125 °C for the β form, only one melting endotherm was observed because enough perfect crystals, not susceptible to recrystallization, were obtained. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1949–1959, 2004