bluuebunny/crossref_metadata_2025_split huggingface dataset:
Students' conceptual structure, search process, and outcome while preparing a research proposal: A longitudinal case study
Authors: Pennanen Mikko , Vakkari Pertti 
Published: May 2003

AbstractThis article focuses on analysing students' information needs in terms of conceptual understanding of the topic they propose to study and its consequences for the search process and outcome. The research subjects were 22 undergraduates of psychology attending a seminar for preparing a research proposal for a small empirical study. They were asked to make searches in the PsycINFO database for their task in the beginning and end of the seminar. A pre‐ and postsearch interview was conducted in both sessions. The students were asked to think aloud in the sessions. This was recorded, as were the transaction logs. The results show that during the preparation of research proposals different features of the students' conceptual structure were connected to the search success. Students' ability to cover their conceptual construct by query terms was the major feature affecting search success during the whole process. In the beginning also the number of concepts and the proportion of subconcepts in the construct contributed indirectly via search tactics to retrieving partly useful references. Students' ability to extract new query terms from retrieved items improved search results.
Dermatomes and the central organization of dermatomes and body surface regions in the spinal cord dorsal horn in rats
Authors: Takahashi Yuzuru , Chiba Tanemichi , Kurokawa Masahiro , Aoki Yasuchika 
Published: May 2003

AbstractDermatomes and the associated central projection fields were studied with the application of fluorescent neurotracer, 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (DiI), to 21 reference points on rat trunk and hindlimb skin. Segmental distribution and rostrocaudal central level of dorsal root ganglion (DRG) neurons innervating reference points were examined and DiI‐induced fluorescent areas were mapped in the horizontal plane through lamina II of the dorsal horn. Segmental levels of DRG neurons innervating reference points were generally identical to the level determined using dye‐extravasation methods. However, innervation of the first digit was situated in the L4 dermatome, not the L3 reported previously using those methods. Generally, afferents from a reference point projected to a single field in the ipsilateral dorsal horn. Reference points on ventral and dorsal median lines of the trunk were represented bilaterally. Afferents from reference points located on the ventral median line of the hindlimb projected to two separate fields: one on the medial margin of spinal cord segments L2–L5 and the other on the medial half of spinal cord segment L5. From the distribution of central projection fields of reference points, central projection fields of dermatomes were revealed as even in shape and located within corresponding spinal cord segments. The arrangement of peripheral and central fields of dermatomes and body surface regions suggests that peripheral and central projection fields of cutaneous afferent fibers are reshaped from the common prototypical pattern that exhibits an orderly and evenly sequenced arrangement. J. Comp. Neurol. 462:29–41, 2003. © 2003 Wiley‐Liss, Inc.
Expression and function of FGF10 in mammalian inner ear development
Authors: Pauley Sarah , Wright Tracy J. , Pirvola Ulla , Ornitz David , Beisel Kirk , Fritzsch Bernd 
Published: May 2003

AbstractWe have investigated the expression of FGF10 during ear development and the effect of an FGF10 null mutation on ear development. Our in situ hybridization data reveal expression of FGF10 in all three canal crista sensory epithelia and the cochlea anlage as well as all sensory neurons at embryonic day 11.5 (E11.5). Older embryos (E18.5) displayed strong graded expression in all sensory epithelia. FGF10 null mutants show complete agenesis of the posterior canal crista and the posterior canal. The posterior canal sensory neurons form initially and project rather normally by E11.5, but they disappear within 2 days. FGF10 null mutants have no posterior canal system at E18.5. In addition, these mutants have deformations of the anterior and horizontal cristae, reduced formation of the anterior and horizontal canals, as well as altered position of the remaining sensory epithelia with respect to the utricle. Hair cells form but some have defects in their cilia formation. No defects were detected in the organ of Corti at the cellular level. Together these data suggest that FGF10 plays a major role in ear morphogenesis. Most of these data are consistent with earlier findings on a null mutation in FGFR2b, one of FGF10's main receptors. Developmental Dynamics 227:203–215, 2003. © 2003 Wiley‐Liss, Inc.
Folic acid and homocysteine affect neural crest and neuroepithelial cell outgrowth and differentiation in vitro
Authors: Boot Marit J. , Steegers‐Theunissen Régine P.M. , Poelmann Robert E. , Van Iperen Liesbeth , Lindemans Jan , Gittenberger‐De Groot Adriana C. 
Published: May 2003

AbstractThe beneficial effect of additional folic acid in the periconceptional period to prevent neural tube defects, orofacial clefts, and conotruncal heart defects in the offspring has been shown. Folate shortage results in homocysteine accumulation. Elevated levels of homocysteine have been related to neural tube defects. We studied the behavior of neuroepithelial cells and cranial and cardiac neural crest cells in vitro. Neural tube explants were cultured for 24 and 48 hr in medium after addition of folic acid and/or homocysteine. Folic acid addition increased neuroepithelial cell outgrowth and increased neural crest cell differentiation into nerve and smooth muscle cells. Addition of homocysteine increased neural crest cell outgrowth and migration from the neural tube and inhibited neural crest cell differentiation. Our findings suggest that neural tube defects caused by folate deficiency and hyperhomocysteinemia develop due to increased neuroepithelial to neural crest cell transformation. This increased transformation leads to a shortage of neuroepithelial cells in the neural tube. Defects in orofacial and conotruncal development are explained by abnormal differentiation of neural crest cells in the presence of high homocysteine concentrations. Our findings supports a critical role for folic acid and homocysteine in the development of neural tube defects and neural crest related heart malformations. Developmental Dynamics 227:301–308, 2003. © 2003 Wiley‐Liss, Inc.
Molecular structure and developmental expression of three muscle‐type troponin T genes in zebrafish
Authors: Hsiao Chung‐Der , Tsai Wei‐Yuan , Horng Long‐Shyan , Tsai Huai‐Jen 
Published: May 2003

AbstractTroponin T (Tnnt), a troponin component, interacts with tropomyosin and is crucial to the regulation of striated muscle contraction. To gain insight into the molecular evolution and developmental regulation of Tnnt gene (Tnnt) in lower vertebrates, zebrafish Tnnt1 (slow Tnnt), Tnnt2 (cardiac Tnnt), and Tnnt3b (fast Tnnt isoform b) were characterized. The polypeptides of zebrafish Tnnt1, Tnnt2, and Tnnt3b were conserved in the central tropomyosin‐ and C‐terminal troponin I‐binding domains. However, the N‐terminal hypervariable regions were highly extended and rich in glutamic acid in polypeptides of Tnnt1 and Tnnt2, but not Tnnt3b. The Tnnt2 and Tnnt3b contain introns, whereas Tnnt1 is intron‐free. During development, large to small, alternatively spliced variants were detected in Tnnt2, but not in Tnnt1 or Tnnt3. Whole‐mount in situ hybridization showed zebrafish Tnnt1 and Tnnt2 are activated during early somitogenesis (10 hr postfertilization, hpf) and cardiogenesis (14 hpf), respectively, but Tnnt3b is not activated until middle somitogenesis (18 hpf). Tnnt2 and Tnnt3b expression was cardiac‐ and fast‐muscle specific, but Tnnt1 was expressed in both slow and fast muscles. We propose that three, distinct, muscle‐type Tnnt evolved after the divergence of fish and deuterostome invertebrates. In zebrafish, the developmental regulation of Tnnt during somitogenesis and cardiogenesis is more restricted and simpler than in tetrapods. These new findings may provide insight into the developmental regulation and molecular evolution of vertebrate Tnnt. Developmental Dynamics 227:266–279, 2003. © 2003 Wiley‐Liss, Inc.
The Substituent Effect of the Phosphaalkenyl Group
Authors: Termaten Arjan , van der Sluis Marcel , Bickelhaupt Friedrich 
Published: May 2003

AbstractSeveral novel phosphaalkenes (E)‐Mes*P=CHC6H4X (6; X = Me3Si, Me3Sn, CHO, COOH, CN) were prepared and, together with other known members of this series, subjected to an analysis of linear free‐energy relationships based on the values of pKa and values of δ(13Cpara) of substituted benzoic acids and on the values of δ(13Cpara) of substituted bromobenzenes. These analyses indicate that the (E)‐Mes*P=CH group is a weak electron donor with a predominantly inductive effect (σp = −0.1) on a neighboring benzene ring; resonance interactions are of minor importance. This result shows that the P=C bond is surprisingly analogous to the C=C bond, and thus confirms the well‐known diagonal relationship in the Periodic System between carbon and phosphorus atoms. The relationship between X and the values of δ(31P) of 6 is quite pronounced. It confirms the dominance of inductive interactions on the value of δ(31P); only with strongly electron‐donating substituents may a certain degree of resonance interaction be involved. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Blocking Fluorine Substitution in Biotransformation of Nortricyclanyl N‐Phenylcarbamates with Beauveria bassiana
Authors: Haufe Günter , Wölker Dörthe 
Published: May 2003

AbstractThe biotransformation of tricyclo[2.2.1.02,6]hept‐3‐yl N‐phenylcarbamate (8) by a standard procedure using Beauveria bassiana gave a 7:1 mixture of optically active exo,exo‐ and exo,endo‐5‐hydroxytricyclo[2.2.1.02,6]hept‐3‐yl N‐phenylcarbamates 15 and 16 in 19% isolated yield. No ring opening of the three‐membered ring was observed. Substitution with a fluorine atom at the 5‐endo‐ or 5‐exo‐position prevented hydroxylation of any alicyclic position of the molecules, p‐hydroxylation of the aromatic ring occurring to a small extent instead. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Ten‐Membered Substituted Cyclic 2‐Oxecanone (Decalactone) Derivatives from Latrunculia corticata, a Red Sea Sponge
Authors: Řezanka Tomáš , Dembitsky Valery M. 
Published: May 2003

AbstractTwo novel glycosides, latrunculinosides A and B, containing substituted 2‐oxecanones (decalactones) were isolated from Latrunculia corticata collected in the Gulf of Aqaba, Israel. They were characterized by spectroscopic methods, predominantly 1H NMR, 13C NMR, MS, IR and UV, and by chemical degradation. Both glycosides contain unusual saccharides such as β‐D‐olivose, β‐L‐digitoxose, α‐L‐amicetose, and β‐D‐oliose. The compounds gave positive results in antifeeding activity assays. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Potential role of radial glia in adult neurogenesis of teleost fish
Authors: Zupanc Günther K.H. , Clint Sorcha C. 
Published: May 2003

AbstractPersistence of radial glia within the adult central nervous system is a widespread phenomenon among fish. Based on a series of studies in the teleost species Apteronotus leptorhynchus, we propose that one function of this persistence is the involvement of radial glia in adult neurogenesis, i.e., the generation and further development of new neurons in the adult central nervous system. In particular, evidence has been obtained for the involvement of radial glia in the guidance of migrating young neurons in both the intact and the regenerating brain; for a possible role as precursor cells from which new neurons arise; and for its role as a source of trophic substances promoting the generation, differentiation, and/or survival of new neurons. These functions contribute not only to the potential of the intact brain to generate new neurons continuously, and of the injured brain to replace damaged cells by newly generated ones, but they also provide an essential part of the cellular substrate of behavioral plasticity. GLIA 43:77–86, 2003. © 2003 Wiley‐Liss, Inc.
Long‐term implantation of zinc‐releasing calcium phosphate ceramics in rabbit femora
Authors: Kawamura H. , Ito A. , Muramatsu T. , Miyakawa S. , Ochiai N. , Tateishi T. 
Published: May 2003

AbstractZinc is an essential trace element that has stimulatory effects on bone formation. Recently, we developed zinc‐releasing calcium phosphate ceramics in order to add the pharmacologic effect of zinc to calcium phosphate ceramics. In our previous study, we showed that the optimum zinc content for promoting bone formation was 0.316 wt %. Therefore a zinc composite ceramic of zinc‐containing β‐tricalcium phosphate and hydroxyapatite, with a zinc content of 0.316 wt %, was chosen for long‐term implantation. Cylindrical rods of the zinc composite ceramic were implanted in rabbit femora for 2 to 60 weeks. Using computer‐aided image analysis, a histomorphometric study was carried out to investigate bone formation and resorption around the implants. The control was a composite ceramic of β‐tricalcium phosphate and hydroxyapatite without zinc. The addition of zinc to the implant demonstrated both favorable and unfavorable effects on bone remodeling. The favorable effect was enhanced bone apposition to the implant surface, demonstrated by a significant increase in intramedullary bone apposition rate at 6 weeks and in cortical bone apposition rate at 24 and 60 weeks (p < 0.05). The unfavorable effect was increased bone resorption, demonstrated by a significant increase in medullary cavity area at 60 weeks (p < 0.05). In order to utilize the favorable effect and avoid the unfavorable effect of zinc, either a reduction in zinc content in the zinc composite ceramic or the selection of implantation sites that do not have excessive exposure to bone marrow are required. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 468–474, 2003
Relative influence of polymer fiber diameter and surface charge on fibrous capsule thickness and vessel density for single‐fiber implants
Authors: Sanders J. E. , Cassisi D. V. , Neumann T. , Golledge S. L. , Zachariah S. G. , Ratner B. D. , Bale S. D. 
Published: May 2003

AbstractSingle polypropylene microfibers plasma‐coated with polymers of different surface charge [N,N‐dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague‐Dawley rats for 5‐week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 μm; (II) 6.0 to 10.9 μm; and (III) 11.0 to 15.9 μm. Fibrous capsule thickness and blood‐vessel density (number of vessels within 100 μm of the fiber) were assessed in tissue sections in the planes of microfiber cross‐sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface‐charge coating. The mean differences in capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 μm; between groups III and I: 10.2 μm; and between groups III and II: 4.7 μm. The mean differences in capsule thickness among surface‐charge coatings were: between MA and NN: 0.7 μm; between MA and HF: 1.4 μm; and between NN and HF: 0.7 μm. Many of the 1.0 to 5.9 μm‐in‐diameter fibers had no capsule and no sign of a foreign‐body reaction. For the vessel density analysis, neither microfiber diameter nor surface‐charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to fibrous capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 462–467, 2003
Enhancing the vascularization of three‐dimensional porous alginate scaffolds by incorporating controlled release basic fibroblast growth factor microspheres
Authors: Perets Anat , Baruch Yaacov , Weisbuch Felix , Shoshany Gideon , Neufeld Gera , Cohen Smadar 
Published: May 2003

AbstractSite‐specific delivery of angiogenic growth factors from tissue‐engineered devices should provide an efficient means of stimulating localized vessel recruitment to the cell transplants and would ensure cell survival and function. In the present article, we describe the construction of a novel porous alginate scaffold that incorporates tiny poly (lactic‐co‐glycolic acid) microspheres capable of controlling the release of angiogenic factors, such as basic fibroblast growth factor (bFGF). The microspheres are an integral part of the solid alginate matrix, and their incorporation does not affect the scaffold porosity or pore size. In vitro, bFGF was released from the porous composite scaffolds in a controlled manner and it was biologically active as assessed by its ability to induce the proliferation of cardiac fibroblasts. The controlled delivery of bFGF from the three‐dimensional scaffolds accelerated the matrix vascularization after implantation on the mesenteric membrane in rat peritoneum. The number of penetrating capillaries into the bFGF‐releasing scaffolds was nearly fourfold higher than into the control scaffolds (those incorporating microspheric BSA and heparin but not bFGF). At day 10 posttransplantation, capillary density in the composite scaffolds was 45 ± 3/mm2 and it increased to 70 ± 7/mm2 by day 21. The released bFGF induced the formation of large and matured blood vessels, as judged by the massive layer of mural cells surrounding the endothelial cells. The control over bFGF delivery and localizing its effects to areas of need, may aid in the wider application of bFGF in therapeutic angiogenesis as well as in tissue engineering. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 489–497, 2003
Effect of biphasic calcium phosphate on human macrophage functions in vitro
Authors: Silva S. N. , Pereira M. M. , Goes A. M. , Leite M. F. 
Published: May 2003

AbstractBioceramics may initiate several and complex biological reactions in host tissues. The cell–biomaterial interaction can determine macrophage activation that may elicit and sustain inflammatory response at the implant site. The current study describes some of the in vitro phenomena regarding the effect of surface reactivity of biphasic calcium phosphate (BCP) granules on human macrophages locomotion and secretion. X‐ray diffraction analysis indicated that the synthesized ceramic presented 80% hydroxyapatite and 20% tricalcium phosphate. When BCP was put in contact with human macrophage cells, we observed that cells and BCP granules attached to each other. Cells attached to BCP presented a higher intracellular free Ca2+ concentration compared with nonattached neighbors and secreted calcium phosphate particles into the medium. Energy dispersive X‐ray analysis showed that the secreted particles presented a calcium/phosphorus ratio of 1.64 ± 0.05, similar to hydroxyapatite. We propose that the secreted particles create a transition zone that allows further macrophage adhesion. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 475–481, 2003
Increased gap junctional intercellular communication is directly related to the anti‐tumor effect of all‐trans‐retinoic acid plus tamoxifen in a human mammary cancer cell line
Authors: Sáez Claudia G. , Velásquez L. , Montoya M. , Eugenín E. , Alvarez M.G. 
Published: May 2003

AbstractAdditive effects against tumor cells might be achieved by combining anti‐neoplastic agents directed against one or more altered mechanisms in cancer. We investigated the participation of gap junctional intercellular communication (GJIC), which is commonly dysfunctional in tumor cells as a possible mediating mechanism of the effect of all‐trans‐retinoic acid (RA) and tamoxifen (Tx) in MCF‐7 human breast cancer cell lines. The combination of RA + Tx stimulated GJIC in approximately 53 ± 3% of MCF‐7 cells as early as after 6 h of treatment remaining communicated through 144 h of culture. The GJIC enhancement occurred along with immunolocalization of Cx26 and 43 at the membrane of contacting cells and correlated with higher protein levels. Cx40 immunoreactive plaques were detected at cell‐to‐cell contacts during 48 h of RA + Tx treatment that did not involve higher protein expression, to the contrary, a downregulation occurred after 72 h of treatment. Cell proliferation inhibition upon RA + Tx exposure was observed with optimal effects at 96–120 h of culture with an accumulation of cells primarily in G2/M and G0/G1 cell cycle boundaries. An enhancement of the pre‐existing E‐cadherin levels was observed after drug exposure along with a downregulation of Bcl‐2 and C‐myc protein levels and a reduction of telomerase activity, suggesting partial tumor phenotype reversion. Blockage of the RA + Tx‐induced GJIC with 18‐β‐glycyrrhetinic acid (β‐Gly) prevented in 34% the inhibition of MCF‐7 proliferation and the E‐cadherin increment in 30% at 96 h of culture. GJIC blockage did not alter the downregulation of Bcl‐2, c‐Myc, or telomerase activity induced by RA + Tx. Our results showed the participation of GJIC as a mediator mechanism of the combined action of RA and Tx in MCF‐7 cells. The chemopreventive modulation of GJIC might represent an approachable alternative for the improvement of cancer therapy. J. Cell. Biochem. 89: 450–461, 2003. © 2003 Wiley‐Liss, Inc.
Regulation of p27 in the process of neuroblastoma N2A differentiation
Authors: Muñoz Juan P. , Sánchez Jaime R. , Maccioni Ricardo B. 
Published: May 2003

AbstractNeuronal differentiation implies morphological and biochemical changes to generate a specialized neuron. N2A neuroblastoma cells can be promoted to undergo differentiation associated to neurites outgrowth, a process linked to the arrest of cell division. Using N2A cells as a model, we investigated the detailed molecular aspects on the involvement of p27 in dibutyryl cAMP‐induced neuronal differentiation. In the undifferentiated N2A phenotype, an unusually high level of accumulated p27 protein mass was evidenced. Data suggest that in proliferating cells, p27 could be sequestered by direct interaction with cyclin D1, thus preventing its inhibitory action on cell cycle Cdks. Studies also indicate that p27 is functionally active and that its loss of action on Cdks in proliferating cells is due to its strong association with cyclin D1. Therefore, when cell differentiation is triggered, the action of p27 on Cdks seems to depend on both p27 and cyclin D1 degradation during the early steps of differentiation followed by late events of re‐synthesis of active p27. In this context, an overexpression of p27 after N2A transfection with a mouse p27 clone induces the outgrowth of neurites associated with a decrease in cyclin D1 expression. On the other hand, treatment of N2A undifferentiated cells with c‐myc antisense oligonucleotides led to a decrease in p27 and cyclin D1 levels, similar events as those in early stages of cell differentiation. Studies suggest that blockage in c‐myc expression triggers early events in neuronal differentiation. These studies are of the utmost importance to elucidate regulatory mechanisms of molecules that play a critical role in the transition from a proliferating phenotype to differentiated cells. © 2003 Wiley‐Liss, Inc.