bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual mechanisms governing muscle cell death in tadpole tail during amphibian metamorphosis
Authors: Nakajima Keisuke , Yaoita Yoshio 
Published: May 2003

AbstractThe tadpole tail, which is twice as long as the body, is induced to resorb completely by thyroid hormone within several days during the anuran metamorphosis. To investigate the underlying mechanism, we undertook two approaches. First, we examined the effect of dominant‐negative thyroid hormone receptor (DNTR) on muscle cell death in vitro. The overexpression of DNTR suppressed the death of a tail‐derived myoblastic cell line induced by thyroid hormone. Second, tadpole tails were injected with a reporter gene and the DNTR expression construct, and the reporter gene expression in muscle cells was followed during the spontaneous metamorphosis. DNTR overexpression inhibited a decrease of the reporter gene expression that began at stage 57 in the control tadpoles but only delayed massive muscle cell death at stage 63 when tails shrink very rapidly. Some remained even a few weeks after the metamorphosis, although most DNTR‐overexpressing cells died by the end of the metamorphosis. These results led us to propose that thyroid hormone induces the suicide of muscle cells (the cell‐autonomous death) in the tail between stage 57 and 62 and that both the murder and suicide mechanisms execute muscle cell death in stage 62–64 to remove muscle promptly and completely. Developmental Dynamics 227:246–255, 2003. © 2003 Wiley‐Liss, Inc.
Platelet‐derived growth factor signaling as a cue of the epithelial–mesenchymal interaction required for anuran skin metamorphosis
Authors: Utoh Rie , Shigenaga Sachi , Watanabe Yusuke , Yoshizato Katsutoshi 
Published: May 2003

AbstractThe anuran remodels the larval skin into the adult counterpart during metamorphosis. The construction of the precursor of adult epidermis (preadult epidermis) in Xenopus laevis larvae was coordinated with the development of the secondary connective tissue (s‐ct) underneath the basement membrane, suggesting that the epithelial–mesenchymal interaction plays a critical role in the metamorphic conversion of the larval skin. mRNAs of platelet‐derived growth factor A (PDGF‐A) and PDGF receptor (PDGFR) ‐α were markedly up‐regulated in the skin during spontaneous and thyroid hormone (TH) ‐induced metamorphosis. In situ hybridization experiments identified preadult epidermal basal cells and fibroblasts in developing subepidermal connective tissues at the late prometamorphic stage as PDGF‐A and PDGFR‐α mRNA‐expressing cells, respectively. We developed an in vitro model of larval skin that was remodeled to the adult skin under the influence of TH. The presence of either of AG1296, a specific inhibitor of PDGFR tyrosine kinase autophosphorylation, or an excess of recombinant proteins of the soluble extracellular domain of PDGFR‐α inhibited the following TH‐induced processes, the proliferation of adult basal cells, the terminal differentiation of adult basal cells, and the activation of subepidermal fibroblasts. However, the inhibitors did not inhibit the TH‐induced proliferation of preadult basal cells. We concluded that PDGF/PDGFR signaling is one of the prime cues in the epithelial‐mesenchymal interaction required for the metamorphic skin remodeling. Developmental Dynamics 227:157–169, 2003. © 2003 Wiley‐Liss, Inc.
Phenotype of the zebrafish masterblind (mbl) mutant is dependent on genetic background
Authors: Sanders L.H. , Whitlock K.E. 
Published: May 2003

AbstractThe zebrafish masterblind (mbl) mutant is characterized by the lack of olfactory placodes and optic vesicles, reduced telencephalon, an expanded epiphysis (Heisenberg et al. [1996] Development 123:191–203), and enlarged jaw. To understand the cellular events giving rise to the olfactory placode defect of this mutant, we examined the expression pattern of the distal‐less‐3 (dlx3) gene in mbl. In the mutant, dlx3, which is normally expressed in the developing nose and ear, showed reduced expression in the olfactory placode field, but normal expression in the developing ear. To determine whether the loss of dlx3 expression was due to cell loss, we assayed cell death by using TUNEL labeling. Although cell death in the mutant was not concentrated in the region of dlx3 expression, there was increased cell death in the forebrain, epiphysis, and jaw region, as compared with that in wild‐type controls. This cell death phenotype was cyclical in nature, showing an increase and decrease in cell death on a roughly 24‐hr cycle. Further analysis showed that this cyclical phenotype was specific to the genetic background. The severity of the mbl phenotype, including cell death, expanded epiphysis, and enlarged jaw, decreased when the mutation was moved from the original “TL” background to the “AB” background. Thus, the severity of developmental defects in the mbl mutant is strongly dependent on genetic background. We examined the contribution of cell death to the morphologic defects of mbl by blocking cell death by using zVADfmk, a known caspase inhibitor. We found that this treatment partially rescued the expanded jaw defect and that this rescue was dependent on the genetic background. Therefore, the mbl mutant phenotypes result, in part, from genetic background effects that alter the pattern of programmed cell death early in development. Developmental Dynamics 227:291–300, 2003. © 2003 Wiley‐Liss, Inc.
EGF‐stimulated signaling by means of PI3K, PLCγ1, and PKC isozymes regulates branching morphogenesis of the fetal mouse submandibular gland
Authors: Koyama Noriko , Kashimata Masanori , Sakashita Hideaki , Sakagami Hiroshi , Gresik Edward W. 
Published: May 2003

AbstractBranching morphogenesis of fetal mouse submandibular glands (SMGs) partly depends on the epidermal growth factor (EGF) receptor that triggers at least three intracellular signaling pathways involving (1) the mitogen‐activated protein kinases ERK‐1/2, (2) phospholipase Cγ1 (PLCγ1), and (3) phosphatidylinositol‐3‐kinase (PI3K). PLCγ1 directly activates protein kinase C (PKC) isozymes; PI3K stimulates protein kinase B (PKB, also known as Akt), which ultimately activates PKCs and other proteins. We reported that the pattern of phosphorylation of ERK‐1/2 in response to EGF in SMGs varies with fetal age and that blockade of EGF‐stimulated ERK‐1/2 signaling partially inhibits branching (Kashimata et al. [2000] Dev. Biol. 220:183–196). Here, we report on components of the PLCγ1, PI3K, and PKC families of signaling molecules in fetal SMGs from the 13th day of gestation to postnatal ages. Western blotting revealed that (1) PLCγ1 is present from E13 to E18 but drops off precipitously to negligible levels on the day of birth and thereafter, and (2) PI3K, PKB(Akt), and several PKC isozymes are expressed from E13 onward through adult life. Both PLCγ1 and PI3K are phosphorylated in response to EGF. Inhibition of PI3K by LY294002 inhibited EGF‐stimulated branching, but inhibition of PLCγ1 by U73122 had no effect. Western blotting showed that the concentrations of 8 PKC isozymes vary with age in the fetal and postnatal SMG. However, general inhibition of PKCs by Calphostin C or specific inhibition of PKCα or of PKCϵ by Gö6976 or Ro‐32‐0432, respectively, increased EGF‐stimulated branching. Calphostin C also increased EGF‐stimulated phosphorylation of ERK‐1/2. These findings indicate that signaling from the EGF receptor in the fetal mouse SMG varies with development and triggers stimulatory effects by means of ERK‐1/2 and PI3K but inhibitory effects by means of PKC isozymes. Developmental Dynamics 227:216–226, 2003. © 2003 Wiley‐Liss, Inc.
Synthesis of 11C‐Labelled Amides by Palladium‐Mediated Carboxamination Using [11C]Carbon Monoxide, in situ Activated Amines and 1,2,2,6,6‐Pentamethylpiperidine
Authors: Karimi Farhad , Langström Bengt 
Published: May 2003

AbstractTwenty‐seven 11C‐labelled amides were synthesised using [11C]carbon monoxide in low concentrations, palladium(0), organohalides and amines in a small micro‐autoclave (200 μL). The focus of the study was to improve the radiochemical yields in this palladium‐mediated amide synthesis when employing less‐reactive amines, such as methylamine, [(2R)‐1‐ethylpyrrolidin‐2‐yl]methylamine (40) and 2‐(pyridin‐2‐yl)ethanamine (41). The radiochemical yields were improved when utilizing 1,2,2,6,6‐pentamethylpiperidine (pempidine) in combination with the amine substrates. The 11C‐labelled amides were obtained mostly in high radiochemical yields (in the range 16−94%) and the specific radioactivity varied between 650 and 1250 GBq/μmol. 1‐(1,3‐Benzodioxol‐5‐yl[13C]carbonyl)piperidine (6a) was synthesised to verify the labelling position (δ = 169.8 ppm) using 13C NMR spectroscopy. The radiochemical purity of the target compounds was determined by analytical HPLC and exceeded 95%. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
(Aryl)(phosphanyl)Carbene: Ground‐ and Excited‐State Reactions
Authors: Despagnet‐Ayoub Emmanuelle , Gornitzka Heinz , Bourissou Didier , Bertrand Guy 
Published: May 2003

AbstractCyclopropanation, carbene coupling, and photolytically induced 1,2‐migration reactions are reported for the stable singlet [bis(diisopropylamino)phosphanyl][o,o′‐bis(trifluoromethyl)phenyl]carbene (1). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
An Efficient Total Synthesis of Pedunculagin by Using a Twofold Intramolecular Double Esterification Strategy
Authors: Khanbabaee Karamali , Großer Mathias 
Published: May 2003

AbstractThe total synthesis of naturally occurring pedunculagin (1) was achieved by the twofold intramolecular double esterification of enantiomerically pure (S)‐hexabenzyloxydiphenic acid (4) with the D‐glucose‐derived sugar 2 as the key step. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Stereoselective Preparation of 10α‐ and 10β‐Aryl Derivatives of Dihydroartemisinin
Authors: Haynes Richard K. , Chan Ho‐Wai , Cheung Man‐Ki , Chung Shuk Ting , Lam Wai‐Lun , Tsang Hing‐Wo , Voerste Arnd , Williams Ian D. 
Published: May 2003

AbstractLewis acid‐catalysed arylation of the 10β‐benzoate and, less effectively, the 10α‐benzoate of dihydroartemisinin [DHA] with activated aromatic compounds, including naphthalenes, stereoselectively, provides 10α‐aryl derivatives including disubstituted naphthalene derivatives. 2‐Methoxynaphthalene provides the 1‐, rather than the 3‐substituted derivative. In contrast, 10β‐aryl derivatives are obtained stereoselectively from the 10β‐bromide, generated in situ from trimethylsilyl bromide and the TMS ether of 10α‐DHA, and the corresponding aryl Grignard reagents. The 10α‐aryl compounds are shown by NMR spectroscopy and X‐ray crystallographic analysis to possess a chair pyranose ring with equatorial aryl group, whereas the 10β‐aryl derivatives have a twist‐boat pyranose ring with equatorial aryl group. The stereochemistry of the Lewis acid‐catalysed arylations, which is common to that observed for the Lewis acid‐catalysed arylation of pyranosyl glycosides with axial anomeric leaving groups in general, may be rationalized in terms of axial attack from the α or si face of the half‐chair oxonium ion intermediate. On the other hand, the Grignard reagents activate the axial bromide to elimination through complexation, and thereby the aryl nucleophile attacks the incipient oxonium ion from the β or re face. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A Binuclear Phthalocyanine Containing Two Different Metals
Authors: Calvete Mario , Hanack Michael 
Published: May 2003

AbstractThe unsymmetrical binuclear phthalocyanine 4a and the symmetrical binuclear phthalocyanine 4b with two different metals (Ni and Cu), as well as the correspondent binuclear phthalocyanines with two Ni atoms (4c and 4d) were synthesized from the benzoannulated dicyano‐substituted Ni phthalocyanine 2. Atomic absorption spectroscopy verified unambiguously the presence of Ni and Cu in the binuclear phthalocyanines. The proposed synthetic route demonstrates great versatility towards substitution at the peripheral positions of the ring and the variation of the chelating central metal. Complexes 4a−4d are soluble in common organic solvents of medium polarity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Gliogenic and neurogenic progenitors of the subventricular zone: Who are they, where did they come from, and where are they going?
Authors: Marshall Christine A.G. , Suzuki Satoshi O. , Goldman James E. 
Published: May 2003

AbstractThe subventricular zone (SVZ) of the perinatal forebrain gives rise to both neurons and glia. The mechanisms governing the phenotypic specification of progenitors within this heterogeneous germinal zone are unclear. However, the characterization of subpopulations of SVZ cells has given us a better understanding of the basic architecture of the SVZ and presents us with the opportunity to ask more detailed questions regarding phenotype specification and cell fate. Recent work demonstrating the embryonic origins of SVZ cells is summarized, and a model describing the formation of the perinatal SVZ, noting contributions of cells from pallial as well as subpallial germinal zones, is presented. We further address differences among classes of SVZ cells based on molecular profile, phenotype, and migration behavior and present a model summarizing the organization of perinatal SVZ cells along coronal, sagittal, and horizontal axes. A detailed description of the SVZ in the adult, outlining classes of cells based on morphology, molecular profile, and proliferative behavior, was recently reported by Doetsch et al. (Proc Natl Acad Sci USA 93:14895–14900, 1997). Potential relationships among cells within the perinatal and adult SVZ will be discussed. GLIA 43:52–61, 2003. © 2003 Wiley‐Liss, Inc.
GFAP: Functional implications gleaned from studies of genetically engineered mice
Authors: Messing Albee , Brenner Michael 
Published: May 2003

AbstractGFAP is the major intermediate filament of mature astrocytes, and its relatively specific expression in these cells suggests an important function. To study the role of the GFAP gene, mice have been created carrying null alleles (no protein), modified alleles (altered protein), or added wild type alleles (elevated protein). Surprisingly, absence of GFAP has relatively subtle effects on development. On the other hand, over‐expression can be lethal, and led to the discovery that GFAP coding mutations are responsible for most cases of Alexander disease, a devastating neurodegenerative disorder. Here we review what the various GFAP mouse models reveal about GFAP and astrocyte function. GLIA 43:87–90, 2003. © 2003 Wiley‐Liss, Inc.
Precursors of neurons, neuroglia, and ependymal cells in the CNS: What are they? Where are they from? How do they get where they are going?
Authors: Morest D. Kent , Silver Jerry 
Published: May 2003

AbstractNeurons, neuroglia (astrocytes and oligodendrocytes), and ependymal cells are three distinct categories of neural cells in the central nervous system. In the mature brain and spinal cord, the classical histological criteria define these cells by their microscopic structure very well. During development, the precursors for all of these cells reside within the epithelium of the neural plate and its successor, the neural tube. These precursor cells are the undifferentiated, primitive neuroepithelium of the classical literature. As the cerebral vesicles enlarge and their walls thicken, the primitive neuroepithelial cells elongate, maintaining a radial orientation until they migrate. Although many, but not all, of these cells span the extent of the ventricular wall, they are the precursors of neurons, neuroglia, and ependymal cells. Thus, it is useful to retain their classical designation as primitive neuroepithelial cells and to treat them as neural precursor cells. Neural precursor cells are neither neuroglia nor neurons. It is not appropriate to call them radial glial cells anymore than it is to call them radial neuronal cells. The term “radial glia” has long been used to describe the mature, elongated astrocytes, represented by Bergmann cells in the cerebellum and Müller cells in the retina. Inevitably, during development, transitional forms between neural precursor cells and the neurons, neuroglia, and ependymal cells will occur. Such transitional cells are known as neuroblasts, glioblasts, or ependymoblasts, even though they may be postmitotic. Alternative terms are “immature neurons,” “immature neuroglia,” and “immature ependymal cells.” The migration of many neural precursor cells is accomplished by translocation rather than free cellular locomotion. There is both direct and indirect evidence to document the translocation of the nuclear/perikaryal/somal complex through the leading process of primitive neuroepithelial cells. This is conspicuous in the neocortex, where the discrete radial arrangement of pyramidal cells may result from translocation of neuroblasts, while their leading processes still contact the pial surface. Migration by translocation occurs throughout the CNS. GLIA 43:6–18, 2003. © 2003 Wiley‐Liss, Inc.
Thromboresistance of alkali‐ and heat‐treated titanium metal formed with apatite
Authors: Muramatsu Kazuaki , Uchida Masaki , Kim Hyun‐Min , Fujisawa Akira , Kokubo Tadashi 
Published: May 2003

AbstractFibrin deposition and platelet adhesion onto alkali‐ and heat‐treated titanium metal (AH‐Ti), alkali‐ and water‐treated titanium metal (Wa‐Ti), and alkali‐ and heat‐treated titanium metal formed with apatite (Ap‐Ti) in simulated body fluid (SBF) were evaluated by exposure to anticoagulated blood or washed platelet suspension (WPS) under static conditions and subsequent observation with scanning electron microscopy (SEM). The results were compared with those for commercially pure titanium metal (cp‐Ti). Thrombus formation on AH‐Ti and Wa‐Ti, which were exposed to heparinized whole blood for 1 h, was significantly less than that on cp‐Ti, on which pronounced depositions of fibrin‐erythrocytes and lymphocytes were observed. No thrombus was observed on Ap‐Ti, possibly because of a high adsorption of heparin. Morphological change of platelets attached to surfaces via adsorbed plasma proteins was found to a significant extent on AH‐Ti and Wa‐Ti exposed to WPS. However, there was almost no difference between cp‐Ti and Ap‐Ti in round morphology of adherent platelets. These findings suggested that Ap‐Ti exhibits stronger antithrombogenic characteristics than cp‐Ti and other materials examined in heparinized blood. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 409–416, 2003
Effects of bioactive glass particles and their ionic products on intracellular concentrations
Authors: Laquerriere Patrice , Jallot Edouard , Kilian Laurence , Benhayoune Hicham , Balossier Gérard 
Published: May 2003

AbstractNumerous studies have described the bioactive properties of glass particles in the SiO2‐CaO‐Na2O‐P2O5 system. This kind of material is capable of developing a direct contact with bone through dissolution and physicochemical reactions. We have investigated the influence of bioactive particles, and ionic products from the same particles, on the intracellular concentrations in monocyte cells, which are among the first cells to colonize implantation sites. The only way to access these concentrations and particularly diffusible ionic concentrations (potassium, sodium, and chlorine) is to use cryomethods coupled to electron probe microanalysis. We have paid particular attention to the potassium:sodium ratio, the most sensitive criterion of viability. We have cultured cells with bioactive glass particles and in a conditioned medium obtained from the dissolution of the glass particles in the standard medium. Our study demonstrates that cells cultured in a conditioned medium are more active than cells cultured in a standard medium, or cells exposed to bioactive particles, and particles are more toxic for cells than are ionic products. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 441–446, 2003
Biodegradation of polyurethane under fatigue loading
Authors: Wiggins Michael J. , Anderson James M. , Hiltner Anne 
Published: May 2003

AbstractA method utilizing expansion of a diaphragm‐type film specimen was developed to study in vitro biodegradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading (fatigue). A finite element model was used to describe the strain state, which ranged from uniaxial at the edges of the film to balanced biaxial tensile strain at the center. During testing, the film was exposed to a H2O2/CoCl2 solution, which simulated in vivo oxidative biodegradation of PEUU. The extent of chemical degradation was determined by infrared analysis. Physical damage of the film surface was characterized by optical microscopy and scanning electron microscopy. Dynamic loading did not affect the rate of degradation relative to unstressed and constant stress (creep) controls in regions of the film that experienced primarily uniaxial fatigue; however, degradation was accelerated in regions that experienced balanced biaxial or almost balanced biaxial fatigue. It was concluded that the combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation in this system. Chemical degradation produced a brittle surface layer that was marked by numerous pits and dimples. Physical damage of the surface in the form of cracking occurred only in fatigue experiments. Cracking was not observed in unstressed or creep tests. Cracks initiated at the dimples produced by chemical degradation, and propagated in a direction that was determined by the strain state. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 524–535, 2003
hMad4, c‐Myc endogenous inhibitor, induces a replicative senescence‐like state when overexpressed in human fibroblasts
Authors: Marcotte Richard , Qian Jing‐Fang , Chen James , Wang Eugenia 
Published: May 2003

AbstractMad family proteins have an antagonistic action on Myc‐dependent cell proliferation and transformation. We isolated a human cDNA clone, human Mad4 (hMad4), encoding a polypeptide of 209 amino acid residues, exhibiting 90% identity with mouse Mad4. Northern blot analysis shows that hMad4 probe hybridizes to a 3.8 kb message; its expression is highest in quiescent human WI38 fibroblasts. Among tissues, hMad4 mRNA is most abundant in brain, lung, and muscle. Consistent with other members of the Mad family, hMad4 can repress the transactivation activity of Myc/Max heterodimers on an E‐box chloramphenicol acteyl transferase (CAT) reporter plasmid; inhibition of both proliferation and clonogenic formation of hMad4‐infected cells correlates with the in vitro reporter repression. Moreover, infection of young human fibroblasts induces a replicative senescence‐like state. This phenotype was accompanied by s‐β‐galactosidase and PAI‐1 expression. These results suggest that hMad4 might be an important regulator of replicative senescence in human cells. J. Cell. Biochem. 89: 576–588, 2003. © 2003 Wiley‐Liss, Inc.