bluuebunny/crossref_metadata_2025 huggingface dataset:
Automated method to measure trabecular thickness from microcomputed tomographic scans and its application
Authors: McColl Daniel J. , Abel Richard L. , Spears Iain R. , Macho Gabriele A.
Published: August 2006

Trabeculae form the internal bony mesh work and provide strength to the bone; interconnectivity, overall density, and trabecular thickness are important measures of the integrity of the internal architecture. Such strength is achieved only gradually during ontogeny, whereby an increase in trabecular thickness precedes an increase in mineralization. Loss of bone mass later in life may be compensated for by thickening of the remaining trabeculae. These facts, and the role of trabeculae in mineral homeostasis, highlight the importance of investigating trabecular thickness within and between species. While nondestructive imaging techniques (i.e., μCT and MRI) are becoming increasingly popular, quantification of trabecular thickness using nondestructive techniques has proved difficult owing to limitations imposed by scanning parameters, uniform thresholding, and partial volume averaging. Here we present a computer application, which aims to overcome these problems. Validation is carried out against a phantom and against trabecular thickness measured in corresponding histological sections. Good agreement was found between these measurements. Furthermore, when trabecular thickness is recorded for modern human fetal ilia, a trend toward trabecular thickness increase is found and is in line with reports of ontogenetic morphometric changes using histological sections. However, there are discrepancies. These may in part be due to partial volume effects of obliquely oriented structures. More crucial, however, are problems inherent in histological sections, e.g., shrinkage and distortion, especially where differences in mineralization are concerned; this may affect biological interpretations. Anat Rec Part A, 288A:982–988, 2006. © 2006 Wiley‐Liss, Inc.
Intrauterine death, fetal malformation, and delayed pregnancy in Ljungan virus‐infected mice
Authors: Samsioe Annika , Feinstein Ricardo , Saade George , Sjöholm Åke , Hörnfeldt Birger , Fundele Reinald , Klitz William , Niklasson Bo
Published: August 2006

BACKGROUND: A picornavirus (Ljunganvirus [LV]) has recently been associated with disease during pregnancy in its natural rodent reservoir and in humans. A study of laboratory mice infected under controlled conditions was therefore undertaken. METHODS: CD‐1 female mice were infected gestational day two and subjected to varying regimes of stress. RESULTS: LV infection in combination with stress resulted in uterine resorptions, malformations, and neonatal death. A short delay in time to first pregnancy and births was observed in pairs infected in utero. CONCLUSIONS: LV is found in different species of native animals in both Europe and the United States and human epidemiological evidence connects LV and human reproduction, while the observations here indicate that LV is responsible for reproductive problems in a laboratory mouse model. The current findings suggest that the hypothesis that LV also causes disease in pregnant women and their offspring deserves further study. Birth Defects Res (Part B) 77, 2006. © 2006 Wiley‐Liss, Inc.
Vanadyl sulfate protects against streptozotocin‐induced morphological and biochemical changes in rat aorta
Authors: Akgün‐Dar Kadriye , Bolkent Sehnaz , Yanardag Refıye , Tunalı Sevim
Published: August 2006

The aim of this study was to investigate the protective effects of vanadyl sulfate on aorta tissue of normal and streptozotocin (STZ)‐induced diabetic rats, morphologically and biochemically. The animals were made diabetic by an intraperitoneal injection of streptozotocin (65 mg/kg) and vanadyl sulfate (100 mg/kg) that was given every day for 60 days by gavage technique to rats. Under the light and transmission electron microscopes, hypertrophy of the vessel wall, focal disruption in the elastic lamellae, an increase in thickness of total aortic wall, tunica intima, subendothelial space and adventitial layer, and a disorganization in smooth muscular cells of the tunica media were observed in diabetic animals. The aorta lipid peroxidation (LPO) levels were significantly increased and the aorta glutathione (GSH) levels were significantly reduced in STZ diabetic rats. In diabetic rats administered vanadyl sulfate for 60 days, aorta LPO levels significantly decreased and the aorta GSH level significantly increased. In conclusion, in vivo treatment with vanadyl sulfate of diabetic rats prevented the morphological and biochemical changes observed in thoracic aorta of diabetic animals. Copyright © 2006 John Wiley & Sons, Ltd.
Human soluble E‐selectin immunoadhesin inhibits leukemic monocyte adhesion to endothelial cells
Authors: Sung Bong Hwan , Kim Sung Hyun , Yeo Myeong Gu , Kim Jin‐Kyoo , Song Woo Keun
Published: August 2006

Immunoadhesins are immunoglobulin (Ig)‐like chimeric proteins comprised of target‐binding regions fused to the Fc‐hinge region of Ig, and are designed to have a long half‐life and antibody‐like properties. In an effort to find a good candidate for therapeutic use for inflammatory responses, we constructed a soluble human E‐selectin immunoadhesin containing the extracellular region of human E‐selectin fused to the Fc‐hinge region of human IgG, and determined its effects on leukocyte adhesion and rolling in vitro. Our results revealed that the adhesion of leukocytes to endothelial cells was efficiently inhibited in the presence of 50 nM E‐selectin immunoadhesin. In addition, the E‐selectin immunoadhesin significantly inhibited leukocyte rolling on endothelial cells in perfusion experiments performed at 1.0 dyne/cm2 wall shear stress. These findings indicate that our E‐selectin immunoadhesin decreases leukocyte attachment and rolling in vitro, suggesting that this immunoadhesin may be a promising candidate for therapeutic anti‐inflammatory use. Copyright © 2006 John Wiley & Sons, Ltd.
Synthetic Peptide Templates for Molecular Recognition: Recent Advances and Applications
Authors: Singh Yashveer , Dolphin Gunnar T. , Razkin Jesus , Dumy Pascal
Published: August 2006

The creation of molecular systems that can mimic some of the properties of natural macromolecules is one of the major endeavors in contemporary protein chemistry. However, the construction of artificial proteins with predetermined structure and function is difficult on account of complex folding pathways. The use of topological peptide templates has been suggested to induce and stabilize defined secondary and tertiary structures. This is because the recent advances in the chemistry of coupling reagents, protecting groups, and solid‐phase synthesis have made the chemical synthesis of peptides with conformationally controlled and complex structures feasible. Besides their use as structure‐inducing devices, these peptide templates can also be utilized to construct novel structures with tailor‐made functions. Herein, we present recent advances in the field of peptide‐template‐based approaches with particular emphasis on the demonstrated utility of this approach in molecular recognition, along with related applications.
Single‐Chain Magnet Behavior in an Alternated One‐Dimensional Assembly of a MnIII Schiff‐Base Complex and a TCNQ Radical
Authors: Miyasaka Hitoshi , Madanbashi Tomokura , Sugimoto Kunihisa , Nakazawa Yasuhiro , Wernsdorfer Wolfgang , Sugiura Ken‐ichi , Yamashita Masahiro , Coulon Claude , Clérac Rodolphe
Published: August 2006

An alternated 1:1 chain compound of a MnIII salen derivative and the TCNQ monoradical was synthesized: [Mn(5‐TMAMsaltmen)(TCNQ)](ClO4)2 (1) (TCNQ=tetracyano‐p‐quinodimethane; 5‐TMAMsaltmen=N,N′‐(1,1,2,2‐tetramethylethylene) bis(5‐trimethylammoniomethylsalicylideneiminato)). Compound 1 has a zigzag chain structure packed with adjacent chains with an interchain Mn⋅⋅⋅Mn distance of over 8 Å. As compound 1 contains no crystallization solvent, the void spaces between chains are occupied only by ClO4− counter ions. Compound 1 has a structure reminiscent of what has been observed in the family of MnIII(porphyrin)‐TCNE or ‐TCNQ compounds reported previously by Miller and co‐workers and we demonstrate herein its unique single‐chain magnet behavior among this family of compounds. The direct current (dc) magnetic measurements established the one‐dimensional nature of compound 1 with an antiferromagnetic exchange coupling, J/kB≈−96 K, between the MnIII ion and TCNQ radical and with an activated correlation length (Δξ=26.5 K) at low temperatures (50–15 K). The slow relaxation of the magnetization was shown in compound 1 by the field hysteresis of the magnetization observed below 3.5 K (with a coercive field up to 14 kOe at 1.8 K). Single‐crystal magnetization measurements demonstrated the uniaxial symmetry of this compound and allowed an estimation of the anisotropy field, Ha≈97 kOe. The absence of magnetic ordered phase or spin‐glass behavior was established by heat‐capacity calorimetry measurements that exhibit no abnormality of Cp between 0.5 K and 10 K. The study of the magnetization relaxation by combined ac (alternating current) and dc techniques showed that compound 1 possesses a single relaxation time (τ). As the consequence of the finite size of the chain, the temperature dependence of τ presents two activated regimes above and below 4.5 K with τ01=2.1×10−10 s, Δτ1=94.1 K and τ02=6.8×10−8 s and Δτ2=67.7 K, respectively. The detailed analysis of these dynamics properties together with the correlation length, allows an unambiguous demonstration of the single‐chain magnet behavior in 1.
Supramolecular Self‐Organization of “Janus‐like” Diblock Codendrimers: Synthesis, Thermal Behavior, and Phase Structure Modeling
Authors: Bury Izabela , Heinrich Benoît , Bourgogne Cyril , Guillon Daniel , Donnio Bertrand
Published: August 2006

We report on the design and synthesis of three series of segmented amphiphilic block codendrimers, and on their self‐organizing behavior in liquid‐crystalline mesophases. Connecting two prefunctionalized monodendrons, each differing in their chemical constitution and generation number, yielded these diblock supermolecules. One wedge of the codendrimer was made hydrophobic, and is based on a branched poly(benzyl ether) monodendron functionalized at the periphery by lipophilic aliphatic fragments (also known as Percec dendrons). The other segment was made hydrophilic by the grafting of hydroxyl‐containing moieties onto the focal functions of the former dendrons. Both types of dendrons were prepared independently by convergent methods and then joined in the ultimate stage of the synthetic procedure by cross‐coupling reactions. In this way, the proportion of the dendritic blocks was varied independently to allow control of the hydrophilic/hydrophobic balance (HHB), the hydrogen‐bonding ability, and consequently the capacity to tune the mesomorphic properties of the resulting “superamphiphiles” was anticipated. Essentially all the dendritic compounds display a thermotropic mesomorphism directly at or near room temperature as determined by using X‐ray diffraction, polarized optical microscopy, and differential scanning calorimetry. The nature and the supramolecular organization of the mesophases, namely columnar and cubic phases, are correlated to the size of the respective block monodendrons and the chemical structures of the dendromesogens. The molecular organization within the cubic phases can be geometrically described and well understood by the space‐filling polyhedron model.
The Molecular Basis of Self‐Assembly of Dendron–Rod–Coils into One‐Dimensional Nanostructures
Authors: Zubarev Eugene R. , Sone Eli D. , Stupp Samuel I.
Published: August 2006

We describe here a comprehensive study of solution and solid‐state properties of self‐assembling triblock molecules composed of a hydrophilic dendron covalently linked to an aromatic rigid rod segment, which is in turn connected to a hydrophobic flexible coil. These dendron–rod–coil (DRC) molecules form well‐defined supramolecular structures that possess a ribbonlike morphology as revealed by transmission‐electron and atomic‐force microscopy. In a large variety of aprotic solvents, the DRC ribbons create stable networks that form gels at concentrations as low as 0.2 % by weight DRC. The gels are thermally irreversible and do not melt at elevated temperatures, indicating high stability as a result of strong noncovalent interactions among DRC molecules. NMR experiments show that the strong interactions leading to aggregation involve mainly the dendron and rodlike blocks, whereas oligoisoprene coil segments remain solvated after gelation. Small‐angle X‐ray scattering (SAXS) profiles of different DRC molecules demonstrate an excellent correlation between the degree‐of‐order in the solid‐state and the stability of gels. Studies on two series of analogous molecules suggest that self‐assembly is very sensitive to subtle structural changes and requires the presence of at least four hydroxyl groups in the dendron, two biphenyl units in the rod, and a coil segment with a size comparable to that of the rodlike block. A detailed analysis of crystal structures of model compounds revealed the formation of stable one‐dimensional structures that involve two types of noncovalent interactions, aromatic π–π stacking and hydrogen bonding. Most importantly, the crystal structure of the rod–dendron compound shows that hydrogen bonding not only drives the formation of head‐to‐head cyclic structures, but also generates multiple linkages between them along the stacking direction. The cyclic structures are tetrameric in nature and stack into ribbonlike objects. We believe that DRC molecules utilize the same arrangement of hydrogen bonds and stacking of aromatic blocks observed in the crystals, explaining the exceptional stability of the nanostructures in extremely dilute solutions as well the thermal stability of the gels they form. This study provides mechanistic insights on self‐assembly of triblock molecules, and unveils general strategies to create well‐defined one‐dimensional supramolecular objects.
Ligand‐Based Virtual Screening, Parallel Solution‐Phase and Microwave‐Assisted Synthesis as Tools to Identify and Synthesize New Inhibitors of Mycobacterium tuberculosis
Authors: Manetti Fabrizio , Magnani Matteo , Castagnolo Daniele , Passalacqua Laura , Botta Maurizio , Corelli Federico , Saddi Manuela , Deidda Delia , De Logu Alessandro
Published: August 2006

In an attempt to identify new inhibitors of the growth of Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis, a procedure for the generation, design, and screening of a ligand‐based virtual library was applied. This used both an in silico protocol centered on a recursive partitioning (RP) model described herein, and a pharmacophoric model for antitubercular agents previously generated by our research group. Two candidates emerged from databases of commercially available compounds, both characterized by a minimum inhibitory concentration (MIC) of 25 μg mL−1. Based on these compounds, two series of derivatives were synthesized by both parallel solution‐phase and microwave‐assisted synthesis, leading to enhanced antimycobacterial activity. During both the design and synthesis, attention was focused on the efficient allocation of available resources with the aim of reducing the overall costs associated with calculation and synthesis.
Treatment of pregnant breast cancer patients and outcomes of children exposed to chemotherapy in utero
Authors: Hahn Karin M.E. , Johnson Peter H. , Gordon Nancy , Kuerer Henry , Middleton Lavinia , Ramirez Mildred , Yang Wei , Perkins George , Hortobagyi Gabriel N. , Theriault Richard L.
Published: August 2006

BACKGROUND

As women in the US delay childbearing, it has been hypothesized that the incidence of breast cancer diagnosed during pregnancy will increase. There are very little prospective data on the treatment of pregnant women with breast cancer with chemotherapy and even less data on the outcomes of their children who were exposed to chemotherapy in utero.

METHODS

Fifty‐seven pregnant breast cancer patients were treated on a single‐arm, multidisciplinary, institutional review board‐approved protocol with FAC (5‐fluorouracil, doxorubicin, cyclophosphamide) in the adjuvant (n = 32) or neoadjuvant (n = 25) setting. Parents/guardians were surveyed by mail or telephone regarding outcomes of children exposed to chemotherapy in utero.

RESULTS

Of the 57 women, 40 are alive and disease‐free, 3 have recurrent breast cancer, 12 died from breast cancer, 1 died from other causes, and 1 was lost to follow‐up. Of the 25 patients who received neoadjuvant FAC, 6 had a pathologic complete response, whereas 4 had no tumor response to chemotherapy and eventually died from their disease. All women who delivered had live births. One child has Down syndrome and 2 have congenital anomalies (club foot; congenital bilateral ureteral reflux). The children are healthy and those in school are doing well, although 2 have special educational needs.

CONCLUSIONS

Breast cancer can be treated with FAC chemotherapy during the second and third trimesters without significant short‐term complications for the majority of children exposed to chemotherapy in utero. Longer follow‐up of the children is needed to evaluate possible late side effects such as impaired cardiac function and fertility. Cancer 2006. © 2006 American Cancer Society.
Metabolic syndrome and growth hormone deficiency in adult survivors of childhood acute lymphoblastic leukemia
Authors: Gurney James G. , Ness Kirsten K. , Sibley Shalamar D. , O'Leary Maura , Dengel Donald R. , Lee Joyce M. , Youngren Nancy M. , Glasser Stephen P. , Baker K. Scott
Published: August 2006

BACKGROUND.

The purpose of the study was to determine the prevalence of metabolic syndrome, growth hormone deficiency, and cardiovascular risk factors among adult survivors of childhood acute lymphoblastic leukemia (ALL) treated with or without cranial irradiation.

METHODS.

Follow‐up was undertaken of 75 randomly selected long‐term childhood ALL survivors. Testing included fasting insulin, glucose, lipids, and growth hormone (GH) releasing hormone plus arginine stimulation test. The prevalence of metabolic syndrome was compared with population norms from 1999–2002 National Health and Nutrition Examination Study (NHANES) data, and internally between those with and without past cranial irradiation and those with normal (>16.5 μg/L) versus insufficient (9–16.5 μg/L) versus deficient (<9 μg/L) peak GH secretion.

RESULTS.

The mean subject age was 30 years and the mean time since ALL diagnosis was 25 years. The prevalence of metabolic syndrome did not differ statistically (P = .87) between study subjects (16.6%) and same‐age, same‐sex population norms (17.5%). However, 60% of subjects treated with cranial irradiation, compared with 20% of those who were not, had 2 or more of the 5 components of metabolic syndrome. Untreated abnormally low GH was present in 64% of subjects overall and 85% of those who received past cranial irradiation. Cranial irradiation was strongly related to GH deficiency, and in turn lower insulin‐like growth factor 1 (IGF‐1), higher fasting insulin, abdominal obesity, and dyslipidemia, particularly in women.

CONCLUSIONS.

Hematologists who treat childhood ALL patients, and particularly those who provide primary care to adult survivors, should be aware of the potential for long‐term GH deficiency and adverse cardiovascular and diabetes risk profiles as a consequence of leukemia treatment. Cancer 2006. © 2006 American Cancer Society.
Role of spinal MRI in the follow‐up of children treated for medulloblastoma
Authors: Bartels Ute , Shroff Manohar , Sung Lillian , Dag‐Ellams Ugo , Laperriere Normand , Rutka James , Bouffet Eric
Published: August 2006

BACKGROUND.

The purpose of the current study was to describe the usefulness of spinal magnetic resonance imaging (MRI) in children with medulloblastoma or primitive neuroectodermal tumor (PNET) of the posterior fossa.

METHODS.

Children consecutively diagnosed with medulloblastoma/PNET and followed in the Hospital for Sick Children/Toronto were identified. A homogenous cohort of children treated with craniospinal irradiation as part of their initial treatment was considered. Contrast‐enhanced spinal MRIs done concomitantly with cranial MRIs (doublets) were reviewed. Recurrence was defined as any new abnormal lesion (in the brain or in the spine) in symptomatic or asymptomatic patients. Doublets after the first recurrence were excluded in the final analysis. The utility of a spinal MRI in the presence of a negative cranial MRI was assessed.

RESULTS.

In all, 73 patients (21 females and 52 males; median age, 6.6 years, median follow‐up time, 4.3 years) had at least 1 evaluable doublet during the follow‐up period. Since concomitant cranial and spinal MRI was introduced as the standard evaluation for medulloblastoma/PNET in 1991, 286 doublets were evaluable. Fourteen spinal MRIs and 25 cranial MRIs showed new nodular or leptomeningeal lesions. In 2 patients, repeat MRIs ruled out recurrence (false‐positive). All confirmed spinal recurrences were associated with intracranial recurrence. Of 261 doublets with negative cranial MRI, no new lesion was identified on spinal MRI.

CONCLUSIONS.

An absence of progression on cranial MRI is highly predictive of absence of progression on spinal MRI. There is little evidence that surveillance spinal MRI (in children who underwent craniospinal radiation as part of their initial treatment) improves the detection of recurrences in children with medulloblastoma. Cancer 2006. © 2006 American Cancer Society.
Increased expression of avian erythroblastosis virus E26 oncogene homolog 1 in World Health Organization grade 1 meningiomas is associated with an elevated risk of recurrence and is correlated with the expression of its target genes matrix metalloproteinase‐2 and MMP‐9
Authors: Okuducu Ali Fuat , Zils Ulrich , Michaelis Silke A. M. , Mawrin Christian , von Deimling Andreas
Published: August 2006

BACKGROUND

The transcription factor avian erythroblastosis virus E26 (V‐Ets) oncogene homolog 1 (Ets‐1) is involved in tumor development and progression through the transcriptional regulation of several matrix‐degrading enzyme systems, including matrix metalloproteinases (MMPs). It has been demonstrated that the MMPs are expressed strongly in high‐grade meningiomas. To determine the biologic significance of Ets‐1 in the progression of benign meningiomas, the authors investigated the expressions of Ets‐1 and its target genes MMP‐2 and MMP‐9 in primary and recurrent, Grade 1 meningiomas.

METHODS

The expression levels of Ets‐1, MMP‐2, and MMP‐9 were examined by immunohistochemistry in 70 Grade 1 meningiomas, including 36 primary tumors without recurrence after 5 years of follow‐up and 17 pairs of primary tumors and subsequent recurrences.

RESULTS

The results demonstrated higher expression of Ets‐1, MMP‐2, and MMP‐9 proteins in meningiomas with subsequent recurrences compared with meningiomas from patients who had no recurrences (P < .001). In addition, Ets‐1 expression was correlated with the expression of both MMP‐2 and MMP‐9.

CONCLUSIONS

Ets‐1 may be involved in meningioma recurrence by up‐regulating MMP‐2 and MMP‐9. Increased expression of these genes in World Health Organization grade 1 meningiomas may serve as an indicator for a high risk of recurrence. Cancer 2006. © 2006 American Cancer Society.
Relevance of extracapsular extension of pelvic lymph node metastasis in patients with bladder cancer treated in the contemporary era
Authors: Kassouf Wassim , Leibovici Dan , Luongo Tony , Munsell Mark F. , Vakar Funda , Dinney Colin P. , Grossman H. Barton , Kamat Ashish M.
Published: August 2006

BACKGROUND.

Previous reports have suggested that extracapsular extension (ECE) is a prognostic factor in patients with urothelial carcinoma who have positive lymph nodes at the time of radical cystectomy. In the current study, the relevance of ECE in patients treated in the contemporary era was evaluated.

METHODS.

A database search from 1993 to 2003 revealed 150 patients with pN+M0 disease detected after radical cystectomy; of these, 108 patients did not receive neoadjuvant chemotherapy and form the basis of the current report. Overall survival (OS), disease‐specific survival (DSS), and recurrence‐free survival (RFS) data were analyzed by the Kaplan‐Meier method, with log‐rank tests used to evaluate associations between survival and variables studied.

RESULTS.

Five‐year OS, DSS, and RFS rates were 30.9%, 45.5%, and 29.7%, respectively. Adjuvant chemotherapy was administered to 70% of patients. On multivariate analysis, adjuvant chemotherapy was significantly associated with prolonged OS, DSS, and RFS (P ≤ .01). For patients overall and when stratified by pN status, the presence of ECE of lymph node metastasis was not found to be significantly associated with OS (P = .52), DSS (P = .43), or RFS (P = .83).

CONCLUSIONS.

The current study suggests that ECE is not an independent prognostic factor in a contemporary series of patients with positive lymph nodes at radical cystectomy. This might be reflective of a paradigm shift that encompasses the adoption of multimodal therapy. Cancer 2006. © 2006 American Cancer Society.
The Possibility of a Liquid Superconductor
Authors: Edwards Peter P. , Rao C. N. R. , Kumar N. , Alexandrov A. Sasha
Published: August 2006

All superconductors are solids in their superconducting state, this canonical electronic state of matter presently having only been observed well below the melting temperature of the solid. The discovery of high‐temperature superconductivity in cuprates has widened significantly our horizons of the theoretical understanding of the physical phenomenon. A number of observations point to the possibility that superconductors with a high superconducting transition temperature may not be conventional Bardeen–Cooper–Schrieffer (BCS) superconductors, but rather derive from the Bose–Einstein condensation of real‐space pairs. While BCS superconductors exist in the solid state (probably with the exception of metallic liquid hydrogen at ultrahigh pressures), we argue here that a superconducting charged Bose liquid may be found in a true liquid state of condensed matter at ambient pressure. An experimental scenario is outlined in fluid metal–ammonia solutions for stabilizing and observing a high‐temperature superconducting liquid (ca. 230 K) or at least a vitreous superconductor in the corresponding quenched solutions (ca. 160 K).
Gadolinium‐Based Mixed‐Metal Nitride Clusterfullerenes GdxSc3−xN@C80 (x=1, 2)
Authors: Yang Shangfeng , Kalbac Martin , Popov Alexey , Dunsch Lothar
Published: August 2006

The first gadolinium‐based mixed‐metal nitride clusterfullerenes GdxSc3−xN@C80 (I) (1, x=2; 2, x=1) have been successfully synthesized by the reactive gas atmosphere method and isolated facilely by recycling high‐performance liquid chromatography (HPLC). The sum yield of 1 and 2 is 30–40 times higher than that of Gd3N@C80 (I). Moreover, an enhanced relative yield of 2 over the Sc3N@C80 (I) is achieved under the optimized synthesis conditions. According to the UV/Vis/NIR spectroscopic characterization, 1 and 2 are both stable fullerenes with large optical band‐gaps while 1 has higher similarity to Gd3N@C80 (I) and 2 resembles Sc3N@C80 (I). The vibrational structures of 1 and 2 are studied by Fourier‐transform infrared (FTIR) spectroscopy as well as density functional theory (DFT) computations. In particular, the structures of the encaged GdxSc3−xN clusters within 1 and 2 are analyzed.
Anteroposterior patterning in the limb and digit specification: Contribution of mouse genetics
Authors: Robert Benoît , Lallemand Yvan
Published: August 2006

The limb has been a privileged object of investigation and reflection for scientists over the past two centuries and continues to provide a heuristic framework to analyze vertebrate development. Recently, accumulation of new data has significantly changed our view on the mechanisms of limb patterning, in particular along the anterior‐posterior axis. These data have led us to revisit the mode of action of the zone of polarizing activity. They shed light on the molecular and cellular mechanisms of patterning linked to the Shh‐Gli3 signaling pathway and give insights into the mechanism of activation of these cardinal factors, as well as the consequences of their activity. These new data are in good part the result of systematic Application of tools used in contemporary mouse molecular genetics. These have extended the power of mouse genetics by introducing mutational strategies that allow fine‐tuned modulation of gene expression, interchromosomal deletions and duplication. They have even made the mouse embryo amenable to cell lineage analysis that used to be the realm of chick embryos. In this review, we focus on the data acquired over the last five years from the analysis of mouse limb development and discuss new perspectives opened by these results. Developmental Dynamics 235:2337–2352, 2006. © 2006 Wiley‐Liss, Inc.
Endogenous bone morphogenetic protein antagonists regulate mammalian neural crest generation and survival
Authors: Anderson Ryan M. , Stottmann Rolf W. , Choi Murim , Klingensmith John
Published: August 2006

We demonstrate here that Chordin and Noggin function as bone morphogenetic protein (BMP) antagonists in vivo to promote mammalian neural crest development. Using Chrd and Nog single and compound mutants, we find that Noggin has a major role in promoting neural crest formation, in which Chordin is partially redundant. BMP signaling is increased in dorsal tissues lacking Noggin and is further increased when Chordin is also absent. The early neural crest domain is expanded with decreased BMP antagonism in vivo. Noggin and Chordin also regulate subsequent neural crest cell emigration from the neural tube. However, reduced levels of these BMP antagonists ultimately result in perturbation of neural crest cell derived peripheral nervous system and craniofacial skeletal elements. Such defects reflect, at least in part, a function to limit apoptosis in neural crest cells. Noggin and Chordin, therefore, function together to regulate both the generation and survival of neural crest cells in mammalian development. Developmental Dynamics 235:2507–2520, 2006. © 2006 Wiley‐Liss, Inc.
Kinetics of tamoxifen‐regulated Cre activity in mice using a cartilage‐specific CreERT to assay temporal activity windows along the proximodistal limb skeleton
Authors: Nakamura Eiichiro , Nguyen Minh‐Thanh , Mackem Susan
Published: August 2006

Cartilage differentiation occurs over a broad time range from early embryonic development, when the mesenchymal condensations that give rise to cartilage models for future bone first appear, and continuing through adult life, when there is ongoing maintenance of articular joint surfaces and re‐activation of cartilage formation after fracture. The chondrogenic response also figures in the pathogenesis of degenerative and inflammatory joint diseases. We have generated a transgenic line expressing tamoxifen‐dependent Cre recombinase that gives efficient recombination in the chondrogenic lineage, both during embryogenesis and postnatally, and provides a valuable tool for analysis of gene function selectively in chondrogenic cells using conditional genetic approaches. Because the cartilage model of the limb skeleton forms progressively in a proximodistal order during discrete, well‐defined time periods, evaluation of the spatial extent of tamoxifen‐induced recombination along the limb axis during these time windows has also enabled us to examine the pharmacokinetics of single‐dose tamoxifen injections during pregnancy. Developmental Dynamics 235:2603–2612, 2006. © 2006 Wiley‐Liss, Inc.
Electroporation and EGFP labeling of gastrulating quail embryos
Authors: Cui Cheng , Lansford Rusty , Filla Mike B. , Little Charles D. , Cheuvront Tracey J. , Rongish Brenda J.
Published: August 2006

Labeling embryonic cells to trace their motion is a classical experimental approach with a host of techniques being used to mark live cells and tissues. Genetically engineered fluorescent protein vectors (DNA plasmids) are a recent technology well suited to time‐resolved studies of cellular motion in live embryos. DNA plasmids encoding fluorescent proteins can be introduced into cells using several methods, including electroporation, a technique used widely for analysis of tissue culture and embryonic cells. Here we describe a technique designed to introduce DNA plasmids into early gastrulation stage quail embryos, ex ovo. The method is effective, and with practice enables an investigator to direct the vectors to relatively confined regions of gastrulating embryos. The required electroporation chamber can be fabricated from common laboratory materials. We anticipate that using this method of labeling cells in a warm‐blooded embryo, during gastrulation, will be a fruitful means of studying subsequent embryogenesis. Developmental Dynamics 235:2802–2810, 2006. © 2006 Wiley‐Liss, Inc.
The origin of the diversity of leaf venation pattern
Authors: Fujita Hironori , Mochizuki Atsushi
Published: August 2006

The leaf venation pattern of plants shows remarkable diversity and species‐specificity. However, the mechanism underlying the pattern formation and pattern diversity remains unclear. We developed a mathematical model that is based on the positive feedback regulation between plant hormone auxin and its efflux carrier. This system can generate auxin flow pathways by self‐organization from an almost homogeneous state. This result explains a well‐known experimental phenomenon referred as to “polar auxin transport.” The model can produce diverse leaf venation patterns with spatial regularity under similar conditions to those of leaf development, that is, in the presence of leaf expansion and auxin sink. Final venation patterns are strikingly affected by leaf shape and leaf expansion. These results indicate that the positive feedback regulation between auxin and its efflux carrier is a central dynamic in leaf venation pattern formation. The diversity of leaf venation patterns in plant species is probably due to the differences of leaf shape and leaf expansion pattern. Developmental Dynamics 235:2710–2721, 2006. © 2006 Wiley‐Liss, Inc.
Expression analysis of IGFBP‐rP10, IGFBP‐like and Mig30 in early Xenopus development
Authors: Kuerner Klaus‐Michael , Steinbeisser Herbert
Published: August 2006

To date, five members of the insulin‐like growth factor‐binding protein (IGFBP) superfamily have been described in Xenopus laevis. Here, we report the isolation of two new IGFBPs: xIGFBP‐rP10, and xIGFBP‐like. The proteins share the same domain architecture, and together with Mig30, form a subgroup within the IGFBP superfamily. Temporal expression analysis shows that they are expressed differentially during early development. xIGFBP‐rP10 is continuously expressed, whereas Mig30 expression peaks during gastrulation. IGFBP‐like is expressed from neurulation onward. The three genes have characteristic spatial expression domains, which overlap in some regions. Both xIGFBP‐rP10 and Mig30 are expressed on the dorsal side of the embryo during gastrulation. Later, xIGFBP‐rP10 is expressed in the notochord, the floor plate, the somites, and the fin. xIGFBP‐like expression is seen primarily in the developing central nervous system and overlaps with Mig30 expression at the end of neurulation in the developing somites and in tail bud stages in the eyes. Developmental Dynamics 235:2861–2867, 2006. © 2006 Wiley‐Liss, Inc.
Critical role of Brg1 member of the SWI/SNF chromatin remodeling complex during neurogenesis and neural crest induction in zebrafish
Authors: Eroglu Binnur , Wang Guanghu , Tu Naxin , Sun Xutong , Mivechi Nahid F.
Published: August 2006

Brg1 is a member of the SWI/SNF chromatin‐remodeling complex, and in some organisms Brg1 has been shown to interact with β‐catenin and positively control the TCF/LEF transcription factor that is located downstream of the Wnt signal transduction pathway. During development, TCF/LEF activity is critical during neurogenesis and head induction. In zebrafish, Brg1‐deficient embryos exhibit retinal cell differentiation and eye defects; however, the role of Brg1 in neurogenesis and neural crest cell induction remains elusive. We used zebrafish deficient in Brg1 (yng) or Brg1 specific‐morpholino oligonucleotide‐mediated knockdown to analyze the embryonic requirements of Brg1. Our results indicate that reduction in Brg1 expression leads to the expansion of the forebrain‐specific transcription factor, six3, and marked reduction in expression of the mid/hind‐brain boundary and hind‐brain genes, engrailed2 and krox20, respectively. At 12 hpf, the expression of neural crest specifiers are severely affected in Brg1‐morpholino‐injected embryos. These results suggest that Brg1 is involved in neural crest induction, which is critical for the development of neurons, glia, pigment cells, and craniofacial structures. Brg1 is a maternal factor, and brg1‐deficient embryos bearing the yng mutation derived from heterozygote intercrosses exhibit lesser effects on neural crest–specific gene expression, but show defects in neurogenesis and neural crest cell differentiation. This is exhibited by the aberrant brain patterning, a reduction in the sensory neurons, and craniofacial defects. These results further elucidate the critical role for Brg1 in neurogenesis, neural crest induction, and differentiation. Developmental Dynamics 235:2722–2735, 2006. © 2006 Wiley‐Liss, Inc.
Analysis of axis induction mutant embryos reveals morphogenetic events associated with zebrafish yolk extension formation
Authors: Lyman Gingerich Jamie , Lindeman Robin , Putiri Emily , Stolzmann Kelly , Pelegri Francisco
Published: August 2006

We analyze patterning and morphogenetic events during somitogenesis in hecate mutant embryos, which exhibit early axis induction defects. The posterior region, in the absence of a dorsal axis, is capable of forming organized gene expression patterns. The aberrant morphogenesis of mutant embryos is associated with anteriorly directed cell movements, underlying the enveloping layer, from the posterior region. In both wild‐type and mutant embryos, these changes result in an accumulation of cells, whose location correlates with a constriction in the posterior yolk cell, which in the wild‐type corresponds to the yolk extension. The region encompassing the constriction corresponds to a region of expression of zangptl2 in the yolk syncytial layer, which expands anteriorly together with the anteriorly migrating tail bud–derived cell population. Our data indicate that yolk extension formation is associated with coordinated changes involving the anterior migration of cells from the posterior region, changes in surface cellular layers, and inductive gene expression events in the YSL. Developmental Dynamics 235:2749–2760, 2006. © 2006 Wiley‐Liss, Inc.
Lineage specification in neural crest cell pathfinding
Authors: Harris Melissa L. , Erickson Carol A.
Published: August 2006

There are two principal models to explain neural crest patterning. One assumes that neural crest cells are multipotent precursors that migrate throughout the embryo and differentiate according to cues present in the local environment. A second proposes that the neural crest is a population of cells that becomes restricted to particular fates early in its existence and migrates along particular pathways dependent on unique cell‐autonomous properties. Although it is now evident that the neural crest cell population, as a whole, is actually heterogenous (composed of both multipotent and restricted progenitors), evidence supporting the model of prespecification has increased over the past few years. This review will begin by telling the story of melanoblasts: a neural crest subpopulation that is biased toward a single fate and subsequently acquires intrinsic properties that guide cells of this lineage to their final destination. The remainder of this review will explore whether this model is exclusive to melanoblasts or if it can also be used to explain the patterning of other neural crest cells like those of the sensory, sympathoadrenal, and enteric lineages. Developmental Dynamics 236:1–19, 2007. © 2006 Wiley‐Liss, Inc.
Three‐dimensional slice cultures from murine fetal gut for investigations of the enteric nervous system
Authors: Metzger Marco , Bareiss Petra M. , Nikolov Ivan , Skutella Thomas , Just Lothar
Published: August 2006

Three‐dimensional intestinal cultures offer new possibilities for the examination of growth potential, analysis of time specific gene expression, and spatial cellular arrangement of enteric nervous system in an organotypical environment. We present an easy to produce in vitro model of the enteric nervous system for analysis and manipulation of cellular differentiation processes. Slice cultures of murine fetal colon were cultured on membrane inserts for up to 2 weeks without loss of autonomous contractility. After slice preparation, cultured tissue reorganized within the first days in vitro. Afterward, the culture possessed more than 35 cell layers, including high prismatic epithelial cells, smooth muscle cells, glial cells, and neurons analyzed by immunohistochemistry. The contraction frequency of intestinal slice culture could be modulated by the neurotransmitter serotonin and the sodium channel blocker tetrodotoxin. Coculture experiments with cultured neurospheres isolated from enhanced green fluorescent protein (eGFP) transgenic mice demonstrated that differentiating eGFP‐positive neurons were integrated into the intestinal tissue culture. This slice culture model of enteric nervous system proved to be useful for studying cell–cell interactions, cellular signaling, and cell differentiation processes in a three‐dimensional cell arrangement. Developmental Dynamics 236:128–133, 2007. © 2006 Wiley‐Liss, Inc.
MEKK4 regulates developmental EMT in the embryonic heart
Authors: Stevens Mark V. , Parker Patti , Vaillancourt Richard R. , Camenisch Todd D.
Published: August 2006

Congenital heart malformations occur at a rate of one per one hundred births and are considered the most frequent birth defects. This high incidence of cardiac defects underscores the complex developmental processes required to form the first functioning organ in mammals. The molecular cues which govern heart development are poorly defined and require an improved understanding in order to advance repair strategies for heart defects. The cytoplasmic MAP kinase kinase kinase, MEKK4, is a critical effector in cellular stress responses; however, the function of MEKK4 during embryonic development and cardiogenesis is not well understood. We have identified MEKK4 as a critical signaling molecule during cardiovascular development. We report the detection of MEKK4 transcripts to early myocardium, endocardium and to cardiac cushion cells that have executed epithelial to mesenchymal transformation (EMT). These observations suggest that MEKK4 may function during production of the cushion mesenchyme as required to create valves and the septated heart. We used a kinase inactive form of MEKK4(MEKK4KI) in an in vitro assay that recapitulates in vivo EMT, and show that MEKK4KI attenuates mesenchyme production. However, addition of a constitutively active MEKK4 into ventricular explants, a system that does not normally undergo EMT, is not able to cause mesenchymal cell outgrowth. Thus, the kinase activity of MEKK4 is essential, but not sufficient, to support developmental EMT. This knowledge provides a basis to understand how MEKK4 may integrate signaling cascades controlling heart development. Developmental Dynamics 235:2761–2770, 2006. © 2006 Wiley‐Liss, Inc.
Chiral Platinum(II) Compounds Containing Ferrocenyl Schiff Bases Acting as (N), (N,O)–, [C(sp2,ferrocene),N]– or [C(sp2,ferrocene),N,O]2– Ligands
Authors: López Concepción , Caubet Amparo , Pérez Sonia , Solans Xavier , Font‐Bardía Mercè , Molins Elies
Published: August 2006

A study of the reactions of the following ferrocenyl Schiff bases: (SC)‐(+)‐[FcCH=NCH(R1)CH2OH] {Fc = (η5‐C5H5)Fe(η5‐C5H4), R1 = Me (1a) or CHMe2 (1b)} with cis‐[PtCl2(dmso)2] under different experimental conditions is reported. This study enabled the isolation and characterisation of the enantiomerically pure platinum(II) complexes trans‐(SC)‐[Pt{FcCH=NCH(R1)CH2OH}Cl2(dmso)] {R1 = Me (2a)or CHMe2 (2b)} and cis‐(SC)‐[Pt{FcCH=NCH(R1)CH2OH}Cl2(dmso)] {R1 = Me (3a) or CHMe2 (3b)} as well as four isomeric forms of (SC)‐[Pt{FcCH=N–CH(R1)CH2O}Cl(dmso)] {R1 = Me or CHMe2} (4–7a,b). These isomers differ in the conformation of the imine {anti‐(E) (in 4 and 6) or syn‐(Z) (in 5 and 7)} or in the relative arrangement of the nitrogen and the dmso group {trans (in 4 and 5) or cis (in 6 and 7)}. Imines 1 behave as a N‐donor ligand in 2 and 3 and as a (N,O)– group in 4–7. We also prepared the diastereomers {(Sp,SC) and (Rp,SC)} of the platinacycles [Pt{[(η5‐C5H3)CH=NCH(R1)CH2OH]Fe(η5‐C5H5)}Cl(dmso)] {8 and 9; R1 = Me (Sp,SC) (8a) and (Rp,SC) (9a) or R1 = CHMe2 (Sp,SC) (8b) and (Rp,SC) (9b)}, [Pt{[(η5‐C5H3)CH=NCH(R1)CH2O]Fe(η5‐C5H5)}(dmso)] {10 and 11; R1 = Me (Sp,SC) (10a) and (Rp,SC) (11a) or R1 = CHMe2 (Sp,SC) (10b) and (Rp,SC) (11b)} and [Pt{[(η5‐C5H3)CH=NCH(R1)CH2OH]Fe(η5‐C5H5)}Cl(PPh3)] {12 and 13; R1 = Me (Sp,SC) (12a) and (Rp,SC) (13a) or R1 = CHMe2 (Sp,SC) (12b) and (Rp,SC) (13b)}, containing a [C(sp2,ferrocene),N]– (in 8, 9, 12 and 13) or a [C(sp2,ferrocene),N,O]2– (in 10 and 11) group. The X‐ray crystal structures of 1b·H2O, 3b, 7b·CH2Cl2·1/2H2O and 9a are also reported. Our study allows the elucidation of the factors affecting the preferential formation of a given platinum(II) complex. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis, Characterization, and Luminescence Properties of Eu3+ 3‐Phenyl‐4‐(4‐toluoyl)‐5‐isoxazolonate Based Organic‐Inorganic Hybrids
Authors: Lima Patricia P. , Junior Severino A. , Malta Oscar L. , Carlos Luis D. , Sá Ferreira Rute A. , Pavithran Rani , Reddy M. L. P.
Published: August 2006

Organic‐inorganic hybrids incorporating Eu(TPI)3·3H2O or Eu(TPI)3·2TOPO [where TPI and TOPO stand for 3‐phenyl‐4‐(4‐toluoyl)‐5‐isoxazolone and tri‐n‐octylphosphane oxide, respectively] were synthesized either by acetic acid solvolysis or a conventional hydrolysis sol‐gel route. The host framework of these materials, named as di‐ureasil, consists of a siliceous skeleton grafted, through urea cross‐linkages, to both ends of poly(ethylene oxide) chains. The resulting Eu3+‐based di‐ureasils were characterized by X‐ray diffraction and Fourier transform mid‐IR, 29Si and 13C NMR, and photoluminescence spectroscopy. The room‐temperature photoluminescence (PL) spectra of the Eu3+‐based di‐ureasils display the typical Eu3+ red emission, assigned to transitions between the first excited state (5D0) and the ground multiplet (7F0–4). Enhanced 5D0 quantum efficiency (η = 13 % vs. 32 %) and a longer lifetime (τ = 0.30 vs. 0.42 ms) was noticed for the hybrid incorporating the Eu(TPI)3·3H2O complex, compared with the undoped complex. The enhancement is explained by the coordination ability of the organic counter part of the host structure, which is strong enough to displace the water molecules of the Eu(TPI)3·3H2O complex from the Eu3+ neighborhood in the hybrids. On the other hand, a decrease in the 5D0 quantum efficiency (η = 76 % vs. 61 %) and lifetime (τ = 0.98 vs. 0.75 ms) was noticed for the hybrid incorporating the Eu(TPI)3·2TOPO complex, relative to the undoped complex, probably because of an increase in the nonradiative transition probability. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)