bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of distinct tyraminergic and octopaminergic neurons innervating the central complex of the desert locust, Schistocerca gregaria
Authors: Homberg Uwe , Seyfarth Jutta , Binkle Ulrike , Monastirioti Maria , Alkema Mark J.
Published: November 2012

The central complex is a group of modular neuropils in the insect brain with a key role in visual memory, spatial orientation, and motor control. In desert locusts the neurochemical organization of the central complex has been investigated in detail, including the distribution of dopamine‐, serotonin‐, and histamine‐immunoreactive neurons. In the present study we identified neurons immunoreactive with antisera against octopamine, tyramine, and the enzymes required for their synthesis, tyrosine decarboxylase (TDC) and tyramine β‐hydroxylase (TBH). Octopamine‐ and tyramine immunostaining in the central complex differed strikingly. In each brain hemisphere tyramine immunostaining was found in four neurons innervating the noduli, 12–15 tangential neurons of the protocerebral bridge, and about 17 neurons that supplied the anterior lip region and parts of the central body. In contrast, octopamine immunostaining was present in two bilateral pairs of ascending fibers innervating the upper division of the central body and a single pair of neurons with somata near the esophageal foramen that gave rise to arborizations in the protocerebral bridge. Immunostaining for TDC, the enzyme converting tyrosine to tyramine, combined the patterns seen with the tyramine‐ and octopamine antisera. Immunostaining for TBH, the enzyme converting tyramine to octopamine, in contrast, was strikingly similar to octopamine immunolabeling. We conclude that tyramine and octopamine act as neurotransmitters/modulators in distinct sets of neurons of the locust central complex with TBH likely being the rate‐limiting enzyme for octopamine synthesis in a small subpopulation of TDC‐containing neurons. J. Comp. Neurol. 521:2025–2041, 2013. © 2012 Wiley Periodicals, Inc.
Scene from above: Retinal ganglion cell topography and spatial resolving power in the giraffe (Giraffa camelopardalis)
Authors: Coimbra João Paulo , Hart Nathan S. , Collin Shaun P. , Manger Paul R.
Published: November 2012

The giraffe (Giraffa camelopardalis) is a browser that uses its extensible tongue to selectively collect leaves during foraging. As the tallest extant terrestrial mammal, its elevated head height provides panoramic surveillance of the environment. These aspects of the giraffe's ecology and phenotype suggest that vision is of prime importance. Using Nissl‐stained retinal wholemounts and stereological methods, we quantitatively assessed the retinal specializations in the ganglion cell layer of the giraffe. The mean total number of retinal ganglion cells was 1,393,779 and their topographic distribution revealed the presence of a horizontal visual streak and a temporal area. With a mean peak of 14,271 cells/mm2, upper limits of spatial resolving power in the temporal area ranged from 25 to 27 cycles/degree. We also observed a dorsotemporal extension (anakatabatic area) that tapers toward the nasal retina giving rise to a complete dorsal arch. Using neurofilament‐200 immunohistochemistry, we also detected a dorsal arch formed by alpha ganglion cells with density peaks in the temporal (14–15 cells/mm2) and dorsonasal (10 cells/mm2) regions. As with other artiodactyls, the giraffe shares the presence of a horizontal streak and a temporal area which, respectively, improve resolution along the horizon and in the frontal visual field. The dorsal arch is related to the giraffe's head height and affords enhanced resolution in the inferior visual field. The alpha ganglion cell distribution pattern is unique to the giraffe and enhances acquisition of motion information for the control of tongue movement during foraging and the detection of predators. J. Comp. Neurol. 521:2042–2057, 2013. © 2012 Wiley Periodicals, Inc.
Neurochemical characterization of neurons expressing melanin‐concentrating hormone receptor 1 in the mouse hypothalamus
Authors: Chee Melissa J.S. , Pissios Pavlos , Maratos‐Flier Eleftheria
Published: November 2012

Melanin‐concentrating hormone (MCH) is a hypothalamic neuropeptide that acts via MCH receptor 1 (MCHR1) in the mouse. It promotes positive energy balance; thus, mice lacking MCH or MCHR1 are lean, hyperactive, and resistant to diet‐induced obesity. Identifying the cellular targets of MCH is an important step to understanding the mechanisms underlying MCH actions. We generated the Mchr1‐cre mouse that expresses cre recombinase driven by the MCHR1 promoter and crossed it with a tdTomato reporter mouse. The resulting Mchr1‐cre/tdTomato progeny expressed easily detectable tdTomato fluorescence in MCHR1 neurons, which were found throughout the olfactory system, striatum, and hypothalamus. To chemically identify MCH‐targeted cell populations that play a role in energy balance, MCHR1 hypothalamic neurons were characterized by colabeling select hypothalamic neuropeptides with tdTomato fluorescence. TdTomato fluorescence colocalized with dynorphin, oxytocin, vasopressin, enkephalin, thyrothropin‐releasing hormone, and corticotropin‐releasing factor immunoreactive cells in the paraventricular nucleus. In the lateral hypothalamus, neurotensin, but neither orexin nor MCH neurons, expressed tdTomato. In the arcuate nucleus, both Neuropeptide Y and proopiomelanocortin cells expressed tdTomato. We further demonstrated that some of these arcuate neurons were also targets of leptin action. Interestingly, MCHR1 was expressed in the vast majority of leptin‐sensitive proopiomelanocortin neurons, highlighting their importance for the orexigenic actions of MCH. Taken together, this study supports the use of the Mchr1‐cre mouse for outlining the neuroanatomical distribution and neurochemical phenotype of MCHR1 neurons. J. Comp. Neurol. 521:2208–2234, 2013. © 2012 Wiley Periodicals, Inc.
Nonlinear Optical Response of a Polymer Electret with Incorporated Organic Chromophores
Authors: Balakina Marina Yu.
Published: November 2012

An analytical approach aimed at modeling the nonlinear optical (NLO) response of a polymer electret with incorporated organic dipole chromophores is extended to the dynamic case. The approach allows the effect of the locally anisotropic, polarizable, deformable polymer matrix on the chromophore NLO response to be accounted for. The method exploits the original cavity ansatz according to which the virtual cavity occupied by the chromophore in the polymer matrix is chosen to be conformal to the characteristic ellipsoid of the generalized permittivity tensor. Analytical expressions for the dynamic electric moments of dipole chromophores and macroscopic polarization of a polymer electret at fundamental and second harmonic frequencies are obtained by using a computational scheme based on two self‐consistency procedures. On the basis of the expressions for dynamic macroscopic polarization, the analytical formulas for linear, ${\chi _j^{i(1)} (\omega )}$, and quadratic, ${\chi _{jk}^{i(2)} (2\omega )}$, electric susceptibilities are obtained. The presented expressions establish the relationship between the molecular polarizabilities of chromophores and the macroscopic electrical properties of the polymer electret.
Towards a Spectroscopic and Theoretical Identification of the Isolated Building Blocks of the Benzene–Acetylene Cocrystal
Authors: Böning Markus , Stuhlmann Benjamin , Engler Gernot , Busker Matthias , Häber Thomas , Tekin Adem , Jansen Georg , Kleinermanns Karl
Published: November 2012

Isomer‐ and mass‐selective UV and IR–UV double resonance spectra of the BA3, B2A, and B2A2clusters of benzene (B) and acetylene (A) are presented. Cluster structures are assigned by comparison with the UV and IR spectra of benzene, the benzene dimer, as well as the BA, BA2, and B2A clusters. The intermolecular vibrations of BA are identified by dispersed fluorescence spectroscopy. Assignment of the cluster structures is supported by quantum chemical calculations of IR spectra with spin‐component scaled second‐order Møller–Plesset (SCS‐MP2) theory. Initial propositions for various structures of the BA3and B2A2aggregates are generated with model potentials based on density functional theory combined with the symmetry‐adapted perturbation theory (DFT‐SAPT) approach. Shape and relative cluster stabilities are then confirmed with SCS‐MP2. T‐shaped geometries are the dominant structural motifs. Higher‐energy isomers are also observed. The detected cluster structures are correlated with possible cluster formation pathways and their role as crystallization seeds is discussed.
IR Spectroscopy of the 4‐Aminobenzonitrile–Ar Cluster in the S0, S1 Neutral and D0 Cationic States
Authors: Nakamura Takashi , Miyazaki Mitsuhiko , Ishiuchi Shun‐ichi , Weiler Martin , Schmies Matthias , Dopfer Otto , Fujii Masaaki
Published: November 2012

The S1–S0 resonant enhanced multiphoton ionization (REMPI) spectrum as well as the infrared (IR) spectra in the S0 and S1 states of 4‐aminobenzonitrile (4ABN) and its van der Waals complex with Ar (4ABN–Ar) were measured by means of IR depletion spectroscopy (REMPI–IR). The IR spectrum of 4ABN–Ar in S0 shows symmetric and antisymmetric NH stretching vibrations (νs and νa) of the amino group at the same positions as those in the 4ABN monomer. This suggests that the Ar ligand locates above the benzene ring by van der Waals interactions (π‐bound). The same coincidence of vibrational frequencies was found in S1, and the π‐bound geometry was kept by the electronic excitation. The REMPI–IR spectrum of 4ABN+–Ar was also measured, and three major vibrational transitions were found. From the comparison to the IR dissociation spectrum with an electron impact source (EI–IR), they were assigned to νs, νa and an NH‐bending overtone of the π‐bound structure. It is concluded that photoionization of 4ABN+–Ar does not promote site‐switching of Ar from the π‐site to the H‐site.
Mesenchymal markers on human adipose stem/progenitor cells
Authors: Zimmerlin Ludovic , Donnenberg Vera S. , Rubin J. Peter , Donnenberg Albert D.
Published: November 2012

The stromal‐vascular fraction (SVF) of adipose tissue is a rich source of multipotent stem cells. We and others have described three major populations of stem/progenitor cells in this fraction, all closely associated with small blood vessels: endothelial progenitor cells (EPC, CD45−/CD31+/CD34+), pericytes (CD45−/CD31−/CD146+), and supra‐adventitial adipose stromal cells (SA‐ASC, CD45−/CD31−/CD146−/CD34+). EPC are luminal, pericytes are adventitial, and SA‐ASC surround the vessel like a sheath. The multipotency of the pericytes and SA‐ASC compartments is strikingly similar to that of CD45−/CD34−/CD73+/CD105+/CD90+ bone marrow‐derived mesenchymal stem cells (BM‐MSC). Here, we determine the extent to which this mesenchymal pattern is expressed on the three adipose stem/progenitor populations. Eight independent adipose tissue samples were analyzed in a single tube (CD105‐FITC/CD73‐PE/CD146‐PETXR/CD14‐PECY5/CD33‐PECY5/CD235A‐PECY5/CD31‐PECY7/CD90‐APC/CD34‐A700/CD45‐APCCY7/DAPI). Adipose EPC were highly proliferative with (14.3 ± 2.8)% (mean ± SEM) having >2N DNA. About half (53.1 ± 7.6)% coexpressed CD73 and CD105, and (71.9 ± 7.4)% expressed CD90. Pericytes were less proliferative [(8.2 ± 3.4)% >2N DNA)] with a smaller proportion [(29.6 ± 6.9)% CD73+/CD105+, (60.5 ± 10.2)% CD90+] expressing mesenchymal associated markers. However, the CD34+ subset of CD146+ pericytes were both highly proliferative [(15.1 ± 3.6)% with >2N DNA] and of uniform mesenchymal phenotype [(93.3 ± 3.7)% CD73+/CD105+, (97.8 ± 0.7)% CD90+], suggesting transit amplifying progenitor cells. SA‐ASC were the least proliferative [(3.7 ± 0.8)%>2N DNA] but were also highly mesenchymal in phenotype [(94.4 ± 3.2)% CD73+/CD105+, (95.5 ± 1.2)% CD90+]. These data imply a progenitor/progeny relationship between pericytes and SA‐ASC, the most mesenchymal of SVF cells. Despite phenotypic and functional similarities to BM‐MSC, SA‐ASC are distinguished by CD34 expression. © 2012 International Society for Advancement of Cytometry
Diastereodivergent Synthesis of Chiral vic‐Disubstituted‐Cyclobutane Scaffolds: 1,3‐Amino Alcohol and 1,3‐Diamine Derivatives – Preliminary Use in Organocatalysis
Authors: Mayans Enric , Gargallo Albert , Álvarez‐Larena Ángel , Illa Ona , Ortuño Rosa M.
Published: November 2012

The synthesis of chiral cyclobutane containing 1,3‐amino alcohols and 1,3‐diamines has been accomplished in an efficient and diastereodivergent manner from a common chiral precursor. Regioselective manipulation of functional groups in the prepared products provides an easy entry to several derivatives, such as thioureas. Preliminary results on the use of these compounds as bifunctional organocatalysts are reported.
Effect of the Dispersing Agent on the Electrochemical Response of Glassy Carbon Electrodes Modified with Dispersions of Carbon Nanotubes
Authors: González‐Segura Karina , Cañete‐Rosales Paulina , del Rio Rodrigo , Yáñez Claudia , Ferreyra Nancy F. , Rivas Gustavo A. , Bollo Soledad
Published: November 2012

The electrochemical response of a glassy carbon electrode modified with carbon nanotubes (CNT) dispersed in two solvents, water and DMF, and two polymers, chitosan and Nafion is reported. The films were homogeneous when the dispersing agent was water or DMF. In the case of polymers, the surfaces present areas with different density of CNTs. A more sensitive electrochemical response was obtained when CNTs are dispersed in the solvents. In the case of CNT dispersed with polymers, the nature of the polymer demonstrated to be a critical parameter not only for dispersing the nanotubes but also for the electrochemical activity of the resulting electrodes.
Runoff and erosion processes and rates in the Zin valley badlands, northern Negev, Israel
Authors: Yair A. , Lavee H. , Bryan R. B. , Adar E.
Published: November 2012

Badland areas are usually regarded as impermeable zones which generate high runoff and are very vulnerable to sheetwash and rainsplash. To test those considerations sprinkling experiments using two rainfall simulators were carried out on slopes of varying aspect in the northern Negev (Israel). For one unit 1·5 m2 plots were used with rainfall of natural characteristics at 36 mm/hr intensity and 43–48 minute duration, runoff being recorded and water/sediment samples taken every 5 minutes. The second unit was used on 30–50 m2 plots but rainfall energy production was below that of natural rainfall. Results show that due to the high stability and strong flocculation of clay‐rich aggregates rainsplash is ineffective in surface sealing so that infiltration capacities remain high despite intense, prolonged rainfall. Aspect differences are reflected in variation of surface properties despite homogenous bed‐rock, which cause marked differences in hydrological response. North‐facing slopes respond more quickly, more frequently and produce more runoff than south‐facing slopes. Non‐uniform runoff generation is also seen within plots of one aspect reflecting subtle variations in surface properties. Comparison of rainfall intensity and duration used during the experiments with those prevailing under natural conditions shows that under present day conditions surface flow in the Zin valley badlands must be extremely infrequent and denudation rates very low.
Erosion and deposition by debris flows at Mt Thomas, North Canterbury, New Zealand
Authors: Pierson Thomas C.
Published: November 2012

The grass‐covered slopes on the southern flank of Mt Thomas, an upfaulted block of highly sheared sandstone and argillite 40 km NW of Christchurch, New Zealand, are presently undergoing severe erosion by a combination of mass‐wasting processes. Gully erosion, soil slips, and debris flows have carved out a number of steep, deeply incised ravines, from which coarse debris is transported (primarily by debris flows) to alluvial fans below. Geologic and historical evidence indicates that debris flows have been episodically active here for at least the last 20,000 years and have been the dominant process in fan building. This demonstrates that catastrophic geomorphic processes, rather than processes acting at relatively uniform rates, can be dominant in humid‐temperate areas as well as in arid and semi‐arid regions.

In April 1978, debris flows were triggered in one of two unstable ravines in the Bullock Creek catchment by a moderate intensity, long duration rainstorm with a return period in excess of 20 years. Surges of fluid debris, moving at velocities up to 5 m/s, transported a dense slurry of gravel, sand, and mud up to 3·5 km over a vertical fall of 600 m. Deposition on the alluvial fan occurred when the flows left the confines of an entrenched fan‐head channel and spread out as a 0·16 km2 sheet averaging 1·2 m thick. In all, 195,000 m3 were deposited, roughly a third of that being reworked sediments from the head of the fan. Sediment yield from this one event would be equivalent to several thousand years worth of erosion at average sediment discharge rates for small South Island mountain catchments.

Samples of viscous fluid debris during surges contained up to 84 per cent solids, composed of 70 per cent gravel, 20 per cent silt, and 4 per cent clay. Fluid density of the material ranged between 1·95 and 2·13 g/cm3, and it was extremely poorly sorted. Between surges the fluid was less viscous, less dense, and unable to carry gravel in suspension. Severe fan‐head entrenchment of the stream channel (approximately 10 m in less than 24 hours) was accomplished by the erosive action of the surges.

Tectonic uplift of the Mt Thomas block and the weak, crushed condition of the bedrock appear to be ultimately responsible for the catastropic erosion of slopes in the Bullock Creek catchment. However, forest clearing within the last few centuries appears to have greatly increased the rate of mass wasting and gully erosion on these slopes.
On the relationship between bedrock lowering and regolith thickness
Authors: Cox Nicholas J.
Published: November 2012

A general equation is proposed for the relationship between bedrock lowering and regolith thickness which includes, as special cases, hypotheses by Ahnert, Armstrong, Culling, Kirkby and Young, at least approximately.
The erosion of drainage ditches and its effect on bed‐load yields in mid‐Wales: Reconnaissance case studies
Authors: Newson Malcolm
Published: November 2012

Open ditching is a common and relatively cheap way of providing drainage for wet upland soils prior to afforestation or improved agriculture; it is sometimes also used to channelize moorland runoff into water storage schemes. In contrast to piped under‐drainage there is considerable danger of erosion in open ditches. Results are reported of investigations into the yield of bed‐load from ditched catchments; compared with unditched catchments there is a considerable increase in yield and this causes costly local problems of sedimentation. However, the implications of the erosion for downstream channel changes and reservoir sedimentation in the uplands are harder to predict without further study of the storage processes affecting bed‐load and of the influence of flood flows. The case studies are used to point to improvements in the design of open drainage networks.
Terracette morphology and soil properties: A note on a canonical correlation study
Authors: Vincent Peter , Clarke Vicki
Published: November 2012

Morphological and soil properties of terracettes have been examined using canonical correlation methods. Highly significant statistical relationships have been found linking some members of the soil property set to the morphological properties of the terracettes studied.
Floodplain inundation: Processes and relationships with channel discharge
Authors: Hughes D. A.
Published: November 2012

The factors affecting the relationship between channel discharge and volume of inundation are discussed. For many floodplains this relationship is not simple, but involves hysteretic effects which vary according to the hydrological characteristics of individual floods and the way in which these interact with the surface form of the floodplain reach. Some methods of deriving or estimating the extent of the hysteresis on floodplain reaches are suggested, although an acute lack of available data prevents detailed examination at present. Further investigations are required before floodplain conductivity relations can be used as an aid to flood routing procedures or in floodplain management problems. A major priority must be the acquisition of sequential inundation data.
Distributed and boundary model predictive control for the heat equation
Authors: Altmüller Nils , Grüne Lars
Published: November 2012

We consider a model predictive control (MPC) scheme without stabilizing terminal constraints applied to the linear heat equation. We apply a method to analyze minimal stabilizing optimization horizons based on an exponential controllability condition. While the method is known to yield conservative quantitative results for concrete examples, our analysis shows that it precisely determines qualitative changes in the horizon for changing parameters and changing problem structures. Particularly, it is able to explain numerically observed differences in the stability behavior of MPC for distributed and for boundary control (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal control of coupled multiphysics problems: Guidelines for real‐life applications demonstrated for a complex fuel cell model
Authors: Rund Armin , Chudej Kurt , Kerler Johanna , Pesch Hans Josef , Sternberg Kati
Published: November 2012

In practice one often is confronted with the simulation and optimization of dynamical processes of multiphysics systems depending on time and space. This paper shall serve as a guidebook for practioneers who wants to proceed from simulation to optimization. We are specially concerned in this paper with optimal control problems involving partial differential equations. After providing an insight into the theory of optimal control problems with partial differential equations, the focus of the paper lies on their numerical treatment to obtain approximate optimal solutions, or more precisely approximate candidate optimal solutions. The two basic approaches, first optimize then discretize (FOTD) and first discretize then optimize (FDTO) are first described in an abstract setting and then evaluated by means of the fuel cell example of this paper which can serve as a prototype problem for multiphysics processes. The example describes the dynamical behaviour inside a certain type of high temperature fuel cell where gas flows, heat distribution, and potential fields as well as chemical reactions are modelled by hyperbolic and parabolic partial differential as well as ordinary differential algebraic equations. The underlying problem is an optimal control problem where up to 28 instationary partial differential algebraic equations in one, respectively two spatial dimensions are involved. In the conclusion pros and cons of the aforementioned approaches are discussed. Hereby, not only the numerical efficiency but also the investigation of human resources are balanced against each other (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive refinement based on asymptotic expansions of finite element solutions for node insertion in 1d
Authors: Friederich Jan , Leugering Günther , Steinmann Paul
Published: November 2012

We consider refinement of finite element discretizations by splitting nodes along edges. For this process, we derive asymptotic expansions of Galerkin solutions of linear second‐order elliptic equations. Thereby, we calculate a topological derivative w.r.t. node insertion for functionals such as the total potential energy, minimization of which decreases the approximation error in the energy norm. Hence, these sensitivities can be used to define indicators for local h ‐refinement. Our results suggest that this procedure leads to an efficient adaptive refinement method. This presentation is concerned with a model problem in 1d. The extension of this concept to higher dimensions will be the subject of forthcoming publications (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regularized nonlinear scalarization for vector optimization problems with PDE‐constraints
Authors: Leugering G. , Schiel R.
Published: November 2012

This paper concerns the generalization and regularization of a nonlinear scalarization method by Pascoletti and Serafini, [14], to abstract partially ordered Banach spaces. In particular, we put emphasis on the possibility that the ordering cone might have an empty interior. All this is motivated by applying the method to a vector optimization problem with PDE‐constraints (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detecting Rare Variant Effects Using Extreme Phenotype Sampling in Sequencing Association Studies
Authors: Barnett Ian J. , Lee Seunggeun , Lin Xihong
Published: November 2012

In the increasing number of sequencing studies aimed at identifying rare variants associated with complex traits, the power of the test can be improved by guided sampling procedures. We confirm both analytically and numerically that sampling individuals with extreme phenotypes can enrich the presence of causal rare variants and can therefore lead to an increase in power compared to random sampling. Although application of traditional rare variant association tests to these extreme phenotype samples requires dichotomizing the continuous phenotypes before analysis, the dichotomization procedure can decrease the power by reducing the information in the phenotypes. To avoid this, we propose a novel statistical method based on the optimal Sequence Kernel Association Test that allows us to test for rare variant effects using continuous phenotypes in the analysis of extreme phenotype samples. The increase in power of this method is demonstrated through simulation of a wide range of scenarios as well as in the triglyceride data of the Dallas Heart Study.
A Multi‐Locus Likelihood Method for Assessing Parent‐of‐Origin Effects Using Case‐Control Mother‐Child Pairs
Authors: Lin Dongyu , Weinberg Clarice R. , Feng Rui , Hochner Hagit , Chen Jinbo
Published: November 2012

Parent‐of‐origin effects have been pointed out to be one plausible source of the heritability that was unexplained by genome‐wide association studies. Here, we consider a case‐control mother‐child pair design for studying parent‐of‐origin effects of offspring genes on neonatal/early‐life disorders or pregnancy‐related conditions. In contrast to the standard case‐control design, the case‐control mother‐child pair design contains valuable parental information and therefore permits powerful assessment of parent‐of‐origin effects. Suppose the region under study is in Hardy‐Weinberg equilibrium, inheritance is Mendelian at the diallelic locus under study, there is random mating in the source population, and the SNP under study is not related to risk for the phenotype under study because of linkage disequilibrium (LD) with other SNPs. Using a maximum likelihood method that simultaneously assesses likely parental sources and estimates effect sizes of the two offspring genotypes, we investigate the extent of power increase for testing parent‐of‐origin effects through the incorporation of genotype data for adjacent markers that are in LD with the test locus. Our method does not need to assume the outcome is rare because it exploits supplementary information on phenotype prevalence. Analysis with simulated SNP data indicates that incorporating genotype data for adjacent markers greatly help recover the parent‐of‐origin information. This recovery can sometimes substantially improve statistical power for detecting parent‐of‐origin effects. We demonstrate our method by examining parent‐of‐origin effects of the gene PPARGC1A on low birth weight using data from 636 mother‐child pairs in the Jerusalem Perinatal Study.
Parental occupational exposure to engine exhausts and childhood brain tumors
Authors: Peters Susan , Glass Deborah C. , Reid Alison , de Klerk Nicholas , Armstrong Bruce K. , Kellie Stewart , Ashton Lesley J. , Milne Elizabeth , Fritschi Lin
Published: November 2012

Childhood brain tumors (CBT) are the leading cause of cancer death in children; their risk factors are still largely unknown. Since most CBTs are diagnosed before five years of age, prenatal exposure and early postnatal factors may be involved in their etiology. We investigated the association between CBT and parental occupational exposure to engine exhausts in an Australian population‐based case–control study. Parents of 306 cases and 950 controls completed detailed occupational histories. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for both maternal and paternal exposure in key time periods. Increased risks were observed for maternal exposure to diesel exhaust any time before the child's birth (OR 2.03, 95% CI 1.09–3.81) and paternal exposure around the time of the child's conception (OR 1.62, 95% CI 1.12–2.34). No clear associations with other engine exhausts were found. Our results suggest that parental occupational exposure to diesel exhaust may increase the risk of CBT.
Blockade of Myd88 signaling induces antitumor effects by skewing the immunosuppressive function of myeloid‐derived suppressor cells
Authors: Hong Eun‐Hye , Chang Sun‐Young , Lee Bo‐Ra , Kim Yun‐Sun , Lee Jeong‐Mi , Kang Chang‐Yuil , Kweon Mi‐Na , Ko Hyun‐Jeong
Published: November 2012

Myd88 is an important adaptor molecule for the activation of NADPH oxidase and arginase‐1, which are responsible for the suppressive function of myeloid‐derived suppressor cells (MDSCs). When wild‐type and Myd88−/− mice were subcutaneously injected with CT26 colon cancer cells expressing human Her‐2/neu, tumor growth was retarded in Myd88−/− mice than in wild‐type mice. Although the generation of CD11b+Gr‐1+ MDSCs was less in Myd88−/− mice than in wild‐type mice, Myd88−/− mice having tumor masses still had significant quantities of MDSCs, suggesting that MDSC generation might be independent of Myd88 signaling. However, MDSCs obtained from tumor‐bearing Myd88−/− mice failed to suppress antigen‐specific proliferation of CD8+ T cells and CD4+ T cells, whereas MDSCs from wild‐type mice significantly suppressed both types of T cells. Consistent with this, we found that the levels of costimulatory molecules and MHC class II were significantly increased in MDSCs obtained from Myd88−/− mice compared with wild‐type mice after tumor challenge. Furthermore, CD4+ T cells residing in tumor‐draining lymph nodes of Myd88−/− mice secreted more TNF‐α than those of wild‐type mice. Finally, the blockade of Myd88 signaling by treatment with Myd88 inhibitory peptide, during later tumor stages, significantly inhibited the growth of immunogenic tumors. Overall, these data suggest that signaling through the Myd88 adaptor molecule is critical for the direct suppressive function of MDSCs and approaches to block Myd88‐mediated signaling in MDSCs might be effective to inhibit the immunosuppressive function of MDSCs.
2.5D constructs for characterizing phase separated polymer blend surface morphology in tissue engineering scaffolds
Authors: Marszalek Jolanta E. , Simon Carl G. , Thodeti Charles , Adapala Ravi Kumar , Murthy Ananth , Karim Alamgir
Published: November 2012

Previously, we used 2D films to identify an annealed PCL‐PDLLA phase‐separated blend morphology which provided nanoscale surface texture and patterning that stimulated osteoblast differentiation. In order to translate these 2D surface nanopatterning effects to the walls of 3D salt‐leached scaffolds, the blend phase morphology of scaffold walls must be characterized. For salt‐leached scaffolds, NaCl is used as a porogen, which may affect phase separation in PCL‐PDLLA blends. However, it is not possible to characterize the surface blend morphology of 3D scaffold walls using standard approaches such as AFM or optical microscopy, since scaffolds are too rough for AFM and do not transmit light for optical microscopy. We introduce a 2.5D approach that mimics the processing conditions of 3D salt‐leached scaffolds, but has a geometry amenable to surface characterization by AFM and optical microscopy. For the 2.5D approach, PCL‐PDLLA blend films were covered with NaCl crystals prior to annealing. The presence of NaCl significantly influenced blend morphology in PCL‐PDLLA 2.5D constructs causing increased surface roughness, higher percent PCL area on the surface and a smaller PCL domain size. During cell culture on 2.5D constructs, osteoblast (MC3T3‐E1) and dermal endothelial cell (MDEC) adhesion were enhanced on PCL‐PDLLA blends that were annealed with NaCl while chondrogenic cell (ATDC5) adhesion was diminished. This work introduces a 2.5D approach that mimicked 3D salt‐leached scaffold processing, but enabled characterization of scaffold surface properties by AFM and light microscopy, to demonstrate that the presence of NaCl during annealing strongly influenced polymer blend surface morphology and cell adhesion. Published 2012 Wiley Periodicals, Inc.† J Biomed Mater Res Part A, 2013.
Chondrogenic differentiation of bone marrow‐derived mesenchymal stromal cells via biomimetic and bioactive poly‐ε‐caprolactone scaffolds
Authors: Schagemann J. C. , Paul S. , Casper M. E. , Rohwedel J. , Kramer J. , Kaps C. , Mittelstaedt H. , Fehr M. , Reinholz G. G.
Published: November 2012

The objective of this study was to develop a scaffold for mesenchymal stromal cell (MSC) recruitment, proliferation, and chondrogenic differentiation. The concept behind the design is to mimic the cartilage matrix and contain stimulatory agents that make continuous supply of inductive factors redundant. Nanofibrous (N: ∼400 nm) and microfibrous (M: ∼10 μm) poly‐ε‐caprolactone (PCL) scaffolds were combined with 1% high‐molecular‐weight sodium hyaluronate (NHA/MHA), 1% hyaluronan (HA) and 200 ng transforming growth factor‐beta 1 (TGF‐β1; NTGF/MTGF), or 0.1% bovine serum albumin (N/M). Scaffolds were seeded with MSCs from bone marrow and cultured without growth factors in vitro. Cultures with chondrogenic medium supplemented with TGF‐β1 served as controls. Proliferation, migration, and release of TGF‐β1 were investigated. Cell differentiation was evaluated by polymerase chain reaction (PCR) and real‐time PCR. NTGF and MTGF exhibited primarily an initial release of TGF‐β1. None of the factors released by the scaffolds recruited MSCs. The expression of aggrecan was dependent on the scaffold ultrastructure with nanofibers promoting increasing and microfibers decreasing expression levels. Composites containing HA demonstrated elevated seeding efficiency and lower type I collagen expression. Expression of type II collagen was dependent on continuous or late supply of TGF‐β1, which was not provided by our scaffold design. The initial release of TGF‐β1 induced an expression of type I collagen and osteogenic marker genes. In conclusion, nanofibrous PCL scaffolds with or without augmentation are suitable for chondrogenic initiation of MSCs. Initial release of HA is sufficient in terms of directing the implanted MSCs toward a chondrogenic end, whereas a late release of TGF‐β1 is preferred to foster type II and avoid type I collagen expression. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
The thermosensitivity of pH/thermoresponsive microspheres activated by the electrostatic interaction of pH‐sensitive units with a bioactive compound
Authors: Fundueanu Gheorghe , Constantin Marieta , Asmarandei Ionela , Harabagiu Valeria , Ascenzi Paolo , Simionescu Bogdan C.
Published: November 2012

pH/thermosensitive hydrogels whose thermosensitivity is activated by the electrostatic interaction of the pH‐sensitive units with a hydrophobic bioactive compound are proposed here as sensor‐based self‐regulated drug delivery systems. Poly(N‐isopropylacrylamide‐co‐acrylamide‐co‐aminoethylacrylamide) (poly(NIPAAm‐co‐AAm‐co‐AEAAm)) was prepared as a new pH/thermoresponsive polymer by hydrolysis of poly(N‐isopropylacrylamide‐co‐acrylamide (poly(NIPAAm‐co‐AAm)) at high temperature (120°C) in the presence of ethylenediamine. Owing to the hydrophilicity of the inserted amine, the copolymers lose the thermosensitivity at physiological temperature and have a slow‐phase transition at temperatures much higher than that of the human body. However, when the positively charged amine groups of the pH‐sensitive units bind electrostatically with the negatively charged drug diclofenac, the copolymers retrieve the thermosensitivity. Poly(NIPAAm‐co‐AAm‐co‐AEAAm) was transformed into pH/thermoresponsive stable microspheres by an original approach based on crosslinking of the amine groups of aminoethylacrylamide (AEAAm) with glutaraldehyde at a temperature slightly below the lower critical solution temperature. The swelling/deswelling processes of microspheres occur only after the interaction of poly(NIPAAm‐co‐AAm‐co‐AEAAm) with the negatively charged drug diclofenac. The pH/temperature‐sensitive microgels and dicofenac act as sensors and as the triggering agent, respectively. Conductometric titration reveals that the thermosensitivity of poly(NIPAAm‐co‐AAm‐co‐AEAAm) is retrieved when just half of its amino groups are complexed with diclofenac. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Development of vapor deposited silica sol–gel particles for use as a bioactive materials system
Authors: Snyder Katherine L. , Holmes Hallie R. , VanWagner Michael J. , Hartman Natalie J. , Rajachar Rupak M.
Published: November 2012

Silica‐based sol–gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol–gel nano‐ and micro‐particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie‐like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell–material interactions to promote osteogenesis. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Use of a poly(ether imide) coating to improve corrosion resistance and biocompatibility of magnesium (Mg) implant for orthopedic applications
Authors: Kim Sang‐Bok , Jo Ji‐Hoon , Lee Sung‐Mi , Kim Hyoun‐Ee , Shin Kwan‐Ha , Koh Young‐Hag
Published: November 2012

This study investigated the utility of poly(ether imide) (PEI) coating for improving the corrosion resistance and biocompatibility of magnesium (Mg) implants for orthopedic application. In particular, the microstructure of the PEI coating layers was controlled by the adjustment of the temperature used to dry the spin‐coated wet PEI films. When a wet PEI film was dried at 4°C, a relatively thick and porous coating layer was achieved as a result of an extensive exchange of the solvent with water in a moist environment. In contrast, when a wet PEI film was dried at 70°C, a relatively thin and dense layer was created due to the faster evaporation of the solvent with a negligible exchange of the solvent with water. The porous PEI coating layer showed higher stability than did the dense one when immersed in a simulated body fluid (SBF), which was presumably attributed to the formation of chemical bonding between the PEI and the Mg substrate. Both the porous and the dense PEI coated Mg specimens showed significantly improved in vitro biocompatibility, which were assessed in terms of cell attachment, proliferation and differentiation. However, interestingly, the dense PEI coating layer showed greater cell proliferation and differentiation than did the porous layer. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Compression‐induced alignment and elongation of human mesenchymal stem cell (hMSC) in 3D collagen constructs is collagen concentration dependent
Authors: Kwok C. B. , Ho F. C. , Li C. W. , Ngan A. H. W. , Chan D. , Chan B. P.
Published: November 2012

Controlling cell organization is important in tissue engineering. Guidance by aligned features on scaffolds or stimulation by physical signals can be used to induce cell alignment. We have previously demonstrated a preferred alignment of human MSCs (hMSCs) along the compression loading axis in 3D collagen construct. In this study, we aim to investigate the collagen concentration dependence of the compression‐induced hMSC organization. Results demonstrated that the compression‐induced alignment and elongation of hMSCs exhibited a biphasic dose‐dependent relationship with collagen concentration, and associated well with both collagen ligand density and elastic modulus of the constructs. Moreover, collagen concentration and compression loading significantly affected the expression level of integrin beta 1 and antibody neutralization against this molecule aborted the compression‐induced alignment and elongation responses. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
A 3D‐matrigel/microbead assay for the visualization of mechanical tractive forces at the neurite–substrate interface of cultured neurons
Authors: Meseke Maurice , Förster Eckart
Published: November 2012

Mechanical properties of neuronal processes contribute to neuronal function, to resistance of fiber tracts against mechanical trauma, and to morphological changes during development and neurodegeneration. Conventional in vitro cell culture systems on inflexible substrates do not allow for the visualization of changing mechanical stress between neurites and their substrate. To solve this problem, we adapted a three‐dimensional gel matrix assay to visualize mechanical traction forces at the neurite–substrate interface. We chose matrigel as substrate because in this matrix various types of neurons initially adapt a bipolar morphology while migrating, similar to migrating neurons in vivo. To visualize emerging traction forces between neurites and their substrate, microbeads were embedded into the matrix as visible landmarks. We first analyzed mechanical distortion of matrigel by stepwise movements of a glass pipette tip under control of a micromanipulator to ensure reproducibility of induced bead displacement. The assay was then used to study the effect of the microtubule disrupting drug nocodazole on neuronal processes. By monitoring displacement of matrigel‐embedded microbeads, we visualized here for the first time emerging mechanical traction forces between the leading process and the substrate during nocodazole‐induced soma translocation. We did not observe bead displacement by processes of aged neurons. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Polyethylene glycol–grafted polyethylenimine used to enhance adenovirus gene delivery
Authors: Singarapu Kumar , Pal Ivy , Ramsey Joshua D.
Published: November 2012

An improved adenoviral‐based gene delivery vector was developed by complexing adenovirus (Ad) with a biocompatible, grafted copolymer PEG‐g‐PEI composed of polyethylene glycol (PEG) and polyethylenimine (PEI). Although an Ad‐based gene vector is considered relatively safe, its native tropism, tendency to elicit an immune response, and susceptibility to inactivating antibodies makes the virus less than ideal. The goal of the current study was to determine whether Ad could be complexed with a PEG‐g‐PEI copolymer that would enable the virus to transduce cells lacking the Ad receptor, while avoiding the issues commonly associated with PEI. A copolymer library was synthesized using 2 kDa PEG and either linear or branched PEI (25 kDa) with a PEG to PEI grafting ratio of 10, 20, or 30. The results of the study indicate that PEG‐g‐PEI/Ad complexes are indeed able to transduce CAR‐negative NIH 3T3 cells. The results also demonstrate that the PEG‐g‐PEI/Ad complexes are less toxic, less hemolytic, and more appropriately sized than PEI/Ad complexes. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Development of a bone reconstruction technique using a solid free‐form fabrication (SFF)‐based drug releasing scaffold and adipose‐derived stem cells
Authors: Lee Jin Woo , Kim Ki‐Joo , Kang Kyung Shin , Chen Shaochen , Rhie Jong‐Won , Cho Dong‐Woo
Published: November 2012

For tissue regeneration, three essential components of scaffolds, signals (biomolecules), and cells are required. Moreover, because bony defects are three‐dimensional in many clinical circumstances, an exact 3D scaffold is important. Therefore, we proposed an effective reconstruction tool for cranial defects using human adipose‐derived stem cells (hADSCs) and a 3D functional scaffold fabricated by solid free‐form fabrication (SFF) technology that secretes biomolecules. We fabricated poly(propylene fumarate)‐based 3D scaffolds with embedded microsphere‐deliverable bone morphogenetic protein‐2 (BMP‐2) by microstereolithography. BMP‐2‐loaded SFF scaffolds with/without hADSCs (SFF/BMP/hADSCs scaffolds and SFF/BMP scaffolds, respectively) and BMP‐2‐unloaded SFF scaffolds (SFF scaffolds) were then implanted in rat crania, and in vivo bone formation was observed. Analyses of bone formation areas using micro‐computed tomography (micro‐CT) showed the superiority of SFF/BMP/hADSCs scaffolds. Hematoxylin and eosin stain, Masson's trichrome stain, and collagen type‐I stain supported the results of the micro‐CT scan. And human leukocyte antigen‐ABC showed that seeded, differentiated hADSCs were well grown and changed to the bone tissue at the inside of the scaffold. Results showed that our combination of a functional 3D scaffold and hADSCs may be a useful tool for improving the reconstruction quality of severe bony defects in which thick bone is required. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.