bluuebunny/crossref_metadata_2025 huggingface dataset:
Major contributions of comparative endocrinology to the development and exploitation of the incretin concept
Authors: Conlon J. Michael , Patterson Steven , Flatt Peter R.
Published: August 2006

An incretin is a factor released by the gut in response to nutrients that facilitates uptake of glucose by peripheral tissues. The incretin concept predates the discovery of insulin but it is now clear that incretins act by stimulating secretion of this hormone. As glucagon has insulin‐releasing activity, it was speculated that intestinal glucagon‐like immunoreactivity (enteroglucagon) was involved in the incretin effect but it was an achievement in the field of comparative endocrinology that led to the demonstration that the preproglucagon gene encodes the most potent incretin in the human. Characterization of cloned cDNAs encoding two preproglucagons from the Brockmann body of the anglerfish Lophius americanus demonstrated that the glucagon sequence is flanked by a 34 amino‐acid‐residue sequence with appreciable structural similarity to glucagon that was termed glucagon‐like peptide (GLP). A 36 amino‐acid‐residue ortholog of anglerfish GLP was subsequently identified in human preproglucagon but this peptide had only weak insulin‐releasing activity. However, alignment of GLP sequences from human and teleost fish showed that the human ortholog is extended from its N‐terminus by a hexapeptide. Removal of this extension by an endogenous protease generates GLP‐1‐(7–36)amide, the potent and effective form of the incretin. More recently, comparative endocrinology has contributed to the exploitation of incretins as antidiabetic drugs. Exendin‐4, a GLP‐1 receptor agonist first isolated from the venom of the Gila monster Heloderma suspectum, is a clinically valuable, long‐acting incretin and the skins of several species of frogs synthesize potent insulin‐releasing peptides with therapeutic potential. J. Exp. Zool. 305A:781–786, 2006. © 2006 Wiley‐Liss, Inc.
Unexpected diversity of aryl hydrocarbon receptors in non‐mammalian vertebrates: insights from comparative genomics
Authors: Hahn Mark E. , Karchner Sibel I. , Evans Brad R. , Franks Diana G. , Merson Rebeka R. , Lapseritis Joy M.
Published: August 2006

Ligand‐activated receptors are well‐known targets of environmental chemicals that disrupt endocrine signaling. Genomic approaches are providing new opportunities to understand the comparative biology and molecular evolution of these receptors. One example of this is the aryl hydrocarbon receptor (AHR), a basic‐helix–loop–helix (bHLH)‐Per–Arnt–Sim (PAS) transcription factor through which planar aromatic hydrocarbons cause altered gene expression and toxicity. In contrast to humans and other mammals, which possess a single AHR, teleosts such as the Atlantic killifish (Fundulus heteroclitus) have at least two AHRs (AHR1 and AHR2). Analysis of sequenced genomes has revealed additional, unexpected AHR diversity in non‐mammalian vertebrates, including the chicken Gallus gallus (three predicted AHR genes), bony fishes such as the pufferfish Takifugu (formerly Fugu) rubripes (five AHR genes) and zebrafish Danio rerio (three AHR genes), and cartilaginous fishes such as the spiny dogfish Squalus acanthias (three AHR genes). In contrast, invertebrates appear to possess single AHRs that do not bind typical ligands of vertebrate AHRs. We suggest that AHR diversity in vertebrates arose through both gene and whole‐genome duplications combined with lineage‐specific gene loss, and that sensitivity to the developmental toxicity of planar aromatic hydrocarbons may have had its origin in the evolution of the ligand‐binding capacity of the AHR in the chordate lineage. Comparative molecular and genomic studies are providing new insights into AHR diversity and function in non‐mammalian species, revealing additional complexity in mechanisms by which environmental chemicals interfere with receptor‐dependent signaling. J. Exp. Zool. 305A:693–706, 2006. © 2006 Wiley‐Liss, Inc.
Induction of splice correction by cell‐penetrating peptide nucleic acids
Authors: El‐Andaloussi Samir , Johansson Henrik J. , Lundberg Pontus , Langel Ülo
Published: August 2006

Background

Directing splicing using oligonucleotides constitutes a promising therapeutic tool for a variety of diseases such as β‐thalassemia, cystic fibrosis, and certain cancers. The rationale is to block aberrant splice sites, thus directing the splicing of the pre‐mRNA towards the desired protein product. One of the difficulties in this setup is the poor bioavailability of oligonucleotides, as the most frequently used transfection agents are unsuitable for in vivo use. Here we present splice‐correcting peptide nucleic acids (PNAs), tethered to a variety of cell‐penetrating peptides (CPPs), evaluating their mechanism of uptake and ability to correct aberrant splicing.

Methods

HeLa cells stably expressing luciferase containing an aberrant splice site were used. A previously described PNA sequence, capable of correcting the aberrant splicing, was conjugated to the CPPs, Tat, penetratin and transportan, via a disulfide bridge. The ability of the CPP‐PNA conjugates to correct splicing was measured, and membrane disturbance and cell viability were evaluated using LDH leakage and WST‐1 assays. Lysosomotropic agents, inhibition of endocytosis at 4 °C and confocal microscopy were used to investigate the importance of endocytosis in the uptake of the cell‐penetrating PNAs.

Results

All the three CPPs were able to promote PNA translocation across the plasma membrane and induce splice correction. Transportan (TP) was the most potent vector and significantly restored splicing in a concentration‐dependent manner. Interestingly, TP also rendered a concentration‐dependent splice correction in serum, in contrast to Tat and penetratin. Addition of the lysosomotrophic agent chloroquine increases the splice correction efficacy of the CPP‐PNA conjugates up to 4‐fold, which together with experiments at 4 °C and the visual information from confocal microscopy, indicate that the mechanism of uptake responsible for internalization of CPP‐PNA conjugates is mainly endocytic. Finally, co‐localization studies with dextran further indicate that conjugates, at least in the case of TP, internalize via endocytosis and in particular macropinocytosis.

Conclusions

These data demonstrate that CPPs can be used for the delivery of splice‐correcting PNAs, with potential to be used as a therapeutic approach for regulating splicing in a variety of diseases. Transportan presents itself as the overall most suitable vector in this study, generating the most efficient conjugates for splice correction. Copyright © 2006 John Wiley & Sons, Ltd.
Managing discontinuity in academic medical centers: Strategies for a safe and effective resident sign‐out
Authors: Vidyarthi Arpana R. , Arora Vineet , Schnipper Jeffrey L. , Wall Susan D. , Wachter Robert M.
Published: August 2006

BACKGROUND

Restrictions in the hours residents can be on duty have resulted in increased sign‐outs, that is, transfer of patient care information and responsibility from one physician to a cross‐coverage physician, leading to discontinuity in patient care. This sign‐out process, which occurs primarily in the inpatient setting, traditionally has been informal, unstructured, and idiosyncratic. Although studies show that discontinuity may be harmful to patients, this is little data to assist residency programs in redesigning systems to improve sign‐out and manage the discontinuity.

PURPOSE

This article reviews the relevant medical literature, current practices in non–health professions in managing discontinuity, and summarizes the existing practice and experiences at 3 academic internal medicine hospitalist‐based programs.

CONCLUSIONS

We provide recommendations and strategies for best practices to design safe and effective sign‐out systems for residents that may also be useful to hospitalists working in academic and community settings. Journal of Hospital Medicine 2006;1:257–266. © 2006 Society of Hospital Medicine.
Nicotine reverses adult‐onset hypothyroidism‐induced impairment of learning and memory: Behavioral and electrophysiological studies
Authors: Alzoubi K.H. , Aleisa A.M. , Gerges N.Z. , Alkadhi K.A.
Published: August 2006

Nicotine alleviates cognitive impairment associated with a variety of health conditions. We examined the effect of chronic nicotine treatment on adult‐onset hypothyroidism‐induced impairment of learning and memory in rats. Hypothyroidism was induced by surgical removal of thyroid glands (thyroidectomy). One month later, chronic nicotine treatment (1 mg/kg sc, twice/day) was instituted for 4–6 weeks. Test of hippocampus‐dependent spatial learning and memory in the radial arm water maze showed that hypothyroidism impaired learning as well as short‐term and long‐term memory retention. Chronic nicotine treatment reversed the hypothyroidism‐induced learning and memory impairment. In normal rats, chronic nicotine treatment had no effect on learning and memory. Extracellular recordings from the CA1 region of anesthetized hypothyroid rats showed severe reduction of both early‐phase and late‐phase long‐term potentiation (LTP) magnitude, which was reversed in nicotine‐treated hypothyroid rats. These results show that chronic nicotine treatment prevents hypothyroidism‐induced impairment of spatial cognition and LTP. © 2006 Wiley‐Liss, Inc.
Estrogen treatment of spinal cord injury attenuates calpain activation and apoptosis
Authors: Sribnick Eric Anthony , Matzelle Deborah Denise , Ray Swapan Kumar , Banik Naren Lal
Published: August 2006

Spinal cord injury (SCI) is a devastating neurologic injury, and currently, the only recommended pharmacotherapy is high‐dose methylprednisolone, which has limited efficacy. Estrogen is a multi‐active steroid with anti‐oxidant and anti‐apoptotic effects. Estrogen may modulate intracellular Ca2+ and prevent inflammation. For this study, male rats were divided into three groups. Sham‐group animals received a laminectomy at T12. Injured rats received both laminectomy and 40 gram centimeter force SCI. Estrogen‐group rats received 4 mg/kg 17β‐estradiol (estrogen) at 15 min and 24 hr post‐injury, and vehicle‐group rats received equal volumes of dimethyl sulfoxide. Animals were sacrificed at 48 hr post‐injury, and 1‐cm segments of the lesion, rostral penumbra, and caudal penumbra were excised. The degradation of 68 kD neurofilament protein (NFP) and estrogen receptors (ER) was examined by Western blot analysis. Protein levels of calpain and the activities of calpain and caspase‐3 were also examined. Levels of cytochrome c were determined in both cytosolic and mitochondrial fractions. Cell death with DNA fragmentation was examined using the TUNEL assay. At the lesion, samples from both vehicle and estrogen treated animals showed increased levels of 68 kD NFP degradation, calpain content, calpain activity, cytochrome c release, and degradation of ERα and ERβ, as compared to sham. In the caudal penumbra, estrogen treatment significantly attenuated 68 kD NFP degradation, calpain content, calpain activity, levels of cytosolic cytochrome c, and ERβ degradation. At the lesion, vehicle‐treated animals displayed more TUNEL+ cells, and estrogen treatment significantly attenuated this cell death marker. We conclude that estrogen may inhibit cell death in SCI through calpain inhibition. © 2006 Wiley‐Liss, Inc.
Heavy metal concentrations and correlations in rain‐fed farm soils of Sifangwu village, central Gansu Province, China
Authors: Gou X. , Li Y. , Wang G.
Published: August 2006

Concentrations of copper (Cu), lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg), arsenic (As), organic carbon (abbreviated to OC) content and pH were measured in rain‐fed farm soils collected in Sifangwu Village which is located central Gansu Province, Northwest China. Concentrations of Cu, Pb, Cd, Hg and As are higher than the background values in grey calcareous soil. Cd concentration exceeds the Threshold of Secondary Environmental Quality Standard for Soil in China by 261 per cent. By bivariate analysis, it was found that OC does not correlate with heavy metal in the village. This is due to the semiarid conditions and agricultural activities. Principal component analysis (PCA) was used to assess the soil data, applying varimax rotation with Kaiser Normalization. The result shows that the data set is defined for three latent components. 1) PC1, which consists of Cu and Cr, and what is characterized as a component subject to strong lithological influence. 2) PC2, dominantly loaded by OC, Pb and Cd, is linked to agricultural influence, i.e. fertilization and cultivation. 3) PC3, the heavy metals Hg and As, in this component are from aerial deposition, thus this PC is named the atmospheric factor. Because PC1 explains 45·026 per cent of total variance, the source of the heavy metal in topsoil in the study area is assumed to be mainly derived from the lithology. Copyright © 2006 John Wiley & Sons, Ltd.
Complete 1H, 13C and 15N NMR assignment of tirapazamine and related 1,2,4‐benzotriazine N‐oxides
Authors: Boyd Maruta , Hay Michael P. , Boyd Peter D. W.
Published: August 2006

1H, 13C and 15N NMR measurements (1D and 2D including 1H15N gs‐HMBC) have been carried out on 3‐amino‐1, 2,4‐benzotriazine and a series of N‐oxides and complete assignments established. N‐Oxidation at any position resulted in large upfield shifts of the corresponding N‐1 and N‐2 resonances and downfield shifts for N‐4 with the exception of the 3‐amino‐1,2,4‐benzotriazine 1‐oxide in which a small upfield shift of N‐4 was observed. Density functional GIAO calculations of the 15N and 13C chemical shifts [B3LYP/6‐31G(d)//B3LYP/6‐311 + G(2d,p)] gave good agreement with experimental values confirming the assignments. The combination of 13C and 15N NMR provides an unambiguous method for assigning the 1H and 13C resonances of N‐oxides of 1,2,4‐benzotriazines. Copyright © 2006 John Wiley & Sons, Ltd.
Transcriptome profiling of the tubular porcine conceptus identifies the differential regulation of growth and developmentally associated genes
Authors: Blomberg Le Ann , Garrett Wesley M. , Guillomot Michel , Miles Jeremy R. , Sonstegard Tad S. , Van Tassell Curtis P. , Zuelke Kurt A.
Published: August 2006

Gastrulation and trophectoderm elongation of the porcine conceptus coincide with peak conceptus estrogen secretion from gestational day 11 to day 12. The current study aim was to identify genes required for elongation by defining the transcriptome profile of this dynamic tubular stage. The gastrulation and proliferative status of ovoid, tubular, and filamentous conceptuses were also examined. Polarization of the embryonic disc and growth throughout the conceptus were evident. An unamplified and two distinct amplified serial analysis of gene expression (SAGE) libraries were generated from tubular conceptus mRNA. Comparing the three libraries at 12,000 tags/library indicated small‐amplified RNA‐SAGE was a reliable amplification procedure. The unamplified library was increased to 42,415 tags and statistical analyses of tag frequencies with previously generated ovoid and filamentous libraries revealed the differential expression (P < 0.05) of 483 and 364 tags between ovoid:tubular or tubular:filamentous libraries, respectively. Annotated transcripts known to be involved in development and also potentially regulated by estrogen (cytokeratins 8 and 18, stratifin, midkine, and glycolytic enzymes) were further analyzed by real‐time PCR. The majority of glycolytic enzyme transcripts were constitutively expressed or downregulated at the filamentous stage. Likewise, cytokeratin mRNAs were less abundant in filamentous conceptuses, whereas stratifin and midkine were more abundant in tubular conceptuses. Analysis of protein revealed distinct expression patterns for cytokeratin 18, stratifin, and midkine. The function(s) of these factors and potential modulation by estrogen clearly needs to be elucidated to understand their physiological role in normal conceptus development. Mol. Reprod. Dev. 73: 1491–1502, 2006. © 2006 Wiley‐Liss, Inc.
Effects of hyaluronan, BSA, and serum on bovine embryo in vitro development, ultrastructure, and gene expression patterns
Authors: Palasz A. T. , Rodriguez‐Martinez H. , Beltran‐Breña P. , Perez‐Garnelo S. , Martinez M. F. , Gutierrez‐Adan A. , De la Fuente J.
Published: August 2006

Effects of hyaluronan (HA), BSA, and FCS on in vitro development, ultrastructure, and mRNA transcription of four developmentally important genes: apoptosis (Bax), oxidative stress (SOX), growth factor (IGF‐II), and cell‐to‐cell adhesion (Ecad) were examined. Two biological origin HA, Hylartil and Hyonate and one produced by fermentation (f‐HA) MAP‐5 were tested. Embryos were cultured in SOF medium with 0.4% BSA or with 0.4% BSA and 10% FCS. HA was added 96 hr post insemination (pi) to half of the embryos from each culture group. Embryo development was not affected by either HA preparation, however, hatching rates were higher in Hyalartil and MAP‐5 than in control and Hyonate (P < 0.05). There was no effect of HA on number of blastocysts developed in SOF + BSA. However, more blastocysts developed in SOF + BSA + f‐HA than in SOF +  BSA + FCS or with BSA + FCS + f‐HA. HA added to SOF + BSA, increased level of expression of epidermal growth factor (EGF)‐II and decreased the levels of expression of BAX, SOX, and Ecad (P < 0.05). Presence of FCS increased the levels of SOX and decreased the level of IGF‐II (P < 0.05) and the addition of f‐HA to SOF containing FCS showed no effect on the level of transcription of any analyzed genes. The fine structure of embryos cultured with f‐HA irrespective of protein sources used was clearly improved. In summary, f‐HA added 96 hr pi to SOF supplemented with BSA but not FCS improved development, molecular composition and fine structure of bovine embryos. Mol. Reprod. Dev. 73: 1503–1511, 2006. © 2006 Wiley‐Liss, Inc.
Subzero water transport characteristics and optimal rates of freezing rhesus monkey (Macaca mulatta) ovarian tissue
Authors: Li G. , Thirumala S. , Leibo S.P. , Devireddy R.V.
Published: August 2006

The purpose of the present study was to examine the effect of two different suprazero (room temperature +25°C to +4°C) cooling conditions on the measured water transport response of primate (Macaca mulatta) ovarian tissue in the presence and absence of cryoprotective agents (CPAs). Freshly collected Macaca mulatta (rhesus monkey) ovarian tissue sections were cooled at either 0.5°C/min or 40°C/min from 25 to 4°C. A shape independent differential scanning calorimeter (DSC) technique was then used to measure the volumetric shrinkage during freezing of ovarian tissue sections at a freezing rate of 5°C/min in the presence and absence of three different CPAs (0.85 M glycerol, 0.85 M dimethylsulfoxide, and 0.85 M ethylene glycol). Thus, water transport during freezing of primate ovarian tissue was obtained at eight different conditions (i.e., at four different freezing media with two different suprazero cooling conditions). The water transport response of ovarian tissue cooled rapidly from 25 to 4°C was significantly different (P < 0.01) than that of slow cooled tissue, in the freezing media without CPAs and with dimethylsulfoxide. However, the differences in the measured water transport response due to the imposed suprazero cooling conditions were reduced with the addition of glycerol and ethylene glycol (statistically different with P < 0.05). By fitting a model of water transport to the experimentally obtained volumetric shrinkage data the best‐fit membrane permeability parameters (Lpg and ELp) were determined. The best‐fit parameters of water transport in primate ovarian tissue sections ranged from: Lpg = 0.7 to 0.15 µm/min‐atm and ELp = 22.1 to 32.1 kcal/mol (the goodness of fit parameter, R2 > 0.96). These parameters suggest that the “optimal rates of cryopreservation” for ovarian tissue are significantly dependent upon suprazero cooling conditions and the choice of CPA. Mol. Reprod. Dev. 73: 1600–1611, 2006. © 2006 Wiley‐Liss, Inc.
Differing mechanisms of cAMP‐ versus seawater‐induced oocyte maturation in marine nemertean worms II. The roles of tyrosine kinases and phosphatases
Authors: Stricker Stephen A. , Smythe Toni L.
Published: August 2006

Instead of blocking oocyte maturation as it does in most animals, cAMP causes oocytes of marine nemertean worms to initiate maturation (=germinal vesicle breakdown, “GVBD”). To characterize cAMP‐induced GVBD in nemerteans, inhibitors of tyrosine kinase signaling were tested on Cerebratulus sp. oocytes that had been incubated in cAMP‐elevating drugs versus seawater (SW) alone. Such tests yielded similar results for Src‐like tyrosine kinase blockers, as the inhibitors prevented mitogen‐activated protein kinase (MAPK) activation without stopping either GVBD or maturation‐promoting factor (MPF) activation in both SW and cAMP‐elevating treatments. Alternatively, genistein, a general tyrosine kinase antagonist, and piceatannol, an inhibitor of the tyrosine kinase Syk, reduced GVBD and MAPK/MPF activities in SW‐, but not cAMP‐induced maturation. Similarly, inhibitors of the human epidermal growth factor receptor‐2 (HER‐2) tyrosine kinase prevented GVBD and MAPK/MPF activations in oocytes treated with SW, but not with cAMP‐elevating drugs. Antagonists of either protein tyrosine phosphatases (PTPs) or the dual‐specificity phosphatase Cdc25 also reduced GVBD and MAPK/MPF activities in SW‐treated oocytes without generally affecting cAMP‐induced maturation. Collectively, these data suggest cAMP triggers GVBD via pathways that do not require MAPK activation or several components of tyrosine kinase signaling. In addition, such differences in tyrosine kinase cascades, coupled with the dissimilar patterns of Ser/Thr kinase signaling described in the accompanying study, indicate that nemertean oocytes are capable of utilizing multiple mechanisms to activate MPF during GVBD. Mol. Reprod. Dev. 73: 1564–1577, 2006. © 2006 Wiley‐Liss, Inc.
Differing mechanisms of cAMP‐ versus seawater‐induced oocyte maturation in marine nemertean worms I. The roles of serine/threonine kinases and phosphatases
Authors: Stricker Stephen A. , Smythe Toni L.
Published: August 2006

Unlike in most animals, oocytes of marine nemertean worms initiate maturation (=germinal vesicle breakdown, GVBD) following an increase, rather than a decrease, in intraoocytic cAMP. To analyze how serine/threonine (Ser/Thr) kinase cascades involving mitogen‐activated protein kinase (MAPK), maturation‐promoting factor (MPF), cAMP‐dependent protein kinase (PKA), and phosphatidylinositol 3‐kinase (PI3K) regulate nemertean GVBD, oocytes of Cerebratulus sp. were treated with pharmacological modulators and stimulated with cAMP‐elevating drugs or seawater (SW) alone. Both cAMP elevators and SW triggered GVBD while activating MAPK, its target p90Rsk, and MPF. Similarly, neither cAMP‐ nor SW‐induced GVBD was affected by several Ser/Thr phosphatase inhibitors, and both stimuli apparently accelerated GVBD via a MAPK‐independent, PI3K‐dependent mechanism. However, inhibitors of Raf‐1, a kinase that activates MAPK kinase, blocked GVBD and MAPK activation during SW‐, but not cAMP‐induced maturation. In addition, MPF blockers more effectively reduced GVBD and MAPK activity in SW versus in cAMP‐elevating treatments. Moreover, the two maturation‐inducing stimuli yielded disparate patterns of PKA‐related MAPK activations and phosphorylations of putative PKA substrates. Collectively, such findings suggest that in maturing oocytes of Cerebratulus sp., Ser/Thr kinase cascades differ during cAMP‐ versus SW‐induced GVBD in several ways, including MAPK activation modes, MPF‐feedback loops, and PKA‐related signaling pathways. Additional differences in cAMP‐ versus SW‐induced oocyte maturation are also described in the accompanying study that deals with the roles of tyrosine kinase signaling during GVBD. Mol. Reprod. Dev. 73: 1578–1590, 2006. © 2006 Wiley‐Liss, Inc.
Blood velocity assessment using 3D bright‐blood time‐resolved magnetic resonance angiography
Authors: Miraux Sylvain , Franconi Jean‐Michel , Thiaudière Eric
Published: August 2006

Blood velocity is a functional parameter that is not easily assessed noninvasively, especially in small animals. A new noninvasive method that uses magnetic resonance angiography (MRA) to measure blood flows is proposed. This method is based on the time‐of‐flight (TOF) phenomenon. By initially suppressing the signal from the stationary spins in the area of interest, it is possible to sequentially visualize only the signal from the moving spins entering a given volume. With this method, 3D cine images of the blood flow can be generated by positive contrast, with unparalleled spatial (<200 μm) and temporal resolutions (<10 ms/image). As a result, it is possible to measure flow in sinuous paths. The present method was applied in vivo to measure the blood velocity in mouse carotid arteries. Because of its robustness and simplicity of implementation, this method has numerous potential applications for fundamental studies in small animal models. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Modified Alderman‐Grant resonator with high‐power stability for proton electron double resonance imaging
Authors: Petryakov Sergey , Samouilov Alexandre , Roytenberg Michael , Li Haihong , Zweier Jay L.
Published: August 2006

Proton‐electron double resonance imaging (PEDRI) requires a dual EPR/NMR resonator. In order to saturate electron spins, long high‐power RF EPR pulses are needed. Dissipated power causes resonator and sample heating, resulting in instability of the resonator frequency and coupling, which in turn causes a reduction in sensitivity. To overcome this problem, we designed, built, and tested a modified Alderman‐Grant (MAG) resonator for in vivo and in vitro applications. We improved the temperature stability by using fused quartz in critical structural components of the resonator and employing a design that minimized moving parts. All of the components of the resonator and matching circuit, including coupling capacitors, were rigidly positioned on the surface of the quartz tube. Electrical coupling circuitry between the feeding cable and resonator was employed to provide independent coupling and tuning adjustments, which improved the ease and speed of operation. The equivalent schematic of the matching circuit is presented along with calculations of critical parameters. The resonator exhibits no frequency shift with 20 W of continuous power irradiation, and can handle intermittent power of 60 W for up to 3 min without detuning, enabling stable and reliable data acquisition for PEDRI of biological samples. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
MRI to detect atherosclerosis with gadolinium‐containing immunomicelles targeting the macrophage scavenger receptor
Authors: Lipinski Michael J. , Amirbekian Vardan , Frias Juan C. , Aguinaldo Juan Gilberto S. , Mani Venkatesh , Briley‐Saebo Karen C. , Fuster Valentin , Fallon John T. , Fisher Edward A. , Fayad Zahi A.
Published: August 2006

The ability to specifically image macrophages may enable improved detection and characterization of atherosclerosis. In this study we evaluated the in vitro uptake of gadolinium (Gd)‐containing immunomicelles (micelles linked to macrophage‐specific antibody), micelles, and standard contrast agents by murine macrophages, and sought to determine whether immunomicelles and micelles improve ex vivo imaging of apolipoprotein E knockout (ApoE KO) murine atherosclerosis. Murine RAW 264.7 macrophages were incubated with Gd‐DTPA, micelles, and immunomicelles. Cell pellets were prepared and imaged using a 1.5 T MR system with an inversion recovery spin‐echo sequence to determine the in vitro T1 values. Ex vivo analysis of mouse aortas was performed using a 9.4T MR system with a high‐spatial‐resolution sequence (78 × 39 × 78 μm3). The T1 value was significantly decreased in cells treated with micelles compared to Gd‐DTPA (P < 0.0001), and in cells incubated at 4°C with immunomicelles compared to micelles (P < 0.05). Ex vivo MRI signal intensity (SI) was significantly increased by 81% and 20% in aortas incubated with immunomicelles and micelles, respectively. Confocal microscopy demonstrated in vitro and ex vivo uptake of fluorescent immunomicelles by macrophages. Immunomicelles and micelles improve in vitro and ex vivo MR detection of macrophages, and may prove useful in the detection of macrophage‐rich plaques. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Three‐dimensional magnetic resonance microscopy of pulmonary solitary tumors in transgenic mice
Authors: Kubo Shigeto , Levantini Elena , Kobayashi Susumu , Kocher Olivier , Halmos Balazs , Tenen Daniel G. , Takahashi Masaya
Published: August 2006

We attempted to accurately detect pulmonary solitary tumors and other complicated pulmonary disorders in aging inbred transgenic mice by cardiac‐ and respiratory‐gated MR microscopy at 4.7 Tesla. A comparison of in vivo MR images with histological results demonstrated that submillimeter lung tumors and most of the nontumor lesions could be detected by screening with two‐dimensional (2D) gradient echo (GRE) imaging. Subsequently performed 2D spin‐echo (SE) imaging provided higher image contrast, which distinguished the tumors from the surrounding complications. On the 3D GRE images and the generated maximum intensity projection (MIP) and volume‐rendered (VR) images, proper spatial localization of solitary tumors relative to the orientation of the pulmonary vessels was exhibited, and the tumor volume could also be measured. This promising method is noninvasive and has the potential to eventually replace invasive histopathology because it obviates the need to kill groups of animals at multiple time points. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Primary role of the serotonergic midline system in synchronized spontaneous activity during development of the embryonic mouse hindbrain
Authors: Hunt P.N. , Gust J. , McCabe A.K. , Bosma M.M.
Published: August 2006

In the developing embryonic mouse hindbrain, we have shown that previously widespread synchronized spontaneous activity at E11.5 retracts to the initiating zone of the rostral hindbrain by E13.5, and ceases completely by E14.5. We now confirm that at E11.5 and E13.5, the primary driver of spontaneous activity is serotonergic input, while other transmitters (GABA, glutamate, NE, and ATP) have only modulatory roles. Using immunocytochemistry, we also show that at E13.5, 5‐HT‐positive neurons in the midline extend over a larger rostro‐caudal distance than at E11.5, and that in the presumptive initiating zone, cell bodies occupy a band that extends 200 μm laterally on each side of the midline, with extensive axonal processes. The 5‐HT2A receptor retains expression in lateral tissue over this developmental time. We find that in addition to being sensitive to 5‐HT receptor antagonists, spontaneous activity is also abolished by blockers of gap junctions, and is increased in frequency and lateral spread by application of ammonium, presumably via increased intracellular pH augmenting gap junction conductance. Thus, 5‐HT neurons of the midline remain the primary drivers of spontaneous activity at several stages of development in the hindbrain, relying in part on gap junctional communication during initiation of activity. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 1239–1252, 2006
Spatial restriction of spontaneous activity towards the rostral primary initiating zone during development of the embryonic mouse hindbrain
Authors: Hunt P.N. , McCabe A.K. , Gust J. , Bosma M.M.
Published: August 2006

In the developing embryonic mouse hindbrain, we have previously shown that synchronized spontaneous activity is driven by midline serotonergic neurons at E11.5. This is mediated, at least in part, by the 5‐HT2A receptor, which is expressed laterally in the hindbrain. Activity at E11.5 is widespread within the hindbrain tissue, propagating from the midline to more lateral regions. Using rapid acquisition of [Ca2+]i events along the midline, we now show that the rostral midline, primarily in the region of former rhombomere r2, is the primary initiating zone for this activity. We propose that at E11.5, the combined events along the rostral‐caudal axis in combination with events propagating along the medial‐lateral axis could assign positional information to developing neurons within the hindbrain. With further development, to E13.5, both the lateral and caudal dimensions of spontaneous activity retract to the rostral midline, occupying an area only 14% of that exhibited at E11.5. We also show that increased levels of [K+]o (to 8 mM) at E13.5 are able to increase the spread of spontaneous activity laterally and rostro‐caudally. This suggests that spontaneous activity in the hindbrain depends in a dynamic way on the dominant initiating zone of the rostral midline, and that this relationship changes over development. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 1225–1238, 2006
Intersegmental transfer of sensory signals in the stick insect leg muscle control system
Authors: Stein Wolfgang , Büschges Ansgar , Bässler Ulrich
Published: August 2006

Intersegmental coordination during locomotion in legged animals arises from mechanical couplings and the exchange of neuronal information between legs. Here, the information flow from a single leg sense organ of the stick insect Cuniculina impigra onto motoneurons and interneurons of other legs was investigated. The femoral chordotonal organ (fCO) of the right middle leg, which measures posture and movement of the femur‐tibia joint, was stimulated, and the responses of the tibial motoneuron pools of the other legs were recorded. In resting animals, fCO signals did not affect motoneuronal activity in neighboring legs. When the locomotor system was activated and antagonistic motoneurons were bursting in alternation, fCO stimuli facilitated transitions from flexor to extensor activity and vice versa in the contralateral leg. Following pharmacological treatment with picrotoxin, a blocker of GABA‐ergic inhibition, the tibial motoneurons of all legs showed specific responses to signals from the middle leg fCO. For the contralateral middle leg we show that fCO signals encoding velocity and position of the tibia were processed by those identified local premotor nonspiking interneurons known to contribute to posture and movement control during standing and voluntary leg movements. Interneurons received both excitatory and inhibitory inputs, so that the response of some interneurons supported the motoneuronal output, while others opposed it. Our results demonstrate that sensory information from the fCO specifically affects the motoneuronal activity of other legs and that the layer of premotor nonspiking interneurons is a site of interaction between local proprioceptive sensory signals and proprioceptive signals from other legs. © 2006 Wiley Periodicals, Inc. J Neurobiol 66: 1253–1269, 2006
A posteriori error estimator for expanded mixed hybrid methods
Authors: Kim Dongho , Park Eun‐Jae
Published: August 2006

In this article, we construct an a posteriori error estimator for expanded mixed hybrid finite‐element methods for second‐order elliptic problems. An a posteriori error analysis yields reliable and efficient estimate based on residuals. Several numerical examples are presented to show the effectivity of our error indicators. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 330–349, 2007
A SAXS study of the structure of gels formed by mixtures of polyoxyalkylene triblock copolymers
Authors: Hamley Ian W , Castelletto Valeria , Ricardo Nágila MPS , Pinho Maria EN , Booth Colin , Attwood David , Yang Zhuo
Published: August 2006

Small‐angle X‐ray scattering was used to characterise aqueous micellar gels of triblock copolymers E137S18E137, E82S9E82, E76S5E76, E62P39E62, and of two mixtures: E137S18E137 and E62P39E62 (Mix 1) and E82S9E82 and E62P39E62 (Mix 2), each 50/50 wt%. E = oxyethylene, CH2CH2O; S = oxyphenylethylene, OCH2CH(C6H5); and P = oxypropylene, OCH2CH(CH3). Within the concentration and temperature ranges investigated (30–40 wt% copolymer, 20–80 °C), spherical micelles of copolymers E137S18E137, E82S9E82 and E62P39E62 packed into body‐centred cubic (BCC) structures. Gels of E76S5E76 were stable only at high concentrations and low temperatures, and a 70 wt% copolymer solution at T = 30 °C formed a hexagonal gel consistent with cylindrical micelles. It is likely that the mixed copolymers would form two distributions of micelles, and more complex structures were expected. However, gels of Mix 2 had well‐ordered BCC structures, while the less ordered gels of Mix 1 were also best characterised as BCC. Copyright © 2006 Society of Chemical Industry
Modeling non‐equilibrium morphologies in specific polymeric materials
Authors: Welch P. M. , Rasmussen K. Ø. , Chitanvis S. M. , Lookman T. , Sewell T. D.
Published: August 2006

We provide a numerical scheme for determining the Ginzburg–Landau free energy density directly from analysis of real or simulated images of phase evolving polymers. Our technique is robust and rapidly converges without requiring that the system reach equilibrium. The coefficients for the functional thus obtained agree with well‐known mean‐field trends. To our knowledge, this is the first prescription for specifying both the magnitudes and temperature dependencies for all of the free energy coefficients from microscopic models. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2605–2611, 2006
Weak polyelectrolytes tethered to surfaces: Effect of geometry, acid–base equilibrium and electrical permittivity
Authors: Nap Rikkert , Gong Peng , Szleifer Igal
Published: August 2006

The structural and thermodynamical properties of weak polyelectrolytes end‐tethered to surfaces of arbitrary geometry are studied using a molecular theory. The theory is based on writing down the free energy functional of the system including all the basic interactions and the explicit acid–base equilibrium for the chargeable groups of the polymer. The theory explicitly includes the size, shape, conformations, and charge distribution of all the molecular species. The electrostatic interactions include a density‐dependent dielectric function, modeled with the Maxwell–Garnett mixing formula, to account for the composition‐dependent permittivity. The minimization of the free energy leads to the distribution of all molecular species and their dependence on bulk pH and salt concentration. We apply the theory to polymer chains end‐tethered to planar, cylindrical, and spherical surfaces. The radius of the curved surfaces is small to enhance the curvature effect. We find that when the grafting surfaces are uncharged, the approximation of a constant dielectric function works very well for both structural and thermodynamic properties. The structure of weak polyelectrolytes tethered on cylindrical and spherical surfaces is different from that of polymers tethered on planar surfaces due to the available volume as a function of the distance from the surface. Specifically, the degree of dissociation increases with increasing curvature of the surface. This is a manifestation of the coupling between the local density of protons, counterions, and polymer segments. The results can be interpreted in terms of the local Le Chatelier principle for the acid–base equilibrium, with proper account of the three local contributions: counterions, protons, and chargeable groups. We find that one can achieve local changes of pH between one to two units within 1–2 nm. The thickness of the tethered layers as a function of bulk pH shows a large increase when the pH is equal to the bulk pK. However, the variation with salt concentration is different for the different geometries. The largest swelling is found for cylindrical surfaces. The predictions from scaling theories of a maximum in the thickness of the film as a function of salt concentration is found for planar films, but not for curved surfaces. Finally, the interactions between cylinders with tethered polyelectrolytes is very different from the equivalent planar surfaces. These results are important for the interpretation of force measurements with nanoscale AFM tips. The implications of the results for the rational design of responsive tethered polymer layers is discussed together with the limitations of the theoretical approach. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2638–2662, 2006
Two tube models of rubber elasticity
Authors: Vandoolaeghe W. L. , Kutter S. , Terentjev E. M.
Published: August 2006

Polymer entanglements lead to complicated topological constraints and interactions between neighboring chains in a dense solution or melt. Entanglements can be treated in a mean field approach, within the famous reptation model, since they effectively confine each individual chain in a tube‐like geometry. In polymer networks, due to crosslinks preventing the global reptation and constraint release, entanglements acquire a different topological meaning and have a much stronger effect on the resulting mechanical response. In this article we discuss two different models of rubber elasticity, both utilizing the reptation ideas. First, we apply the classical ideas of reptation statistics to calculate the effective rubber‐elastic free energy of an entangled rubbery network. In the second approach, we examine the classical Rouse dynamics of chains with quenched constraints at their ends by crosslinks, and along the primitive path by entanglements. We then proceed to average amicroscopicstress tensor for the network system and present it in a manageable form in the equilibriumt→ ∞ limit. Particular attention is paid to the treatment of compressibility and hydrostatic pressure in a sample with open boundaries. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2679–2697, 2006
Free volume and stochastic theory of volume relaxation
Authors: Simha Robert , Roberston Richard E.
Published: August 2006

The stochastic theory of volume relaxation previously applied to the physical aging process in the glassy state of polymers had been formulated as a discrete set of coupled differential equations for the time‐dependent, discrete free volume state probabilities. A reformulation of this theory for a continuum of free volume states is described in the present article. The result is a Schrödinger‐like equation, which has the advantage of an extensive availability of numerical procedures for its solution under various conditions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2663–2666, 2006
Dynamics of polyethylene melts studied by Monte Carlo simulations on a high coordination lattice
Authors: Lin Heng , Mattice Wayne L. , Von Meerwall Ernst D.
Published: August 2006

A detailed comparison is made between the experiment, prior simulations by other groups, and our simulation based on a newly designed dynamic Monte Carlo algorithm, on the dynamics of polyethylene (PE) melts. The new algorithm, namely, noncross random two‐bead move has been developed on a high coordination lattice (the 2nnd lattice) for studying the dynamics of realistic polymers. The chain length (molecular weight) in our simulation ranges from C40 (562 Da) to C324 (4538 Da). The effects of finite chain length have been confirmed and significant non‐Gaussian statistics evidently results in nonstandard static and dynamic properties of short PE chains. The diffusion coefficients scale with molecular weight (M) to the −1.7 power for short chains and −2.2 for longer chains, which coincides very well with experimental results. No pure Rouse scaling in diffusion has been observed. The transitional molecular weight to the entanglement regime is around 1500 Da. The detailed mean square displacements of middle bead (g1) are presented for several chain lengths. The reptation‐like slowdown can be clearly observed only above M ∼ 2400 Da. The slope 0.25 predicted by the theory for the intermediate regime is missing; instead a slope close to 0.4 appears, indicating that additional relaxation mechanism exists in this transitional region. The relaxation times extracted by fitting the autocorrelation function of end‐to‐end vectors with reptation model scale with M to 2.5 for long chains, which seemingly conflicts with the scaling of diffusion. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2556–2571, 2006
Molecular characterization of the two‐component histidine kinase gene from Monilinia fructicola
Authors: Ma Zhonghua , Luo Yong , Michailides Themis
Published: August 2006

Brown rot of stone fruit caused by Monilinia fructicola (G. Wint) Honey is one of the most common fungal diseases in California. In this study, two laboratory‐induced iprodione‐resistant (LIR) mutants of M. fructicola were characterized by osmotic sensitivity, virulence on prune and sequence of the two‐component histidine kinase gene (Mfos‐1). The LIR mutants showed more sensitivity to osmotic stress and lower virulence on prune than their wild‐type parent. Analysis of deduced amino acid of Mfos‐1 showed that this protein exhibited all the characteristic features of the two‐component histidine kinase genes, including osmotic sensing domain, six 90‐amino‐acid repeat motifs (coiled coil region) and kinase core and response regulator domains. Comparison of DNA sequences of the Mfos‐1 from LIR mutants and the wild‐type sensitive (S) isolate showed that LIR mutants had single point mutations in the coiled coil region of Mfos‐1. Copyright © 2006 Society of Chemical Industry
An in vitro screening assay to discover novel inhibitors of 4‐coumarate:CoA ligase
Authors: Yun Min‐Soo , Chen Weijun , Deng Fan , Kiyokawa Takahiro , Mametsuka Koki , Yogo Yasuhiro
Published: August 2006

4‐Coumarate:CoA ligase (4CL, EC 6.2.1.12) exists only in plants and plays an important role in the phenylpropanoid pathway. Identification of inhibitors targeting 4CL provides a novel approach for developing effective plant growth inhibitors (PGIs). The full‐length gene of tobacco 4CL (Nt4CL1) was cloned and expressed in Escherichia coli Cast & Chalm. The recombinant 4CL protein was extracted and purified by several purification steps including gel‐filtration and anion‐exchange chromatography. 4CL activity assay was miniaturized and optimized using a 96‐well microplate and a reader. Among 28 existing herbicides, propanil and swep strongly inhibited in vitro 4CL enzyme activity, and they were selected for further studies. The process of this assay can be developed into a high‐throughput screening system of PGI targeting 4CL in the phenylpropanoid pathway. Copyright © 2006 Society of Chemical Industry
Thickness scaling of space‐charge‐limited currents in organic layers with field‐ or density‐dependent mobility
Authors: Bisquert Juan , Montero José M. , Bolink Henk J. , Barea Eva M. , Garcia‐Belmonte Germà
Published: August 2006

An exact solution is provided for the current density‐voltage (J –V) characteristics of space‐charge limited transport of a single carrier in organic layers with field‐dependent mobility of the type μ (E) = μ 0 exp (γ √E. The general scaling relationship for field‐dependent mobility occurs in terms of the variables JL and V /L. For the density‐dependence of the mobility found in organic field‐effect transistor measurements, the thickness scaling occurs in terms of different variables, J 1/β L and V /L. The proposed scaling is a useful test for distinguishing field‐ and carrier density‐dependent mobility in disordered organic semiconductors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)