bluuebunny/crossref_metadata_2025 huggingface dataset:
Interleukin-2, interleukin-12, and interferon-γ levels and risk of young adult Hodgkin lymphoma
Authors: Cozen Wendy , Gill Parkash S. , Salam Muhammad T. , Nieters Alexandra , Masood Rizwan , Cockburn Myles G. , Gauderman W. James , Martínez-Maza Otoniel , Nathwani Bharat N. , Pike Malcolm C. , Van Den Berg David J. , Hamilton Ann S. , Deapen Dennis M. , Mack Thomas M.
Published: December 2007

Young adult Hodgkin lymphoma (YAHL) is associated clinically with altered immunity, including a systemic defect in cell-mediated responses. There is strong evidence of a genetic contribution to risk, so we hypothesized that heritable alterations in cytokine production associated with Th1 function may contribute to susceptibility. We identified twin pairs in whom at least one member had YAHL and measured interleukin-2 (IL-2), interleukin-12 (IL-12), and interferon-γ (IFN-γ) levels in PHA-stimulated peripheral blood mononuclear cell supernatant in 90 case-twins, 84 of their disease-free twins (unaffected cotwins), and 90 matched controls. Mean difference and mean percentage difference in cytokine levels between case-twins and controls, and unaffected cotwins and controls were determined using analysis of covariance. YAHL case-twins and their unaffected cotwins had IL-12 levels that were 60.6% (P = .002) and 49% (P = .04) lower than those of their matched controls, respectively. IL-2 levels were significantly higher in case-twins (P = .049), but not unaffected cotwins (P = .57), compared with controls. Differences in IFN-γ levels were not statistically significant in either comparison. An IL-12 polymorphism known to regulate expression was associated with a 2.8-fold (P = .03) increase in YAHL risk. Thus, both case-twins and their unaffected cotwins had a decreased ability to produce IL-12, which may contribute to YAHL susceptibility.
Requirement for CD1d expression by B cells to stimulate NKT cell–enhanced antibody production
Authors: Lang Gillian A. , Devera T. Scott , Lang Mark L.
Published: December 2007

Activation of natural killer-like T (NKT) cells with the CD1d ligand α-galactosylceramide enhances T-dependent humoral immune responses against coadministered T-dependent Ag. At present, there is little information on the mechanisms involved other than a dependence on CD1d expression by antigen-presenting cells and/or development of the NKT subset. We therefore tested the hypothesis that direct presentation of α-GC by B cells was required for NKT-enhanced Ab responses against T-dependent Ag. We reconstituted B cell–deficient μMT mice with B cells from C57Bl/6 donors or CD1d−/− donors before immunization with NP-KLH alone or NP-KLH mixed with α-GC. We made the surprising observation that B-cell expression of CD1d is absolutely required for the NKT-enhanced Ab response. Our data show that the mechanism by which NKT cells enhance humoral immune responses involves interaction with CD1d-expressing B cells.
Plasmid-based genetic modification of human bone marrow-derived stromal cells: analysis of cell survival and transgene expression after transplantation in rat spinal cord
Authors: Ronsyn Mark W , Daans Jasmijn , Spaepen Gie , Chatterjee Shyama , Vermeulen Katrien , D'Haese Patrick , Van Tendeloo Viggo FI , Van Marck Eric , Ysebaert Dirk , Berneman Zwi N , Jorens Philippe G , Ponsaerts Peter
Published: December 2007

Background

Bone marrow-derived stromal cells (MSC) are attractive targets for ex vivo cell and gene therapy. In this context, we investigated the feasibility of a plasmid-based strategy for genetic modification of human (h)MSC with enhanced green fluorescent protein (EGFP) and neurotrophin (NT)3. Three genetically modified hMSC lines (EGFP, NT3, NT3-EGFP) were established and used to study cell survival and transgene expression following transplantation in rat spinal cord.

Results

First, we demonstrate long-term survival of transplanted hMSC-EGFP cells in rat spinal cord under, but not without, appropriate immune suppression. Next, we examined the stability of EGFP or NT3 transgene expression following transplantation of hMSC-EGFP, hMSC-NT3 and hMSC-NT3-EGFP in rat spinal cord. While in vivo EGFP mRNA and protein expression by transplanted hMSC-EGFP cells was readily detectable at different time points post-transplantation, in vivo NT3 mRNA expression by hMSC-NT3 cells and in vivo EGFP protein expression by hMSC-NT3-EGFP cells was, respectively, undetectable or declined rapidly between day 1 and 7 post-transplantation. Further investigation revealed that the observed in vivo decline of EGFP protein expression by hMSC-NT3-EGFP cells: (i) was associated with a decrease in transgenic NT3-EGFP mRNA expression as suggested following laser capture micro-dissection analysis of hMSC-NT3-EGFP cell transplants at day 1 and day 7 post-transplantation, (ii) did not occur when hMSC-NT3-EGFP cells were transplanted subcutaneously, and (iii) was reversed upon re-establishment of hMSC-NT3-EGFP cell cultures at 2 weeks post-transplantation. Finally, because we observed a slowly progressing tumour growth following transplantation of all our hMSC cell transplants, we here demonstrate that omitting immune suppressive therapy is sufficient to prevent further tumour growth and to eradicate malignant xenogeneic cell transplants.

Conclusion

In this study, we demonstrate that genetically modified hMSC lines can survive in healthy rat spinal cord over at least 3 weeks by using adequate immune suppression and can serve as vehicles for transgene expression. However, before genetically modified hMSC can potentially be used in a clinical setting to treat spinal cord injuries, more research on standardisation of hMSC culture and genetic modification needs to be done in order to prevent tumour formation and transgene silencing in vivo.
Quantification of global transcription patterns in prokaryotes using spotted microarrays
Authors: Sidders Ben , Withers Mike , Kendall Sharon L , Bacon Joanna , Waddell Simon J , Hinds Jason , Golby Paul , Movahedzadeh Farahnaz , Cox Robert A , Frita Rosangela , ten Bokum Annemieke MC , Wernisch Lorenz , Stoker Neil G
Published: December 2007

We describe an analysis, applicable to any spotted microarray dataset produced using genomic DNA as a reference, that quantifies prokaryotic levels of mRNA on a genome-wide scale. Applying this to Mycobacterium tuberculosis, we validate the technique, show a correlation between level of expression and biological importance, define the complement of invariant genes and analyze absolute levels of expression by functional class to develop ways of understanding an organism's biology without comparison to another growth condition.
Negative Regulation of Otic Capsule Chondrogenesis
Authors: LIU WEI , BUTTS SYDNEY , KIM HAROLD , FRENZ DOROTHY A.
Published: December 2007

Abstract:  The transforming growth factor‐beta (TGF‐β) superfamily, including TGF‐β1 and bone morphogenetic protein (BmP2, BmP4), participates in the regulation of the developing cartilaginous otic capsule, which prefigures the endochondral bony labyrinth of the inner ear. This study investigates Smad‐6 and ‐7, downstream components of the TGF‐β/BMP signaling pathway, in otic capsule chondrogenic control, and supports a function for these inhibitory Smads as negative regulators of capsule chondrogenesis. The importance of otic capsule chondrogenic control and implications of Smad signaling for otosclerosis, a disease affecting the endochondral bony labyrinth, are indicated.
Bone Loss after Temporarily Induced Muscle Paralysis by Botox Is Not Fully Recovered After 12 Weeks
Authors: GRIMSTON SUSAN K. , SILVA MATTHEW J. , CIVITELLI ROBERTO
Published: December 2007

Abstract:  To study the effect of unloading followed by reloading on hindlimb bone mineral content (BMC), we used botulinum toxin A (Botox). We studied the timing and degree of recovery upon restoration of muscle function. We also tested to see if reaction to Botox injection occurred as a function of the degree of expression of connexin43 (Cx43). Sixteen mice were divided by gender and genotype; wild‐type equivalent (Gja1+/flox) and heterozygous (Gja1+/−) mice were injected with a single dose of 2U/100 g Botox i.m. in the quadriceps, hamstrings, and posterior calf muscle groups (day 0). Regional BMC was monitored for 12 weeks in the injected and contralateral control limb. Significant bone loss was observed in the injected limb by week 2 in the Gja1+/flox mice, and by week 3–4 in the Gja1+/− mice. By week 12, BMC in the Botox‐treated limb of both male and female wild‐type and heterozygous mice was still at least 14% less than that of the noninjected limb. Cortical thickness and BV/TV were lower in the Botox femur compared to the noninjected femur. The heterozygous mice tended to show a slower response to Botox injection as reflected in a slower loss of BMC. Our results show that the rapid and profound bone loss following temporary muscle paralysis is not fully recovered upon restoration of muscle function within 12 weeks. These results underscore the significance of normal muscle function in the maintenance of bone mass.
TRAIL Is Involved in Human Osteoclast Apoptosis
Authors: BRUNETTI GIACOMINA , ORANGER ANGELA , MORI GIORGIO , TAMMA ROBERTO , DI BENEDETTO ADRIANA , PIGNATARO PAOLO , GRASSI FELICE R. , ZALLONE ALBERTA , GRANO MARIA , COLUCCI SILVIA
Published: December 2007

Abstract:  Control of osteoclast (OC) apoptosis has been recognized as a critical regulatory factor in bone remodeling. TRAIL, a member of the TNF superfamily, induces apoptosis in neoplastic and normal cells. However, few data are available on the effects of TRAIL on bone cells, thus in the present study we investigated TRAIL role on the apoptosis of human mature OCs. We show that TRAIL treatment causes reduced cell viability, loss of nuclei integrity, and derangement of the actin microfilament in OCs. We also demonstrated that the death receptor DR5, upregulated by TRAIL, could be the mediator of TRAIL‐induced OC apoptosis.
Regulation of Skeletal Remodeling by the Endocannabinoid System
Authors: BAB ITAI A.
Published: December 2007

Abstract: Since the discovery of the endocannabinoid system, its presence and involvement have been reported in a handful of biological systems. Recently, the skeleton has been identified as a major endocannabinoid target through both the neuronal CB1 and predominantly peripheral CB2 cannabinoid receptors. CB1 is present in sympathetic nerve terminals in bone, whereas CB2 is expressed in osteoblasts and osteoclasts, the respective bone‐forming and ‐resorbing cells. Furthermore, the skeleton appears as the main system physiologically regulated by CB2. CB2‐deficient mice show a markedly accelerated age‐related bone loss and the CB2 locus in women is associated with low bone density and osteoporotic fractures. Since activation of CB2 attenuates experimentally induced bone loss by inhibiting bone resorption and stimulating bone formation, and because synthetic cannabinoids are stable and orally available, a therapy based on synthetic CB2 agonists is a promising novel target for antiosteoporotic drug development.
Osteocytes as Dynamic Multifunctional Cells
Authors: BONEWALD LYNDA F.
Published: December 2007

Abstract:  The target of bone systemic factors and therapeutics has been assumed to be primarily osteoblasts and/or osteoclasts and their precursors. All the action with regard to bone modeling or remodeling has been assumed to take place on the bone surface. In this scenario, cells below the bone surface, that is, osteocyte, are considered to be inactive placeholders in the bone matrix. New data show osteocytes are involved. In addition to the function of osteocytes translating mechanical strain into biochemical signals between osteocytes and cells on the bone surface to affect (re)modeling, new functions are emerging. Osteocytes are exquisitely sensitive to mechanical strain in the form of shear stress compared to osteoblasts or osteoclasts and communicate with each other, with cells on the bone surface, and with marrow cells. Osteocytes are able to move their cell body and their dendritic processes and appear to be able to modify their local microenvironment. A novel function now attributed to osteocytes includes regulation of phosphate metabolism. Therefore, in addition to osteoblasts and osteoclasts, osteocytes are also important for bone health.
Proteomic Analysis of Hydroxyapatite Interaction Proteins in Bone
Authors: ZHOU HAI‐YAN
Published: December 2007

Abstract:  Biomineralization involves proteins and/or other macromolecules directly in controlling the mineral crystal nucleation/induction, growth, and maturation. To identify these proteins in bone, bovine bone EDTA/NaCl extract was passed through a hydroxyapatite column followed by washing with 0.5 M NaCl and the bound proteins were collected and analyzed by mass spectrometry. More than 30 proteins were identified. While as described previously, albumin, α2‐HS glycoprotein, decorin, biglycan, osteoadherin, osteonectin, etc. were included, collagen α2 (I), matrix extracellular phosphoglycoprotein, secreted phosphoprotein 24, chondroadherin, lumican, perlecan, thrombospondin 1, nucleobindin, etc. were for the first time shown to directly interact with calcium phosphate mineral.
Differential Effects of Vascular Endothelial Growth Factor on Joint Formation during Limb Development
Authors: CORTINA‐RAMÍREZ GLORIA EMELÍ , CHIMAL‐MONROY JESÚS
Published: December 2007

Abstract:  During skeletal development the proliferating chondrocytes choose between two fates: to differentiate into prejoint cells or undergo hypertrophy. Vascular endothelial growth factor (VEGF) participates in endochondral ossification, but it is unknown whether it has a role in joint development. We evaluated the VEGF effects on joints, implanting VEGF‐beads in the presumptive limb joints of chick embryos. The wrist and elbow showed partial and complete fusions. Using the model of ectopic digits induced by transforming growth factor‐β (TGF‐β), VEGF inhibited joint formation when it was applied after TGF‐β. These data suggest differential effects of VEGF on different joints during development.
Identification of Additional Dimerization Partners of FIAT, the Factor Inhibiting ATF4‐Mediated Transcription
Authors: ST‐ARNAUD RENÉ , ELCHAARANI BILAL
Published: December 2007

Abstract:  FIAT is a leucine zipper protein whose name was coined for its interaction with ATF4 and the subsequent blockage of ATF4‐directed osteocalcin gene transcription. FIAT is a nuclear protein that lacks a basic DNA‐binding domain but contains three identifiable leucine zipper domains. FIAT heterodimerizes with ATF4 through one of these zippers and thereby prohibits ATF4 from binding to its cognate DNA sequence. We tested whether FIAT also interacts with additional basic domain‐leucine zipper transcriptional regulators of osteoblast activity, such as the Fos family member Fra‐1 or one of its dimerization partners, c‐Jun. Transient transfection assays in osteoblastic MC3T3‐E1 cells with the heterologous AP‐1‐tk‐luciferase reporter revealed that FIAT does not affect c‐Jun‐mediated transcription, even in the presence of the c‐Jun coactivator αNAC. However, FIAT inhibited transcriptional activation by a c‐Jun∼Fra‐1 heterodimer. Thus FIAT specifically inhibits Fra‐1 transcriptional activity. These data identify a second target of the FIAT transcriptional repressor activity and suggest that FIAT can modulate early osteoblast activity by interacting with ATF4, as well as regulate later osteoblast function through inhibition of Fra‐1.
Osteoblast and Osteoclast Differentiation in Modeled Microgravity
Authors: SAXENA RITU , PAN GEORGE , McDONALD JAY M.
Published: December 2007

Abstract:  Prolonged microgravity experienced by astronauts is associated with a decrease in bone mineral density. To investigate the effect of microgravity on differentiation of osteoclasts and osteoblasts, we used a NASA‐recommended, ground‐based, microgravity‐simulating system, the Rotary Cell Culture System (RCCS). Using the RCCS, we demonstrated that modeled microgravity (MMG) inhibited osteoblastogenesis and increased adipocyte differentiation in human mesenchymal stem cells incubated under osteogenic conditions. This transformation involves reduced RhoA activity and cofilin phosphorylation, disruption of F‐actin stress fibers, and decreased integrin signaling through focal adhesion kinase. We have used the system to show that MMG also stimulates osteoclastogenesis. These systems provide the opportunity to develop pharmacological agents that will stimulate osteoblastogenesis and inhibit osteoclastogenesis.
Parathyroid Hormone Regulates Histone Deacetylases in Osteoblasts
Authors: SHIMIZU EMI , SELVAMURUGAN NAGARAJAN , WESTENDORF JENNIFER J. , PARTRIDGE NICOLA C.
Published: December 2007

Abstract:  Parathyroid hormone (PTH) functions as an essential regulator of calcium homeostasis and as a mediator of bone remodeling. We have already shown that PTH stimulates the expression of matrix metalloproteinase‐13 (MMP‐13), which is responsible for degrading components of extracellular matrix. We have hypothesized that histone deacetylases (HDACs) are involved with PTH‐induced MMP‐13 gene expression in the osteoblastic cell line, UMR 106–01. We have shown that PTH profoundly regulates HDAC4 in UMR 106–01 cells through a PKA‐dependent pathway, leading to removal of HDAC4 from the MMP‐13 promoter and its enhanced transcription. Understanding the mechanism of how HDACs affect osteoblast differentiation and mineralization will identify new theraupeutic methods for bone diseases, such as osteoporosis and multiple myeloma.
Morphogen Receptor Genes and Metamorphogenes
Authors: KAPLAN FREDERICK S. , GROPPE JAY , PIGNOLO ROBERT J. , SHORE EILEEN M.
Published: December 2007

Abstract:  Morphogen receptors are nodal points in signal transduction pathways that regulate morphogenesis during embryonic development. A recent discovery identified a recurrent missense mutation in a gene encoding a morphogen receptor responsible for the elusive process of skeletal metamorphosis in humans. Metamorphosis, the postnatal transformation of one normal tissue or organ system into another, is a biological process rarely seen in higher vertebrates or mammals, but exemplified pathologically by the disabling autosomal dominant disorder, fibrodysplasia ossificans progressiva (FOP). Individuals with FOP experience episodes of spontaneous or trauma‐induced metamorphosis that convert normal functioning aponeuroses, fascia, ligaments, tendons, and skeletal muscles into a highly ramified and disabling second skeleton of heterotopic bone. The recurrent single nucleotide missense mutation in the gene encoding activin receptor IA/activin‐like kinase 2 (ACVR1/ALK2), a bone morphogenetic protein (BMP) type I receptor that causes FOP in all classically affected individuals worldwide, is one of the most specific disease‐causing mutations in the human genome and the first identified human metamorphogene. These findings provide deep insight into a signaling pathway that regulates tissue and organ stability following morphogenesis, and that when dysregulated in a specific manner, orchestrates the metamorphosis of one normal tissue or organ system into another. The study of skeletal metamorphosis in FOP provides profound insight into the molecular mechanisms that ensure phenotypic stability following morphogenesis and that ordinarily lay deeply hidden in the highly conserved signaling pathways that regulate cell fate. Such insight is applicable to a broad range of human afflictions.
The Role of the Perichondrium in Fetal Bone Development
Authors: KRONENBERG HENRY M.
Published: December 2007

Abstract:  Most cells in mesenchymal condensations that form endochondral bone become chondrocytes; cells at the outer edges of the condensations, however, become perichondrial cells with distinct properties and functions. Some perichondrial cells become osteoblasts that populate both the future cortical and trabecular bone; others probably become chondrocytes. Perichondrial cells both send signals to the underlying growth cartilage and receive signals from the cartilage. Here I illustrate briefly examples of the complicated interactions between the perichondrium and the underlying growth cartilage.
A Novel Transgenic Mouse Model to Study the Osteoblast Lineage in Vivo
Authors: MAES CHRISTA , KOBAYASHI TATSUYA , KRONENBERG HENRY M.
Published: December 2007

Abstract:  Over the past few decades, osteoblast differentiation has been studied extensively in a variety of culture systems and findings from these experiments have shaped our understanding of the bone‐forming cell lineage. However, in vitro assays are bound by intrinsic limitations and are unable to effectively mirror many aspects related to osteoblasts in vivo, including their origin, destiny, and life span. Therefore, these fundamental questions strongly advocate the need for novel models to characterize the osteoblast lineage in vivo. Here, we developed a transgenic mouse system to study stage‐specific subsets of osteoblast lineage cells. We believe that this system will prove to be a helpful tool in deciphering multiple aspects of osteoblast biology in vivo.
Synovial Joint Formation during Mouse Limb Skeletogenesis
Authors: KOYAMA EIKI , OCHIAI TAKANAGA , ROUNTREE RYAN B. , KINGSLEY DAVID M. , ENOMOTO‐IWAMOTO MOTOMI , IWAMOTO MASAHIRO , PACIFICI MAURIZIO
Published: December 2007

Abstract:  Indian hedgehog (Ihh) has been previously found to regulate synovial joint formation. To analyze mechanisms, we carried out morphological, molecular, and cell fate map analyses of interzone and joint development in wild‐type and Ihh−/− mouse embryo long bones. We found that Ihh−/− cartilaginous digit anlagen remained fused and lacked interzones or mature joints, whereas wrist skeletal elements were not fused but their joints were morphologically abnormal. E14.5 and E17.5 wild‐type digit and ankle prospective joints expressed hedgehog target genes including Gli1 and Gli2 and interzone‐associated genes including Gdf5, Erg, and tenascin‐C, but expression of all these genes was barely detectable in mutant joints. For cell fate map analysis of joint progenitor cells, we mated Gdf5‐Cre+/−/Rosa R26R+/− double transgenic mice with heterozygous Ihh+/− mice and monitored reporter β‐galactosidase activity and gene expression in triple‐transgenic progeny. In control Gdf5‐Cre+/−/R26R+/−/Ihh+/− limbs, reporter‐positive cells were present in developing interzones, articulating layers, and synovial lining tissue and absent from underlying growth plates. In mutant Gdf5‐Cre+/−/R26R+/−/Ihh−/− specimens, reporter‐positive cells were present also. However, the cells were mostly located around the prospective and uninterrupted digit joint sites and, interestingly, still expressed Erg, tenascin‐C, and Gdf5. Topographical analysis revealed that interzone and associated cells were not uniformly distributed, but were much more numerous ventrally. A similar topographical bias was seen for cavitation process and capsule primordia formation. In sum, Ihh is a critical and possibly direct regulator of joint development. In its absence, distribution and function of Gdf5‐expressing interzone‐associated cells are abnormal, but their patterning at prospective joint sites still occurs. The joint‐forming functions of the cells appear to normally involve a previously unsuspected asymmetric distribution along the ventral‐to‐dorsal plane of the developing joint.
The Role of NFAT in Osteoclast Formation
Authors: TAKAYANAGI HIROSHI
Published: December 2007

Abstract:  Osteoclasts are cells of monocyte–macrophage origin that degrade bone matrix. Receptor activator of NF‐κB ligand (RANKL) induces osteoclast formation in the presence of macrophage‐colony‐stimulating factor (M‐CSF) and costimulatory signals. RANKL induces activation of the TNF receptor‐associated factor 6 (TRAF6) and c‐Fos pathways, which lead to the osteoclast‐specific event, that is, autoamplification of nuclear factor of activated T cells (NFAT)c1, the master transcription factor for osteoclast differentiation. Autoamplification of NFATc1 is dependent on the calcium signaling of immunoglobulin‐like receptors associated with immunoreceptor tyrosine‐based activation motif (ITAM)‐harboring adaptors. In addition to the calcineurin–NFATc1 axis, calcium signaling activates the calmodulin‐dependent kinase pathway, which also plays a critical role in osteoclast formation. Such advances in the understanding of the molecular mechanism of osteoclast differentiation are expected to lead to novel therapeutic approaches to bone diseases.
Axin1 and Axin2 Are Regulated by TGF‐β and Mediate Cross‐talk between TGF‐β and Wnt Signaling Pathways
Authors: DAO DEBBIE Y. , YANG XUE , CHEN DI , ZUSCIK MICHAEL , O'KEEFE REGIS J.
Published: December 2007

Abstract:  Chondrocyte maturation during endochondral bone formation is regulated by a number of signals that either promote or inhibit maturation. Among these, two well‐studied signaling pathways play crucial roles in modulating chondrocyte maturation: transforming growth factor‐beta (TGF‐β)/Smad3 signaling slows the rate of chondrocyte maturation, while Wingless/INT‐1‐related (Wnt)/β‐catenin signaling enhances the rate of chondrocyte maturation. Axin1 and Axin2 are functionally equivalent and have been shown to inhibit Wnt/β‐catenin signaling and stimulate TGF‐β signaling. Here we show that while Wnt3a stimulates Axin2 in a negative feedback loop, TGF‐β suppresses the expression of both Axin1 and Axin2 and stimulates β‐catenin signaling. In Axin2 ‐/‐ chondrocytes, TGF‐β treatment results in a sustained increase in β‐catenin levels compared to wild‐type chondrocytes. In contrast, overexpression of Axin enhanced TGF‐β signaling while overexpression of β‐catenin inhibited the ability of TGF‐β to induce Smad3‐sensitive reporters. Finally, the suppression of the Axins is Smad3‐dependent since the effect is absent in Smad3 ‐/‐ chondrocytes. Altogether these findings show that the Axins act to integrate signals between the Wnt/β‐catenin and TGF‐β/Smad pathways. Since the suppression Axin1 and Axin2 expression by TGF‐β reduces TGF‐β signaling and enhances Wnt/β‐catenin signaling, the overall effect is a shift from TGF‐β toward Wnt/β‐catenin signaling and an acceleration of chondrocyte maturation.
Hematopoietic Stem Cell Trafficking
Authors: MÉNDEZ‐FERRER SIMÓN , FRENETTE PAUL S.
Published: December 2007

Abstract:  Hematopoiesis takes place preferentially within bone cavities, suggesting that bone‐derived factors contribute to blood formation. Hematopoietic stem and progenitor cells (HSPCs) can be mobilized from the bone marrow parenchyma to the circulation by various agonists whose common downstream action leads to alteration in the expression or function of the chemokine CXCL12 and adhesion molecules mediating migration. Granulocyte colony‐stimulating factor (G‐CSF), the most prevalent drug used to mobilize HSPCs, dramatically suppresses osteoblast function. Recent studies suggest that G‐CSF‐mediated suppression requires signals from the sympathetic nervous system (SNS). This review summarizes emerging concepts thought to contribute to stem cell migration.
Stress Mediators Regulate Brain Prostaglandin Synthesis and Peroxisome Proliferator-Activated Receptor-γ Activation after Stress in Rats
Authors: García-Bueno Borja , Madrigal José L. M. , Pérez-Nievas Beatriz G. , Leza Juan Carlos
Published: December 2007

Stress exposure leads to oxidative/nitrosative and neuroinflammatory changes that have been shown to be regulated by antiinflammatory pathways in the brain. In particular, acute restraint stress is followed by cyclooxygenase (COX)-2 up-regulation and subsequent proinflammatory prostaglandin (PG) E2 release in rat brain cortex. Concomitantly, the synthesis of the antiinflammatory prostaglandin 15d-PGJ2 and the activation of its nuclear target the peroxisome proliferator-activated receptor (PPAR)-γ are also produced. This study aimed to determine the possible role of the main stress mediators: catecholamines, glucocorticoids, and excitatory amino acids (glutamate) in the above-mentioned stress-related effects. By using specific pharmacological tools, our results show that the main mediators of the stress response are implicated in the regulation of prostaglandin synthesis and PPARγ activation in rat brain cortex described after acute restraint stress exposure. Pharmacological inhibition (predominantly through β-adrenergic receptor) of the stress-released catecholamines in the central nervous system regulates 15d-PGJ2 and PGE2 synthesis, by reducing COX-2 overexpression, and reduces PPARγ activation. Stress-produced glucocorticoids carry out their effects on prostaglandin synthesis through their interaction with mineralocorticoid and glucocorticoid receptors to a very similar degree. However, in the case of PPARγ regulation, only the actions through the glucocorticoid receptor seem to be relevant. Finally, the selective blockade of the N-methyl-d-aspartate type of glutamate receptor after stress also negatively regulates 15d-PGJ2 and PGE2 production by COX-2 down-regulation and decrease in PPARγ transcriptional activity and expression. In conclusion, we show here that the main stress mediators, catecholamines, GCs, and glutamate, concomitantly regulate the activation of proinflammatory and antiinflammatory pathways in a possible coregulatory mechanism of the inflammatory process induced in rat brain cortex by acute restraint stress exposure.
Rapid Action of Estrogens on Intracellular Calcium Oscillations in Primate Luteinizing Hormone-Releasing Hormone-1 Neurons
Authors: Abe Hideki , Keen Kim L. , Terasawa Ei
Published: December 2007

Feedback controls of estrogen in LHRH-1 neurons play a pivotal role in reproductive function. However, the mechanism of estrogen action in LHRH-1 neurons is still unclear. In the present study, the effect of estrogens on intracellular calcium ([Ca2+]i) oscillations in primate LHRH-1 neurons was examined. Application of 17β-estradiol (E2, 1 nm) for 10 min increased the frequency of [Ca2+]i oscillations within a few minutes. E2 also increased the frequency of [Ca2+]i synchronization among LHRH-1 neurons. Similar E2 effects on the frequency of [Ca2+]i oscillations were observed under the presence of tetrodotoxin, indicating that estrogen appears to cause direct action on LHRH-1 neurons. Moreover, application of a nuclear membrane-impermeable estrogen dendrimer conjugate, not control dendrimer, resulted in a robust increase in the frequencies of [Ca2+]i oscillations and synchronizations, indicating that effects estrogens on [Ca2+]i oscillations and their synchronizations do not require their entry into the cell nucleus. Exposure of cells to E2 in the presence of the estrogen receptor antagonist ICI 182,780 did not change the E2-induced increase in the frequency of [Ca2+]i oscillations or the E2-induced increase in the synchronization frequency. Collectively, estrogens induce rapid, direct stimulatory actions through receptors located in the cell membrane/cytoplasm of primate LHRH-1 neurons, and this action of estrogens is mediated by an ICI 182,780-insensitive mechanism yet to be identified.
Corticotropin-Releasing Hormone (CRH) Depresses N-Methyl-d-Aspartate Receptor-Mediated Current in Cultured Rat Hippocampal Neurons via CRH Receptor Type 1
Authors: Sheng Hui , Zhang Yanmin , Sun Jihu , Gao Lu , Ma Bei , Lu Jianqiang , Ni Xin
Published: December 2007

CRH, the primary regulator of the neuroendocrine responses to stress, has been shown to modulate synaptic efficacy and the process of learning and memory in hippocampus. However, effects of CRH on N-methyl-d-aspartate (NMDA) receptor, the key receptor for synaptic plasticity, remain unclear. In primary cultured hippocampal neurons, using the technique of whole-cell patch-clamp recordings, we found that CRH (1 pmol/liter to 10 nmol/liter) inhibited NMDA-induced currents in a dose-dependent manner. This effect was reversed by the CRH receptor type 1 (CRHR1) antagonist antalarmin but not by the CRHR2 antagonist astressin-2B, suggesting that CRHR1 mediated the inhibitory effect of CRH. Investigations on the signaling pathways of CRH showed that CRH dose-dependently induced phosphorylated phospholipase C (PLC)-β3 expression and increased intracellular cAMP content in these cells. Blocking PLC activity with U73122 prevented CRH-induced depression of NMDA current, whereas blocking protein kinase A (H89) and adenylate cyclase (SQ22536) failed to affect the CRH-induced depression of NMDA current. Application of inositol-1,4,5-triphosphate receptor (IP3R) antagonist, Ca2+ chelators or protein kinase C (PKC) inhibitors also mainly blocked CRH-induced depression of NMDA currents, suggesting involvement of PLC/IP3R/Ca2+and PLC/PKC signaling pathways in CRH down-regulation of NMDA receptors. Our results suggest that CRH may exert neuromodulatory actions on hippocampus through regulating NMDA receptor function.
Position fine-tuning of caudal primary motoneurons in the zebrafish spinal cord
Authors: Sato-Maeda Mika , Obinata Masuo , Shoji Wataru
Published: December 2007

In zebrafish embryos, each myotome is typically innervated by three primary motoneurons (PMNs): the caudal primary (CaP), middle primary (MiP) and rostral primary (RoP). PMN axons first exit the spinal cord through a single exit point located at the midpoint of the overlying somite, which is formed beneath the CaP cell body and is pioneered by the CaP axon. However, the placement of CaP cell bodies with respect to corresponding somites is poorly understood. Here, we determined the early events in CaP cell positioning using neuropilin 1a (nrp1a):gfp transgenic embryos in which CaPs were specifically labeled with GFP. CaP cell bodies first exhibit an irregular pattern in presence of newly formed corresponding somites and then migrate to achieve their proper positions by axonogenesis stages. CaPs are generated in excess compared with the number of somites, and two CaPs often overlap at the same position through this process. Next, we showed that CaP cell bodies remain in the initial irregular positions after knockdown of Neuropilin1a, a component of the class III semaphorin receptor. Irregular CaP position frequently results in aberrant double exit points of motor axons, and secondary motor axons form aberrant exit points following CaP axons. Its expression pattern suggests that sema3ab regulates the CaP position. Indeed, irregular CaP positions and exit points are induced by Sema3ab knockdown, whose ectopic expression can alter the position of CaP cell bodies. Results suggest that Semaphorin-Neuropilin signaling plays an important role in position fine-tuning of CaP cell bodies to ensure proper exit points of motor axons.
Initiation of Wnt signaling: control of Wnt coreceptor Lrp6 phosphorylation/activation via frizzled, dishevelled and axin functions
Authors: Zeng Xin , Huang He , Tamai Keiko , Zhang Xinjun , Harada Yuko , Yokota Chika , Almeida Karla , Wang Jianbo , Doble Brad , Woodgett Jim , Wynshaw-Boris Anthony , Hsieh Jen-Chieh , He Xi
Published: December 2007

Canonical Wnt/β-catenin signaling has central roles in development and diseases, and is initiated by the action of the frizzled (Fz) receptor, its coreceptor LDL receptor-related protein 6 (Lrp6), and the cytoplasmic dishevelled (Dvl) protein. The functional relationships among Fz, Lrp6 and Dvl have long been enigmatic. We demonstrated previously that Wnt-induced Lrp6 phosphorylation via glycogen synthase kinase 3 (Gsk3) initiates Wnt/β-catenin signaling. Here we show that both Fz and Dvl functions are critical for Wnt-induced Lrp6 phosphorylation through Fz-Lrp6 interaction. We also show that axin, a key scaffolding protein in the Wnt pathway, is required for Lrp6 phosphorylation via its ability to recruit Gsk3, and inhibition of Gsk3 at the plasma membrane blocks Wnt/β-catenin signaling. Our results suggest a model that upon Wnt-induced Fz-Lrp6 complex formation, Fz recruitment of Dvl in turn recruits the axin-Gsk3 complex, thereby promoting Lrp6 phosphorylation to initiate β-catenin signaling. We discuss the dual roles of the axin-Gsk3 complex and signal amplification by Lrp6-axin interaction during Wnt/β-catenin signaling.
Myogenesis and muscle metabolism in juvenile Atlantic salmon (Salmo salar) made transgenic for growth hormone
Authors: Levesque H. M. , Shears M. A. , Fletcher G. L. , Moon T. W.
Published: December 2007

Atlantic salmon (Salmo salar) made transgenic for growth hormone(GH) and non-transgenic salmon were sampled at 4 and 7 months of age to estimate myogenic factors, satellite cell proliferation and metabolic enzyme activities. The growth rate of 4 month old transgenic salmon was higher than that of non-transgenic salmon. Myosatellite cell (MC) proliferation rates were higher in cells isolated from GH-transgenic salmon compared with cells from non-transgenic salmon of the same mass. Moreover, MCs extracted from non-transgenic salmon demonstrated a higher proliferation capacity when exposed in vitro to salmon GH. White muscle MyoD I mRNA content was higher in transgenic and non-transgenic salmon at 7 months compared with that at 4 months, indicating an effect of age on MyoD I mRNA expression. White muscle myogenin mRNA content varied with fish age and presence of the transgene, and was higher in transgenic fish at 7 months, suggesting a higher differentiation capacity. MyoD I, MyoD II and myogenin mRNA content was higher in red muscle of GH-transgenic fish at 7 months compared with non-transgenic salmon at 7 months. However, red muscle myogenic factor expression was not different between transgenic and non-transgenic fish of the same weight. Enzyme activities in white muscle and liver were highly affected by the presence of the transgene, although this effect was generally dependent on the age of the fish. Glycolytic and oxidative enzyme activities were increased in transgenic salmon liver, indicating a higher metabolic rate in transgenics. This study demonstrates that (1) the higher growth rate of transgenic salmon particularly at 4 months of age could be explained at least in part by higher numbers and proliferation rates of MCs, (2) GH can directly stimulate the proliferation of myosatellite cells extracted from salmon, indicating that GH is one possible factor involved in the higher myosatellite cell proliferation rates in transgenic salmon, (3) MyoD and myogenin mRNA expression are affected by fish age, and (4) metabolic enzyme activities are affected by the age of the fish at least in liver and white muscle, and any transgene effect is dependent upon the age of the fish.
The thermal properties of beeswaxes: unexpected findings
Authors: Buchwald Robert , Breed Michael D. , Greenberg Alan R.
Published: December 2007

Standard melting point analyses only partially describe the thermal properties of eusocial beeswaxes. Differential scanning calorimetry (DSC)revealed that thermal phase changes in wax are initiated at substantially lower temperatures than visually observed melting points. Instead of a sharp,single endothermic peak at the published melting point of 64°C, DSC analysis of Apis mellifera Linnaeus wax yielded a broad melting curve that showed the initiation of melting at approximately 40°C. Although Apis beeswax retained a solid appearance at these temperatures, heat absorption and initiation of melting could affect the structural characteristics of the wax. Additionally, a more complete characterization of the thermal properties indicated that the onset of melting, melting range and heat of fusion of beeswaxes varied significantly among tribes of social bees(Bombini, Meliponini, Apini). Compared with other waxes examined, the relatively malleable wax of bumblebees (Bombini) had the lowest onset of melting and lowest heat of fusion but an intermediate melting temperature range. Stingless bee (Meliponini) wax was intermediate between bumblebee and honeybee wax (Apini) in heat of fusion, but had the highest onset of melting and the narrowest melting temperature range. The broad melting temperature range and high heat of fusion in the Apini may be associated with the use of wax comb as a free-hanging structural material, while the Bombini and Meliponini support their wax structures with exogenous materials.
Steady locomotion in dogs: temporal and associated spatial coordination patterns and the effect of speed
Authors: Maes Ludovic D. , Herbin Marc , Hackert Rémi , Bels Vincent L. , Abourachid Anick
Published: December 2007

Only a few studies on quadrupedal locomotion have investigated symmetrical and asymmetrical gaits in the same framework because the mechanisms underlying these two types of gait seem to be different and it took a long time to identify a common set of parameters for their simultaneous study. Moreover,despite the clear importance of the spatial dimension in animal locomotion,the relationship between temporal and spatial limb coordination has never been quantified before. We used anteroposterior sequence (APS) analysis to analyse 486 sequences from five malinois (Belgian shepherd) dogs moving at a large range of speeds (from 0.4 to 10.0 m s–1) to compare symmetrical and asymmetrical gaits through kinematic and limb coordination parameters. Considerable continuity was observed in cycle characteristics,from walk to rotary gallop, but at very high speeds an increase in swing duration reflected the use of sagittal flexibility of the vertebral axis to increase speed. This change occurred after the contribution of the increase in stride length had become the main element driving the increase in speed– i.e. when the dogs had adopted asymmetrical gaits. As the left and right limbs of a pair are linked to the same rigid structure, spatial coordination within pairs of limbs reflected the temporal coordination within pairs of limbs whatever the speed. By contrast, the relationship between the temporal and spatial coordination between pairs of limb was found to depend on speed and trunk length. For trot and rotary gallop, this relationship was thought also to depend on the additional action of trunk flexion and leg angle at footfall.
Singing with reduced air sac volume causes uniform decrease in airflow and sound amplitude in the zebra finch
Authors: Plummer Emily Megan , Goller Franz
Published: December 2007

Song of the zebra finch (Taeniopygia guttata) is a complex temporal sequence generated by a drastic change to the regular oscillations of the normal respiratory pattern. It is not known how respiratory functions,such as supply of air volume and gas exchange, are controlled during song. To understand the integration between respiration and song, we manipulated respiration during song by injecting inert dental medium into the air sacs. Increased respiratory rate after injections indicates that the reduction of air affected quiet respiration and that birds compensated for the reduced air volume. During song, air sac pressure, tracheal airflow and sound amplitude decreased substantially with each injection. This decrease was consistently present during each expiratory pulse of the song motif irrespective of the air volume used. Few changes to the temporal pattern of song were noted, such as the increased duration of a minibreath in one bird and the decrease in duration of a long syllable in another bird. Despite the drastic reduction in air sac pressure, airflow and sound amplitude, no increase in abdominal muscle activity was seen. This suggests that during song, birds do not compensate for the reduced physiological or acoustic parameters. Neither somatosensory nor auditory feedback mechanisms appear to effect a correction in expiratory effort to compensate for reduced air sac pressure and sound amplitude.
Heat increment of feeding in double-crested cormorants (Phalacrocorax auritus) and its potential for thermal substitution
Authors: Enstipp Manfred R. , Grémillet David , Jones David R.
Published: December 2007

Diving endotherms inhabiting polar regions face potentially high thermoregulatory costs. Unless properly insulated, these animals will lose vast amounts of heat when diving in cold water, which has to be balanced by heat production. Heat generated as a by-product of digestion (heat increment of feeding, HIF) or from exercising muscles might be important in maintaining thermal balance under such conditions, as it would reduce the need for shivering thermogenesis. Recording the rate of oxygen consumption(V̇O2),respiratory exchange ratio (RER), and stomach temperature, we studied the magnitude and duration of HIF in seven double-crested cormorants(Phalacrocorax auritus) following the voluntary ingestion of a single herring (Clupea pallasi) while birds rested in air. Conducting trials at thermoneutral (21.1±0.2°C) and sub-thermoneutral temperatures(5.5±0.7°C), we investigated the potential of HIF for thermal substitution. After the ingestion of a 100 g herring at thermoneutral conditions, V̇O2was elevated for an average of 328±28 min, during which time birds consumed 2697±294 ml O2 in excess of the resting rate. At sub-thermoneutral conditions, duration (228±6 min) and magnitude(1391±271 ml O2) of V̇O2elevation were significantly reduced. This indicates that cormorants are able to use the heat generated as by-product of digestion to substitute for regulatory thermogenesis, if heat loss is sufficiently high. Altering meal size during sub-thermoneutral trials, we also found that HIF in cormorants was significantly greater after larger food intake. Based on these experimental results, a simple calculation suggests that substitution from HIF might reduce the daily thermoregulatory costs of double-crested cormorants wintering in coastal British Columbia by ∼38%. Magnitude of HIF and its potential for thermal substitution should be integrated into bioenergetic models to avoid overestimating energy expenditure in these top predators.
Conservation of structure, signaling and pharmacology between two serotonin receptor subtypes from decapod crustaceans,Panulirus interruptusandProcambarus clarkii
Authors: Spitzer Nadja , Edwards Donald H. , Baro Deborah J.
Published: December 2007

Serotonin (5-HT) plays important roles in the maintenance and modulation of neural systems throughout the animal kingdom. The actions of 5-HT have been well characterized for several crustacean model circuits; however, a dissection of the serotonergic transduction cascades operating in these models has been hampered by the lack of pharmacological tools for invertebrate receptors. Here we provide pharmacological profiles for two 5-HT receptors from the swamp crayfish, Procambarus clarkii: 5-HT2βand 5-HT1α. In so doing, we also report the first functional expression of a crustacean 5-HT1 receptor, and show that it inhibits accumulation of cAMP. The drugs mCPP and quipazine are 5-HT1α agonists and are ineffective at 5-HT2β. Conversely, methiothepin and cinanserin are antagonists of 5-HT2β but do not block 5-HT1α. A comparison of these two receptors with their orthologs from the California spiny lobster, Panulirus interruptus,indicates conservation of protein structure, signaling and pharmacology. This conservation extends beyond crustacean infraorders. The signature residues that form the ligand-binding pocket in mammalian 5-HT receptors are found in the crustacean receptors. Similarly, the protein domains involved in G protein coupling are conserved between the two crustacean receptors and other characterized arthropod and mammalian 5-HT receptors. Considering the apparent conservation of pharmacological properties between crustacean 5-HT receptors,these tools could be applicable to related crustacean physiological preparations.