bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyp11b1 Is Induced in the Murine Gonad by Luteinizing Hormone/Human Chorionic Gonadotropin and Involved in the Production of 11-Ketotestosterone, a Major Fish Androgen: Conservation and Evolution of the Androgen Metabolic Pathway
Authors: Yazawa Takashi , Uesaka Miki , Inaoka Yoshihiko , Mizutani Tetsuya , Sekiguchi Toshio , Kajitani Takashi , Kitano Takeshi , Umezawa Akihiro , Miyamoto Kaoru
Published: December 2007

We have shown previously that Cyp11b1, an 11β-hydroxylase responsible for glucocorticoid biosynthesis in the adrenal gland, was induced by cAMP in androgen-producing Leydig-like cells derived from mesenchymal stem cells. We found that Cyp11b1 was induced in male Leydig cells, or female theca cells, when human chorionic gonadotropin was administered in immature mice. Expression of Cyp11b1 in rodent gonads caused the production of 11-ketotestosterone (11-KT), a major fish androgen, which induces male differentiation or spermatogenesis in fish. As in teleosts, plasma concentrations of 11-KT were elevated in human chorionic gonadotropin-treated mice. In contrast to teleosts, however, plasma concentrations of 11-KT were similar in both sexes, despite levels of testosterone, a precursor substrate, being about 20 times higher in male mice. Because expression of 11β-hydroxysteroid dehydrogenase type 2, was much higher in the mouse ovary than in the testis, conversion of testosterone into 11-KT may occur more efficiently in the ovary. In a luciferase reporter system that was responsive to and activated by androgens, 11-KT efficiently activated mammalian androgen receptor-mediated transactivation. Our results suggest that the androgen metabolic pathway is conserved between teleosts and mammals, despite sexual dominance and reproductive functions of 11-KT being altered during evolution.
The Proinflammatory Cytokine Tumor Necrosis Factor-α Increases the Amount of Glucose Transporter-4 at the Surface of Muscle Cells Independently of Changes in Interleukin-6
Authors: Roher Nerea , Samokhvalov Victor , Díaz Mònica , MacKenzie Simon , Klip Amira , Planas Josep V.
Published: December 2007

TNFα is a proinflammatory cytokine secreted by macrophages in response to bacterial infection. Recently new evidence has emerged suggesting that stressed or injured myocytes produce TNFα that then acts as an autocrine and/or paracrine mediator. TNFα receptors types 1 and 2 are present in skeletal muscle cells, and muscle cells can secrete, in addition to TNFα, other cytokines such as IL-1β or IL-6. Furthermore, the plasma concentration of TNFα is elevated in insulin-resistant states associated with obesity and type 2 diabetes. Here we show that TNFα increased the amount of glucose transporter (GLUT)-4 at the plasma membrane and also glucose uptake in the L6 muscle cell line stably expressing GLUT4 tagged with the c-myc epitope. Regardless of the state of differentiation of the L6 cells, TNFα did not affect the rate of proliferation or of apoptosis. The stimulatory effects of TNFα on cell surface GLUT4 and glucose uptake were blocked by nuclear factor-κB and p38MAPK pathway specific inhibitors (Bay 11-7082 and SB220025), and these two pathways were stimulated by TNFα. Furthermore, although TNFα increased IL-6 mRNA and protein expression, IL-6 did not mediate the effects of TNFα on cell surface GLUT4 levels, which also did not require de novo protein synthesis. The results indicate that TNFα can stimulate glucose uptake in L6 muscle cells by inducing GLUT4 translocation to the plasma membrane, possibly through activation of the nuclear factor-κB and p38MAPK signaling pathways and independently of the production of IL-6.
Collective and Individual Functions of Leptin Receptor Modulated Neurons Controlling Metabolism and Ingestion
Authors: van de Wall Esther , Leshan Rebecca , Xu Allison W. , Balthasar Nina , Coppari Roberto , Liu Shun Mei , Jo Young Hwan , MacKenzie Robert G. , Allison David B. , Dun Nae J. , Elmquist Joel , Lowell Bradford B. , Barsh Gregory S. , de Luca Carl , Myers Martin G. , Schwartz Gary J. , Chua Streamson C.
Published: December 2007

Two known types of leptin-responsive neurons reside within the arcuate nucleus: the agouti gene-related peptide (AgRP)/neuropeptide Y (NPY) neuron and the proopiomelanocortin (POMC) neuron. By deleting the leptin receptor gene (Lepr) specifically in AgRP/NPY and/or POMC neurons of mice, we examined the several and combined contributions of these neurons to leptin action. Body weight and adiposity were increased by Lepr deletion from AgRP and POMC neurons individually, and simultaneous deletion in both neurons (A+P LEPR-KO mice) further increased these measures. Young (periweaning) A+P LEPR-KO mice exhibit hyperphagia and decreased energy expenditure, with increased weight gain, oxidative sparing of triglycerides, and increased fat accumulation. Interestingly, however, many of these abnormalities were attenuated in adult animals, and high doses of leptin partially suppress food intake in the A+P LEPR-KO mice. Although mildly hyperinsulinemic, the A+P LEPR-KO mice displayed normal glucose tolerance and fertility. Thus, AgRP/NPY and POMC neurons each play mandatory roles in aspects of leptin-regulated energy homeostasis, high leptin levels in adult mice mitigate the importance of leptin-responsiveness in these neurons for components of energy balance, suggesting the presence of other leptin-regulated pathways that partially compensate for the lack of leptin action on the POMC and AgRP/NPY neurons.
Degradation of MEPE, DMP1, and Release of SIBLING ASARM-Peptides (Minhibins): ASARM-Peptide(s) Are Directly Responsible for Defective Mineralization in HYP
Authors: Martin Aline , David Valentin , Laurence Jennifer S. , Schwarz Patricia M. , Lafer Eileen M. , Hedge Anne-Marie , Rowe Peter S. N.
Published: December 2007

Mutations in PHEX (phosphate-regulating gene with homologies to endopeptidases on the X chromosome) and DMP1 (dentin matrix protein 1) result in X-linked hypophosphatemic rickets (HYP) and autosomal-recessive hypophosphatemic-rickets (ARHR), respectively. Specific binding of PHEX to matrix extracellular phosphoglycoprotein (MEPE) regulates the release of small protease-resistant MEPE peptides [acidic serine- and aspartate-rich MEPE-associated motif (ASARM) peptides]. ASARM peptides are potent inhibitors of mineralization (minhibins) that also occur in DMP1 [MEPE-related small integrin-binding ligand, N-linked glycoprotein (SIBLING) protein]. It is not known whether these peptides are directly responsible for the mineralization defect. We therefore used a bone marrow stromal cell (BMSC) coculture model, ASARM peptides, anti-ASARM antibodies, and a small synthetic PHEX peptide (SPR4; 4.2 kDa) to examine this. Surface plasmon resonance (SPR) and two-dimensional 1H/15N nuclear magnetic resonance demonstrated specific binding of SPR4 peptide to ASARM peptide. When cultured individually for 21 d, HYP BMSCs displayed reduced mineralization compared with wild type (WT) (−87%, P < 0.05). When cocultured, both HYP and WT cells failed to mineralize. However, cocultures (HYP and WT) or monocultures of HYP BMSCs treated with SPR4 peptide or anti-ASARM neutralizing antibodies mineralized normally. WT BMSCs treated with ASARM peptide also failed to mineralize properly without SPR4 peptide or anti-ASARM neutralizing antibodies. ASARM peptide treatment decreased PHEX mRNA and protein (−80%, P < 0.05) and SPR4 peptide cotreatment reversed this by binding ASARM peptide. SPR4 peptide also reversed ASARM peptide-mediated changes in expression of key osteoclast and osteoblast differentiation genes. Western blots of HYP calvariae and BMSCs revealed massive degradation of both MEPE and DMP1 protein compared with the WT. We conclude that degradation of MEPE and DMP-1 and release of ASARM peptides are chiefly responsible for the HYP mineralization defect and changes in osteoblast-osteoclast differentiation.
Orexin-A Inhibits Glucagon Secretion and Gene Expression through a Foxo1-Dependent Pathway
Authors: Göncz Eva , Strowski Mathias Z. , Grötzinger Carsten , Nowak Krzysztof W. , Kaczmarek Przemek , Sassek Maciej , Mergler Stefan , El-Zayat Bilal F. , Theodoropoulou Marily , Stalla Günter K. , Wiedenmann Bertram , Plöckinger Ursula
Published: December 2007

Orexin-A (OXA) regulates food intake and energy homeostasis. It increases insulin secretion in vivo and in vitro, although controversial effects of OXA on plasma glucagon are reported. We characterized the effects of OXA on glucagon secretion and identify intracellular target molecules in glucagon-producing cells. Glucagon secretion from in situ perfused rat pancreas, isolated rat pancreatic islets, and clonal pancreatic A-cells (InR1-G9) were measured by RIA. The expression of orexin receptor 1 (OXR1) was detected by Western blot and immunofluorescence. The effects of OXA on cAMP, adenylate-cyclase-kinase (AKT), phosphoinositide-dependent kinase (PDK)-1, forkhead box O-1 (Foxo1), and cAMP response element-binding protein were measured by ELISA and Western blot. Intracellular calcium (Ca2+i) concentration was detected by fura-2and glucagon expression by real-time PCR. Foxo1 was silenced in InR1-G9 cells by transfecting cells with short interfering RNA. OXR1 was expressed on pancreatic A and InR1-G9 cells. OXA reduced glucagon secretion from perfused rat pancreas, isolated rat pancreatic islets, and InR1-G9 cells. OXA inhibited proglucagon gene expression via the phosphatidylinositol 3-kinase-dependent pathway. OXA decreased cAMP and Ca2+i concentration and increased AKT, PDK-1, and Foxo1 phosphorylation. Silencing of Foxo1 caused a reversal of the inhibitory effect of OXA on proglucagon gene expression. Our study provides the first in vitro evidence for the interaction of OXA with pancreatic A cells. OXA inhibits glucagon secretion and reduces intracellular cAMP and Ca2+i concentration. OXA increases AKT/PDK-1 phosphorylation and inhibits proglucagon expression via phosphatidylinositol 3-kinase- and Foxo-1-dependent pathways. As a physiological inhibitor of glucagon secretion, OXA may have a therapeutic potential to reduce hyperglucagonemia in type 2 diabetes.
Profiling Postprandial Thermogenesis in Muscle and Fat of Sheep and the Central Effect of Leptin Administration
Authors: Henry Belinda A. , Dunshea Frank R. , Gould Merryn , Clarke Iain J.
Published: December 2007

Brown adipose tissue thermogenesis is an important component of energy expenditure as exemplified in rodents. Other tissues such as white adipose tissue and muscle are also capable of thermogenesis, but regulation of heat production in these tissues is poorly understood. We used a relatively large animal model, the ovariectomized sheep, in which site-specific temperature measurements were made as an index of thermogenic output. Dataloggers were implanted into the retroperitoneal (visceral) fat, gluteal (sc) fat, and skeletal muscle of the hind limb, and were programmed to record temperature every 15 min. Animals (n = 4) were then placed on a feeding schedule (fed between 1100 and 1600 h) to entrain a postprandial response in thermogenesis. Baseline thermogenesis (0800–1100 h) was higher (P < 0.05) in visceral fat and muscle than in gluteal fat, whereas the amplitude of the postprandial increase was similar at all three sites. Intracerebroventricular infusion into the lateral ventricle of either vehicle (artificial cerebrospinal fluid) or leptin (10 μg/h at 100 μl/h) for 24 h (0900–0900) was performed in a cross-over design with a 1-wk recovery period between treatments. Central leptin infusion did not alter the basal thermogenic rate but markedly enhanced the postprandial response in both fat and muscle tissues. This was manifest by increased (P < 0.05) amplitude and duration of the postprandial thermogenic response, and the effect was greater in muscle and visceral fat than in gluteal fat. These data demonstrate that leptin is able to regulate thermogenesis in muscle, providing a novel target for the manipulation of energy balance.
Induction of Apoptosis in Human Prostate Cancer Cells by Insulin-Like Growth Factor Binding Protein-3 Does Not Require Binding to Retinoid X Receptor-α
Authors: Zappala Giovanna , Elbi Cem , Edwards Joanna , Gorenstein Julie , Rechler Matthew M. , Bhattacharyya Nisan
Published: December 2007

IGF binding protein (IGFBP)-3 can induce apoptosis in human prostate cancer cells directly without sequestering IGF-I and -II. The molecular mechanisms responsible for the IGF-independent actions of IGFBP-3 remain unclear. IGFBP-3, a secreted protein, can be internalized and translocate to the nucleus. It binds to the nuclear retinoid X receptor (RXR)-α. Binding to RXR-α has been proposed to be required for IGFBP-3 to induce apoptosis. The present study tests this hypothesis in the PC-3 human prostate cancer cell line. PC-3 cells express RXR-α, and apoptosis is induced by incubation with RXR-specific ligand. A COOH-terminal region in IGFBP-3 (residues 215–232) contains a nuclear localization signal, and binding domains for RXR-α and heparin (HBD). Different combinations of the 11 amino acids in this region that differ from IGFBP-1, a related IGFBP, which does not localize to the nucleus or bind RXR-α, were mutated to the IGFBP-1 sequence. By confocal imaging, mutation of residues 228-KGRKR-232 in nonsecreted IGFBP-3 diminished its nuclear localization. IGFBP-3 binding to glutathione S-transferase-RXR-α only was lost when all 11 sites were mutated (HBD-11m-IGFBP-3). Expressed nuclear RXR-α did not transport cytoplasmic IGFBP-3 nuclear localization signal mutants that can bind RXR-α to the nucleus even after treatment with RXR ligand. Expressed HBD-11m-IGFBP-3 still induced apoptosis in PC-3 cells in an IGF-independent manner as determined by flow cytometric analysis of Annexin V staining. We conclude that in PC-3 cells, RXR-α is not required for the nuclear translocation of IGFBP-3 and that IGFBP-3 can induce apoptosis in human prostate cancer cells without binding RXR-α.
Kisspeptin Acts Directly and Indirectly to Increase Gonadotropin-Releasing Hormone Neuron Activity and Its Effects Are Modulated by Estradiol
Authors: Pielecka-Fortuna Justyna , Chu Zhiguo , Moenter Suzanne M.
Published: December 2007

GnRH neurons play a pivotal role in the central regulation of fertility. Kisspeptin greatly increases GnRH/LH release and GnRH neuron firing activity and may be involved in estradiol feedback, but the neurobiological mechanisms for these actions are unknown. G protein-coupled receptor 54, the receptor for kisspeptin, is expressed by GnRH neurons as well as other hypothalamic neurons, suggesting both direct and indirect effects are possible. To investigate this and determine whether kisspeptin activation of GnRH neurons is estradiol sensitive, we recorded the firing rate of GnRH neurons in brain slices from adult female mice that were ovariectomized (OVX) and either treated with estradiol (E) capsules (OVX+E) or left without further treatment. Kisspeptin increased GnRH neuronal activity in a dose-dependent manner in cells from both OVX and OVX+E mice, and estradiol significantly potentiated the response. To begin to distinguish direct from indirect actions of kisspeptin, fast synaptic transmission mediated by ionotropic γ-aminobutyric acid and glutamate receptors was pharmacologically blocked (blockade). Blockade reduced GnRH response to kisspeptin in OVX+E but not in OVX mice. Actions of kisspeptin were also assessed using whole-cell voltage- and current-clamp recording in slices from OVX animals. Kisspeptin application depolarized GnRH neurons in current-clamp and generated inward current in voltage-clamp recordings, even after blocking action potential-dependent neural communication, consistent with a direct effect. Blockers of potassium channels abolished the inward current. Together our data indicate that kisspeptin activates GnRH neurons via both direct and transsynaptic mechanisms and that transsynaptic mechanisms are either enabled and/or potentiated by estradiol.
Runt-Related Transcription Factor 2 (RUNX2) and RUNX2-Related Osteogenic Genes Are Down-Regulated throughout Osteogenesis in Type 1 Diabetes Mellitus
Authors: Fowlkes John L. , Bunn R. Clay , Liu Lichu , Wahl Elizabeth C. , Coleman Hannah N. , Cockrell Gael E. , Perrien Daniel S. , Lumpkin Charles K. , Thrailkill Kathryn M.
Published: December 2007

Type 1 diabetes mellitus is associated with a number of disorders of skeletal health, conditions that rely, in part, on dynamic bone formation. A mouse model of distraction osteogenesis was used to study the consequences of streptozotocin-induced diabetes and insulin treatment on bone formation and osteoblastogenesis. In diabetic mice compared with control mice, new bone formation was decreased, and adipogenesis was increased in and around, respectively, the distraction gaps. Although insulin treatment restored bone formation to levels observed in nondiabetic control mice, it failed to significantly decrease adipogenesis. Molecular events altered during de novo bone formation in untreated type 1 diabetes mellitus, yet restored with insulin treatment were examined so as to clarify specific osteogenic genes that may contribute to diabetic bone disease. RNA from distraction gaps was analyzed by gene microarray and quantitative RT-PCR for osteogenic genes of interest. Runt-related transcription factor 2 (RUNX2), and several RUNX2 target genes, including matrix metalloproteinase-9, Akp2, integrin binding sialoprotein, Dmp1, Col1a2, Phex, Vdr, osteocalcin, and osterix, were all significantly down-regulated in the insulin-deficient, hyperglycemic diabetic animals; however, insulin treatment of diabetic animals significantly restored their expression. Expression of bone morphogenic protein-2, transcriptional coactivator with PDZ-binding motif, and TWIST2, all important regulators of RUNX2, were not impacted by the diabetic condition, suggesting that the defect in osteogenesis resides at the level of RUNX2 expression and its activity. Together, these data demonstrate that insulin and/or glycemic status can regulate osteogenesis in vivo, and systemic insulin therapy can, in large part, rescue the diabetic bone phenotype at the tissue and molecular level.
Kisspeptin Is Present in Ovine Hypophysial Portal Blood But Does Not Increase during the Preovulatory Luteinizing Hormone Surge: Evidence that Gonadotropes Are Not Direct Targets of Kisspeptin in Vivo
Authors: Smith J. T. , Rao A. , Pereira A. , Caraty A. , Millar R. P. , Clarke I. J.
Published: December 2007

There is strong evidence that kisspeptin acts to regulate GnRH secretion, but whether there is also a component of action on the gonadotropes is not clear. Using quantitative RT-PCR, we found that G protein-coupled receptor-54 mRNA is expressed in ovine pituitary cell fractions enriched for gonadotropes as well as in somatotropes and lactotropes. To test whether kisspeptin acts directly on the pituitary gonadotropes, we first examined LH release from primary ovine pituitary cell cultures treated with kisspeptin. We found that kisspeptin treatment increased the concentration of LH in culture media by 80%, compared with control, but only in pituitary cultures from ewes during the follicular phase of the estrous cycle. After this, we determined whether kisspeptin acts on the pituitary gland in vivo. Using GnRH-replaced ovariectomized hypothalamo-pituitary-disconnected ewes, we were not able to achieve any effect of kisspeptin on LH under steady-state conditions or during the period of an estrogen-induced LH surge. Finally, we collected hypophysial portal blood samples from ovariectomized ewes and measured kisspeptin levels. Low but detectable amounts of kisspeptin were found in portal plasma, but levels were similar in ovariectomized ewes that were untreated or given estrogen to elicit an LH surge. Thus, although we observed an effect of kisspeptin on LH release in vitro in some situations, similar findings were not obtained in vivo. Moreover, the low concentrations of kisspeptin in hypophysial portal blood and the lack of any change during the period of an estrogen-induced GnRH/LH surge suggest that action on the pituitary gland is not of major consequence in terms of LH release.
Shared and Unique Susceptibility Genes in a Mouse Model of Graves’ Disease Determined in BXH and CXB Recombinant Inbred Mice
Authors: McLachlan Sandra M. , Aliesky Holly A. , Pichurin Pavel N. , Chen Chun-Rong , Williams Robert W. , Rapoport Basil
Published: December 2007

Susceptibility genes for TSH receptor (TSHR) antibodies and hyperthyroidism can be probed in recombinant inbred (RI) mice immunized with adenovirus expressing the TSHR A-subunit. The RI set of CXB strains, derived from susceptible BALB/c and resistant C57BL/6 (B6) mice, were studied previously. High-resolution genetic maps are also available for RI BXH strains, derived from B6 and C3H/He parents. We found that C3H/He mice develop TSHR antibodies, and some animals become hyperthyroid after A-subunit immunization. In contrast, the responses of the F1 progeny of C3H/He × B6 mice, as well as most BXH RI strains, are dominated by the B6 resistance to hyperthyroidism. As in the CXB set, linkage analysis of BXH strains implicates different chromosomes (Chr) or loci in the susceptibility to induced TSHR antibodies vs. hyperthyroidism. Importantly, BXH and CXB mice share genetic loci controlling the generation of TSHR antibodies (Chr 17, major histocompatibility complex region, and Chr X) and development of hyperthyroidism (Chr 1 and 3). Moreover, some chromosomal linkages are unique to either BXH or CXB strains. An interesting candidate gene linked to thyroid-stimulating antibody generation in BXH mice is the Ig heavy chain locus, suggesting a role for particular germline region genes as precursors for these antibodies. In conclusion, our findings reinforce the importance of major histocompatibility complex region genes in controlling the generation of TSHR antibodies measured by TSH binding inhibition. Moreover, these data emphasize the value of RI strains to dissect the genetic basis for induced TSHR antibodies vs. their effects on thyroid function in Graves’ disease.
Flow patterns of larval fish: undulatory swimming in the intermediate flow regime
Authors: Müller Ulrike K. , van den Boogaart Jos G. M. , van Leeuwen Johan L.
Published: December 2007

Fish larvae, like many adult fish, swim by undulating their body. However,their body size and swimming speeds put them in the intermediate flow regime,where viscous and inertial forces both play an important role in the interaction between fish and water. To study the influence of the relatively high viscous forces compared with adult fish, we mapped the flow around swimming zebrafish (Danio rerio) larvae using two-dimensional digital particle image velocimetry (2D-DPIV) in the horizontal and transverse plane of the fish. Fish larvae initiate a swimming bout by bending their body into a C shape. During this initial tail-beat cycle, larvae shed two vortex pairs in the horizontal plane of their wake, one during the preparatory and one during the subsequent propulsive stroke. When they swim `cyclically' (mean swimming speed does not change significantly between tail beats), fish larvae generate a wide drag wake along their head and anterior body. The flow along the posterior body is dominated by the undulating body movements that cause jet flows into the concave bends of the body wave. Patches of elevated vorticity form around the jets, and travel posteriorly along with the body wave, until they are ultimately shed at the tail near the moment of stroke reversal. Behind the larva, two vortex pairs are formed per tail-beat cycle (the tail beating once left-to-right and then right-to-left) in the horizontal plane of the larval wake. By combining transverse and horizontal cross sections of the wake, we inferred that the wake behind a cyclically swimming zebrafish larva contains two diverging rows of vortex rings to the left and right of the mean path of motion, resembling the wake of steadily swimming adult eels. When the fish larva slows down at the end of a swimming bout, it gradually reduces its tail-beat frequency and amplitude, while the separated boundary layer and drag wake of the anterior body extend posteriorly to envelope the entire larva. This drag wake is considerably wider than the larval body. The effects of the intermediate flow regime manifest as a thick boundary layer and in the quick dying-off of the larval wake within less than half a second.
Vortex-wake interactions of a flapping foil that models animal swimming and flight
Authors: Lentink David , Muijres Florian T. , Donker-Duyvis Frits J. , van Leeuwen Johan L.
Published: December 2007

The fluid dynamics of many swimming and flying animals involves the generation and shedding of vortices into the wake. Here we studied the dynamics of similar vortices shed by a simple two-dimensional flapping foil in a soap-film tunnel. The flapping foil models an animal wing, fin or tail in forward locomotion. The vortical flow induced by the foil is correlated to(the resulting) thickness variations in the soap film. We visualized these thickness variations through light diffraction and recorded it with a digital high speed camera. This set-up enabled us to study the influence of foil kinematics on vortex-wake interactions. We varied the dimensionless wavelength of the foil (λ*=4–24) at a constant dimensionless flapping amplitude (A*=1.5) and geometric angle of attack amplitude (Aα,geo=15°). The corresponding Reynolds number was of the order of 1000. Such values are relevant for animal swimming and flight.

We found that a significant leading edge vortex (LEV) was generated by the foil at low dimensionless wavelengths (λ*<10). The LEV separated from the foil for all dimensionless wavelengths. The relative time(compared with the flapping period) that the unstable LEV stayed above the flapping foil increased for decreasing dimensionless wavelengths. As the dimensionless wavelength decreased, the wake dynamics evolved from a wavy von Kármán-like vortex wake shed along the sinusoidal path of the foil into a wake densely packed with large interacting vortices. We found that strongly interacting vortices could change the wake topology abruptly. This occured when vortices were close enough to merge or tear each other apart. Our experiments show that relatively small changes in the kinematics of a flapping foil can alter the topology of the vortex wake drastically.
Contractile properties of the pigeon supracoracoideus during different modes of flight
Authors: Tobalske Bret W. , Biewener Andrew A.
Published: December 2007

The supracoracoideus (SUPRA) is the primary upstroke muscle for avian flight and is the antagonist to the downstroke muscle, the pectoralis (PECT). We studied in vivo contractile properties and mechanical power output of both muscles during take-off, level and landing flight. We measured muscle length change and activation using sonomicrometry and electromyography, and muscle force development using strain recordings on the humerus. Our results support a hypothesis that the primary role of the SUPRA is to supinate the humerus. Antagonistic forces exerted by the SUPRA and PECT overlap during portions of the wingbeat cycle, thereby offering a potential mechanism for enhancing control of the wing. Among flight modes, muscle strain was approximately the same in the SUPRA (33–40%) and the PECT(35–42%), whereas peak muscle stress was higher in the SUPRA(85–126 N m–2) than in the PECT (50–58 N m–2). The SUPRA mainly shortened relative to resting length and the PECT mainly lengthened. We estimated that elastic energy storage in the tendon of the SUPRA contributed between 28 and 60% of the net work of the SUPRA and 6–10% of the total net mechanical work of both muscles. Mechanical power output in the SUPRA was congruent with the estimated inertial power required for upstroke, but power output from the PECT was only 42–46% of the estimated aerodynamic power requirements for flight. There was a significant effect of flight mode upon aspects of the contractile behavior of both muscles including strain, strain rate, peak stress, work and power.
When wings touch wakes: understanding locomotor force control by wake–wing interference in insect wings
Authors: Lehmann Fritz-Olaf
Published: December 2007

Understanding the fluid dynamics of force control in flying insects requires the exploration of how oscillating wings interact with the surrounding fluid. The production of vorticity and the shedding of vortical structures within the stroke cycle thus depend on two factors: the temporal structure of the flow induced by the wing's own instantaneous motion and the flow components resulting from both the force production in previous wing strokes and the motion of other wings flapping in close proximity. These wake–wing interactions may change on a stroke-by-stroke basis,confronting the neuro-muscular system of the animal with a complex problem for force control. In a single oscillating wing, the flow induced by the preceding half stroke may lower the wing's effective angle of attack but permits the recycling of kinetic energy from the wake via the wake capture mechanism. In two-winged insects, the acceleration fields produced by each wing may strongly interact via the clap-and-fling mechanism during the dorsal stroke reversal. Four-winged insects must cope with the fact that the flow over their hindwings is affected by the presence of the forewings. In these animals, a phase-shift between the stroke cycles of fore- and hindwing modulates aerodynamic performance of the hindwing via leading edge vortex destruction and changes in local flow condition including wake capture. Moreover, robotic wings demonstrate that phase-lag during peak performance and the strength of force modulation depend on the vertical spacing between the two stroke planes and the size ratio between fore- and hindwing. This study broadly summarizes the most prominent mechanisms of wake–wing and wing–wing interactions found in flapping insect wings and evaluates the consequences of these processes for the control of locomotor forces in the behaving animal.
An overview of a Lagrangian method for analysis of animal wake dynamics
Authors: Peng Jifeng , Dabiri John O.
Published: December 2007

The fluid dynamic analysis of animal wakes is becoming increasingly popular in studies of animal swimming and flying, due in part to the development of quantitative flow visualization techniques such as digital particle imaging velocimetry (DPIV). In most studies, quasi-steady flow is assumed and the flow analysis is based on velocity and/or vorticity fields measured at a single time instant during the stroke cycle. The assumption of quasi-steady flow leads to neglect of unsteady (time-dependent) wake vortex added-mass effects,which can contribute significantly to the instantaneous locomotive forces. In this paper we review a Lagrangian approach recently introduced to determine unsteady wake vortex structure by tracking the trajectories of individual fluid particles in the flow, rather than by analyzing the velocity/vorticity fields at fixed locations and single instants in time as in the Eulerian perspective. Once the momentum of the wake vortex and its added mass are determined, the corresponding unsteady locomotive forces can be quantified. Unlike previous studies that estimated the time-averaged forces over the stroke cycle, this approach enables study of how instantaneous locomotive forces evolve over time. The utility of this method for analyses of DPIV velocity measurements is explored, with the goal of demonstrating its applicability to data that are typically available to investigators studying animal swimming and flying. The methods are equally applicable to computational fluid dynamics studies where velocity field calculations are available.
Muscle specialization in the squid motor system
Authors: Kier William M. , Schachat Frederick H.
Published: December 2007

Although muscle specialization has been studied extensively in vertebrates,less is known about the mechanisms that have evolved in invertebrate muscle that modulate muscle performance. Recent research on the musculature of squid suggests that the mechanisms of muscle specialization in cephalopods may differ from those documented in vertebrates. Muscle diversity in the development and the evolution of cephalopods appears to be characterized by modulation of the dimensions of the myofilaments, in contrast to the relatively fixed myofilament dimensions of vertebrate muscle. In addition, the arrangement of the myofilaments may also be altered, as has been observed in the extensor muscle fibres of the prey capture tentacles of squid and cuttlefish, which show cross-striation and thus differ from the obliquely striated pattern of most cephalopod locomotor muscle fibres. Although biochemical specializations that reflect differences in aerobic capacity have been documented previously for specific layers of the mantle muscle of squid,comparison of protein profiles of myofilament preparations from the fast cross-striated tentacle fibres and slow obliquely striated fibres from the arms has revealed remarkably few differences in myofilament lattice proteins. In particular, previous studies using a variety of SDS-PAGE techniques and peptide mapping of the myosin heavy chain were unable to resolve differences in the myosin light and heavy chains. Since these techniques cannot exclude the presence of a highly conserved variant that differs in only a few amino acids, in this study semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) analysis of myosin heavy chain messenger RNAs (mRNAs) from the cross-striated tentacle and obliquely striated arm muscle fibres was conducted. This analysis showed that a previously reported alternatively spliced isoform of the squid myosin motor domain is present only in low abundance in both muscle types and therefore differential expression of the two myosins cannot explain the difference in contractile properties. It thus appears that modulation of the contractile properties of the musculature of squid and other cephalopods occurs primarily through variation in the arrangement and dimensions of the myofilaments.
Near- and far-field aerodynamics in insect hovering flight: an integrated computational study
Authors: Aono Hikaru , Liang Fuyou , Liu Hao
Published: December 2007

We present the first integrative computational fluid dynamics (CFD) study of near- and far-field aerodynamics in insect hovering flight using a biology-inspired, dynamic flight simulator. This simulator, which has been built to encompass multiple mechanisms and principles related to insect flight, is capable of `flying' an insect on the basis of realistic wing–body morphologies and kinematics. Our CFD study integrates near-and far-field wake dynamics and shows the detailed three-dimensional (3D)near- and far-field vortex flows: a horseshoe-shaped vortex is generated and wraps around the wing in the early down- and upstroke; subsequently, the horseshoe-shaped vortex grows into a doughnut-shaped vortex ring, with an intense jet-stream present in its core, forming the downwash; and eventually,the doughnut-shaped vortex rings of the wing pair break up into two circular vortex rings in the wake. The computed aerodynamic forces show reasonable agreement with experimental results in terms of both the mean force (vertical,horizontal and sideslip forces) and the time course over one stroke cycle(lift and drag forces). A large amount of lift force (approximately 62% of total lift force generated over a full wingbeat cycle) is generated during the upstroke, most likely due to the presence of intensive and stable,leading-edge vortices (LEVs) and wing tip vortices (TVs); and correspondingly,a much stronger downwash is observed compared to the downstroke. We also estimated hovering energetics based on the computed aerodynamic and inertial torques, and powers.
Biorobotic insights into how animals swim
Authors: Bandyopadhyay Promode R. , Beal David N. , Menozzi Alberico
Published: December 2007

Many animals maneuver superbly underwater using their pectoral appendages. These animals range from sunfish, which have flexible, low aspect ratio fins,to penguins, which have relatively stiff, high aspect ratio wings. Biorobotics is a means of gaining insight into the mechanisms these animals use for maneuvering. In this study, experiments were carried out with models of abstracted penguin wings, and hydrodynamic characteristics – in particular, efficiency – were measured directly. A cross-flow vortex model of the unsteady force mechanism was developed that can compute instantaneous lift and drag forces accurately. This makes use of the steady characteristics of the fin and proposes that cross-flow drag vortices of bluff bodies in steady flow are analogous to dynamic stall vortices and that fin oscillation is a means for keeping the vortices attached to the fin. From what has been reported for sunfish with pectoral fins to our current measurements for single abstracted penguin wings, we infer that the maximum hydrodynamic efficiency has remained largely unchanged. A selection algorithm was used to rapidly find the fin oscillation parameters for optimum efficiency. Finally,we compared the measurements on the penguin-like relatively stiff fins and the reported flow visualization of flexible sunfish pectoral fins. The flexible pectoral fins of station-keeping sunfish exhibit a rich repertoire of capability such as the formation of dynamic stall vortices simultaneously on two leading edges during part of the cycle, changes in projected area in different planes, and the vectoring of jets. However, such fins may not be scalable to larger biorobotic vehicles and relatively stiff fins appear to be better suited instead, albeit with somewhat limited station-keeping ability.
A spatially explicit model of muscle contraction explains a relationship between activation phase, power and ATP utilization in insect flight
Authors: Tanner Bertrand C. W. , Regnier Michael , Daniel Thomas L.
Published: December 2007

Using spatially explicit, stochastically kinetic, molecular models of muscle force generation, we examined the relationship between mechanical power output and energy utilization under differing patterns of length change and activation. A simulated work loop method was used to understand prior observations of sub-maximal power output in the dominant flight musculature of the hawkmoth Manduca sexta L. Here we show that mechanical work output and energy consumption (via ATP) vary with the phase of activation, although they do so with different phase sensitivities. The phase relationship for contraction efficiency (the ratio of power output to power input) differs from the phase relationships of energy consumption and power output. To our knowledge, this is the first report to suggest that ATP utilization by myosin cross-bridges varies strongly with the phase of activation in muscle undergoing cyclic length changes.
Over-Cladding of Aluminum Framed Curtainwalls and Skylights
Authors: Boyd Jon M.
Published: December 2007

The need to upgrade the performance of existing building façade systems provides many opportunities for innovation and the creative reuse of existing building components. As many mid-20th century building enclosure systems age, they exhibit performance deficiencies, both in the form of deteriorating performance and in lagging performance as weighed against newer technologies. The installation of replacement exterior envelope systems on existing facilities provides many challenges, especially in fully occupied buildings. Over-cladding of existing metal and glass curtainwall and skylight systems, wherein portions of the pre-existing systems are integrated into the new construction, provides significant opportunities to resolve construction phase issues while providing improved functionality to the completed building envelope.

This paper will address two case studies in which contemporary aluminum and glass elements were combined with pre-existing mid-1900s aluminum framed cladding elements to provide two wholly new enclosure systems with significantly improved performance characteristics. The case studies deal with two very different sets of project objectives, site constraints and project solutions, but share common approaches and eventual solutions. The paper presents the problems posed by the pre-existing systems, the site investigations conducted to confirm existing conditions and site restrictions, reasons for considering the specific replacement cladding approaches, specific project constraints, the approaches used in development of the new over-clad solutions, and considerations in the design, development, and construction phase delivery of these projects. Applicability of these approaches to other types of contemporary building enclosure types is explored as well.
Proposed Method for Determining the Residual Mortar Content of Recycled Concrete Aggregates
Authors: Abbas Abdelgadir , Fathifazl Gholamreza , Burkan Isgor O. , Razaqpur A. G. , Fournier Benoit , Foo Simon
Published: December 2007

Recycling concrete from demolition of existing structures and using it as recycled concrete aggregates (RCAs) in structural-grade concrete have significant economic and environmental benefits. Currently, only a small portion of the concrete waste is reused in building construction, while most of it is used as either pavement base course or sent to landfills for disposal. The lack of confidence in the material properties of the concrete produced with RCAs is generally the main reason for its under-utilization in structural concrete. It has been demonstrated in the literature that the amount of residual mortar attached to the original (or “virgin”) aggregate particles is one of the factors affecting the material properties of RCAs. Therefore, before using RCAs in new concrete, it is crucial that the residual mortar content (RMC) is determined accurately; however, currently there is no standard procedure to determine this quantity. In this paper, an experimental method is proposed to determine the RMC of RCAs. The method comprises a combination of mechanical and chemical stresses that disintegrate the residual mortar and destroy the bond between the mortar and the natural aggregates. The mechanical stresses are created through subjecting RCA to freeze-and-thaw action, while the chemical degradation is achieved through exposure of the RCA to a sodium sulphate solution. The results of the proposed test procedure are validated by means of comprehensive image analysis. With the proposed approach, the attached residual mortar can be adequately removed, and the residual mortar content can be determined.
Continuous Improvement of the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED®) Rating System™
Authors: Todd Joel Ann , Boecker John
Published: December 2007

The U.S. Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED) Rating System™ has had a significant impact on the market in the United States and is beginning to affect markets around the world. First launched in the late 1990s, LEED has undergone periodic revision, including updates as well as addition of new versions that address different markets and enhance technical quality of the credits. In 2006, the USGBC initiated a continuous improvement process that will result in a LEED system that is more technically robust and easier to use. This paper describes improvements that are underway using a proposed framework for analyzing green building rating systems. This framework encourages a broader and deeper analysis of rating systems, looking beyond the technical metrics to include the purpose and goals of the system, the context in which it is applied, the scope of the system, the metrics, and the processes used in its implementation.
Design of a New Rheometer for Concrete
Authors: Laskar Aminul Islam , Talukdar Sudip
Published: December 2007

A new concrete rheometer has been presented including its concept, actual design, working principle, calibration, and repeatability. Resistance offered by vertical wall of cylindrical container to concrete has been taken into consideration to represent actual flow condition of concrete during shearing. An expression for total shear stress has been derived whereby shear stress versus torque and overall shear strain rate versus rotational frequency relationships have been established for the given geometry of the rheometer. A magneto-rheological fluid has been tested with the present rheometer and the results have been compared with the test results obtained by HAAKE RS1 rheometer to validate the present analytical approach. Repeatability tests were conducted with different concrete mixes and results were found to be reasonable.
Some Investigations for Establishing Suitability of Watson’s Strength-Porosity Model for Concrete
Authors: Das B. B. , Singh D. N. , Pandey S. P.
Published: December 2007

Micro-structural characteristics of concrete were determined with the help of a helium gas pycnometer and a mercury intrusion porosimeter. Details of the methodology adopted for these studies are presented in this technical note. Results in the form of ratio of solids to the pore volume were plotted with respect to the compressive strength of concrete and suitability of Watson’s strength-porosity model for concrete was evaluated. In addition to this, based on the study attempts have been made to recommend the value of parameters for concrete that appear in Watson’s strength-porosity model, which otherwise is applicable to hydrated portland cement pastes only.
Interactions between Cage-Cultured Hybrid Tilapia and a Marine Monogenean, Neobenedenia melleni, in Jamaica
Authors: Robinson Ralph D , O'Connor Nicola P G , Steele R Dunbar
Published: December 2007

Interactions between caged hybrid tilapia Oreochromis aureus × O. mossambicus and Neobenedenia melleni, a marine monogenean, were examined in coastal waters off Jamaica. Tilapia fingerlings were maintained in mesh cages (30 fish per 0.75 m3) from September 2004 to August 2005. Infection prevalence and mean intensity were recorded every 4–5 weeks after freshwater dipping of infected fish and physical dislodgement of the parasites. Surviving fish were returned to a seawater cage, allowing reinfection with N. melleni. The prevalence of infection initially peaked (89.3%; n = 28) at 12 weeks' exposure and fell to 14.3% (n = 7) in week 20; by week 29, all 5 of the fish that had survived were infected. The mean intensity of infection followed a similar profile, peaking at 12 weeks' exposure, dipping in week 20, and rising thereafter (Pearson r = 0.841; P = 0.002). Differential blood cell counts showed no significant differences between infected and uninfected fish, nor was there evidence of a humoral response in a radial diffusion assay. However, mucus from caged fish that had been exposed for 9–15 weeks killed approximately 100% of the N. melleni in 3 h. Maricultured red tilapia are highly susceptible to infection with N. melleni and appear to develop temporary, largely innate resistance to the parasite.