bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in muscle cell cation regulation and meat quality traits are associated with genetic selection for high body weight and meat yield in broiler chickens
Authors: Sandercock Dale A , Barker Zoe E , Mitchell Malcolm A , Hocking Paul M
Published: June 2009

Between-breed genetic variation for muscle and meat quality traits was determined at eight weeks of age in 34 lines of purebred commercial broiler and layer lines and traditional breeds (categories) of chickens. Between-breed genetic variation for plasma ion concentrations and element concentration in muscle dry matter and ash were determined. Plasma from broilers had higher concentrations of Na+, K+, Mg++, total and free Ca++and lower free:total Ca++than plasma from layer and traditional lines. Muscle from broilers contained more Na and higher concentrations of K, Mg and Ca per mg of ash but not of dry matter compared with layer and traditional lines. In comparison with layer and traditional lines, broiler genotypes were over three times heavier, their plasma creatine kinase activity (CK), a marker of muscle tissue damage, was higher, their breast muscle colour was lighter (L*) and less red (a*) and yellow (b*) in appearance, the initial and final pH of their muscles were lower, the pH change was higher and their breast muscle was more tender. Thus, genetic selection for broiler traits has markedly altered cation regulation in muscle cells and may be associated with changes in muscle cell function and the development of pathology and meat quality problems.
Evaluating regional blood spinal cord barrier dysfunction following spinal cord injury using longitudinal dynamic contrast-enhanced MRI
Authors: Tatar Ilkan , Chou Peter Cheng-te , Desouki Mohamed Mokhtar , El Sayed Hanaa , Bilgen Mehmet
Published: June 2009

Background

In vivo preclinical imaging of spinal cord injury (SCI) in rodent models provides clinically relevant information in translational research. This paper uses multimodal magnetic resonance imaging (MRI) to investigate neurovascular pathology and changes in blood spinal cord barrier (BSCB) permeability following SCI in a mouse model of SCI.

Methods

C57BL/6 female mice (n = 5) were subjected to contusive injury at the thoracic T11 level and scanned on post injury days 1 and 3 using anatomical, dynamic contrast-enhanced (DCE-MRI) and diffusion tensor imaging (DTI). The injured cords were evaluated postmortem with histopathological stains specific to neurovascular changes. A computational model was implemented to map local changes in barrier function from the contrast enhancement. The area and volume of spinal cord tissue with dysfunctional barrier were determined using semi-automatic segmentation.

Results

Quantitative maps derived from the acquired DCE-MRI data depicted the degree of BSCB permeability variations in injured spinal cords. At the injury sites, the damaged barriers occupied about 70% of the total cross section and 48% of the total volume on day 1, but the corresponding measurements were reduced to 55% and 25%, respectively on day 3. These changes implied spatio-temporal remodeling of microvasculature and its architecture in injured SC. Diffusion computations included longitudinal and transverse diffusivities and fractional anisotropy index. Comparison of permeability and diffusion measurements indicated regions of injured cords with dysfunctional barriers had structural changes in the form of greater axonal loss and demyelination, as supported by histopathologic assessments.

Conclusion

The results from this study collectively demonstrated the feasibility of quantitatively mapping regional BSCB dysfunction in injured cord in mouse and obtaining complementary information about its structural integrity using in vivo DCE-MRI and DTI protocols. This capability is expected to play an important role in characterizing the neurovascular changes and reorganization following SCI in longitudinal preclinical experiments, but with potential clinical implications.
Beyond the EPR: Complementary roles of the hospital-wide electronic health record and clinical departmental systems
Authors: Vedvik Eivind , Tjora Aksel H , Faxvaag Arild
Published: June 2009

Background

Many hospital departments have implemented small clinical departmental systems (CDSs) to collect and use patient data for documentation as well as for other department-specific purposes. As hospitals are implementing institution-wide electronic patient records (EPRs), the EPR is thought to be integrated with, and gradually substitute the smaller systems. Many EPR systems however fail to support important clinical workflows. Also, successful integration of systems has proven hard to achieve. As a result, CDSs are still in widespread use. This study was conducted to see which tasks are supported by CDSs and to compare this to the support offered by the EPR.

Methods

Semi-structured interviews with users of 16 clinicians using 15 different clinical departmental systems (CDS) at a Medium-sized University hospital in Norway. Inductive analysis of transcriptions from the audio taped interviews.

Results

The roles of CDSs were complementary to those of the hospital-wide EPR system. The use of structured patient data was a characteristic feature. This facilitated quality development and supervision, tasks that were poorly supported by the EPR system. The structuring of the data also improved filtering of information to better support clinical decision-making. Because of the high value of the structured patient data, the users put much effort in maintaining their integrity and representativeness. Employees from the departments were also engaged in the funding, development, implementation and maintenance of the systems.

Conclusion

Clinical departmental systems are vital to the activities of a clinical hospital department. The development, implementation and clinical use of such systems can be seen as bottom-up, user-driven innovations.
Fatty acid desaturation index correlates with body mass and adiposity indices of obesity in Wistar NIN obese mutant rat strains WNIN/Ob and WNIN/GR-Ob
Authors: Jeyakumar Shanmugam M , Lopamudra Pratti , Padmini Suryaprakash , Balakrishna Nagalla , Giridharan Nappan V , Vajreswari Ayyalasomayajula
Published: June 2009

Background

Microsomal stearoyl-CoA desaturase1 (SCD1) is the rate limiting enzyme involved in the biosynthesis of monounsaturated fatty acids (MUFAs); palmitoleic (16:1) and oleic (18:1) acid from their respective substrates palmitic (16:0) and stearic (18:0) acids. The ratio of 18:1 to 18:0 has been implicated in the regulation membrane fluidity and function. SCD1 is abundantly expressed in obese humans as well as rodent models. However, no studies have correlated the fatty acid desaturation index (16:1/16:0 and 18:1/18:0), an indicator of SCD1 activity with the markers of obesity in terms of body mass index (BMI) and adiposity index (AI). Therefore, here, we attempted to relate the fatty acid desaturation index with BMI and AI in Wistar NIN-obese mutant rat strains namely, WNIN/Ob and WNIN/GR-Ob (with impaired glucose tolerance).

Methods

For this purpose, 200 days old male 6 lean and 6 obese rats of both strains were taken. Fatty acid composition was analyzed in plasma, various tissues such as liver, white adipose tissues (retroperitoneal, epididymal, omental, and subcutaneous) and brown adipose tissue.

Results

Fatty acid composition data showed significant increase in palmitoleic (16:1) and oleic (18:1) acid levels, which were reflected in increased desaturation index (16:1/16:0 and 18:1/18:0) in plasma and all the tissues of obese rats of both strains, when compared with their respective age and sex-matched lean rats. Further, we found a strong positive correlation between desaturation index, BMI and AI in plasma and most of the tissues analyzed.

Conclusion

So far, plasma Δ9 desaturation index has been well correlated with hypertriglyceridemia and we, by employing two models of obesity namely, WNIN/Ob and WNIN/GR-Ob, have shown Δ9 desaturation index of plasma correlated with physical markers of obesity such as BMI and AI. In conclusion, Δ9 desaturation index may serve as a potential sensitive biochemical marker to assess the degree of obesity and impact of therapeutic/nutritional interventions to combat obesity, along with other indicators.
The relationship between lower extremity alignment and Medial Tibial Stress Syndrome among non-professional athletes
Authors: Raissi Golam Reza D , Cherati Afsaneh D Safar , Mansoori Kourosh D , Razi Mohammad D
Published: June 2009

Objective

To determine the relationship between lower extremity alignment and MTSS amongst non-professional athletes

Design

In a prospective Study, sixty six subjects were evaluated. Bilateral navicular drop test, Q angle, Achilles angle, tibial angle, intermalleolar and intercondylar distance were measured. In addition, runner's height, body mass, history of previous running injury, running experience was recorded. Runners were followed for 17 weeks to determine occurrence of MTSS.

Results

The overall injury rate for MTSS was 19.7%. The MTSS injury rate in girls (22%) was not significantly different from the rate in boys (14.3%). Most MTSS injuries were induced after 60 hours of exercise, which did not differ between boys and girls. There was a significant difference in right and left navicular drop (ND) in athletes with MTSS. MTSS had no significant correlation with other variables including Quadriceps, Tibia and Achilles angles, intercondylar and intermaleolar lengths and lower extremity lengths.

Limitation

All measurements performed in this study were uniplanar and static. The small sample size deemed our main limitation. The accurate assessment of participants with previous history of anterior leg pain for MTSS was another limitation.

Conclusion

Although a significant relationship between navicular drop and MTSS was found in this study; there was not any significant relationship between lower extremity alignment and MTSS in our sample study.
The conservation and evolutionary modularity of metabolism
Authors: Peregrín-Alvarez José M , Sanford Chris , Parkinson John
Published: June 2009

Background

Cellular metabolism is a fundamental biological system consisting of myriads of enzymatic reactions that together fulfill the basic requirements of life. The recent availability of vast amounts of sequence data from diverse sets of organisms provides an opportunity to systematically examine metabolism from a comparative perspective. Here we supplement existing genome and protein resources with partial genome datasets derived from 193 eukaryotes to present a comprehensive survey of the conservation of metabolism across 26 taxa representing the three domains of life.

Results

In general, metabolic enzymes are highly conserved. However, organizing these enzymes within the context of functional pathways revealed a spectrum of conservation from those that are highly conserved (for example, carbohydrate, energy, amino acid and nucleotide metabolism enzymes) to those specific to individual taxa (for example, those involved in glycan metabolism and secondary metabolite pathways). Applying a novel co-conservation analysis, KEGG defined pathways did not generally display evolutionary coherence. Instead, such modularity appears restricted to smaller subsets of enzymes. Expanding analyses to a global metabolic network revealed a highly conserved, but nonetheless flexible, 'core' of enzymes largely involved in multiple reactions across different pathways. Enzymes and pathways associated with the periphery of this network were less well conserved and associated with taxon-specific innovations.

Conclusions

These findings point to an emerging picture in which a core of enzyme activities involving amino acid, energy, carbohydrate and lipid metabolism have evolved to provide the basic functions required for life. However, the precise complement of enzymes associated within this core for each species is flexible.
Seismic critical-angle anisotropy analysis in the τ -p domain
Authors: Sil Samik , Sen Mrinal K.
Published: June 2009

Seismic critical-angle reflectometry is a relatively new field for estimating seismic anisotropy parameters. The theory relates changes in the critical angle with azimuth of the seismic line to the principal axis and anisotropy parameters. Current implementation of the critical-angle reflectometry process has certain shortcomings in that the critical angle is determined from critical offset and the process is vulnerable to different approximation errors. Seismic critical-angle analysis in the plane-wave [Formula: see text] domain can handle these issues and has the potential to become an independent tool for estimating anisotropy parameters. The theory of seismic critical-angle reflectometry is modified to make it suitable for [Formula: see text] domain analysis. Then using full-wave synthetic seismograms at three different azimuths for a transversely isotropic medium with a horizontal axis of symmetry (HTI), the effectiveness of anisotropy parameter estimation is demonstrated.
Paracrine Signals from the Mouse Conceptus Are Not Required for the Normal Progression of Decidualization
Authors: Herington Jennifer L. , Underwood Tawny , McConaha Melinda , Bany Brent M.
Published: June 2009

The purpose of this study was to determine whether the conceptus directs the formation of a tight- and adherens-dependent permeability barrier formed by the primary decidual zone and normal progression of decidual cell differentiation during embryo implantation. Four artificial models of decidualization were used, some apparently more physiological than others. The results show that both the formation of the permeability barrier and decidual cell differentiation of three of the artificial models were quite different from that of pregnant uteri. One artificial model of decidualization, namely pseudopregnant animals receiving concanavalin A-coated Sepharose bead transfers on d 2.5 of pseudopregnancy, better recapitulated the decidual changes that occur in the pregnant uterus undergoing decidualization. This included the formation of a primary decidual zone-like permeability barrier and decidual growth. This model also exhibited similar temporal changes of the expression of genes involved in decidualization that are markers of decidual cell differentiation. Overall, the results of this study indicate that some models of inducing decidualization artificially produce responses that are more similar to those occurring in the pregnant uterus, whereas others are quite different. More importantly, the results suggest that concanavalin A-coated Sepharose beads can provide an equivalent stimulus as the trophectoderm to cause the formation of the primary decidual zone permeability barrier.
Adiponectin Attenuation of Endocrine Function within Human Term Trophoblast Cells
Authors: McDonald E. A. , Wolfe M. W.
Published: June 2009

The hormone adiponectin has been shown to be important in maintaining insulin sensitivity throughout the body, whereas potential effects on the placenta have not been assessed. Pregnancy constitutes a unique physiological environment in which metabolism has a profound effect on the health of both the mother and the developing fetus. It is imperative that a delicate balance in glucose delivery be maintained between maternal tissues and the fetal/placental unit. Adiponectin’s role in regulating peripheral insulin responsiveness suggests it may be a factor in maintaining this balance during gestation as well. Examination of human cytotrophoblast cells revealed that mRNA for both adiponectin receptors, adipoR1 and adipoR2, are abundantly expressed at term. We were, however, unable to reliably detect mRNA for adiponectin in primary cytotrophoblasts. Expression of both receptors was maintained after induction of syncytium formation by exogenous epidermal growth factor treatment. Treatment of cytotrophoblasts with adiponectin resulted in a significant drop, as assessed by quantitative RT-PCR, in expression for a number of genes involved in the endocrine function of the placenta, including the chorionic gonadotropin subunits, placental lactogen, and some steroidogenic enzymes. Immunofluorescent staining for connexin 43 and desmoplakin in primary trophoblasts revealed that adiponectin does not inhibit syncytialization of trophoblast cells in culture. Taken together, these data describe a novel role for maternal adiponectin in regulating the placental environment. Determination of the effects of such adipokines on the maternal-fetal interface is increasingly important, because the incidence of pregnancies complicated by gestational diabetes remains a significant health problem in developed countries.
Matrix Extracellular Phosphoglycoprotein (MEPE) Is a New Bone Renal Hormone and Vascularization Modulator
Authors: David Valentin , Martin Aline , Hedge Anne-Marie , Rowe Peter S. N.
Published: June 2009

Increased matrix extracellular phosphoglycoprotein (MEPE) expression occurs in several phosphate and bone-mineral metabolic disorders. To resolve whether MEPE plays a role, we created a murine model overexpressing MEPE protein (MEPE tgn) in bone. MEPE tgn mice displayed a growth and mineralization defect with altered bone-renal vascularization that persisted to adulthood. The growth mineralization defect was due to a decrease in bone remodeling, and MEPE tgn mice were resistant to diet-induced renal calcification. MEPE protein-derived urinary ASARM peptides and reduced urinary Ca X PO4 product mediated the suppressed renal calcification. Osteoblastic cells displayed reduced activity but normal differentiation. Osteoclastic precursors were unable to differentiate in the presence of osteoblasts. In the kidney, NPT2a up-regulation induced an increase in phosphate renal reabsorption, leading to hyperphosphatemia. We conclude MEPE and MEPE-phosphate-regulating gene with homologies to endopeptidases on the X chromosome (MEPE-PHEX) interactions are components to an age-diet-dependent pathway that regulates bone turnover and mineralization and suppresses renal calcification. This novel pathway also modulates bone-renal vascularization and bone turnover.
Suppression of Peroxisome Proliferator-Activated Receptor γ-Coactivator-1α Normalizes the Glucolipotoxicity-Induced Decreased BETA2/NeuroD Gene Transcription and Improved Glucose Tolerance in Diabetic Rats
Authors: Kim Ji-Won , You Young-Hye , Ham Dong-Sik , Cho Jae-Hyoung , Ko Seung-Hyun , Song Ki-Ho , Son Ho-Young , Suh-Kim Haeyoung , Lee In-Kyu , Yoon Kun-Ho
Published: June 2009

Peroxisome proliferator-activated receptor γ-coactivator-1α (PGC-1α) is significantly elevated in the islets of animal models of diabetes. However, the molecular mechanism has not been clarified. We investigated whether the suppression of PGC-1α expression protects against β-cell dysfunction in vivo and determined the mechanism of action of PGC-1α in β-cells. The studies were performed in glucolipotixicity-induced primary rat islets and INS-1 cells. In vitro and in vivo approaches using adenoviruses were used to evaluate the role of PGC-1α in glucolipotoxicity-associated β-cell dysfunction. The expression of PGC-1α in cultured β-cells increased gradually with glucolipotoxicity. The overexpression of PGC-1α also suppressed the expression of the insulin and β-cell E-box transcription factor (BETA2/NeuroD) genes, which was reversed by PGC-1α small interfering RNA (siRNA). BETA2/NeuroD, p300-enhanced BETA2/NeuroD, and insulin transcriptional activities were significantly suppressed by Ad-PGC-1α but were rescued by Ad-siPGC-1α. PGC-1α binding at the glucocorticoid receptor site on the BETA2/NeuroD promoter increased in the presence of PGC-1α. Ad-siPGC-1α injection through the celiac arteries of 90% pancreatectomized diabetic rats improved their glucose tolerance and maintained their fasting insulin levels. The suppression of PGC-1α expression protects the glucolipotoxicity-induced β-cell dysfunction in vivo and in vitro. A better understanding of the functions of molecules such as PGC-1α, which play key roles in intracellular fuel regulation, could herald a new era of the treatment of patients with type 2 diabetes mellitus by providing protection from glucolipotoxicity, which is an important cause of the development and progression of the disease.
Sox7 and Sox17 are strain-specific modifiers of the lymphangiogenic defects caused by Sox18 dysfunction in mice
Authors: Hosking Brett , François Mathias , Wilhelm Dagmar , Orsenigo Fabrizio , Caprini Andrea , Svingen Terje , Tutt Desmond , Davidson Tara , Browne Catherine , Dejana Elisabetta , Koopman Peter
Published: June 2009

Developmental defects caused by targeted gene inactivation in mice are commonly subject to strain-specific modifiers that modulate the severity of the phenotype. Although several genetic modifier loci have been mapped in mice, the gene(s) residing at these loci are mostly unidentified, and the molecular mechanisms of modifier action remain poorly understood. Mutations in Sox18 cause a variable phenotype in the human congenital syndrome hypotrichosis-lymphedema-telangiectasia, and the phenotype of Sox18-null mice varies from essentially normal to completely devoid of lymphatic vasculature and lethal, depending on the strain of the mice,suggesting a crucial role for strain-specific modifiers in this system. Here we show that two closely related Group F Sox factors, SOX7 and SOX17, are able to functionally substitute for SOX18 in vitro and in vivo. SOX7 and SOX17 are not normally expressed during lymphatic development, excluding a conventional redundancy mechanism. Instead, these genes are activated specifically in the absence of SOX18 function, and only in certain strains. Our studies identify Sox7 and Sox17 as modifiers of the Sox18 mutant phenotype, and reveal their mechanism of action as a novel mode of strain-specific compensatory upregulation.
Essential role of the TRIC-B channel in Ca2+ handling of alveolar epithelial cells and in perinatal lung maturation
Authors: Yamazaki Daiju , Komazaki Shinji , Nakanishi Hiroki , Mishima Aya , Nishi Miyuki , Yazawa Masayuki , Yamazaki Tetsuo , Taguchi Ryo , Takeshima Hiroshi
Published: June 2009

TRIC channels function as monovalent cation-specific channels that mediate counter ion movements coupled with ryanodine receptor-mediated Ca2+release from intracellular stores in muscle cells. Mammalian tissues differentially contain two TRIC channel subtypes: TRIC-A is abundantly expressed in excitable cells, whereas TRIC-B is ubiquitously expressed throughout tissues. Here, we report the physiological role of TRIC-B channels in mouse perinatal development. TRIC-B-knockout neonates were cyanotic owing to respiratory failure and died shortly after birth. In the mutant neonates,the deflated lungs exhibited severe histological defects, and alveolar type II epithelial cells displayed ultrastructural abnormalities. The metabolic conversion of glycogen into phospholipids was severely interrupted in the mutant type II cells, and surfactant phospholipids secreted into the alveolar space were insufficient in the mutant neonates. Moreover, the mutant type II cells were compromised for Ca2+ release mediated by inositol-trisphosphate receptors, despite Ca2+ overloading in intracellular stores. Our results indicate that TRIC-B channels take an active part in Ca2+ signalling to establish specialised functions in type II cells and are thus essential for perinatal lung maturation.
A novel tilapia prolactin receptor is functionally distinct from its paralog
Authors: Fiol Diego F. , Sanmarti Enio , Sacchi Romina , Kültz Dietmar
Published: June 2009

A novel tilapia prolactin (PRL) receptor (OmPRLR2) was identified based on its induction during hyperosmotic stress. OmPRLR2 protein shows 28% identity to tilapia OmPRLR1 and 26% identity to human PRLR. Comparison of OmPRLR1 and OmPRLR2 revealed conserved features of cytokine class I receptors (CKR1): a WS domain and transmembrane domain, two pairs of cysteines and N-glycosylation motifs in the extracellular region, CKR1 boxes I and II, and three tyrosines in the intracellular region. However, OmPRLR2 lacked the ubiquitin ligase and 14-3-3 binding motifs. OmPRLR2 mRNA was present in all tissues analyzed, with highest expression in gills, intestine, kidney and muscle, similar to OmPRLR1. Transfer of fish from fresh water to sea water transiently increased gill OmPRLR2 mRNA levels within 4 h but decreased its protein abundance in the long term. OmPRLR2 is expressed in part as a truncated splice variant of 35 kDa in addition to the 55 kDa full-length protein. Cloning of the mRNA encoding the 35 kDa variant revealed that it lacks the extracellular region. It is expressed at significantly higher levels in males than in females. In stably transfected HEK293 cells over-expressing tetracycline-inducible OmPRLR1 and OmPRLR2, activation of these receptors by tilapia PRL177 and PRL188 triggered different downstream signaling pathways. Moreover, OmPRLR2 significantly increased HEK293 salinity tolerance. Our data reveal that tilapia has two PRLR genes whose protein products respond uniquely to PRL and activate different downstream pathways. Expression of a short PRLR2 variant may serve to inhibit PRL binding during osmotic stress and in male tissues.
Decoupling development and energy flow during embryonic diapause in the cricket,Allonemobius socius
Authors: Reynolds Julie A. , Hand Steven C.
Published: June 2009

Respiration rate increases 6.3-fold during 15 days of post-oviposition development in embryos of the Southern ground cricket, Allonemobius socius. This ontogenetic increase in metabolism of non-diapause insects is blocked during diapause, such that metabolic rate is only 36% of the rate measured for 15 days developing embryos. Surprisingly, however, there is not an acute metabolic depression during diapause entry at the point when developmental ceases (4–5 days post-oviposition), as measured by blockage of morphological change and DNA proliferation. The results indicate a decoupling of developmental arrest from metabolism. Both non-diapause and diapause embryos have unusually high [AMP]:[ATP] ratios and low [ATP]:[ADP]ratios during early embryogenesis, which suggests embryos may have experienced hypoxia as a result of an insect chorion that limits water loss but may restrict oxygen diffusion. The similar adenylate profiles for these two developmental states indicate the atypical energy status is not a specific feature of diapause. In addition embryos at day 3 have high levels of lactate that decrease as development proceeds up to day 7. Calorimetric-respirometric(CR) ratios of –353 (day 3) to –333 (day 7) kJ mol–1 O2 are consistent with embryos that are aerobically recovering from hypoxia, but are inconsistent with an ongoing anaerobic contribution to metabolism. Superfusing 3-day embryos with O2 enriched air (40% O2) forces these metabolic indicators toward a more aerobic poise, but only partially. Taken together these biochemical data indicate the metabolic poise of A. socius is only partly explained by hypoxia in early development, and that the atypical set points are also intrinsic features of this ontogenetic period in the life cycle.
Dynamics of goat distal hind limb muscle–tendon function in response to locomotor grade
Authors: McGuigan M. Polly , Yoo Edwin , Lee David V. , Biewener Andrew A.
Published: June 2009

The functional roles of the lateral gastrocnemius (LG), medial gastrocnemius (MG) and superficial digital flexor (SDF) muscle–tendon units (MTUs) in domestic goats (N=6) were studied as a function of locomotor grade, testing the hypothesis that changes in distal limb muscle work would reflect changes in mechanical work requirements while goats walked or trotted on the level, 15 deg. decline and 15 deg. incline. As steep terrain-adapted animals, changes in muscle work output are expected to be particularly important for goats. In vivo muscle–tendon forces,fascicle length changes and muscle activation were recorded viatendon force buckles, sonomicrometry and electromyography to evaluate the work performance and elastic energy recovery of the three distal MTUs. These recordings confirmed that fascicle strain and force within goat distal hind limb muscles are adjusted in response to changes in mechanical work demand associated with locomotor grade. In general, muscle work was modulated most consistently by changes in fascicle strain, with increased net shortening(P<0.001) observed as goats switched from decline to level to incline locomotion. Peak muscle stresses increased as goats increased speed from a walk to a trot within each grade condition (P<0.05), and also increased significantly with grade (P<0.05 to P<0.01). Due to the increase in net fascicle shortening and muscle force, net muscle work per cycle also increased significantly(P<0.05 to P<0.005) as goats switched from decline to level to incline conditions (LG work: 20 mJ to 56 mJ to 209 mJ; MG work:–7 mJ to 34 mJ to 179 mJ; SDF work: –42 mJ to 14 mJ to 71 mJ, at a 2.5 ms–1 trot). Although muscle work was modulated in response to changes in grade, the amount of work produced by these three distal pennate muscles was small (being <3%) in comparison with the change in mechanical energy required of the limb as a whole. Elastic energy recovery in the SDF and gastrocnemius (GA) tendons was substantial across all three grades, with the SDF tendon recovering 2.4 times more energy, on average, than the GA tendon. In parallel with the increase in muscle–tendon force,tendon energy recovery also increased as goats increased speed and changed gait, reaching the highest levels when goats trotted on an incline at 2.5 ms–1 (GA: 173 mJ; SDF: 316 mJ). In general, tendon elastic energy exceeded net muscle work across all grade and gait conditions. These results demonstrate, for the first time in a quadruped, similar findings to those observed in ankle extensor muscles in humans, wallabies, turkeys and guinea fowl, suggesting that distal muscle–tendon architecture more generally favors a design for economic force production and tendon elastic energy recovery, with the majority of limb work during incline or decline running performed by larger proximal muscles.
Spider silk as a novel high performance biomimetic muscle driven by humidity
Authors: Agnarsson Ingi , Dhinojwala Ali , Sahni Vasav , Blackledge Todd A.
Published: June 2009

The abrupt halt of a bumble bee's flight when it impacts the almost invisible threads of an orb web provides an elegant example of the amazing strength and toughness of spider silk. Spiders depend upon these properties for survival, yet the impressive performance of silk is not limited solely to tensile mechanics. Here, we show that silk also exhibits powerful cyclic contractions, allowing it to act as a high performance mimic of biological muscles. These contractions are actuated by changes in humidity alone and repeatedly generate work 50 times greater than the equivalent mass of human muscle. Although we demonstrate that this response is general and occurs weakly in diverse hydrophilic materials, the high modulus of spider silk is such that it generates exceptional force. Furthermore, because this effect already operates at the level of single silk fibers, only 5 μm in diameter,it can easily be scaled across the entire size range at which biological muscles operate. By contrast, the most successful synthetic muscles developed so far are driven by electric voltage, such that they cannot scale easily across large ranges in cross-sectional areas. The potential applicability of silk muscles is further enhanced by our finding that silkworm fibers also exhibit cyclic contraction because they are already available in commercial quantities. The simplicity of using wet or dry air to drive the biomimetic silk muscle fibers and the incredible power generated by silk offer unique possibilities in designing lightweight and compact actuators for robots and micro-machines, new sensors, and green energy production.
How super is supercontraction? Persistent versus cyclic responses to humidity in spider dragline silk
Authors: Blackledge Todd A. , Boutry Cecilia , Wong Shing-Chung , Baji Avinash , Dhinojwala Ali , Sahni Vasav , Agnarsson Ingi
Published: June 2009

Spider dragline silk has enormous potential for the development of biomimetic fibers that combine strength and elasticity in low density polymers. These applications necessitate understanding how silk reacts to different environmental conditions. For instance, spider dragline silk`supercontracts' in high humidity. During supercontraction, unrestrained dragline silk contracts up to 50% of its original length and restrained fibers generate substantial stress. Here we characterize the response of dragline silk to changes in humidity before, during and after supercontraction. Our findings demonstrate that dragline silk exhibits two qualitatively different responses to humidity. First, silk undergoes a previously unknown cyclic relaxation–contraction response to wetting and drying. The direction and magnitude of this cyclic response is identical both before and after supercontraction. By contrast, supercontraction is a `permanent' tensioning of restrained silk in response to high humidity. Here, water induces stress,rather than relaxation and the uptake of water molecules results in a permanent change in molecular composition of the silk, as demonstrated by thermogravimetric analysis (TGA). Even after drying, silk mass increased by∼1% after supercontraction. By contrast, the cyclic response to humidity involves a reversible uptake of water. Dried, post-supercontraction silk also differs mechanically from virgin silk. Post-supercontraction silk exhibits reduced stiffness and stress at yield, as well as changes in dynamic energy storage and dissipation. In addition to advancing understanding supercontraction, our findings open up new applications for synthetic silk analogs. For example, dragline silk emerges as a model for a biomimetic muscle, the contraction of which is precisely controlled by humidity alone.
Fingerprints are unlikely to increase the friction of primate fingerpads
Authors: Warman Peter H. , Ennos A. Roland
Published: June 2009

It is generally assumed that fingerprints improve the grip of primates, but the efficiency of their ridging will depend on the type of frictional behaviour the skin exhibits. Ridges would be effective at increasing friction for hard materials, but in a rubbery material they would reduce friction because they would reduce contact area. In this study we investigated the frictional performance of human fingertips on dry acrylic glass using a modified universal mechanical testing machine, measuring friction at a range of normal loads while also measuring the contact area. Tests were carried out on different fingers, fingers at different angles and against different widths of acrylic sheet to separate the effects of normal force and contact area. The results showed that fingertips behaved more like rubbers than hard solids;their coefficients of friction fell at higher normal forces and friction was higher when fingers were held flatter against wider sheets and hence when contact area was greater. The shear stress was greater at higher pressures,suggesting the presence of a biofilm between the skin and the surface. Fingerprints reduced contact area by a factor of one-third compared with flat skin, however, which would have reduced the friction; this casts severe doubt on their supposed frictional function.
Hearing ability in three clownfish species
Authors: Parmentier Eric , Colleye Orphal , Mann David
Published: June 2009

Clownfish live in social groups in which there is a size-based dominance hierarchy. In such a context, sonic cues could play a role in social organisation because dominant frequency and pulse length of sounds are strongly correlated with fish size. Data on the hearing ability of these fish are, however, needed to show that they have the sensory ability to detect the frequencies in their sounds. The present study determines the hearing sensitivity in three different anemonefish species (Amphiprion frenatus,Amphiprion ocellaris and Amphiprion clarkii), and compares it with the frequencies in their calls. The frequency range over which the three species can detect sounds was between 75 and 1800 Hz, and they were most sensitive to frequencies below 200 Hz. During sound production, dominant frequency is clearly related (R=0.95) to the fish size, whatever the species. Dominant frequency extends from 370 to 900 Hz for specimens having a size between 55 and 130 mm. The best hearing sensitivity of small specimens were found to be lower than the dominant frequency of their own calls. However, they were found to be close to the dominant frequency of larger fish calls. The interest of juveniles lies in localising the adults and thus their location on the reef.
Phthalocyanine, Porphyrin, Cyclodextrin, and Polymer Systems Suitable for Studying by Circular Dichroism, Magnetic Circular Dichroism, and/or Electrochemistry
Authors: Kobayashi Nagao , Fukuda Takamitsu
Published: June 2009

We introduce some representative studies from our laboratory, mostly from the 21st Century. We are interested in the synthesis, optical spectroscopy, such as magnetic circular dichroism (MCD), circular dichroism (CD), and electrochemistry of large aromatic molecules such as porphyrins and phthalocyanines, as well as cyclodextrin and polymer systems showing CD activity.
Effect of Hydration on the Very Slow Droplet–Lamellar Transition in Dioleylsulfosuccinate/Decane/Water System: A Small Angle X-ray Scattering Study
Authors: Ghosh Swapan K , Ichiyanagi Naoki , Okabayashi Hiro-Fumi , Yoshino Aki-Hiro , Takeda Takayoshi , O’Connor Charmian J
Published: June 2009

Time- and temperature-dependence of the small angle X-ray scattering (SAXS) profiles for homogeneous and transparent solutions of the sodium dioleylsulfosuccinate (SDOleS)–decane–water system with various molar ratios of [H2O]/[SDOleS] have been examined. The time-dependence of the SAXS profiles has provided evidence that the droplet–lamellar transition occurs spontaneously but very slowly at 298 K. This behavior depends upon the quantity of water solubilized into the SDOleS microemulsions. Some microstructural models have been proposed to explain this very slow transition.
Aromaticity and Conjugation in Sapphyrin and Orangarin
Authors: Aihara Jun-ichi , Makino Masakazu
Published: June 2009

We analyzed aromatic and magnetic properties of two typical expanded porphyrins, sapphyrin and orangarin, using our theory of aromaticity and ring-current diamagnetism and confirmed that, as in the case of free-base porphine, global aromaticity and macrocyclic circulation are associated primarily with five pyrrolic rings and the macrocyclic annulenoid pathway, respectively. For orangarin, the main pathway of macrocyclic circulation is different from the [20]annulene pathway so far proposed as a main macrocyclic conjugation pathway. A new method was proposed for associating the main macrocyclic conjugation pathway with the π-current density pattern.
Purity Effects on the Charge-Transport Properties in One-Dimensional TPP[CoIII(Pc)(CN)2]2 (TPP = Tetraphenylphosphonium and Pc = Phthalocyaninato) Conductors
Authors: Yamashita Satoshi , Naito Toshio , Inabe Tamotsu
Published: June 2009

Purity effects on the temperature dependence of electrical resistivity in TPP[Co(Pc)(CN)2]2 with a typical one-dimensional metallic electronic system have been examined. In this system, no dependence on the impurity content has been observed, suggesting that the apparent thermally activated behavior is dominated by charge disproportionation.
Chloride Complexation of Zr and Hf in HCl Investigated by Extended X-ray Absorption Fine Structure Spectroscopy: Toward Characterization of Chloride Complexation of Element 104, Rutherfordium (Rf)
Authors: Haba Hiromitsu , Akiyama Kazuhiko , Tsukada Kazuaki , Asai Masato , Toyoshima Atsushi , Yaita Tsuyoshi , Hirata Masaru , Sueki Keisuke , Nagame Yuichiro
Published: June 2009

Chloride complexation of the group-4 elements Zr and Hf in 8.0–11.9 M HCl is investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy to characterize chloro complexes of the transactinide element, rutherfordium (Rf). The complexes of Zr and Hf successively vary with the concentration of HCl from a hydrated complex [M(H2O)8]4+ at 8.0 M to a hexachloro complex [MCl6]2− at 11.9 M (M = Zr and Hf). The present structural changes of the Zr and Hf complexes well reflect the previously studied anion-exchange behavior of Zr and Hf in HCl. From both the EXAFS and anion-exchange results, we suggest that Rf forms the same complexes as those of Zr and Hf in HCl, and that the complexation strength of the hexachloro complexes of the group-4 elements, [MCl6]2− (M = Zr, Hf, and Rf), is in the sequence of Rf > Zr > Hf.
Synthesis and Photochemical Characteristics of Amphiphilic Enediyne Dendrimers
Authors: Yoshimura Nao , Momotake Atsuya , Shinohara Yoshihiro , Takahashi Kayori , Nagahata Ritsuko , Nishimura Yoshinobu , Arai Tatsuo
Published: June 2009

Amphiphilic enediyne-cored dendrimers were prepared as pure cis and trans isomers. All dendrimers were fluorescent to give fluorescence quantum yield of 0.10–0.64, and they underwent efficient photochemical isomerization with quantum yields of 0.22–0.50 in THF. In water, other photochemical reactions took place. Fluorescence or triplet lifetimes were also strongly affected by dendrimer generation and solvent polarity. The structure–photochemical property relationship of new photoresponsive dendrimers is discussed.
Photolysis of 1,2-Naphthoquinone in Oxygen-Doped Argon Matrix at Low Temperature
Authors: Itoh Takayoshi , Tatsugi Jiro , Tomioka Hideo
Published: June 2009

Photolysis of 1,2-naphthoquinone (1) in argon matrix either with or without oxygen at 10 K was investigated by IR spectroscopy in combination with DFT calculations. The results indicate that 1 gave bis(ketene) 2 as a main product along with a small amount of inden-1-one (4), most probably as a result of Type I cleavage, followed by electron reorganization and decarbonylation in the resulting diacyl radical, respectively. Bis(ketene) 2 was shown to transform to isomeric ketene 3 upon continued irradiation under these conditions. When the irradiation was carried out in argon matrix doped with 20% oxygen, 1 decomposed much more efficiently than that in argon matrix and six- and eight-membered cyclic peroxides presumably formed by trapping of initial diradical originating from α-cleavage by molecular oxygen were detected at complete expense of 3 and 4. The formation of 2 even in the presence of oxygen suggested that 2 may partly be formed by a concerted pathway in the singlet excited state. The present observation reveals that photolysis of α-diketones in oxygen-doped matrix at low temperature provides useful information concerning the reaction pathway of the diketone upon photoexcitation.
A Stable Electroactive Monolayer Composed of Soluble Single-Walled Carbon Nanotubes on ITO
Authors: Wang Qiguan , Moriyama Hiroshi
Published: June 2009

Self-assembled monolayers (SAMs) of single-walled carbon nanotubes (SWNTs) covalently attached to a (3-aminopropyl)trimethoxysilane-modified ITO surface (SAM–ITO) were prepared by the coupling reaction of the amine groups with the carboxyl groups from the soluble SWNTs, which were safely obtained via a two-step process assisted by microwave irradiation. The surface composition of the SAM–ITO was examined using X-ray photoelectron spectroscopy. The cyclic voltammetry (CV) behavior of the SAM–ITO in an organic system showed a higher capacitor charging current, which indicated the presence of a tethered SWNT monolayer. However, the CV behavior of the SAM–ITO in acidic aqueous solutions showed unexpected oxidation signals because of redox reactions involving the defects and sidewalls of soluble functionalized SWNTs. To make the CVs of the resulting SWNT monolayers more stable in acidic aqueous solutions, a conductive oligomer of tetramer aniline was additionally incorporated onto the residual carboxyl groups on the SWNTs. The UV–vis spectrum showed that the SWNT monolayer was successfully endcapped by the conductive oligomer, and atomic force microscopy images showed that the SWNTs from the self-assembled monolayer were thickened and the SWNT surfaces were roughened. The CV data showed a single reversible redox couple, which indicated a more stable state.
Anchoring Effects: Evidence from Art Auctions
Authors: Beggs Alan , Graddy Kathryn
Published: June 2009

This paper shows that the price of a painting sold at an art auction and the experts' pre-sale valuations are anchored on the price at which the painting previously sold at auction. We are able to separate anchoring from rational learning by using the identifying strategy that the unobservable component of quality for a particular painting remains constant between the last auction sale and the current auction sale. We interpret these results as anchoring on the part of the buyers, with the sellers and auctioneers either anticipating anchoring on the part of the buyers or exhibiting anchoring effects themselves. (JEL D44, Z11)
Not All Oil Price Shocks Are Alike: Disentangling Demand and Supply Shocks in the Crude Oil Market
Authors: Kilian Lutz
Published: June 2009

Shocks to the real price of oil may reflect oil supply shocks, shocks to the global demand for all industrial commodities, or demand shocks that are specific to the crude oil market. Each shock has different effects on the real price of oil and on US macroeconomic aggregates. Changes in the composition of shocks help explain why regressions of macroeconomic aggregates on oil prices tend to be unstable. Evidence that the recent surge in oil prices was driven primarily by global demand shocks helps explain why this shock so far has failed to cause a major recession in the United States. (JEL E31, E32, Q41, Q43)
Exclusive Dealing and Entry, when Buyers Compete: Comment
Authors: Wright Julian
Published: June 2009

In a recent paper, Chiara Fumagalli and Massimo Motta (2006) challenge the idea that an incumbent can foreclose efficient entry in the face of scale economies by using exclusive contracts. They claim that inefficient exclusion does not arise when buyers are homogenous firms that compete downstream. However, when upstream firms can compete in two-part tariffs, their equilibrium analysis contains some errors. Fixing these errors, inefficient exclusion arises when scale economies are sufficiently large or the entrant's cost advantage is not too big. Inefficient exclusion arises to protect industry profits from competition. (JEL L11, L13, L14)
Should Urban Transit Subsidies Be Reduced?
Authors: Parry Ian W. H , Small Kenneth A
Published: June 2009

This paper derives empirically tractable formulas for the welfare effects of fare adjustments in passenger peak and off-peak rail and bus transit, and for optimal pricing of those services. The formulas account for congestion, pollution, accident externalities, scale economies, and agency adjustment of transit service offerings. We apply them using parameter values for Washington (DC), Los Angeles, and London. The results support the efficiency of the large current fare subsidies; even starting with fares at 50 percent of operating costs, incremental fare reductions are welfare improving in almost all cases. These findings are robust to alternative assumptions and parameters. (JEL L92, R41, R42, R48)
Strategic Leniency and Cartel Enforcement
Authors: Miller Nathan H
Published: June 2009

The cornerstone of cartel enforcement in the United States and elsewhere is a commitment to the lenient prosecution of early confessors. A burgeoning game-theoretical literature is ambiguous regarding the impacts of leniency. I develop a theoretical model of cartel behavior that provides empirical predictions and moment conditions, and apply the model to the complete set of indictments and information reports issued over a 20-year span. Statistical tests are consistent with the notion that leniency enhances deterrence and detection capabilities. The results have implications for market efficiency and enforcement efforts against cartels and other forms of organized crime. (JEL D43, L12, L13, K21)