bluuebunny/crossref_metadata_2025_split huggingface dataset:
Giant impact, planetary merger, and diversity of planetary-core mass
Authors: Li S.-L. , Agnor C. , Lin D. N. C. 
Published: May 2008

AbstractTransit observations indicate a large dispersion in the internal structure among the known gas giants. This is a big challenge to the conventional sequential planetary formation scenario because the diversity is inconsistent with the expectation of some well defined critical condition for the onset of gas accretion in this scenario. We suggest that giant impacts may lead to the merger of planets or the accretion of planetary embryos and cause the diversity of the core mass. By using an SPH scheme, we show that direct parabolic collisions generally lead to the total coalescence of impinging gas giants whereas, during glancing collisions, the efficiency of core retention is much larger than that of the envelope. We also examine the adjustment of the gaseous envelope with a 1D Lagrangian hydrodynamic scheme. In the proximity of their host stars, the expansion of the planets' envelopes, shortly after sufficiently catastrophic impacts, can lead to a substantial loss of gas through Roche-lobe overflow. We are going to examine the possibility that the accretion of several Earth-mass objects can significantly enlarge the planets' photosphere and elevate the tidal dissipation rate over the time scale of 100 Myr.
Baroclinic generation of potential vorticity in an embedded planet-disk system
Authors: JI Jianghui , OU Shangli , LIU Lin 
Published: May 2008

AbstractWe use a multi-dimensional hydrodynamics code to study the gravitational interaction between an embedded planet and a protoplanetary disk with emphasis on the generation of vortensity (Potential Vorticity or PV) through a Baroclinic Instability. We show that the generation of PV is very common and effective in non-barotropic disks through the Baroclinic Instability, especially within the coorbital region. Our results also complement previous work that non-axisymmetric Rossby-Wave Instabilities (RWIs) are likely to develop at local minima of PV distribution that are generated by the interaction between a planet and an inviscid barotropic disk. The development of RWIs results in non-axisymmetric density blobs, which exert stronger torques onto the planet when they move to the vicinity of the planet. Hence, large amplitude oscillations are introduced to the time behavior of the total torque acted on the planet by the disk. In current simulations, RWIs do not change the overall picture of inward orbital migration but cause a non-monotonic behavior to the migration speed. As a side effect, RWIs also introduce interesting structures into the disk. These structures may help the formation of Earth-like planets in the Habitable Zone or Hot Earths interior to a close-in giant planet.
Effects of dissipating gas drag on planetesimal accretion in binary systems
Authors: Xie Ji-Wei , Zhou Ji-Lin 
Published: May 2008

AbstractWe numerically investigate the conditions for planetesimal accretion in the circumprimary disk under the perturbing presence of a companion star, with focus on the γ Cephei system. Gas drag is included with a dissipating time scale of 105years. We show at the beginning(within 103∼ 104years), gas drag damps the ΔVbetween planetesimals of same sizes and increases ΔVbetween planetesimals of different sizes. However, after increasing to high values(300∼800m/s), we find the ΔVbetween bodies of different sizes decrease to very low values (below 10m/s) in a few 105yrs(depending on the gas-dissipating time scaleTdamp, radial sizeRpand semi-major axisapof planetesimals). Hence, the high ΔVis somewhat short-lived, and runaway accretion can be turned on later. We conclude that the conditions for planetary formation in binary systems (even close binary systems) are much better than what we expected before.
Program Studies the Kuroshio Extension
Authors: Donohue Kathleen , Watts D. Randolph , Tracey Karen , Wimbush Mark , Park Jae‐Hun , Bond Nicholas , Cronin Meghan , Chen Shuiming , Qiu Bo , Hacker Peter , Hogg Nelson , Jayne Steven , McClean Julie , Rainville Luc , Mitsudera Humio , Tanimoto Youichi , Xie Shang‐Ping 
Published: May 2008

The Kuroshio Extension system links to North Pacific climate through its role in subtropical‐subpolar exchange, the formation and distribution of mode waters, and the intensification of the extratropical storm track across the North Pacific. The Kuroshio Extension System Study (KESS) offers a window into these processes through integrated measurements of the ocean and atmosphere and through modeling efforts (Figure 1).The northward flowing waters of the Kuroshio western boundary current leave the Japanese coast to flow eastward as a free jet—the Kuroshio Extension. The Extension forms a vigorously meandering boundary between the warm subtropical and cold northern waters.
Geodetic Observations Help Scientists Understand Geohazards and Mitigate Disasters: The GGOS Contribution to GEOSS and an Observing System for Geohazards and Disaster Prevention; Frascati, Italy, 5–6 October 2007
Authors: Plag Hans‐Peter , Zerbini Susanna 
Published: May 2008

Modern space‐geodetic observations have revolutionized our understanding of geohazards, and these observations have a great potential for further scientific discovery and applications, including early warning.To discuss this, about 50 scientists from the geodetic and geohazards communities took part in a workshop organized by the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) as a contribution to the intergovernmental Group on Earth Observations (GEO). Highest‐level representatives of space agencies (European Space Agency, NASA, and Agenzia Spaziale Italiana) emphasized the fundamental importance of the geodetic reference frames for satellite missions and Earth observation. Although high, the present accuracy of these reference frames still is a key limitation in quantifying global change processes such as changes in ice sheets and sea level. Improvements of the reference frame are a pivotal step toward a better understanding of these processes and their impact on society. The representative of GEO identified GGOS as a core element in the Global Earth Observation System of Systems (GEOSS), which aims to integrate Earth observations in order to better serve users in a number of societal benefit areas, including disasters.
The histamine H3receptor: an attractive target for the treatment of cognitive disorders
Authors: Esbenshade T A , Browman K E , Bitner R S , Strakhova M , Cowart M D , Brioni J D 
Published: May 2008

The histamine H3receptor, first described in 1983 as a histamine autoreceptor and later shown to also function as a heteroreceptor that regulates the release of other neurotransmitters, has been the focus of research by numerous laboratories as it represents an attractive drug target for a number of indications including cognition. The purpose of this review is to acquaint the reader with the current understanding of H3receptor localization and function as a modulator of neurotransmitter release and its effects on cognitive processes, as well as to provide an update on selected H3antagonists in various states of preclinical and clinical advancement. Blockade of centrally localized H3receptors by selective H3receptor antagonists has been shown to enhance the release of neurotransmitters such as histamine, ACh, dopamine and norepinephrine, among others, which play important roles in cognitive processes. The cognitive‐enhancing effects of H3antagonists across multiple cognitive domains in a wide number of preclinical cognition models also bolster confidence in this therapeutic approach for the treatment of attention deficit hyperactivity disorder, Alzheimer's disease and schizophrenia. However, although a number of clinical studies examining the efficacy of H3receptor antagonists for a variety of cognitive disorders are currently underway, no clinical proof of concept for an H3receptor antagonist has been reported to date. The discovery of effective H3antagonists as therapeutic agents for the novel treatment of cognitive disorders will only be accomplished through continued research efforts that further our insights into the functions of the H3receptor.British Journal of Pharmacology(2008)154, 1166–1181; doi:10.1038/bjp.2008.147; published online 12 May 2008
The crystal structure of peroxymyoglobin generated through cryoradiolytic reduction of myoglobin compound III during data collection
Authors: Hersleth Hans-Petter , Hsiao Ya-Wen , Ryde Ulf , Görbitz Carl Henrik , Andersson K. Kristoffer 
Published: May 2008

Myoglobin has the ability to react with hydrogen peroxide, generating high-valent complexes similar to peroxidases (compounds I and II), and in the presence of excess hydrogen peroxide a third intermediate, compound III, with an oxymyoglobin-type structure is generated from compound II. The compound III is, however, easily one-electron reduced to peroxymyoglobin by synchrotron radiation during crystallographic data collection. We have generated and solved the 1.30 Å (1 Å=0.1 nm) resolution crystal structure of the peroxymyoglobin intermediate, which is isoelectric to compound 0 and has a Fe–O distance of 1.8 Å and O–O bond of 1.3 Å in accordance with a FeII–O–O− (or FeIII–O–O2−) structure. The generation of the peroxy intermediate through reduction of compound III by X-rays shows the importance of using single-crystal microspectrophotometry when doing crystallography on metalloproteins. After having collected crystallographic data on a peroxy-generated myoglobin crystal, we were able (by a short annealing) to break the O–O bond leading to formation of compound II. These results indicate that the cryoradiolytic-generated peroxymyoglobin is biologically relevant through its conversion into compound II upon heating. Additionally, we have observed that the Xe1 site is occupied by a water molecule, which might be the leaving group in the compound II to compound III reaction.
Calmodulin binding to cellular FLICE-like inhibitory protein modulates Fas-induced signalling
Authors: Pawar Pritish S. , Micoli Keith J. , Ding Haitao , Cook William J. , Kappes John C. , Chen Yabing , McDonald Jay M. 
Published: May 2008

We and others have demonstrated that Fas-mediated apoptosis is a potential therapeutic target for cholangiocarcinoma. Previously, we reported that CaM (calmodulin) antagonists induced apoptosis in cholangiocarcinoma cells through Fas-related mechanisms. Further, we identified a direct interaction between CaM and Fas with recruitment of CaM into the Fas-mediated DISC (death-inducing signalling complex), suggesting a novel role for CaM in Fas signalling. Therefore we characterized the interaction of CaM with proteins recruited into the Fas-mediated DISC, including FADD (Fas-associated death domain)-containing protein, caspase 8 and c-FLIP {cellular FLICE [FADD (Fas-associated death domain)-like interleukin 1β-converting enzyme]-like inhibitory protein}. A Ca2+-dependent direct interaction between CaM and FLIPL, but not FADD or caspase 8, was demonstrated. Furthermore, a 37.3±5.7% increase (n=6, P=0.001) in CaM–FLIP binding was observed at 30 min after Fas stimulation, which returned to the baseline after 60 min and correlated with a Fas-induced increase in intracellular Ca2+ that reached a peak at 30 min and decreased gradually over 60 min in cholangiocarcinoma cells. A CaM antagonist, TFP (trifluoperazine), inhibited the Fas-induced increase in CaM–FLIP binding concurrent with inhibition of ERK (extracellular-signal-regulated kinase) phosphorylation, a downstream signal of FLIP. Direct binding between CaM and FLIPL was demonstrated using recombinant proteins, and a CaM-binding region was identified in amino acids 197–213 of FLIPL. Compared with overexpression of wild-type FLIPL that resulted in decreased spontaneous as well as Fas-induced apoptosis, mutant FLIPL with deletion of the CaM-binding region resulted in increased spontaneous and Fas-induced apoptosis in cholangiocarcinoma cells. Understanding the biology of CaM–FLIP binding may provide new therapeutic targets for cholangiocarcinoma and possibly other cancers.
Dihydropteroate synthase from Streptococcus pneumoniae: structure, ligand recognition and mechanism of sulfonamide resistance
Authors: Levy Colin , Minnis David , Derrick Jeremy P. 
Published: May 2008

DHPS (dihydropteroate synthase) catalyses an essential step in the biosynthesis of folic acid and is the target for the sulfonamide group of antimicrobial drugs. In the present paper we report two crystal structures of DHPS from the respiratory pathogen Streptococcus pneumoniae: the apoenzyme at 1.8 Å (1 Å=0.1 nm) resolution and a complex with DHPP (6-hydroxymethyl-7,8-dihydropterin monophosphate) at 2.4 Å resolution. The enzyme forms a α/β barrel structure, with a highly conserved binding pocket for recognition of the pterin substrate, DHPPP (6-hydroxymethyl-7,8-dihydropterin pyrophosphate). There is a fixed order of substrate binding: DHPPP binds first, followed by the second substrate, pABA (p-aminobenzoic acid). Binding of PPi also allows the enzyme to recognize pABA or sulfonamide drugs, which act as pABA analogues. Using equilibrium and pre-steady state kinetic fluorescence measurements, we show that the on-rate for DHPPP binding to the enzyme is relatively low (2.6×105 M−1·s−1) and propose that binding of this substrate induces a large scale movement of the second loop in the enzyme structure to participate in the formation of the pABA-binding site. Two mutations which confer resistance to sulfonamide drugs do not affect DHPPP binding, but have a substantial effect on pABA and sulfonamide recognition. The results show that binding of DHPPP and pABA are separate distinguishable events in the reaction cycle, and that mutations which confer resistance to sulfonamide drugs act exclusively on the second step in the binding process.
Angiopoietin-1 gene transfer improves impaired wound healing in genetically diabetic mice without increasing VEGF expression
Authors: Bitto Alessandra , Minutoli Letteria , Galeano Maria Rosaria , Altavilla Domenica , Polito Francesca , Fiumara Tiziana , Calò Margherita , Lo Cascio Patrizia , Zentilin Lorena , Giacca Mauro , Squadrito Francesco 
Published: May 2008

Ang-1 (angiopoietin-1) improves the ineffective angiogenesis and impaired wound healing in diabetes; however, the mechanism underlying this positive effect is still far from being completely understood. In the present study, we investigated whether rAAV (recombinant adeno-associated virus)–Ang-1 gene transfer could improve wound repair in genetically diabetic mice (db+/db+) and the mechanism(s) by which it causes new vessel formation. An incisional skin-wound model in diabetic and normoglycaemic mice was used. After the incision, animals received rAAV–LacZ or rAAV–Ang-1 in the wound edge. After 7 and 14 days, wounds were used to (i) confirm Ang-1 gene transfer, (ii) assess histologically the healing process, (iii) evaluate wound-breaking strength, and (iv) study new vessel formation by PECAM-1 (platelet/endothelial cell adhesion molecule-1) immunostaining. Finally, we investigated VEGF (vascular endothelial growth factor) mRNA and protein levels, eNOS (endothelial NO synthase) expression and VEGFR-1 and VEGFR-2 (VEGF receptor-1 and -2 respectively) immunostaining. The efficiency of Ang-1 gene transfer was confirmed by increased mRNA and protein expression of the protein. rAAV–Ang-1 significantly improved the healing process, stimulating re-epithelization and collagen maturation, increasing breaking strength and significantly augmenting the number of new vessels, as indicated by PECAM-1 immunostaining. However, Ang-1 gene transfer did not modify the decrease in VEGF mRNA and protein expression in diabetic mice; in contrast, Ang-1 increased eNOS expression and augmented nitrate wound content and VEGFR-2 immunostaining and protein expression. Ang-1 gene transfer did not change vascular permeability. Similar results were obtained in normoglycaemic animals. In conclusion, our results provide strong evidence that Ang-1 gene transfer improves the delayed wound repair in diabetes by inducing angiogenesis in a VEGF-independent manner.
Effects of chronic L-NAME on nitrotyrosine expression and renal vascular reactivity in rats with chronic bile-duct ligation
Authors: Alcaraz Antonia , Hernández David , Iyú David , Mota Rubén , Atucha Noemí M. , Ortiz Antonio J. , García-Estañ Joaquín , Ortiz María C. 
Published: May 2008

In liver cirrhosis, elevated levels of NO and ROS (reactive oxygen species) might greatly favour the generation of peroxynitrite. Peroxynitrite is a highly reactive oxidant and it can potentially alter the vascular reactivity and the function of different organs. In the present study, we evaluated whether peroxynitrite levels are related to the progression of renal vascular and excretory dysfunction during experimental cirrhosis induced by chronic BDL (bile-duct ligation) in rats. Experiments were performed at 7, 15 and 21 days after BDL in rats and in rats 21 days post-BDL chronically treated with L-NAME (NG-nitro-L-arginine methyl ester). Sodium balance, BP (blood pressure), basal RPP (renal perfusion pressure) and the renal vascular response to PHE (phenylephrine) and ACh (acetylcholine) in isolated perfused kidneys were measured. NO levels were calculated as 24-h urinary excretion of nitrites, ROS as TBARS (thiobarbituric acid-reacting substances), and peroxynitrite formation as the renal expression of nitrotyrosine. BDL rats had progressive sodium retention, and decreased BP, RPP and renal vascular responses to PHE and ACh in the time following BDL. They also had increasing levels of NO and ROS, and renal nitrotyrosine accumulation, especially in the medulla. All of these changes were either prevented or significantly decreased by chronic L-NAME administration. In conclusion, these results suggest that the increasing levels of peroxynitrite might contribute to the altered renal vascular response and sodium retention in the development of the experimental biliary cirrhosis. Moreover, the beneficial effects of decreasing NO synthesis are, at least in part, mediated by anti-peroxinitrite-related effects.
Both aerobic endurance and strength training programmes improve cardiovascular health in obese adults
Authors: Schjerve Inga E. , Tyldum Gjertrud A. , Tjønna Arnt E. , Stølen Tomas , Loennechen Jan P. , Hansen Harald E. M. , Haram Per M. , Heinrich Garreth , Bye Anja , Najjar Sonia M. , Smith Godfrey L. , Slørdahl Stig A. , Kemi Ole J. , Wisløff Ulrik 
Published: May 2008

Regular exercise training is recognized as a powerful tool to improve work capacity, endothelial function and the cardiovascular risk profile in obesity, but it is unknown which of high-intensity aerobic exercise, moderate-intensity aerobic exercise or strength training is the optimal mode of exercise. In the present study, a total of 40 subjects were randomized to high-intensity interval aerobic training, continuous moderate-intensity aerobic training or maximal strength training programmes for 12 weeks, three times/week. The high-intensity group performed aerobic interval walking/running at 85–95% of maximal heart rate, whereas the moderate-intensity group exercised continuously at 60–70% of maximal heart rate; protocols were isocaloric. The strength training group performed ‘high-intensity’ leg press, abdominal and back strength training. Maximal oxygen uptake and endothelial function improved in all groups; the greatest improvement was observed after high-intensity training, and an equal improvement was observed after moderate-intensity aerobic training and strength training. High-intensity aerobic training and strength training were associated with increased PGC-1α (peroxisome-proliferator-activated receptor γ co-activator 1α) levels and improved Ca2+ transport in the skeletal muscle, whereas only strength training improved antioxidant status. Both strength training and moderate-intensity aerobic training decreased oxidized LDL (low-density lipoprotein) levels. Only aerobic training decreased body weight and diastolic blood pressure. In conclusion, high-intensity aerobic interval training was better than moderate-intensity aerobic training in improving aerobic work capacity and endothelial function. An important contribution towards improved aerobic work capacity, endothelial function and cardiovascular health originates from strength training, which may serve as a substitute when whole-body aerobic exercise is contra-indicated or difficult to perform.
Postprandial paradoxical IGFBP-1 response in obese patients with Type 2 diabetes
Authors: Lehtihet Mikael , Efendic Suad , Brismar Kerstin 
Published: May 2008

IGFs (insulin-like growth factors), which in an unbound form induce glucose and amino acid uptake, circulate bound to IGFBPs (IGF-binding proteins), which modulate their bioavailability and activity. The aim of the present study was to examine the effect of a standard meal [2301 kJ (550 kcal)] on the serum levels of IGFBP-1 in obese patients with T2DM (Type 2 diabetes mellitus), non-obese patients with T1DM (Type 1 diabetes mellitus) and healthy controls, using the artificial pancreas (Biostator®) to obtain a normal glycaemic response to the meal. IGFBP-1 levels decreased by 50% over 2 h following the meal at a similar clearance in both the healthy controls and patients with T1DM, but no significant decline was seen in the patients with T2DM, despite a several-fold increase in insulin levels. The patients with T2DM were also studied during Sandostatin® (somatostatin) infusion to decrease the inappropriate secretion of glucagon during the meal. During the 210 min of somatostatin infusion, the glucagon response was suppressed and IGFBP-1 levels were increased concomitantly with the peak in insulin levels, without any significant decrease after the meal. In conclusion, the impaired IGFBP-1 response to meal-related hyperinsulinaemia in obese patients with T2DM suggests a decreased availability of active IGF-1, leading to a decrease in glucose uptake during and after a meal in these patients. The stimulated meal response to glucagon, which contributes to postprandial hyperglycaemia, could not explain the increase in serum IGFBP-1 in these obese patients with T2DM.