bluuebunny/crossref_metadata_2025 huggingface dataset:
A meteorite crater on Earth formed on September 15, 2007: The Carancas hypervelocity impact
Authors: Tancredi G. , Ishitsuka J. , Schultz P. H. , Harris R. S. , Brown P. , Revelle D. O. , Antier K. , Pichon A. Le , Rosales D. , Vidal E. , Varela M. E. , Sánchez L. , Benavente S. , Bojorquez J. , Cabezas D. , Dalmau A.
Published: February 2010

Abstract— On September 15, 2007, a bright fireball was observed and a big explosion was heard by many inhabitants near the southern shore of Lake Titicaca. In the community of Carancas (Peru), a 13.5 m crater and several fragments of a stony meteorite were found close to the site of the impact. The Carancas event is the first impact crater whose formation was directly observed by several witnesses as well as the first unambiguous seismic recording of a crater‐forming meteorite impact on Earth. We present several lines of evidence that suggest that the Carancas crater was a hypervelocity impact. An event like this should have not occurred according to the accepted picture of stony meteoroids ablating in the Earth's atmosphere, therefore it challenges our present models of entry dynamics. We discuss alternatives to explain this particular event. This emphasizes the weakness in the pervasive use of “average” parameters (such as tensile strength, fragmentation behavior and ablation behavior) in current modeling efforts. This underscores the need to examine a full range of possible values for these parameters when drawing general conclusions from models about impact processes.
Predictive and correlative techniques for the design, optimisation and manufacture of solid dosage forms
Authors: Hardy Ian J , Cook Walter G
Published: February 2010

There is much interest in predicting the properties of pharmaceutical dosage forms from the properties of the raw materials they contain. Achieving this with reasonable accuracy would aid the faster development and manufacture of dosage forms. A variety of approaches to prediction or correlation of properties are reviewed. These approaches have variable accuracy, with no single technique yet able to provide an accurate prediction of the overall properties of the dosage form. However, there have been some successes in predicting trends within a formulation series based on the physicochemical and mechanical properties of raw materials, predicting process scale-up through mechanical characterisation of materials and predicting product characteristics by process monitoring. Advances in information technology have increased predictive capability and accuracy by facilitating the analysis of complex multivariate data, mapping formulation characteristics and capturing past knowledge and experience.
Daily transdermal administration of selegiline to guinea-pigs preferentially inhibits monoamine oxidase activity in brain when compared with intestinal and hepatic tissues
Authors: Mawhinney Michael , Cole Dennis , Azzaro Albert J
Published: February 2010

Selegiline has been formulated in an acrylic polymer adhesive mixture to be employed as a constant release topical patch for daily transdermal administration. Application of this selegiline transdermal system (STS) to guinea-pigs resulted in an average delivery of 1.185 mg selegiline/cm2 patch/24 h. STS dose-response curves were generated by altering patch size (cm2). A transdermal dose range was identified which inhibited guinea-pig brain monoamine oxidase-B (MAO-B) by greater than 95 % yet provided for a dose-dependent inhibition of monoamine oxidase-A (MAO-A) activity. The ID50 for inhibition of MAO-A activity in response to a 21-day daily regimen with transdermal selegiline was approximately 7.5-fold lower for cortical and striatal brain regions compared with that obtained for duodenum; hepatic MAO-A was unaffected following the same dosing regimen. By contrast, orally administered selegiline inhibited brain and duodenal MAO-A to the same extent, and generated a shallower dose–inhibition curve for brain MAO-A inhibition. In addition, transdermal delivery was approximately 6–8-times more potent than oral selegiline for the inhibition of brain MAO-A activity. It is concluded that daily transdermal selegiline administration may provide therapeutic advantages over oral treatment, based on its preferential, dose-dependent inhibition of brain vs peripheral MAO-A activity.
Physical stability and enthalpy relaxation of drug-hydroxypropyl methylcellulose phthalate solvent change co-precipitates
Authors: Sertsou Gabriel , Butler James , Hempenstall John , Rades Thomas
Published: February 2010

The poorly water-soluble drug GWX was co-precipitated with hydroxypropyl methylcellulose phthalate (HPMCP) using a solvent change method. The two co-precipitate formulations made, with drug-HPMCP ratios of 2:8 and 5:5, were analysed using modulated temperature differential scanning calorimetry. They were found to consist of completely amorphous solid solution and a mixture of amorphous solid solution, crystalline drug and amorphous drug, respectively. Stability with respect to crystallization of the two co-precipitates and pure amorphous drug made by quench cooling was compared by storing preparations at 25°C and 40°C, under vacuum over P2O5, and at 75% relative humidity (r.h.). Humidity (75% r.h. compared with dry) had a larger influence on crystallization of the amorphous drug than temperature (25°C compared with 40°C). The solid solution phase in co-precipitates had a relatively higher stability than amorphous drug alone, with respect to crystallization, in presence of the plasticizer water, and crystalline drug. These findings were partly explained by evidence of decreased molecular mobility in the amorphous solid solution with respect to amorphous drug alone, using enthalpy relaxation measurements. At an ageing temperature of 65°C, the calculated half-life for enthalpy relaxation of the 2:8 drug–HPMCP ratio coprecipitate was about 6 orders of magnitude greater than that of amorphous drug alone, indicating a large difference in relative molecular mobility.
Influence of route of administration on the absorption and disposition of α,- γ- and δ-tocotrienols in rats
Authors: Yap Siew Ping , Yuen Kah Hay , Lim Ai Beoy
Published: February 2010

A study was conducted to evaluate the bioavailability of α-, γ- and δ-tocotrienols administered via oral, intravenous, intramuscular and intraperitoneal routes in rats. Three separate experiments, each conducted according to a two-way crossover design, were carried out to compare intravenous and oral, intramuscular and oral, and intraperitoneal and oral administration. Oral absorption of all three tocotrienols was found to be incomplete. Of the three tocotrienols, α-tocotrienol had the highest oral bioavailability, at about 27.7 ± 9.2%, compared with γ- and δ-tocotrienols, which had values of 9.1 ± 2.4% and 8.5 ± 3.5%, respectively. Such biodiscrimination was also observed in their total clearance rates (estimated from the intravenous data). α-Tocotrienol showed the lowest clearance rate at about 0.16 L kg−1 h−1, whereas that of δ- and γ-tocotrienols was quite similar, with values of 0.24 and 0.23 L kg−1 h−1, respectively. Interestingly, all three tocotrienols were found to be negligibly absorbed when administered intraperitoneally and intramuscularly. Thus, these two routes of administration should be avoided when evaluating the biological activities of the tocotrienols in whole animal experiments.
Age-related alteration of haloperidol–serum protein binding
Authors: Koyama Hikaru , Mori Satoru , Sugioka Nobuyuki , Nishihara Takehiro , Nakajima Kenji
Published: February 2010

Serum haloperidol levels were determined in 59 patients, 50–88 years old, with psychosis, receiving long-term treatment with haloperidol. Although the total (bound and free form) haloperidol level in serum showed a linear correlation with daily dose, there was a larger variation in the relationship between free form and the daily dose compared with total because of inter-individual variation in the serum protein binding of haloperidol. The free fraction of haloperidol in serum increased with age. There was no difference in the ratio of total haloperidol level per daily dose between the adult and elderly groups, whereas the ratio of free haloperidol level per daily dose was significantly higher in the elderly than in the adult group. In the elderly, therefore, the therapeutic window of haloperidol should be assessed using free form level ratherthan total level, which is influenced by serum protein binding of the drug.
Involvement of nuclear factor-κB in lipoteichoic acid-induced cyclooxygenase-2 expression in RAW 264.7 macrophages
Authors: Chiang L L , Kuo C T , Wang C H , Chen T F , Ho Y S , Kuo H P , Lin C H
Published: February 2010

We have investigated the role of protein kinase C (PKC) and nuclear factor-κB (NF-κB) in cyclooxygenase-2 (COX-2) expression caused by Staphylococcus aureus lipoteichoic acid in RAW 264.7 macrophages. A phosphatidylcholine-phospholipase C (PC-PLQ inhibitor (D-609) and a phosphatidyl-inositol-phospholipase C (Pl-PLC) inhibitor (U-73122) attenuated lipoteichoic acid-induced COX-2 expression, while a phosphatidate phosphohydrolase inhibitor (propranolol) had no effect. Two PKC inhibitors (Go 6976 and Ro 31–8220) and the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), also attenuated lipoteichoic acid-induced COX-2 expression. Lipoteichoic acid resulted in a decrease in PKC activity in the cytosol and an increase in PKC activity in membranes. The lipoteichoic acid-induced translocation of p65 NF-κB from the cytosol to the nucleus was inhibited by D-609, U-73122, Go 6976, Ro 31–8220, and PDTC., but not by propranolol. The results suggested that lipoteichoic acid might have activated PC-PLC and Pl-PLC to induce PKC activation, which in turn initiated NF-κB activation, and finally induced COX-2 expression in RAW 264.7 macrophages.
Assessment and prevention of gastrointestinal toxicity of non-steroidal anti-inflammatory drugs
Authors: Lane Majella E , Kim Mi-Jeong
Published: February 2010

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for analgesic, anti-inflammatory and, in the case of aspirin, for anti-thrombotic actions. The serious gastrointestinal side-effects associated with these drugs are of concern and pose a significant obstacle to their use. This review discusses the pathogenic mechanisms by which the conventional acidic NSAIDs induce gastrointestinal toxicity, with particular emphasis on non-prostaglandin effects. Methods of assessment of NSAID-induced enteropathy are reviewed, with particular emphasis on the use of functional measurement of NSAID-induced changes in the gastrointestinal tract. The advances in our knowledge of the pathogenesis of these effects have resulted in the development of a range of novel NSAIDs. Where functional assessment of the effects of NSAIDs has been employed, it appears to be more useful as an indicator of early-stage changes rather than a predictor of the effects of long-term NSAID exposure. Successful pharmaceutical strategies now offer considerable promise for reducing the severity of NSAID damage to the gastrointestinal tract. The utility of intestinal permeability measurements for selection and assessment of these strategies is discussed.
Science to Bridge the Americas
Authors: DeVoogd Timothy J.
Published: February 2010

It is broadly recognized across the Western Hemisphere that science can provide answers to health and environmental problems and stimulate national development. But in a given region, scientists often face overwhelming barriers to conducting research, and there is far too little interaction among academia, industry, and government on an international level to effect change. Scientists in developing regions have repeatedly raised ways in which help from the United States could be transformational. It is now time to do more.
CKAMP44: A Brain-Specific Protein Attenuating Short-Term Synaptic Plasticity in the Dentate Gyrus
Authors: von Engelhardt Jakob , Mack Volker , Sprengel Rolf , Kavenstock Netta , Li Ka Wan , Stern-Bach Yael , Smit August B. , Seeburg Peter H. , Monyer Hannah
Published: February 2010

Dancing with AMPARs

A type of transmembrane receptor for glutamate, known as AMPAR, mediates most of the fast excitatory transmission in the mammalian central nervous system. Their function is regulated by the composition of their subunits, posttranslational modifications, and protein-protein interactions. Recently, several proteins that interact with AMPARs have been identified that affect their subcellular localization, synaptic stabilization, and kinetics. Using proteomic analysis, immunohistochemistry, and electrophysiology,

von Engelhardt
et al.

(p.
1518
, published online 25 February; see the Perspective by

Farrant and Cull-Candy

) identified a protein, CKAMP44, which modulates postsynaptic AMPA receptor gating, deactivation, and desentization.
Constraints on the Formation Age of Cometary Material from the NASA Stardust Mission
Authors: Matzel J. E. P. , Ishii H. A. , Joswiak D. , Hutcheon I. D. , Bradley J. P. , Brownlee D. , Weber P. K. , Teslich N. , Matrajt G. , McKeegan K. D. , MacPherson G. J.
Published: February 2010

Sun Stuff

Comets are thought to be remnants of the Sun's protoplanetary disk; hence, they hold important clues to the processes that originated the solar system.

Matzel
et al.

(p.
483
, published online 25 February) present Al-Mg isotope data on a refractory particle recovered from comet Wild 2 by the NASA Stardust mission. The lack of evidence for the extinct radiogenic isotope
26
Al implies that this particle crystallized 1.7 million years after the formation of the oldest solar system solids. This observation, in turn, requires that material formed near the Sun was transported to the outer reaches of the solar system and incorporated into comets over a period of at least two million years.
Is a Dolphin a Person?
Authors: Grimm David
Published: February 2010

Are dolphins as smart as people? And if so, shouldn't we be treating them a bit better? Those were the questions scientists and philosophers debated at a session at the annual meeting of the American Association for the Advancement of Science.
NEUTRINO OSCILLATIONS IN A MINIMAL CPT VIOLATION FRAME
Authors: ARIAS PAOLA , GAMBOA J.
Published: February 2010

The oscillation neutrino problem in the extended standard model with minimal number of parameters is considered. The dispersion relations with explicit neutrino–antineutrino asymmetry are discussed and an explanation to the MINIBooNE and solar neutrino controversy is offered. Bounds for the CPT violation symmetry are also found.
FAST A* WITH ITERATIVE RESOLUTION FOR NAVIGATION
Authors: WALSH KYLE , BANERJEE BIKRAMJIT
Published: February 2010

We argue that A*, the popular technique for path-finding for NPCs in games, suffers from three limitations that are pertinent to game worlds: (a) the grid maps often restrict the optimality of the paths, (b) A* paths exhibit wall-hugging behavior, and (c) optimal paths are more predictable. We present a new algorithm, VRA*, that varies map-resolution as needed, and repeatedly calls A*. We also present an extension of an existing post-smoothing technique, and show that these two techniques together produce more realistic looking paths than A*, that overcome the above limitations, while using significantly less memory and time than A*.
Kung Long's Big Dream of the Blue Ocean
Authors: Lin Chiawu , Chu Tsai-Hsin , Chang Kuo-I
Published: February 2010

This case discussion looks at the challenges that an enterprise might face during its transition into a new industry by describing Kung Long Corporation's transition from the stone industry to the deep-sea water industry. Kung Long's case reveals the importance of strategy formulation when an enterprise shifts into a new and unfamiliar industry. The effectiveness of strategy formulation depends not only on how well the five essential elements (i.e., arenas, vehicles, differentiators, staging, and economic logic) are integrated into the strategy (Hambrick and Fredrickson, 2001), but also on the strategy maker's awareness of the differences between industrial properties and, thereafter, changing her or his mindset accordingly (Ansoff, 1990). In this case analysis, we firstly assess Kung Long's advantages and its limitations in the deep-sea water industry. Then, we look into the two important challenges for strategy formation. First of all, we focus on Kung Long's strategy in the deep-sea water industry and analyze the integration level of the five dimensions in strategy formation (Hambrick and Fredrickson, 2001), so as to highlight the potential problems in Kung Long's current strategy. Second, we illustrate the challenge of management mentality in this transition into deep-sea water business. In this part, we discuss the differences between the stone industry and the deep-sea water industry in order to present the managerial challenges that Kung Long needs to overcome. Finally, we apply the perspective of double-loop learning (Sterman, 1994) to recommend the learning style and mentality that best suit the deep-sea water industry.
Diffusion of Innovative Teaching Method: Case of The Heritage School (A) and (B)
Authors: Dasgupta Meeta , Sahay Arun
Published: February 2010

This case comes in two parts: case (A) and (B). It traces the journey of The Heritage School, Gurgaon (India) from 2003, when the school was deliberating to launch an innovative teaching methodology in the junior school to 2007 when the school had to make a decision whether to extend the teaching methodology to the senior school. The new teaching methodology based on experiential and project based learning, questions the relevance of the conventional teaching methodology which was based on memorization of content. The case highlights the changing opinion and attitude of the teachers and parents, towards the new teaching methodology. It also deals with how the school management went about implementing the innovative teaching methodology. The case allows students to examine the fundamental challenges in diffusion or acceptance of innovation by potential users. It aims to discuss the dynamics of the innovation and diffusion process, and the factors which drive or hinder the process of diffusion.
Knowing When to Merge: A Small IT Business in Korea Considers Its Options
Authors: Park Chan-Soo
Published: February 2010

This case study focuses on how a Korean software firm, CCMedia, executed a successful global strategy by merging with its technology partner to gain access to international markets. The case study also reviews the key challenges CCMedia faced after the merger. Intangible assets, such as IT technology, could allow CCMedia to earn overseas capital investment through the merger. With capital and human resources backup from IT Inspire Inc., its former technology partner, CCMedia could enter foreign markets. This case examines the transformation of a strategic technology alliance to a hierarchical structure as a result of a merger. It shows that technology-related alliances could play an important role in possible takeover activities. It provides insights into strategies that technology-based small businesses in Korea could follow to enter international markets.
South Beauty Group: In Quest of a 'Beautiful' Growth Story
Authors: Xu Leiping , Velamuri S. Ramakrishna
Published: February 2010

Since the 1990s, China's catering industry had boomed sharply with over 15% CAGR (Compound Annual Growth Rate). In 2007, the catering market size of RMB1,200 billion (US$155 billion) accounted for 4.87% of GDP (Gross Domestic Product) in China. This percentage was only 1.5% in 1978. China's restaurant market was in a typical state of perfect competition, not only in terms of the number of players, but also in terms of the food varieties. Intrigued by the successful story of western fast food in China, the leading Chinese players were exploring how to expand their scale through the development of restaurant chains. Considering the difficulties of standardizing Chinese cuisine, the scale expansion of the Chinese Dinner segment was slower than that of Hot Pot and Chinese fast food segments.

It was October 18th, 2007. As an innovative upper-middle player in the Chinese Dinner segment, the South Beauty Group, with 20 restaurants and two soon-to-be-opened restaurants under three different brands, was dreaming about expanding its scale to 100 restaurants in three years (35 in China and 65 in the international market). To meet this ambitious target, the Group faced many challenges, including standardizing Chinese cuisine, selection of domestic and international locations, development of franchising operations and the launch of an IPO. Moreover, as the only Food Service Partner of Chinese cuisine for the 2008 Beijing Olympics, the Group also had to organize the company's resources efficiently to fulfill this prestigious contract.

This case had been developed mainly for MBA and EMBA students, with the main teaching objective being to understand the challenges of growth. The students will also be exposed to the dynamic Chinese business environment and the dreams, innovativeness and decision-making behaviors of Chinese entrepreneurs, even in such a traditional industry. An audio-visual support, including an introduction to the company, the restaurants and the dishes, and two interviews with Ms. Zhang Lan is available to instructors.
COMPACT REPRESENTATION AND PANORAMIC REPRESENTATION FOR CAPSULE ENDOSCOPE IMAGES
Authors: HU CHAO , LIU LI , SUN BO , MENG MAX Q.-H.
Published: February 2010

A capsule endoscope robot is a miniature medical instrument for inspection of gastrointestinal tract. In this paper, we present image compact representation and preliminary panoramic representation methods for the capsule endoscope. First, the characteristics of the capsule endoscopic images are investigated and different coordinate representations of the circular image are discussed. Secondly, effective compact representation methods including special DPCM and wavelet compression techniques are applied to the endoscopic images to get high compression ratio and signal to noise ratio. Then, a preliminary approach to panoramic representation of endoscopic images is presented.
SYNTHESIS OF FULLEROPYRROLIDINE PYRIDINIUM SALTS BY FACILE ANION EXCHANGE AND THEIR SOLUBILITY
Authors: TOLLAN CHRISTOPHER M. , POMPOSO JOSE A. , MECERREYES DAVID
Published: February 2010

Several ionic fullerene salts have been prepared based on a fulleropyrrolidine pyridinium cation and four different anions. The initial ionic fullerene can be easily prepared by quaternization of a pyridine-appended fulleropyrrolidine derivative in high yield. Anion exchange is a simple procedure giving several different salts of varying polarity. In addition to their characterization, the quantitative solubility of these salts has been studied in seven different solvents, including an imidazolium ionic liquid.
Differential processing of pro-glucose-dependent insulinotropic polypeptide in gut
Authors: Fujita Yukihiro , Asadi Ali , Yang Gary K. , Kwok Yin Nam , Kieffer Timothy J.
Published: February 2010

Glucose-dependent insulinotropic polypeptide (GIP) is a hormone released from enteroendocrine K cells in response to meals. Posttranslational processing of the precursor protein pro-GIP at residue 65 by proprotein convertase subtilisin/kexin type 1 (PC1/3) in gut K cells gives rise to the established 42-amino-acid form of GIP (GIP1–42). However, the pro-GIP peptide sequence contains a consensus cleavage site for PC2 at residues 52–55 and we identified PC2 immunoreactivity in a subset of K cells, suggesting the potential existence of a COOH-terminal truncated GIP isoform, GIP1–30. Indeed a subset of mouse and human K cells display GIP immunoreactivity with GIP antibodies directed to the mid portion of the peptide, but not with a COOH-terminal-directed GIP antibody, indicative of the presence of a truncated form of GIP. This population of cells represents ∼5–15% of the total GIP-immunoreactive cells in mice, depending on the region of intestine, and is virtually absent in mice lacking PC2. Amidated GIP1–30and GIP1–42have comparable potency at stimulating somatostatin release in the perfused mouse stomach. Therefore, GIP1–30represents a naturally occurring, biologically active form of GIP.
Advances of endomicroscopy for gastrointestinal physiology and diseases
Authors: Goetz Martin , Kiesslich Ralf
Published: February 2010

Confocal endomicroscopy is a novel technique that permits in vivo microscopy of the human gastrointestinal mucosa during ongoing endoscopy, thereby providing optical virtual biopsies. Endomicroscopy has been demonstrated to reveal histological information in a multitude of diseases in the upper and lower gastrointestinal tract in vivo. Most studies have focused on inflammation and neoplasia, such as Barrett's esophagus, gastric cancer, celiac disease, Crohn's disease and ulcerative colitis, or colorectal neoplasias. Endomicroscopy allows obtainment of “smart,” targeted biopsies from regions with microscopic alterations rather than having to rely on random untargeted tissue sampling. This reduces the number of biopsies while increasing the diagnostic yield. In addition, immediate histological information is available, enabling immediate therapy. Apart from morphological visualization, endomicroscopy offers a unique possibility to study pathophysiological events in their natural environment (functional imaging). Molecular imaging with endomicroscopy applied in clinical and basic science will permit advances in understanding of the cellular basis of gastrointestinal physiology and pathophysiology.
Amplification loop of the inflammatory process is induced by P2X7R activation in intestinal epithelial cells in response to neutrophil transepithelial migration
Authors: Cesaro Annabelle , Brest Patrick , Hofman Véronique , Hébuterne Xavier , Wildman Scott , Ferrua Bernard , Marchetti Sandrine , Doglio Alain , Vouret-Craviari Valérie , Galland Franck , Naquet Philippe , Mograbi Baharia , Unwin Robert , Hofman Paul
Published: February 2010

Inflammatory bowel diseases (IBD) are characterized during their active phase by polymorphonuclear leukocyte (PMNL) transepithelial migration. The efflux of PMNL into the mucosa is associated with the production of proinflammatory cytokines and the release of ATP from damaged and necrotic cells. The expression and function of purinergic P2X7receptor (P2X7R) in intestinal epithelial cells (IEC) and its potential role in the “cross talk” between IEC and PMNL have not been explored. The aims of the present study were 1) to examine P2X7R expression in IEC (T84 cells) and in human intestinal biopsies; 2) to detect any changes in P2X7R expression in T84 cells during PMNL transepithelial migration, and during the active and quiescent phases of IBD; and 3) to test whether P2X7R stimulation in T84 monolayers can induce caspase-1 activation and IL-1β release by IEC. We found that a functional ATP-sensitive P2X7R is constitutively expressed at the apical surface of IEC T84 cells. PMNL transmigration regulates dynamically P2X7R expression and alters its distribution from the apical to basolateral surface of IEC during the early phase of PMNL transepithelial migration in vitro. P2X7R expression was weak in intestinal biopsies obtained during the active phase of IBD. We show that activation of epithelial P2X7R is mandatory for PMNL-induced caspase-1 activation and IL-1β release by IEC. Overall, these changes in P2X7R function may serve to tailor the intensity of the inflammatory response and to prevent IL-1β overproduction and inflammatory disease.
Presynaptic inhibition of neural vasodilator pathways to submucosal arterioles by release of purines from sympathetic nerves
Authors: Lomax Alan E. , Vanner Stephen J.
Published: February 2010

Capsaicin-sensitive extrinsic sensory nerves and submucosal vasodilator neurons provide important vasodilator input to submucosal arterioles, but relatively little is known about the signaling between these populations and the sympathetic vasoconstrictor innervation. This study examined whether release of sympathetic purines can modulate dilator nerves. In vitro submucosal preparations from guinea pig ileum were modified to leave the parent mesenteric artery intact so that perivascular sympathetic and extrinsic afferent nerves could be activated by a bipolar stimulating electrode placed on the parent artery, and submucosal vasodilator neurons were activated using focal electrodes placed on submucosal ganglia. The outside diameter of submucosal arterioles was monitored using videomicroscopy, and dilator responses were examined after preconstricting vessels 80–95% with prostaglandin F2α(400 nM). Mesenteric nerve stimulation evoked a frequency-dependent dilation, with suramin (100 μM) present throughout to inhibit P2Xreceptor-mediated vasoconstrictions. In the presence of guanethidine (10 μM) to inhibit sympathetic purine release, superfusion of ATP (200 nM-6 μM) caused a concentration-dependent inhibition of nerve-evoked dilations. Vasodilations to substance P (10 nM) were not inhibited by ATP in the presence of guanethidine, implicating a presynaptic effect of ATP on neurotransmitter release. The inhibitory effect of ATP was blocked by the adenosine receptor antagonist 8-phenyltheophylline (8-PT; 10 μM). In addition, 8-PT increased the amplitude of nerve-evoked dilations, suggesting a tonic inhibitory effect of adenosine receptors on vasodilator release. Dilations evoked by electrical stimulation of submucosal ganglia were also inhibited almost 50% by ATP (2 μM) and its nonhydrolyzable analog, α,β-methylene-ATP (10 μM). These data suggest that sympathetic varicosities release ATP or a related purine that can act at presynaptic adenosine receptors on extrinsic sensory and submucosal vasodilator neurons to inhibit neurotransmitter release.
Tetrahydrobiopterin (BH4), a cofactor for nNOS, restores gastric emptying and nNOS expression in female diabetic rats
Authors: Gangula Pandu R. R. , Mukhopadhyay Sutapa , Ravella Kalpana , Cai Shijie , Channon Keith M. , Garfield Robert E. , Pasricha Pankaj J.
Published: February 2010

Gastroparesis is a debilitating disease predominantly affecting young women. Recently, dysregulation of neuronal nitric oxide synthase (nNOS) in myenteric plexus neurons has been implicated for delayed solid gastric emptying/gastroparesis in diabetic patients. In this study, we have explored the role of tetrahydrobiopterin (BH4), a major cofactor for nNOS activity and NO synthesis in diabetic gastroparesis. Diabetes was induced with single injection of streptozotocin (55 mg/kg body wt, ip) in female rats, with experiments performed on week 3 or 9 following induction, with or without 3-wk BH4 supplementation. Gastric pyloric BH4 levels were significantly decreased in diabetic female rats compared with control (18.6 ± 1.45 vs. 31.0 ± 2.31 pmol/mg protein). In vitro studies showed that 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of BH4 synthesis, significantly decreased gastric NO release and nitrergic relaxation. Three-week dietary supplementation of BH4 either from day 1 or week 6 significantly attenuated diabetes-induced delayed gastric emptying for solids (3 wk: BH4, 67 ± 6.7 vs. diabetic, 36.05 ± 7.09; 9 wk: BH4, 57 ± 8.45 vs. diabetic, 33 ± 9.91) and diabetes-induced reduction in pyloric nNOS-α protein expression in female rats. Supplementation of BH4 significantly restored gastric nNOS-α dimerization in 9-wk-old diabetic female rats. In addition, BH4 treatment reversed (17.23 ± 5.81 vs. 42.0 ± 2.70 mmHg × s) the diabetes-induced changes in intragastric pressures (IGP) and gastric pyloric nitrergic relaxation (−0.62 ± 0.01 vs. −0.22 ± 0.07). BH4 deficiency plays a critical role in diabetes-induced alterations including delayed solid gastric emptying, increased IGP, reduced pyloric nitrergic relaxation, and nNOS-α expression in female rats. Supplementation of BH4 accelerates gastric emptying by restoring nitrergic system in diabetic female rats. Therefore, BH4 supplementation is a potential therapeutic option for female patients of diabetic gastroparesis.
Sox9expression marks a subset of CD24-expressing small intestine epithelial stem cells that form organoids in vitro
Authors: Gracz Adam D. , Ramalingam Sendhilnathan , Magness Scott T.
Published: February 2010

The inability to identify, isolate, and culture intestinal epithelial stem cells (IESCs) has been prohibitive to the study and therapeutic utilization of these cells. Using a Sox9EGFPmouse model, we demonstrate that Sox9EGFPfluorescence signatures can be used to differentiate between and enrich for progenitors ( Sox9EGFPsubLo) and multipotent IESCs ( Sox9EGFPlo). Sox9EGFPlocells generate “organoids” in a recently defined culture system that mimics the native IESC niche. These organoids possess all four differentiated cell types of the small intestine epithelium, demonstrating the multipotent capacity of Sox9EGFPlocells. Our results are consistent with the previously reported observation that single IESCs generate cryptlike units without a detectable mesenchymal cell component. A prospective search revealed that CD24 is expressed in the Sox9EGFPlopopulation and marks IESCs that form organoids in culture. CD24 represents the first cell surface marker that facilitates fluorescence-activated cell sorting enrichment of IESCs with widely available antibodies without requiring a specialized fluorescent reporter gene mouse model.
Additive effect of contraction and insulin on glucose uptake and glycogen synthase in muscle with different glycogen contents
Authors: Lai Yu-Chiang , Zarrinpashneh Elham , Jensen Jørgen
Published: February 2010

Insulin and contraction regulate glucose uptake and glycogen synthase (GS) via distinct mechanisms in skeletal muscles, and an additive effect has been reported. Glycogen content is known to influence both contraction- and insulin-stimulated glucose uptake and GS activity. Our study reports that contraction and insulin additively stimulate glucose uptake in rat epitrochlearis muscles with normal (NG) and high (HG) glycogen contents, but the additive effect was only partial. In muscles with low glycogen (LG) content no additive effect was seen, but glucose uptake was higher in LG than in NG and HG during contraction, insulin stimulation, and when the two stimuli were combined. In LG, contraction-stimulated AMP-activated protein kinase (AMPK) activity and insulin-stimulated PKB phosphorylation were higher than in NG and HG, but phosphorylation of Akt substrate of 160 kDa was not elevated correspondingly. GLUT4 content was 50% increased in LG (rats fasted 24 h), which may explain the increased glucose uptake. Contraction and insulin also additively increased GS fractional activity in NG and HG but not in LG. GS fractional activity correlated most strongly with GS Ser641phosphorylation ( R −0.94, P < 0.001). GS fractional activity also correlated with GS Ser7,10phosphorylation, but insulin did not reduce GS Ser7,10phosphorylation. In conclusion, an additive effect of contraction and insulin on glucose uptake and GS activity occurs in muscles with normal and high glycogen content but not in muscles with low glycogen content. Furthermore, contraction, insulin, and glycogen content all regulate GS Ser641phosphorylation and GS fractional activity in concert.
Low flow-mediated constriction occurs in the radial but not the brachial artery in healthy pregnant and nonpregnant women
Authors: Weissgerber Tracey L. , Davies Gregory A. L. , Tschakovsky Michael E.
Published: February 2010

Radial artery diameter decreases when a wrist cuff is inflated to stop blood flow to distal tissue. This phenomenon, referred to as low flow-mediated vasoconstriction (L-FMC), was proposed as a vascular function test. Recommendations that L-FMC be measured concurrently with flow-mediated dilation (FMD) were based on radial artery data. However, cardiovascular disease prediction studies traditionally measure brachial artery FMD. Therefore, studies should determine whether L-FMC occurs in the brachial artery. The hypothesis that reduced shear causes L-FMC has not been tested. Brachial and radial artery L-FMC and FMD were assessed in active nonpregnant ( n = 17), inactive nonpregnant ( n = 10), active pregnant ( n = 15, 34.1 ± 1.2 wk gestation), and inactive pregnant ( n = 8, 34.2 ± 2.2 wk gestation) women. Radial artery diameter decreased significantly during occlusion in all groups (nonpregnant, −4.4 ± 4.2%; pregnant, −6.4 ± 3.2%). Brachial artery diameter did not change in active and inactive nonpregnant, and inactive pregnant women; however, the small decrease in active pregnant women was significant. Occlusion decreased shear rate in both arteries, yet L-FMC only occurred in the radial artery. Radial artery L-FMC was not correlated with the reduction in shear rate. L-FMC occurs in the radial but not the brachial artery and is not related to changes in shear rate. Positive correlations between L-FMC (negative values) and FMD (positive values) suggest that radial artery FMD may be reduced among women who experience greater L-FMC. Studies should clarify the underlying stimulus and mechanisms regulating L-FMC, and test the hypothesis that endothelial dysfunction is manifested as enhanced brachial artery L-FMC, but attenuated radial artery L-FMC.
Extent to which pulmonary vascular responses to Pco2 and Po2 play a functional role within the healthy human lung
Authors: Dorrington Keith L. , Balanos George M. , Talbot Nick P. , Robbins Peter A.
Published: February 2010

Regional blood flow in the lung is known to be influenced by the alveolar Pco2 and alveolar Po2. For the healthy lung, the extent to which this influence is of functional importance in limiting heterogeneity in alveolar gas composition by matching regional perfusion (q̇) to regional ventilation (v̇) remains unclear. To address this issue, the efficiency of regulation ( E) was defined as the percent correction to an initial perturbation in regional alveolar gas composition generated by the pulmonary vascular response to the disturbance. This study develops the theory to calculate E from global measurements of vascular reactivity to CO2 and O2 in human volunteers. For O2, these data were available from the literature. For CO2, an experimental component of the present study used Doppler echocardiography to evaluate the magnitude of the global vascular response to hypercapnia and hypocapnia in 12 volunteers over a timescale of ∼0.5 h. The results suggest a value for E of ∼60% over a wide range of values for v̇-to-q̇ ratio (∼0.1–10) encompassing those found in normal lung. At low v̇/q̇ (<0.65), the vascular response to O2 forms the dominant mechanism; however, at higher v̇/q̇ (>0.65), the response to CO2 dominates. The values for E suggest that the pulmonary vascular responses to both CO2 and O2 play a significant role in ventilation-perfusion matching in the healthy human lung.
Cortical and brain stem changes in neural activity during static handgrip and postexercise ischemia in humans
Authors: Sander Mikael , Macefield Vaughan G. , Henderson Luke A.
Published: February 2010

Static isometric exercise increases muscle sympathetic nerve activity (MSNA) and mean arterial pressure, both of which can be maintained at the conclusion of the exercise by occlusion of the arterial supply [postexercise ischemia (PEI)]. To identify the cortical and subcortical sites involved, and to differentiate between central command and reflex inputs, we used blood oxygen level-dependent (BOLD) functional MRI (fMRI) of the whole brain (3 T). Subjects performed submaximal static handgrip exercise for 2 min followed by 6 min of PEI; MSNA was recorded on a separate day. During the contraction phase, parallel increases in BOLD signal intensity occurred in the contralateral primary motor cortex and cerebellar nuclei and cortex; these matched the effort profile and ceased at the conclusion of the contraction. Progressive increases in the contralateral insula and primary and secondary somatosensory cortices, with progressive decreases in the perigenual anterior cingulate and midcingulate cortices, were sustained during the period of PEI and thus did not depend on central command. Discrete bilateral activation of the medial and lateral dorsal medulla was also observed during the contraction and PEI; we believe that these represent the nucleus tracts solitarius (NTS) and rostral ventrolateral medulla (RVLM), respectively. Given that metaboreceptor afferents are known to project to the NTS and that the RVLM is the primary output nucleus for MSNA, our data support that the metaboreflex is mediated by the medulla, whereas the somatosensory, insular, and anterior cingulate cortices are involved in the sensory and affective components of the maneuver.
Therapeutically Relevant Concentrations of Raloxifene Dilate Pressurized Rat Resistance Arteries via Calcium-Dependent Endothelial Nitric Oxide Synthase Activation
Authors: Chan Yau Chi , Leung Fung Ping , Wong Wing Tak , Tian Xiao Yu , Yung Lai Ming , Lau Chi Wai , Tsang Suk Ying , Yao Xiaoqiang , Chen Zhen Yu , Huang Yu
Published: February 2010

Objective—

Selective estrogen receptor modulators (SERMs) inhibit constriction of mammalian conduit arteries. However, it is unknown whether SERMs at therapeutically achievable concentrations could reduce vascular tone in resistance arteries. The present study aimed to examine roles of Ca
2+
influx in endothelium and endothelial nitric oxide synthase (eNOS) activation in dilatations induced by raloxifene, a second-generation SERM in myogenically active arteries.

Methods and Results—

Small mesenteric arteries from Sprague-Dawley rats were isolated and mounted in a pressure myograph for measurement of changes in vessel diameter. [Ca
2+
]
i
images on native endothelial cells of intact arteries were determined by the fluorescence imaging technique, and phosphorylation of eNOS was assayed by Western blotting. Raloxifene (0.3 to 10 nmol/L) produced dilatations on established steady myogenic constriction. Female rat arteries dilated significantly more in response to raloxifene than male arteries. Raloxifene-induced dilatations of female arteries were blunted by
N
G
-nitro-
l
-arginine methyl ester but unaffected by 1400W, charybdotoxin plus apamin, wortmannin, or LY294002. Raloxifene (3 nmol/L) triggered rises in endothelial cell [Ca
2+
]
i
and increased eNOS phosphorylation at Ser1177. Both effects were greater in arteries from female rats than in arteries from male rats. Increases in endothelial cell [Ca
2+
]
i
and in eNOS phosphorylation were prevented by removal of extracellular Ca
2+
ions. Finally, ICI 182,780 did not affect the raloxifene-stimulated rise in endothelial cell [Ca
2+
]
i
, eNOS phosphorylation, and vasodilatations. Chronic raloxifene treatment reduced myogenic constriction in arteries from female but not male rats.

Conclusion—

Raloxifene at therapeutically relevant concentrations inhibits myogenic constriction by an NO-dependent mechanism that causally involves the elevated [Ca
2+
]
i
in endothelial cells and subsequent eNOS activation. Raloxifene dilates resistance arteries more effectively in female rats, indicating its significant gender-related action on endothelial cells in microcirculation.
Sox2 Transduction Enhances Cardiovascular Repair Capacity of Blood-Derived Mesoangioblasts
Authors: Koyanagi Masamichi , Iwasaki Masayoshi , Rupp Stefan , Tedesco Francesco Saverio , Yoon Chang-Hwan , Boeckel Jes-Niels , Trauth Janina , Schütz Corina , Ohtani Kisho , Goetz Rebekka , Iekushi Kazuma , Bushoven Philipp , Momma Stefan , Mummery Christine , Passier Robert , Henschler Reinhard , Akintuerk Hakan , Schranz Dietmar , Urbich Carmen , Galvez Beatriz G. , Cossu Giulio , Zeiher Andreas M. , Dimmeler Stefanie
Published: February 2010

Rationale
:

Complementation of pluripotency genes may improve adult stem cell functions.

Objectives
:

Here we show that clonally expandable, telomerase expressing progenitor cells can be isolated from peripheral blood of children. The surface marker profile of the clonally expanded cells is distinct from hematopoietic or mesenchymal stromal cells, and resembles that of embryonic multipotent mesoangioblasts. Cell numbers and proliferative capacity correlated with donor age. Isolated circulating mesoangioblasts (cMABs) express the pluripotency markers Klf4, c-Myc, as well as low levels of Oct3/4, but lack Sox2. Therefore, we tested whether overexpression of Sox2 enhances pluripotency and facilitates differentiation of cMABs in cardiovascular lineages.

Methods and Results
:

Lentiviral transduction of Sox2 (Sox-MABs) enhanced the capacity of cMABs to differentiate into endothelial cells and cardiomyocytes in vitro. Furthermore, the number of smooth muscle actin positive cells was higher in Sox-MABs. In addition, pluripotency of Sox-MABs was shown by demonstrating the generation of endodermal and ectodermal progenies. To test whether Sox-MABs may exhibit improved therapeutic potential, we injected Sox-MABs into nude mice after acute myocardial infarction. Four weeks after cell therapy with Sox-MABs, cardiac function was significantly improved compared to mice treated with control cMABs. Furthermore, cell therapy with Sox-MABs resulted in increased number of differentiated cardiomyocytes, endothelial cells, and smooth muscle cells in vivo.

Conclusions
:

The complementation of Sox2 in Oct3/4-, Klf4-, and c-Myc-expressing cMABs enhanced the differentiation into all 3 cardiovascular lineages and improved the functional recovery after acute myocardial infarction.
Wt1 and Retinoic Acid Signaling in the Subcoelomic Mesenchyme Control the Development of the Pleuropericardial Membranes and the Sinus Horns
Authors: Norden Julia , Grieskamp Thomas , Lausch Ekkehart , van Wijk Bram , van den Hoff Maurice J.B. , Englert Christoph , Petry Marianne , Mommersteeg Mathilda T.M. , Christoffels Vincent M. , Niederreither Karen , Kispert Andreas
Published: February 2010

Rationale
:

The cardiac venous pole is a common focus of congenital malformations and atrial arrhythmias, yet little is known about the cellular and molecular mechanisms that regulate its development. The systemic venous return myocardium (sinus node and sinus horns) forms only late in cardiogenesis from a pool of pericardial mesenchymal precursor cells.

Objective
:

To analyze the cellular and molecular mechanisms directing the formation of the fetal sinus horns.

Methods and Results
:

We analyzed embryos deficient for the
Wt1
(Wilms tumor 1) gene and observed a failure to form myocardialized sinus horns. Instead, the cardinal veins become embedded laterally in the pleuropericardial membranes that remain tethered to the lateral body wall by the persisting subcoelomic mesenchyme, a finding that correlates with decreased apoptosis in this region. We show by expression analysis and lineage tracing studies that
Wt1
is expressed in the subcoelomic mesenchyme surrounding the cardinal veins, but that this
Wt1
-positive mesenchyme does not contribute cells to the sinus horn myocardium. Expression of the
Raldh2
(aldehyde dehydrogenase family 1, subfamily A2) gene was lost from this mesenchyme in
Wt1
−
/
−
embryos. Phenotypic analysis of
Raldh2
mutant mice rescued from early cardiac defects by retinoic acid food supply revealed defects of the venous pole and pericardium highly similar to those of
Wt1
−
/
−
mice.

Conclusions
:

Pericardium and sinus horn formation are coupled and depend on the expansion and correct temporal release of pleuropericardial membranes from the underlying subcoelomic mesenchyme.
Wt1
and downstream
Raldh2
/retinoic acid signaling are crucial regulators of this process. Thus, our results provide novel insight into the genetic and cellular pathways regulating the posterior extension of the mammalian heart and the formation of its coelomic lining.