bluuebunny/crossref_metadata_2025 huggingface dataset:
Respiratory modulation of the autonomic nervous system during Cheyne–Stokes respirationThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigator's Forum.
Authors: Leung Richard S.T. , Floras John S. , Bradley T. Douglas
Published: April 2006

Cheyne–Stokes respiration (CSR) is associated with increased mortality among patients with heart failure. However, the specific link between CSR and mortality remains unclear. One possibility is that CSR results in excitation of the sympathetic nervous system. This review relates evidence that CSR exerts acute effects on the autonomic nervous system during sleep, and thereby influences a number of cardiovascular phenomena, including heart rate, blood pressure, atrioventricular conduction, and ventricular ectopy. In patients in sinus rhythm, heart rate and blood pressure oscillate during CSR in association with respiratory oscillations, such that both peak heart rate and blood pressure occur during the hyperpneic phase. Inhalation of CO2 abolishes both CSR and the associated oscillations in heart rate and blood pressure. In contrast, O2 inhalation sufficient to eliminate hypoxic dips has no significant effect on CSR, heart rate, or blood pressure. In patients with atrial fibrillation, ventricular rate oscillates in association with CSR despite the absence of within-breath respiratory arrhythmia. The comparison of RR intervals between the apneic and hyperpneic phases of CSR indicates that this breathing disorder exerts its effect on ventricular rate by inducing cyclical changes in atrioventricular node conduction properties. In patients with frequent ventricular premature beats (VPBs), VPBs occur more frequently during the hyperpneic phase than the apneic phase of CSR. VPB frequency is also higher during periods of CSR than during periods of regular breathing, with or without correction of hypoxia. In summary, CSR exerts multiple effects on the cardiovascular system that are likely manifestations of respiratory modulation of autonomic activity. It is speculated that the rhythmic oscillations in autonomic tone brought about by CSR may ultimately contribute to the sympatho-excitation and increased mortality long observed in patients with heart failure and CSR.
Classification and phylogeny of Hexactinellida (Porifera)
Authors: Reiswig H M
Published: April 2006

Development of the present classification scheme of the class Hexactinellida was delayed because authors of the early species descriptions did not figure their specimens and few of them had access to compound microscopes necessary to visualize characters important in determining relationships. When microscopic information on spicule symmetry became available, Wyville Thomson in 1868 recognized the distinctive triaxial symmetry of the group and named it Vitrea. Schmidt's 1870 name, Hexactinellidae, was without the contamination associated with Thomson's Vitrea, and gained widespread support. Through a series of proposals and refinements, the present scheme recognizes two main lineages, Amphidiscophora and Hexasterophora, differing in shape and type of their microscleres. Since these structures are generally not retained in fossil material, paleontologists have long had an independent classification for hexactinellids, but the trend to unify the systems is now nearly complete. Hypotheses on phylogeny of the group remain virtually dependent upon scarce paleontological information, pending data from nucleic acid and protein sequence analyses that are not yet available for unravelling relationships among hexactinellids.
Antennal glands of the slave-making antPolyergus rufescensand its slave speciesFormica cunicularia(Hymenoptera, Formicidae)
Authors: Romani Roberto , Grasso Donato Antonio , Mori Alessandra , Isidoro Nunzio , Moli Francesco Le
Published: April 2006

The fine morphology of glandular structures associated with the antennae is reported for the first time in a social parasite ant, the obligate slave-maker Polyergus rufescens (Latreille, 1798). In this species, external pores have been detected through scanning electron microscopy only on the scape of the female castes (queen and worker). Each pore is associated internally with a bicellular secretory unit by means of a cuticular duct. The number of secretory cells appears to be higher in queens than in workers. Similar exocrine structures have been found also in workers of Formica cunicularia Latreille, 1798, a common host species of P. rufescens. The possible functional role of this gland is discussed.
The influence of multi-stage predation on population growth and the distribution of the pond-breeding salamander, Ambystoma jeffersonianum
Authors: Rubbo M J , Shea K , Kiesecker J M
Published: April 2006

Understanding the drivers of distributional patterns is a fundamental goal of ecology. For many organisms, distributions are determined by the habitats in which breeding occurs. Therefore, determining the factors that limit post-ovipositional success in specific habitats is critical to deciphering the factors that shape distributions. Using field surveys and laboratory, mesocosm, and field experiments, we conducted a study of the breeding effort of the salamander Ambystoma jeffersonianum (Green, 1827) in sites of varying predation pressure and the susceptibility of its embryos and larvae to predators. We then used these data to parameterize a matrix model examining the effects of predation on population growth. We found that A. jeffersonianum egg masses were less abundant in ponds with higher predation pressure. Moreover, A. jeffersonianum performance was negatively affected by both embryonic and larval predators. The results of the model suggest that only predation acting upon multiple life-history stages can limit population growth for A. jeffersonianum. These data provide support for the hypothesis that multi-stage predation can shape breeding distributions by imposing strong selective costs in specific environments. Furthermore, these data highlight the importance of conducting multi-stage studies and utilizing multiple ecological methodologies when addressing the factors that limit the distribution and abundance of organisms.
Ecological interactions of marine sponges
Authors: Wulff Janie L
Published: April 2006

Sponges interact with most other organisms in marine systems as competitors, symbionts, hosts of symbionts, consumers, and prey. Considerable creative energy has been required to study and describe the amazing variety of sponge interactions, as sponges can hide symbionts deep inside, rapidly regenerate wounds from grazers, carry on important associations with unculturable microscopic organisms, and otherwise foil attempts to determine how they are interacting with other organisms. This review of sponge interactions covers (i) competition among sponge species, and between sponges and other sessile organisms; (ii) predation on sponges by sponge specialists and by opportunistic sponge feeders, and aspects of predation such as the importance of nutritional quality, trade-offs between growth and defense against predators, biogeographic patterns in predation, and the advantages of various techniques for studying predation; and (iii) symbiotic associations of sponges with a variety of organisms representing all types of life, and with results ranging from parasitism and disease to mutual benefit. A hint that some generalizations about ecological interactions of sponges may be possible is just becoming evident, as accumulating data appear to show taxonomic and geographic patterns; however, it is also clear that surprises will continue to emerge from every probing new study.
A SELECTION RULE FOR MULTIQUARK DECAYS
Authors: BUCCELLA F.
Published: April 2006

By assuming SU (6) CS symmetry for pentaquark decays one finds a selection rule, which strongly reduces the number of states able to decay into a baryon and a meson final state and allows an intriguing identification for the Θ+ particle recently discovered with the prediction of a narrow width.
COULOMB PROBLEM FOR VECTOR BOSONS IN STANDARD MODEL
Authors: KUCHIEV MICHAEL , FLAMBAUM VICTOR
Published: April 2006

The Coulomb problem for vector bosons W± propagating in an attractive Coulomb field incorporates a known difficulty, i.e. the total charge of the boson localized on the Coulomb center turns out to be infinite. This difficulty is shown to be resolved by the QED vacuum polarization, which brings in a strong effective repulsion and eradicates the infinite charge of the boson on the Coulomb center. The effect makes the Coulomb problem for vector bosons well defined and consistent with the Standard Model.
MICROWAVE ABSORPTION PROPERTIES OF β-SiC–C COMPOSITES WITH SOLID PHASE SINTERING AT X BAND
Authors: ZHOU ZEHUA , TAN SHOUHONG , JIANG DONGLIANG , YI YU
Published: April 2006

In this paper, by using β- SiC powder as a matrix and mixing different content of C , a series of SiC–C composites with solid phase sintering under different temperature were prepared. The relative density, electrical properties and microwave absorption properties at X band were measured systemically. The microwave absorption mechanisms of the composites were studied comprehensively by the test results, together with the microstructure and composition analysis. The main results show that the composites are good microwave absorption ceramics at X band because of the good interface's match of wave impedance by the control of properties and process, C content and sintering process influence effectively all test properties. For the SiC –3 wt % C composites (which is the best microwave absorption one) under 2200° sintering, the biggest microwave attenuation is -40.5 dB and almost all attenuations are above -30 dB in the whole X band.
SURFACE MODIFICATION OF PRINTED CARBON NANOTUBES AND ITS APPLICATION OF FIELD EMISSION
Authors: FENG TAO , ZHANG JIHUA , WANG XI , LIU XIANGHUAI , ZOU SHICHANG , LI QIONG , XU JINGFANG
Published: April 2006

A surface-modified carbon nanotubes (CNTs), which shows an excellent electron field emission property was obtained in the present work. Conventional screen-printing technology was applied to prepare the CNT films. After hydrogen plasma surface treating process, the morphology of nanotubes surface were totally changed. Those modified CNTs exhibited low turn-on electron field of 0.98 V/μm, current density of 1 mA/cm2 at a field of 6.53 V/μm and a very high emission site density of about 106/cm2, which is three orders of magnitude higher than that of untreated CNT films. Diode-type prototype devices were obtained which proved the modified CNTs is suitable for field emission displays.
LUMINESCENCE AND THERMAL ANNEALING OF SPUTTERED DEPOSITED THULIUM- AND SAMARIUM-DOPED AMORPHOUS AlN FILMS
Authors: MAQBOOL MUHAMMAD
Published: April 2006

Thin films of thulium- and samarium-doped AlN are deposited on silicon (111) substrates at 77 K by RF magnetron sputtering method. 200–400 nm thick films are grown at 100–200 watts RF power and 5–8 mTorr nitrogen, using a metal target of Al with Tm and Sm separately. X-rays diffraction results show that films are amorphous. Cathodoluminescence studies are performed at room temperature and two dominant peaks are observed in Tm at 467 nm from 1 D 2 → 3 F 4 transition and 480 nm from 1 G 4 to the ground state 3 H 6 transition. Other peaks in the visible region are obtained at 650 nm and 685 nm due to 1 G 4 → 3 F 4 and 1 D 2 → 3 H 4 transitions. Peaks in the ultraviolet and infrared region are also obtained at 371 nm and 802 nm as a result from 1 D 2 → 3 H 6 and 3 H 4 → 3 H 6 transition, respectively. Sm gives four peaks at 564 nm, 600 nm, 648 nm and 707 nm as a result of 4 G 5/2 → 6 H 5/2, 4 G 5/2 → 6 H 7/2, 4 G 5/2 → 6 H 9/2 and 4 G 5/2 → 6 H 11/2 transitions. Films are thermally annealed at 1200 K for half an hour in a nitrogen atmosphere. Thermal annealing enhances the intensity of luminescence.
KINETIC SURFACE ROUGHENING OF PLATINUM AND GOLD THIN FILMS
Authors: CATTANI M. , SALVADORI M. C.
Published: April 2006

Platinum and gold thin films have been fabricated by filtered vacuum arc deposition perpendicularly on rough silicon and glass substrates. Four sets of samples have been prepared with different thickness (d). Two sets were very thin films of Pt (1.31 ≤ d ≤ 11.66 nm ) and Au (1.77 ≤ d ≤ 10.46 nm ) and two sets were thicker films also of Pt (7 ≤ d ≤ 80 nm ) and Au (34 ≤ d ≤ 200 nm ). The roughness mean-square ω of the films have been measured, as a function of the film thickness d, by scanning tunneling microscopy (STM). We verified that the dynamical scaling relation ω(t) ~ tβ, where β is the growth exponent, is obeyed for the thicker films but it is not obeyed for the very thin films. These cases are analyzed taking into account the films growth theory.
CRACK-FREE WEAR RESISTANCE COATINGS PRODUCED ON PURE TITANIUM AND Ti-6Al-4V BY LASER NITRIDING
Authors: TIAN Y. S. , CHEN C. Z. , CHEN L. X. , HUO Q. H.
Published: April 2006

Cracks-free wear resistance coatings are fabricated by laser surface nitriding pure titanium and Ti-6Al-4V in an open system. The titanium nitrides which are formed in situ in the top layers of the samples are undeveloped dendritic, and thus reduce the possibility of the crack formation in the coatings during laser processing. The test results show that the nitride layers have higher microhardness and more resistant to sliding wear compared to the as-received sample.
SOLIDIFICATION MECHANISM OF LASER REMELTED BIOACTIVE HA COATINGS
Authors: CHEN CHUANZHONG , WANG DIANGANG , BAO QUANHE , ZHANG LIANG , LEI TINGQUAN
Published: April 2006

In this paper, as-sprayed HA coatings were remelted by CW laser. The morphologies and the development of microstructures were analyzed by electron probe microanalysis. The solidification mechanism of laser remelted bioactive HA coatings is usually determined by the parameters of the temperature gradient G and the solidification velocity R. In the region of bottom pool, the G/R value is high which will result in the forming of planar crystal. With the decrease of G/R value, cellular and cellular dendrites will form. Near the surface, the coating can radiate heat to the atmosphere which will form a negative temperature gradient, consequently the structure is composed of dendrites.
OPTICAL BAND GAP EXCITATION AND PHOTOELECTRON GENERATION IN TITANIUM DIOXIDE-BASED SOLID STATE SOLAR CELLS
Authors: RUSOP M. , SHIRATA T. , SOGA T. , JIMBO T.
Published: April 2006

The properties and optical band gap excitation of nanoporous titanium dioxide ( TiO 2) and transparent semiconducting copper iodide ( CuI ) films prepared by a XeCl excimer laser were investigated. The CuI films exhibited optical transmittance over 80% in the wavelength range from 400 to 900 nm with minimum resistivity of about 2 KΩcm. The optical absorption of these films showed a remarkable blue shift compared to that of polycrystalline of CuI , which can be explained from the formation of ultra fine of CuI grains. The properties of pulsed laser deposited CuI and TiO 2 in power output of p- CuI | dye |n- TiO 2 cells were studied. The photoelectron generation and mechanism in fabricated p- CuI | dye |n- TiO 2 cells were also studied. An efficient charge generation was observed through the illumination of the TiO 2 layer of the fabricated p- CuI | dye |n- TiO 2 cells. The band gap excitation of TiO 2 was observed only under illumination through TiO 2 layer. The adsorbed dye molecules to the TiO 2 surface act as a relay, especially under illumination through TiO 2 layer in the wave range region of 300–400 nm.
OPTICAL AND ELECTRICAL PROPERTIES OF ZINC OXIDE THIN FILMS DIP-COATED OF SOL–GEL METHOD
Authors: RUSOP M. , UMA K. , SOGA T. , JIMBO T.
Published: April 2006

The transparent c-axis oriented ZnO thin films have been prepared by sol–gel method using zinc acetate as cations source, 2-mrthoxiethanol as solvent and monoethanolamine as sol stabilizer. Film deposition was performed by dip coating technique at a withdrawal rate of 10 mm/min on quartz and silicon substrates. The effect of annealing temperature in air ambient from 100 to 800°C on the structural, optical and electrical properties of the films is discussed. ZnO films annealed with higher temperature showed an extremely sharp (002) peak in the XRD patterns, indicates increased crystallization. The optical transmittance spectra of the films is found to change with annealing temperature and showed a very good transmittance (between 80 to 90%) with the films prepared at 600°C showed highest optical transparency within the visible wavelength region. The absorption edge analysis revealed that the optical band gap is found to increase with annealing temperature up to 3.5 eV at 600°C and decreased with higher temperature. Electronic transition was found to be direct transition type. The minimum electrical resistivity of 55 Ω-cm was obtained for the films annealed at 600°C.
SURFACE MODIFICATION OF POLY(VINYLIDENE FLUORIDE) FILMS BY CONTROLLED GRAFTING POLYMER BRUSHES
Authors: CHEN YIWANG , LIU DONGMEI , ZHANG NING
Published: April 2006

Controlled grafting of well-defined polymer brushes on the poly(vinylidene fluoride) (PVDF) films was carried out by the surface-initiated Atom Transfer Radical polymerization (ATRP). Surface-initiators were immobilized on the PVDF films by surface hydroxylation and esterification of the surface-tethered hydroxyl groups with 2-bromoisobutyrate bromide. Water contact angles on PVDF films were reduced by surface grafting of poly(ethylene glycol) monomethacrylate (PEGMA) and methyl methacrylate (MMA). Kinetics study revealed a linear increase in the graft concentration of PMMA and PEGMA with the reaction time, indicating that the chain growth from the surface, was consistence with a "controlled" or "living" process.
CALCULATION AND PLOTTING OF STANDARD FREE ENERGY CHANGES AND EQUILIBRIUM CONSTANTS FOR CVD HARD COATINGS REACTIONS
Authors: LIU SHA , ZHANG JING QIU
Published: April 2006

CVD (chemical vapor deposition) coatings such as TiC , TiN , Al 2 O 3 and so on are widely used as tools' surface preserved materials with corrosion resistance and wear resistance. Standard Gibbs free energy changes for reactions are widely used to approximately analyze the trends of substance reactions and phase transitions in chemical reactions, metallurgy processes, materials synthesis and processing. Hard coatings and thin films can be prepared by CVD process. Accurate calculation and plotting of the standard free energy changes and equilibrium constants for CVD TiC , TiN , Al 2 O 3 coatings reactions are realized using the developed general computer program. Only inputting the basic thermodynamic data tabulated in data books into the computer program, the relationships of the standard free energy changes and equilibrium constants for most reactions with the temperatures can be gained in the same diagrams.
RESONANT THIRD-ORDER OPTICAL NONLINEARITIES OF HIGHLY-SUBSTITUTED PHTHALOCYANINE DERIVATIVES
Authors: FU GANG , KASATANI KAZUO , OKAMOTO HIROAKI
Published: April 2006

Third-order optical nonlinearities of three highly-substituted phthalocyanines (Pcs) containing central metal atom VO , Al , and Cu were investigated under resonant conditions by femtosecond degenerate four-wave mixing. The dynamics of the nonlinear response was found to be strongly dependent on the nature of the central metal atom and molecular stacking form. The electronic molecular hyperpolarizability of the Pcs was evaluated and compared with their structure-related analogues. The electronic third-order susceptibilities of the solid films containing the Pcs were determined to be in the range of 10-10 to 10-9 esu. We attempt to give structure-property relationships in these macrocyclic compounds.
Mechanisms of Site-Specific Recombination
Authors: Grindley Nigel D.F. , Whiteson Katrine L. , Rice Phoebe A.
Published: April 2006

Integration, excision, and inversion of defined DNA segments commonly occur through site-specific recombination, a process of DNA breakage and reunion that requires no DNA synthesis or high-energy cofactor. Virtually all identified site-specific recombinases fall into one of just two families, the tyrosine recombinases and the serine recombinases, named after the amino acid residue that forms a covalent protein-DNA linkage in the reaction intermediate. Their recombination mechanisms are distinctly different. Tyrosine recombinases break and rejoin single strands in pairs to form a Holliday junction intermediate. By contrast, serine recombinases cut all strands in advance of strand exchange and religation. Many natural systems of site-specific recombination impose sophisticated regulatory mechanisms on the basic recombinational process to favor one particular outcome of recombination over another (for example, excision over inversion or deletion). Details of the site-specific recombination processes have been revealed by recent structural and biochemical studies of members of both families.
Animal Cytokinesis: From Parts List to Mechanisms
Authors: Eggert Ulrike S. , Mitchison Timothy J. , Field Christine M.
Published: April 2006

The mechanism underlying cytokinesis, the final step in cell division, remains one of the major unsolved questions in basic cell biology. Thanks to advances in functional genomics and proteomics, we are now able to assemble a “parts list” of proteins involved in cytokinesis. In this review, we discuss how to relate this parts list to biological mechanism. For easier analysis, we split cytokinesis into discrete steps: cleavage plane specification, rearrangement of microtubule structures, contractile ring assembly, ring ingression, and completion. We report on the advances that have been made to understand these steps and how they can be integrated into a global understanding of cytokinesis. We also discuss the extent to which classic questions have been answered and identify major outstanding questions.
Asparagine Synthetase Chemotherapy
Authors: Richards Nigel G. J. , Kilberg Michael S.
Published: April 2006

Modern clinical treatments of childhood acute lymphoblastic leukemia (ALL) employ enzyme-based methods for depletion of blood asparagine in combination with standard chemotherapeutic agents. Significant side effects can arise in these protocols and, in many cases, patients develop drug-resistant forms of the disease that may be correlated with up-regulation of the enzyme glutamine-dependent asparagine synthetase (ASNS). Though the precise molecular mechanisms that result in the appearance of drug resistance are the subject of active study, potent ASNS inhibitors may have clinical utility in treating asparaginase-resistant forms of childhood ALL. This review provides an overview of recent developments in our understanding of (a) the structure and catalytic mechanism of ASNS, and (b) the role that ASNS may play in the onset of drug-resistant childhood ALL. In addition, the first successful, mechanism-based efforts to prepare and characterize nanomolar ASNS inhibitors are discussed, together with the implications of these studies for future efforts to develop useful drugs.
MECHANISM AND DYNAMICS OF CADHERIN ADHESION
Authors: Leckband Deborah , Prakasam Anil
Published: April 2006

Cadherins are essential cell adhesion molecules involved in tissue morphogenesis and the maintenance of tissue architecture in adults. The adhesion and selectivity functions of cadherins are located in their extracellular regions. Biophysical studies show that the adhesive activity is not confined to a single interface. Instead, multiple cadherin domains contribute to binding. By contrast, the specificity-determining site maps to the N-terminal domains, which adhere by the reciprocal binding of Trp2 residues from opposing proteins. Structural cooperativity can transmit the effects of subtle structural changes or ligand binding over large distances in the protein. Increasingly, studies show that differential cadherin-mediated adhesion, rather than exclusive homophilic binding between identical cadherins, direct cell segregation and the organization of tissue interfaces during morphogenesis. Force measurements quantified both kinetic and strength differences between different classical cadherins that may underlie cell sorting behavior. Despite the complex adhesion mechanisms and differences in binding properties, cadherin-mediated cell adhesion is also regulated by many other biochemical processes. Elucidating the mechanisms by which cadherins organize cell junctions and tissue architecture requires not only quantitative, mechanistic investigations of cadherin function but also investigations of the biochemical and cellular processes that can modulate those functions.
FLUORESCENCE MOLECULAR IMAGING
Authors: Ntziachristos Vasilis
Published: April 2006

There is a wealth of new fluorescent reporter technologies for tagging of many cellular and subcellular processes in vivo. This imposed contrast is now captured with an increasing number of available imaging methods that offer new ways to visualize and quantify fluorescent markers distributed in tissues. This is an evolving field of imaging sciences that has already achieved major advances but is also facing important challenges. It is nevertheless well poised to significantly impact the ways of biological research, drug discovery, and clinical practice in the years to come. Herein, the most pertinent technologies associated with in vivo noninvasive or minimally invasive fluorescence imaging of tissues are summarized. Focus is given to small-animal imaging. However, while a broad spectrum of fluorescence reporter technologies and imaging methods are outlined, as necessary for biomedical research, and clinical translation as well.
POLYMERSOMES
Authors: Discher Dennis E. , Ahmed Fariyal
Published: April 2006

Polymersomes are self-assembled polymer shells composed of block copolymer amphiphiles. These synthetic amphiphiles have amphiphilicity similar to lipids, but they have much larger molecular weights, so for this reason—along with others reviewed here—comparisons of polymersomes with viral capsids composed of large polypeptide chains are highly appropriate. We summarize the wide range of polymers used to make polymersomes along with descriptions of physical properties such as stability and permeability. We also elaborate on emerging studies of in vivo stealthiness, programmed disassembly for controlled release, targeting in vitro, and tumor-shrinkage in vivo. Comparisons of polymersomes with viral capsids are shown to encompass and inspire many aspects of current designs.
PROGNOSIS IN CRITICAL CARE
Authors: Ohno-Machado Lucila , Resnic Frederic S. , Matheny Michael E.
Published: April 2006

Prognostic risk prediction models have been employed in the intensive care unit (ICU) setting since the 1980s and provide health care providers with important information to help inform decisions related to treatment and prognosis, as well as to compare outcomes across institutions. Prognostic models for critical care are among the most widely utilized and tested predictive models in healthcare. In this article, we review and compare mortality prediction models, including the APACHE (1981), SAPS (1984), APACHE-II (1985), MPM (1987), APACHE-III (1991), SAPS-II (1993), and MPM-II (1993). We emphasize the importance of model calibration in this domain. In addition, we present a brief review of the statistical methodology, multiple logistic regression, which underlies most of the models currently used in critical care.
RIBOSOME DYNAMICS: Insights from Atomic Structure Modeling into Cryo-Electron Microscopy Maps
Authors: Mitra Kakoli , Frank Joachim
Published: April 2006

Single-particle cryo-electron microscopy (cryo-EM) is the method of choice for studying the dynamics of macromolecular machines both at a phenomenological and, increasingly, at the molecular level, with the advent of high-resolution component X-ray structures and of progressively improving fitting algorithms. Cryo-EM has shed light on the structure of the ribosome during the four steps of translation: initiation, elongation, termination, and recycling. Interpretation of cryo-EM reconstructions of the ribosome in quasi-atomic detail reveals a picture in which the ribosome uses RNA not only to catalyze chemical reactions, but also as a means for signal transduction over large distances.
THE USE OF POLYMER DESIGN IN RESORBABLE COLLOIDS
Authors: Finne-Wistrand Anna , Albertsson Ann-Christine
Published: April 2006

▪ Abstract  During the past decade, researchers in the field of polymer chemistry have developed a wide range of very powerful procedures for constructing ever-more-sophisticated polymers. These methods subsequently have been used in suitable systems to solve specific medical problems. This is complicated, and many key factors such as mechanical properties, biocompatibility, biodegradation, stability, and degradation profile must be considered. Colloid particle systems can be used to solve many biomedical- and pharmaceutical-related problems, and it is expected that nanotechnology can be used to develop these materials, devices, and systems even further. For example, an injectible scaffold system with a defined release and degradation profile has huge potential for the repair and regeneration of damaged tissues. This short, nonexhaustive review presents examples of polymer architecture in resorbable particles that have been compared and tested in biomedical applications. We also discuss the design of polymers for core-shell structures.
HOMEOSTATIC CONTROL OF NEURAL ACTIVITY: From Phenomenology to Molecular Design
Authors: Davis Graeme W.
Published: April 2006

Homeostasis is a specialized form of regulation that precisely maintains the function of a system at a set point level of activity. Recently, homeostatic signaling has been suggested to control neural activity through the modulation of synaptic efficacy and membrane excitability ( Davis & Goodman 1998a , Turrigiano & Nelson 2000 , Marder & Prinz 2002 , Perez-Otano & Ehlers 2005 ). In this way, homeostatic signaling is thought to constrain neural plasticity and contribute to the stability of neural function over time. Using a restrictive definition of homeostasis, this review first evaluates the phenomenological and molecular evidence for homeostatic signaling in the nervous system. Then, basic principles underlying the design and molecular implementation of homeostatic signaling are reviewed on the basis of work in other, simplified biological systems such as bacterial chemotaxis and the heat shock response. Data from these systems are then discussed in the context of homeostatic signaling in the nervous system.
RNA-MEDIATED NEUROMUSCULAR DISORDERS
Authors: Ranum Laura P.W. , Cooper Thomas A.
Published: April 2006

Myotonic dystrophy type 1 (DM1) is caused by a CTG expansion mutation located in the 3′ untranslated portion of the dystrophica myotonin protein kinase gene. The identification and characterization of RNA-binding proteins that interact with expanded CUG repeats and the discovery that a similar transcribed but untranslated CCTG expansion in an intron causes myotonic dystrophy type 2 (DM2) have uncovered a new type of mechanism in which microsatellite expansion mutations cause disease through an RNA gain-of-function mechanism. This review discusses RNA pathogenesis in DM1 and DM2 and evidence that similar mechanisms may play a role in a growing number of dominant noncoding expansion disorders, including fragile X tremor ataxia syndrome (FXTAS), spinocerebellar ataxia type 8 (SCA8), SCA10, SCA12, and Huntington's disease-like 2 (HDL2).
Fatty Acids as Modulators of the Immune Response
Authors: Fritsche Kevin
Published: April 2006

▪ Abstract  Research describing fatty acids as modulators of inflammation and immune responses abounds. Many of these studies have focused on one particular group of fatty acids, omega-3. The data from animal studies have shown that these fatty acids can have powerful anti-inflammatory and immunomodulatory activities in a wide array of diseases (e.g., autoimmunity, arthritis, and infection). However, the evidence from human trials is more equivocal. In this review, a historical framework for understanding how and why fatty acids may affect the immune system is provided. Second, highlights of two recent landmark reports from the Agency for Healthcare Research and Quality are presented. These reports critically evaluate the evidence from human clinical trials of omega-3 fatty acids and rheumatoid arthritis, asthma, and a few other immune-mediated diseases. Third, the data from human clinical trials investigating the impact of various bioactive fatty acids on ex vivo and in vivo immune response are reviewed. Limitations in experimental design and immune assays commonly used are discussed. The discordance between expectation and evidence in this field has been a disappointment. Recommendations for improving both animal-based and human studies are provided.
Hereditary Hemochromatosis
Authors: Pietrangelo Antonello
Published: April 2006

▪ Abstract  In recent years, the number of proteins implicated in iron homeostasis has increased dramatically, and genetic causes have apparently been identified for the major disorders associated with tissue iron overload. These dramatic steps forward have transformed the way we look at iron-related disorders, particularly hemochromatosis. This review presents a concept of this disease that is based on this new knowledge and stems from the idea that, beyond their genetic diversities, all known hemochromatoses originate from the same metabolic error, the genetic disruption of human tendency for circulatory iron constancy. Hepcidin, the iron hormone, seems to hold a central pathogenic place in hemochromatosis, similar to insulin in diabetes: Genetically determined lack of hepcidin synthesis or activity may cause the disease.
Results of Bariatric Surgery
Authors: Hansen Erik N. , Torquati Alfonso , Abumrad Naji N.
Published: April 2006

▪ Abstract  Overweight and obesity are rapidly growing to epidemic proportions in the United States and globally. Since sustainable weight loss is only achieved by bariatric surgery, medicine has seen an explosion in the diversity and number of bariatric procedures performed over the past few years. Systematic studies of postoperative outcomes and investigations into the physiology and biology of weight loss provide a more comprehensive understanding of the sequelae of bariatric surgery. Adipose tissue is the predominant site of fat stores. Increasing obesity results in an overload of lipids within the body's natural storage sink (i.e., the adipocyte) followed by the necessary deposition of fat within ectopic sites such as muscle, liver, and pancreas. The resulting metabolic derangements are associated with insulin resistance, central obesity, and chronic inflammation as adipose tissue acts as an endocrine organ, producing and secreting a host of biologic mediators. Whereas there are conflicting data on the cardiovascular effects of peripheral, subcutaneous liposuction, malabsorptive bariatric procedures result almost universally in significant amelioration of insulin resistance, hypertension, dyslipidemia, and hepatic steatosis. Concomitant changes in adipocyte-derived hormones may provide mechanistic explanations to the observed improvements.
The Clinical Significance of Asymmetric Dimethylarginine
Authors: Siroen Michiel P. C. , Teerlink Tom , Nijveldt Robert J. , Prins Hubert A. , Richir Milan C. , Leeuwen Paul A.M. van
Published: April 2006

▪ Abstract  In 1992, asymmetrical dimethylarginine (ADMA) was first described as an endogenous inhibitor of the arginine-nitric oxide (NO) pathway. From then, its role in regulating NO production has attracted increasing attention. Nowadays, ADMA is regarded as a novel cardiovascular risk factor. The role of the kidney and the liver in the metabolism of ADMA has been extensively studied and both organs have proven to play a key role in the elimination of ADMA. Although the liver removes ADMA exclusively via degradation by the enzyme dimethylarginine dimethylaminohydrolase (DDAH), the kidney uses both metabolic degradation via DDAH and urinary excretion to eliminate ADMA. Modulating activity and/or expression of DDAH is still under research and may be a potential therapeutic approach to influence ADMA plasma levels. Interestingly, next to its association with cardiovascular disease, ADMA also seems to play a role in other clinical conditions, such as critical illness, hepatic failure, and preeclampsia. To elucidate the clinical significance of ADMA in these conditions, the field of research must be enlarged.
WHAT IS ETHNIC IDENTITY AND DOES IT MATTER?
Authors: Chandra Kanchan
Published: April 2006

▪ Abstract  Since the publication of Horowitz's Ethnic Groups in Conflict, comparative political scientists have increasingly converged on their classification of ethnic identities. But there is no agreement on the definition that justifies this classification—and the definitions that individual scholars propose do not match their classifications. I propose a definition that captures the conventional classification of ethnic identities in comparative political science to a greater degree than the alternatives. According to this definition, ethnic identities are a subset of identity categories in which membership is determined by attributes associated with, or believed to be associated with, descent (described here simply as descent-based attributes). I argue, on the basis of this definition, that ethnicity either does not matter or has not been shown to matter in explaining most outcomes to which it has been causally linked by comparative political scientists. These outcomes include violence, democratic stability, and patronage.
The Texture of Hardship: Qualitative Sociology of Poverty, 1995–2005
Authors: Newman Katherine S. , Massengill Rebekah Peeples
Published: April 2006

Focusing on the past decade, this review considers advances in the qualitative study of working poverty, welfare reform, patterns of family formation, neighborhood effects, class-based patterns of childhood socialization, and the growing European literature on social exclusion. We highlight the increasing importance of qualitative research embedded in large-scale quantitative studies of poverty. Within each of these areas, we suggest new directions for research that take into account the changing contours of poverty, including the increasing diversity of poor neighborhoods (reflecting the in-migration of the foreign born) and the growth of poverty in the older suburbs surrounding the city centers. The reintroduction of the language of class has been a hallmark of the past decade, drawing it closer to some of the original concerns of sociologists in the 1940s, contrasted with a nearly universal emphasis on race and ethnicity characteristic of more recent decades.
Globalization of Law
Authors: Halliday Terence C. , Osinsky Pavel
Published: April 2006

Globalization of law may be defined as the worldwide progression of transnational legal structures and discourses along the dimensions of extensity, intensity, velocity, and impact. We propose that a theory of the global penetration of law will require at least four elements—actors, mechanisms, power, and structures and arenas. A comparison of four approaches to globalization and law—world polity, world systems, postcolonial globalism, and law and economic development—indicates considerable variation in perceived outcomes and gaps in explanation, but with possible complementarities in both outcomes and explanatory factors. Research demonstrates that globalization is variably contested in several domains of research on law: (a) the construction and regulation of global markets, (b) crimes against humanity and genocide, (c) the diffusion of political liberalism and constitutionalism, and (d) the institutionalization of women's rights. We propose that the farther globalizing legal norms and practices are located from core local cultural institutions and beliefs, the less likely global norms will provoke explicit contestation and confrontation. Future research will be productively directed to where and how global law originates, how and when global norms and law are transmitted and enforced, and how global-local settlements are negotiated.
Estimating the Causal Effect of Social Capital: A Review of Recent Research
Authors: Mouw Ted
Published: April 2006

Although there is a large literature on social capital, empirical estimates of the effect of social capital may be biased because of social homophily, the tendency of similar people to become friends with each other. Despite the methodological difficulties, a recent literature has emerged across several different disciplines that tries to estimate the causal effect of social capital. This paper reviews this recent empirical literature on social capital, paying close attention to the statistical and theoretical assumptions involved. Overall, there is evidence that genuine progress has been made in estimating the effect of social capital. The reviewed articles should provide useful examples for future research.
UCP1 is essential for adaptive adrenergic nonshivering thermogenesis
Authors: Golozoubova Valeria , Cannon Barbara , Nedergaard Jan
Published: April 2006

Participation of brown adipose tissue [through the action of the uncoupling protein-1 (UCP1)] in adaptive adrenergic nonshivering thermogenesis is recognized, but the existence of a response to adrenergic stimulation in UCP1-ablated mice implies that a mechanism for an alternative adaptive adrenergic thermogenesis may exist. Here, we have used UCP1-ablated mice to examine the existence of an alternative adaptive adrenergic nonshivering thermogenesis, examined as the oxygen consumption response to systemically injected norepinephrine into anesthetized or conscious mice acclimated to different temperatures. We confirm that UCP1-dependent adrenergic nonshivering thermogenesis is adaptive, but we demonstrate that the adrenergic UCP1-independent thermogenesis is not recruitable by cold acclimation. Thus, at least in the mouse, no other proteins or enzymatic pathways exist that can participate in or with time take over the UCP1 mediation of adaptive adrenergic nonshivering thermogenesis, even in the total absence of UCP1. UCP1 is thus the only protein capable of mediating cold acclimation-recruited adaptive adrenergic nonshivering thermogenesis.
Effects of DGAT1 deficiency on energy and glucose metabolism are independent of adiponectin
Authors: Streeper Ryan S. , Koliwad Suneil K. , Villanueva Claudio J. , Farese Robert V.
Published: April 2006

Mice lacking acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), an enzyme that catalyzes the terminal step in triacylglycerol synthesis, have enhanced insulin sensitivity and are protected from obesity, a result of increased energy expenditure. In these mice, factors derived from white adipose tissue (WAT) contribute to the systemic changes in metabolism. One such factor, adiponectin, increases fatty acid oxidation and enhances insulin sensitivity. To test the hypothesis that adiponectin is required for the altered energy and glucose metabolism in DGAT1-deficient mice, we generated adiponectin-deficient mice and introduced adiponectin deficiency into DGAT1-deficient mice by genetic crosses. Although adiponectin-deficient mice fed a high-fat diet were heavier, exhibited worse glucose tolerance, and had more hepatic triacylglycerol accumulation than wild-type controls, mice lacking both DGAT1 and adiponectin, like DGAT1-deficient mice, were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis. These findings indicate that adiponectin is required for normal energy, glucose, and lipid metabolism but that the metabolic changes induced by DGAT1-deficient WAT are independent of adiponectin and are likely due to other WAT-derived factors. Our findings also suggest that the pharmacological inhibition of DGAT1 may be useful for treating human obesity and insulin resistance associated with low circulating adiponectin levels.
A quasi‐linear parabolic system of chemotaxis
Authors: Senba Takasi , Suzuki Takasi
Published: April 2006

We consider a quasi‐linear parabolic system with respect to
unknown functions u and v on a bounded domain of
n‐dimensional Euclidean space. We assume that the diffusion
coefficient of u is a positive smooth function A(u), and that
the diffusion coefficient of v is a positive constant. If A(u)
is a positive constant, the system is referred to as so‐called
Keller‐Segel system. In the case where the domain is a bounded
domain of two‐dimensional Euclidean space, it is shown that some
solutions to Keller‐Segel system blow up in finite time. In three
and more dimensional cases, it is shown that solutions to
so‐called Nagai system blow up in finite time. Nagai system is
introduced by Nagai. The diffusion coefficients of Nagai system
are positive constants. In this paper, we describe that solutions
to the quasi‐linear parabolic system exist globally in time, if
the positive function A(u) rapidly increases with respect to
u.
Synthesis, Characterization, and Biotoxicity of NN⌢ Donor Sulphonamide Imine Silicon(IV) Complexes
Authors: Jain Mukta , Singh R. V.
Published: April 2006

The organosilicon derivatives of 2‐[1‐(2‐furayl)ethyledene]sulphathiazole with organosilicon
chlorides have been synthesised and characterized on the basis of
analytical, conductance, and spectroscopic techniques. Probable
trigonal bipyramidal and octahedral structures for the resulting
derivatives have been proposed on the basis of electronic, IR, 1H, 13C NMR, and 29Si NMR spectral studies. In the search for better fungicides, bactericides,
nematicides, and insecticides studies were conducted to assess the
growth‐inhibiting potential of the synthesized complexes against
various pathogenic fungal, bacterial strains, root‐knot
nematode Meloidogyne incognita, and insect Trogoderma granarium These studies demonstrate that the
concentrations reached levels which are sufficient to inhibit and
kill the pathogens, nematode, and insect.
Effect of Benzothiazoline Ligand and Corresponding Organoantimony(V) Derivative on the Reproductive System of Male Rats
Authors: Shanker D. , Rai A. K. , Singh Y. P. , Rehwani H. , Khushalani V. , Gupta R. S.
Published: April 2006

Benzothiazoline 1 prepared by the condensation reaction of aroyl
pyruvate and 2‐aminothiophenol has been treated with to yield 2. These compounds have been characterized by elemental
analyses and molecular weight determinations. The probable
structures of the ligand as well as antimony complex have been
tentatively proposed on the basis of IR and NMR (H1 and C13) spectral evidences. Both compounds have been tested
for their antifertility activity in male albino rats. The oral
administration of compounds 1 and 2 at the dose level of
10 mg/rat/day significantly reduced the weights of testes,
epididymides, ventral prostate, and seminal vesicles. The
production of preleptotene spermatocytes was decreased by
36.57%; 57.23%, pachytene spermatocytes by 40.06%; 62.01%, and secondary spermatocytes by 52.45%; 63.22%, following the treatment of compounds 1 and 2, respectively. The marked reduction
in sperm motility and density resulted in infertility by
100%. Significant (P < .01) alterations were found in biochemical parameters of
reproductive organs in treated animals as compared to control
group. It is concluded that all these effects may finally impair
the fertility of male rats.