bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency and length of stomata of 21 Populus clones
Authors: Pallardy S. G. , Kozlowski T. T.
Published: November 2007

Frequency and length of stomata of field-grown plants of 21 Populus clones were studied. All clones except one were amphistomatous, and all clones had the greatest number of stomata per unit of leaf area on the abaxial surface. Variation in stomatal frequency, length, and relative distribution of stomata between abaxial and adaxial leaf surfaces among clones was found. Although differences in stomatal frequency and length were observed in some cases between early and late leaves of a clone, pore area differences were small because of the tendency for leaves with fewer stomata to have larger stomata. Cluster analysis utilizing abaxial and adaxial stomatal frequency and length as independent variables indicated that stomatal characteristics were related to parentage. Relationships between clonal stomatal characteristics and preliminary shoot dry weight data were not significant.
Scanning electron microscope observations on resting sporangia of Plasmodiophora brassicae in clubroot tissues after alcohol cracking
Authors: Yukawa Yosio , Tanaka Shuhei
Published: November 2007

Clubroot galls taken from 40-day-old Brassica rapa L. var. glabra Kitamura, grown in soil infested with Plasmodiophora brassicae Wor. were examined by scanning (SEM) and transmission (TEM) microscopy. SEM materials were prepared by freeze fracturing followed by ion etching. A thin layer enveloped the mass of sporangia which in etched specimens appeared to be embedded in a fibrillar net deposited among the sporangia. Both SEM and TEM micrographs revealed a circular germ pore (ca. 1 μm in diameter) with a thickened plug-like region in the pore orifice. The wall of the mature resting sporangium consisted of three layers W1, W2, and W3.
The early morphogenesis of Glycine max and Pisum sativum root nodules
Authors: Newcomb William , Sippell David , Peterson R. L.
Published: November 2007

The development of preemergent and early emergent stages of soybean (Glycine max) and garden pea (Pisum sativum) root nodules has been studied utilizing the superior preservation and resolution obtained by noncoagulative fixatives and subsequent embedding in plastic. In both species, extensive mitotic activity and cytological changes occur in the root cortical cells while the infection thread is restricted to the infected root hair cell. In soybean the central mass of infected tissue is derived mainly from the outer layer of cortical cells whereas the inner cortical cells contribute extensively to the infected tissue of the pea nodules. The temporal and spatial patterns of mitosis differ in the nodules of the two species. Mitotic activity is restricted to a nodule meristem and occurs over a period of many weeks in pea nodules. In soybean nodules, mitotic activity occurs throughout the central zone and before decreasing, persists over a period of a few weeks. The timing and distribution of mitotic activity affects nodule morphogenesis.
Electron microscopy of susceptible and resistant near-isogenic (sr6/Sr6) lines of wheat infected by Puccinia graminis tritici. II. Expression of incompatibility in mesophyll and epidermal cells and the effect of temperature on host–parasite interactions in these cells
Authors: Harder D. E. , Rohringer R. , Samborski D. J. , Rimmer S. R. , Kim W. K. , Chong J.
Published: November 2007

Primary leaves of near-isogenic lines of Chinese Spring wheat, either with or without the temperature-sensitive resistance gene Sr6, were inoculated with an avirulent race of stem rust, maintained at 19, 26, or 28 °C, and harvested 1–4 days after inoculation. The infected tissues were examined with an electron microscope to determine the effects of these temperatures on the expression of the Sr6 gene. At 26 °C in the Sr6 line about one-half of the haustoria in mesophyll cells were disorganized or collapsed. None of the haustoria in epidermal cells showed any structural abnormality. In the susceptible (sr6) line, most haustoria were structurally normal at 26 °C whether they were in mesophyll or epidermal cells. There were no signs of disorganization or necrosis of infected host cells of either (Sr6 or sr6) line at 26 °C. At 28 °C in both lines, all haustoria in mesophyll cells were necrotic or collapsed, but those in epidermal cells were not. No host cell necrosis was observed in genotypically resistant leaves. At 19 °C, most haustoria and invaded mesophyll cells in the Sr6 line were necrotic. In the invaded epidermal cells neither haustoria nor host protoplasts were necrotic. In contrast, in a backcross line of Marquis wheat containing resistance gene Sr5 and infected with an avirulent race, both invaded mesophyll and epidermal cells were necrotic.
Mutations affecting virulence in Phyllosticta maydis
Authors: Gabriel Dean W. , Ellingboe Albert H. , Rossman Elmer C.
Published: November 2007

Nitrosoguanidine was used as a mutagenic agent to obtain 4 constitutive and 20 temperature-sensitive mutations of Phyllosticta maydis for increased virulence on a single host line. The temperature-sensitive mutants were of three types: those temperature sensitive on agar and not on the host, those temperature sensitive on the host and not on agar, and those temperature sensitive on both agar and the host. These mutations for increased virulence are interpreted to indicate that host–parasitic specificity is for incompatibility, and that increases in virulence involve selected losses in function, rather than gains. The pattern of temperature sensitivity of certain mutants indicates that avirulence may be one pleiotrophic function of genes which otherwise function in support of basic life processes for the organism.
Colony initiation in flax rust in axenic culture: involvement of a volatile factor
Authors: Boasson Rosalinda , Shaw Michael
Published: November 2007

In axenic cultures of flax rust (Melampsora lini) colonies are initiated after a lag period of 12–20 days, depending partly on incubation temperatures. Colony initiation is completely inhibited by removal of a volatile factor which is absorbed by KOH in the air space of the culture flask. The fungus remains sensitive to this inhibition for 8–10 days, i.e., until shortly before visible colonies would normally have developed. While in the presence of KOH, the fungus is not killed; cultures grow normally after removal of the KOH.Although conclusive evidence must await further work, the available data strongly suggest that carbon dioxide is responsible for this effect.
Isotropic layers in the secondary cell walls of fibers in the roots of banana and other monocotyledons
Authors: Mueller W. C. , Beckman C. H.
Published: November 2007

Mature roots from banana and representatives of eight other families of the Monocotyledonae examined by electron microscopy showed isotropic layers (IL) in the secondary cell walls of mature fibers. These IL were shown by histochemical tests to be rich in pectin and lignin and to correspond to the primary wall in composition. The IL occurred between layers of cellulosic secondary walls that exhibited differentiation into the typical S1 and S2 layers. The resultant structure gave the appearance of a succession of complete cell walls laid down inside one another. This structure appears to be of common occurrence in the mature fibers of woody monocotyledons.
Ultrastructure and X-ray analysis of phosphorus granules in a vesicular–arbuscular mycorrhizal fungus
Authors: White J. A. , Brown M. F.
Published: November 2007

The vesicular–arbuscular mycorrhizal fungus Glomus mosseae was examined by transmission electron microscopy and energy dispersive X-ray analysis. Electron-dense granules, found within vacuoles, were analyzed by X-ray analysis and found to contain high concentrations of phosphorus and calcium. These granules were similar in appearance to the polyphosphate granules described in other organisms. Highly vacuolated intercellular hyphae and vesicles possessed the greatest number of phosphorus granules. The granules were present in vacuolated arbuscular hyphae but absent from completely collapsed arbuscules. It was determined that the active arbuscule was the most probable site of breakdown of phosphorus granules. There were two other types of cellular inclusions, one vacuolar and one cytoplasmic, that could not be identified by X-ray analysis but that could easily be mistaken for phosphorus granules. It was concluded that general morphological appearance and location were not adequate criteria for the identification of phosphorus granules.
Rehydration response of nitrogenase activity and carbon fixation in terrestrial Nostoc commune from Stipa–Bouteloa grassland
Authors: Coxson D. S. , Kershaw K. A.
Published: November 2007

The effects of wetting–drying cycles on patterns of carbon dioxide exchange and acetylene reduction were examined for colonies of the terrestrial cyanophyte Nostoc commune collected from a semiarid grassland site in southern Alberta, Canada. At 14 and 21 °C acetylene reduction takes ca. 14 h to resume maximal rates, although activity is detected within minutes of rehydration. Net photosynthesis reaches compensation minutes after rehydration and is maximal in under 80 min at 21 °C. No respiratory burst is evident, either for replicates previously dried rapidly (0.5 h) or slowly (5 h). In marked contrast, however, at 7 °C only minimal recovery of acetylene reduction is evident after 48 h diurnal treatment, while net photosynthesis requires a recovery time of 6 h. Again no respiratory burst is evident. After rehydration, the magnitude of acetylene reduction is strongly dependent on both the previous illumination level and temperature. The rapid decline in activity on transfer to darkness or on addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea can be moderated by increasing the duration of the previous light exposure or by incubation at lower temperature. This suggests the presence of substrate pools, the replenishment of which by photosynthesis allows oxidative phosphorylative support of nitrogenase activity in the dark. The extreme resistance of N. commune to desiccation and heat stress combined with its ability to resume metabolic activity within minutes of wetting should allow very effective utilization of small precipitation events during the summer months. The slower recovery of nitrogenase activity upon rehydration at lower temperatures may restrict winter field activity on rare occasions when thalli become dehydrated between snowfall periods.
Response of citrus to vesicular–arbuscular mycorrhizal inoculation in unsterile soils
Authors: Manjunath A. , Mohan R. , Bagyaraj D. J.
Published: November 2007

Response of citrus to inoculation with the endomycorrhizal fungus Glomus fasciculatum in four soil types of India was studied under greenhouse conditions. Inoculation increased the dry weight of shoot and root and nutrient content of plants. Plants grown in sandy soils responded to a greater extent compared with plants grown in clayey or lateritic soils. The results brought out that mycorrhizal inoculation could be beneficial in certain unsterile soils in spite of the presence of native endophytes.
Morphological, chemical, and biogeographical analyses of a hybrid zone involving Juniperus virginiana and J. horizontalis in Wisconsin
Authors: Palma-Otal M. , Moore W. S. , Adams R. P. , Joswiak G. R.
Published: November 2007

Natural hybridization between Juniperus virginiana (L.) and J. horizontalis (Moench.) has been reported in the Driftless Area in Wisconsin. We applied multivariate statistical techniques to morphological and terpene data both to document the phenomenon of hybridization and to determine more accurately the distribution of hybrids and parentals in the Driftless Area. Analysis of morphological, terpene, and electrophoretic data is consistent with the hypothesis that hybridization is occurring beyond the F1 generation. The biogeography of hybridization resembles an archipelago of hybrid populations arrayed along the Driftless boundary. The situation is unusual in that while most hybrid populations are in contact with extensive J. virginiana populations, none appear to be in contact with J. horizontalis. The one-sided structure of the hybrid zone suggests that hybrids are favored by selection along the eastern boundary of the Driftless Area.
PRESUMED CAUSE OF MASS DEATHS OF ROOKS (CORVUS FRUGILEGUS PASTINATOR) USING PIXE ANALYSIS
Authors: SAITOH KATSUMI , KOBAYASHI TAKASHI , SERA KOICHIRO , YASUDA MASAAKI , KAKINO JUN
Published: November 2007

Eighty-nine wild birds were found dead in Ogata Village in northern Japan in March 2006. Eighty-eight of the birds were rooks (Corvus Frugilegus Pastinator), which are migratory birds. Since the use of rodenticide (thallium sulfide and zinc phosphide) in the area around where the birds had been found was revealed by a survey, etiological and pathological examinations including elemental analysis by means of particle induced X-ray emission (PIXE) were conducted. Elemental analysis showed high concentrations (56–365 dry-μg/g) of thallium in the lungs, gastric contents, intestines, livers and kidneys. Histopathological examination revealed vacuolar degeneration of hepatic cells and granular and/or hyaline droplet degeneration of renal tubular epithelia. The results suggest that the mass deaths were caused by thallium poisoning.
ANALYSIS OF LACQUERWARE USING IN-AIR SUBMILLI-PIXE CAMERA
Authors: MATSUYAMA S. , ISHII K. , YAMAZAKI H. , KIKUCHI Y. , OYAMA R. , KAWAMURA Y. , ISHIZAKI A. , MOMOSE G. , FUJISAWA A. , KYONO K.
Published: November 2007

Pigments used in lacquerware pieces excavated from the Edo-period stratum at the southern part of Kawauchi campus of Tohoku University are analyzed using an in-air submilli-PIXE camera. That area is located at the former secondary citadel area of Sendai's Aoba Castle. The lacquerware pieces were analyzed as elemental images without sample degradation and without sample preparation. Pigments used in the red lacquer resin were cinnabar and Bengala. This analytical method, which uses images, was effective for discrimination of contaminant elements through comparison with the decoration. Results show that PIXE analysis using the in-air submilli-PIXE camera is an effective tool for use in archeological studies.
SOFTWARE ARCHITECTURE DECOMPOSITION USING ATTRIBUTES
Authors: LUNG CHUNG-HORNG , XU XIA , ZAMAN MARZIA
Published: November 2007

Software architectural design has an enormous effect on downstream software artifacts. Decomposition of function for the final system is one of the critical steps in software architectural design. The process of decomposition is typically conducted by designers based on their intuition and past experiences, which may not be robust sometimes. This paper presents a study of applying the clustering technique to support system decomposition based on requirements and their attributes. The approach can support the architectural design process by grouping closely related requirements to form a subsystem or module. In this paper, we demonstrate our experiments in applying the approach to an industrial communication protocol software system and comparing several clustering algorithms. The result obtained from WPGMA (weighted pair-group method using arithmetic averages) shows closer resemblance than other clustering methods to the one developed by the designer.
IC CARD: VISUAL SPECIFICATION FOR RAPID PROTOTYPING OF TIME-CRITICAL APPLICATIONS
Authors: CHANG SHI-KUO , RAJNOVIC PERRY , ZALAR MARK
Published: November 2007

We describe IC card, which is a visual specification scheme for the rapid prototyping of time-critical applications. The software developer can use IC cards to describe the entities of an application and their interaction patterns to capture user's requirements. The IC card management system, which is a visual specification tool, supports the creation and editing of IC cards and the transformation of IC cards into an XML specification. The XML specification can be transformed into an IC system and compiled into codes, thus creating a working prototype. Application examples are described.
XML SCHEMA MATCHING
Authors: LU JIANGUO , WANG JU , WANG SHENGRUI
Published: November 2007

XML Schema matching problem can be formulated as follows: given two XML Schemas, find the best mapping between the elements and attributes of the schemas, and the overall similarity between them. XML Schema matching is an important problem in data integration, schema evolution, and software reuse. This paper describes a matching system that can find accurate matches and scales to large XML Schemas with hundreds of nodes. In our system, XML Schemas are modeled as labeled and unordered trees, and the schema matching problem is turned into a tree matching problem. We proposed Approximate Common Structures in trees, and developed a tree matching algorithm based on this concept. Compared with the traditional tree edit-distance algorithm and other schema matching systems, our algorithm is faster and more suitable for large XML Schema matching.
THE CONJUGACY PROBLEM IN AMALGAMATED PRODUCTS I: REGULAR ELEMENTS AND BLACK HOLES
Authors: BOROVIK ALEXANDRE V. , MYASNIKOV ALEXEI G. , REMESLENNIKOV VLADIMIR N.
Published: November 2007

We discuss the time complexity of the word and conjugacy search problems for free products G = A ⋆C B of groups A and B with amalgamation over a subgroup C. We stratify the set of elements of G with respect to the complexity of the word and conjugacy problems and show that for the generic stratum the conjugacy search problem is decidable under some reasonable assumptions about groups A, B, C.
AUTOMATA COMPUTATION OF BRANCHING LAWS FOR ENDOMORPHISMS OF CUNTZ ALGEBRAS
Authors: KAWAMURA KATSUNORI
Published: November 2007

We study the representation theory of C*-algebras by using semigroup theory and automata theory. The Cuntz algebra [Formula: see text] is a finitely generated, infinite-dimensional, noncommutative C*-algebra. A certain class of cyclic representations of [Formula: see text] is characterized by words from the alphabet 1,…,N, which is called a cycle. A class of endomorphisms of [Formula: see text] is defined by polynomial functions in canonical generators and their conjugates. Such an endomorphism ρ of [Formula: see text] transforms a cycle π to π ◦ ρ which is a direct sum of cycles π1,…,πn unique up to unitary equivalence. The passage from π to π1,…,πn is called a branching law for ρ. In this article, we construct a Mealy machine from the endomorphism in order to compute its branching law. We show that the branching law is obtained as outputs from the machine for the input information of a given representation. Furthermore the actual computation of the branching law is executed by using a generalized de Bruijn graph associated with the Mealy machine.
THE QUADRATIC SPINOR LAGRANGIAN, AXIAL TORSION CURRENT AND GENERALIZATIONS
Authors: DA ROCHA R. , PEREIRA J. G.
Published: November 2007

We show that the Einstein–Hilbert, the Einstein–Palatini, and the Holst actions can be derived from the Quadratic Spinor Lagrangian (QSL), when the three classes of Dirac spinor fields, under Lounesto spinor field classification, are considered. To each one of these classes, there corresponds an unique kind of action for a covariant gravity theory. In other words, it is shown to exist a one-to-one correspondence between the three classes of non-equivalent solutions of the Dirac equation, and Einstein–Hilbert, Einstein–Palatini, and Holst actions. Furthermore, it arises naturally, from Lounesto spinor field classification, that any other class of spinor field — Weyl, Majorana, flagpole, or flag-dipole spinor fields — yields a trivial (zero) QSL, up to a boundary term. To investigate this boundary term, we do not impose any constraint on the Dirac spinor field, and consequently we obtain new terms in the boundary component of the QSL. In the particular case of a teleparallel connection, an axial torsion one-form current density is obtained. New terms are also obtained in the corresponding Hamiltonian formalism. We then discuss how these new terms could shed new light on more general investigations.
THIN-SHELL WORMHOLE IN THE HETEROTIC STRING THEORY
Authors: RAHAMAN F. , CHAKRABORTY S. , KALAM M.
Published: November 2007

Using a 'Cut and Paste' technique, we develop a thin-shell wormhole in the heterotic string theory. We determine the surface stresses, which are localized in the shell, by using Darmois–Israel formalism. The linearized stability of this thin wormhole is also analyzed.
NETWORKS OF COSMOLOGICAL HISTORIES, CROSSING OF THE PHANTOM DIVIDE LINE AND POTENTIALS WITH CUSPS
Authors: CANNATA FRANCESCO , KAMENSHCHIK ALEXANDER Y.
Published: November 2007

We discuss the phenomenon of the smooth dynamical gravity induced crossing of the phantom divide line in a framework of simple cosmological models where it appears to occur rather naturally, provided the potential of the unique scalar field has some kind of cusp. The behavior of cosmological trajectories in the vicinity of the cusp is studied in some detail and a simple mechanical analogy is presented. The phenomenon of certain complementarity between the smoothness of the space–time geometry and matter equations of motion is elucidated. We introduce a network of cosmological histories and qualitatively describe some of its properties.
DO RECENT SUPERNOVAE Ia OBSERVATIONS TEND TO RULE OUT ALL THE COSMOLOGIES?
Authors: VISHWAKARMA RAM GOPAL
Published: November 2007

Dark energy and the accelerated expansion of the universe have been the direct predictions of the distant supernovae Ia observations which are also supported, indirectly, by the observations of the CMB anisotropies, gravitational lensing and the studies of galaxy clusters. Today these results are accommodated in what has become the concordance cosmology: a universe with flat spatial sections t = constant with about 70% of its energy in the form of Einstein's cosmological constant Λ and about 25% in the form of dark matter (made of perhaps weakly-interacting massive particles). Though the composition is weird, the theory has shown remarkable successes at many fronts.

However, we find that as more and more supernovae Ia are observed, more accurately and towards higher redshift, the probability that the data are well-explained by the cosmological models decreases alarmingly, finally ruling out the concordance model at more than 95% confidence level. This raises doubts against the "standard candle"-hypothesis of the supernovae Ia and their use in constraining the cosmological models. We need a better understanding of the entire SN Ia phenomenon in order to extract cosmological consequences from them.
OPTION BETAS: RISK MEASURES FOR OPTIONS
Authors: BRANGER NICOLE , SCHLAG CHRISTIAN
Published: November 2007

This paper deals with the problem of determining the correct risk measure for options in a Black–Scholes (BS) framework when time is discrete. For the purposes of hedging or testing simple asset pricing relationships previous papers used the "local", i.e., the continuous-time, BS beta as the measure of option risk even over discrete time intervals. We derive a closed-form solution for option betas over discrete return periods where we distinguish between "covariance betas" and "asset pricing betas". Both types of betas involve only simple Black–Scholes option prices and are thus easy to compute. However, the theoretical properties of these discrete betas are fundamentally different from those of local betas. We also analyze the impact of the return interval on two performance measures, the Sharpe ratio and the Treynor measure. The dependence of both measures on the return interval is economically significant, especially for OTM options.
EQUILIBRIUM WITH EXCESSIVE HOLDINGS CONSTRAINT: AN APPLICATION TO DC PENSION PLANS
Authors: SOUMARÉ ISSOUF
Published: November 2007

In this paper, I study the equilibrium implications when some investors in the economy overweight a subset of stocks within their portfolio. I find that the excess returns for the overweighted stocks are lower, all else being equal. This has strong testable implications for stock returns. In the special case of logarithmic preferences, the riskfree rate increases and the market price of risk for the overweighted stock decreases, which create extra incentive for unconstrained agents to exit the stock market and hold bonds, hence clearing the market. The changes of stocks' volatilities are ambiguous. Finally, I provide an accurate quantification for agents' welfare. I also discuss the implications of my model in the context of defined contribution pension plans where workers hold large shares of their employer.
NONLINEAR ANALYSIS OF AXIALLY MOVING PLATES USING FEM
Authors: HATAMI S. , AZHARI M. , SAADATPOUR M. M.
Published: November 2007

In the present study, a nonlinear finite element formulation is developed for analysis of axially moving two-dimensional materials, based on the classical thin plate theory. Using Green's strain definition, the membrane stresses variation due to transverse displacements is considered. Hamilton's principle is employed to obtain the secant stiffness matrix, the in-plane and out-of-plane gyroscopic matrices and the dynamic stability matrix due to centripetal acceleration for a traveling thin plate. In order to extract the numerical results, a p-version finite element is adopted by selecting only an quadrilateral super element with Lagrangian interpolation functions. With a few test cases, the reliability of the formulation and the solution procedure is shown.
A NEW APPROACH IN BICOVARIANT DIFFERENTIAL CALCULUS ON SUq(2)
Authors: BENTALHA Z. , TAHIRI M.
Published: November 2007

When reviewing the work of Aschieri–Castellani concerning the bicovariant differential calculus on GLq(2), we remarked that a peculiar basis within the space of quantum one-forms over SUq(2) can lead to a new bicovariant differential calculus on SUq(2) easy to handle than those known in the literature. New results have been obtained for the exterior product, the exterior differential, the C-structure constants, the Cartan–Maurer equations, and the q-Lie algebra.
The Impact of Health Insurance on Health
Authors: Levy Helen , Meltzer David
Published: November 2007

How does health insurance affect health? After reviewing the evidence on this question, we reach three conclusions. First, many of the studies claiming to show a causal effect of health insurance on health do not do so convincingly because the observed correlation between insurance and good health may be driven by other, unobservable factors. Second, convincing evidence demonstrates that health insurance can improve health measures of some population subgroups, some of which, although not all, are the same subgroups that would be the likely targets of coverage expansion policies. Third, for policy purposes we need to know whether the results of these studies generalize. Solid answers to the multitude of important questions about how specific health insurance policy options may affect health seem likely to be forthcoming only with investment of substantial resources in social experiments.
Heat Stress and Public Health: A Critical Review
Authors: Kovats R. Sari , Hajat Shakoor
Published: November 2007

Heat is an environmental and occupational hazard. The prevention of deaths in the community caused by extreme high temperatures (heat waves) is now an issue of public health concern. The risk of heat-related mortality increases with natural aging, but persons with particular social and/or physical vulnerability are also at risk. Important differences in vulnerability exist between populations, depending on climate, culture, infrastructure (housing), and other factors. Public health measures include health promotion and heat wave warning systems, but the effectiveness of acute measures in response to heat waves has not yet been formally evaluated. Climate change will increase the frequency and the intensity of heat waves, and a range of measures, including improvements to housing, management of chronic diseases, and institutional care of the elderly and the vulnerable, will need to be developed to reduce health impacts.
Creating Healthy Food and Eating Environments: Policy and Environmental Approaches
Authors: Story Mary , Kaphingst Karen M. , Robinson-O'Brien Ramona , Glanz Karen
Published: November 2007

Food and eating environments likely contribute to the increasing epidemic of obesity and chronic diseases, over and above individual factors such as knowledge, skills, and motivation. Environmental and policy interventions may be among the most effective strategies for creating population-wide improvements in eating. This review describes an ecological framework for conceptualizing the many food environments and conditions that influence food choices, with an emphasis on current knowledge regarding the home, child care, school, work site, retail store, and restaurant settings. Important issues of disparities in food access for low-income and minority groups and macrolevel issues are also reviewed. The status of measurement and evaluation of nutrition environments and the need for action to improve health are highlighted.
AGE-receptor-1 counteracts cellular oxidant stress induced by AGEs via negative regulation of p66shc-dependent FKHRL1 phosphorylation
Authors: Cai Weijing , He John Cijiang , Zhu Li , Chen Xue , Striker Gary E. , Vlassara Helen
Published: November 2007

Advanced glycation end products (AGEs) promote reactive oxygen species (ROS) formation and oxidant stress (OS) in diabetes and aging-related diseases. AGE-induced OS is suppressed by AGER1, an AGE-receptor that counteracts receptor for advanced glycation end products (RAGE) and epidermal growth factor receptor (EGFR)-mediated Shc/Ras signal activation, resulting in decreased OS. Akt, FKHRL1, and antioxidants; e.g., MnSOD, regulate OS. Serine phosphorylation of p66 shc also promotes OS. We examined the effects of two defined AGEs Nε-carboxy-methyl-lysine (CML) and methyl-glyoxal derivatives (MG) on these cellular pathways and their functional relationship to AGER1 in human embryonic kidney cells (HEK293). Stimulation of HEK293 cells with either AGE compound increased phosphorylation of Akt and FKHRL1 by approximately threefold in a redox-dependent manner. The use of p66 shc mutants showed that the AGE-induced effects required Ser-36 phosphorylation of p66 shc. AGE-induced phosphorylation of FKHRL1 led to a 70% downregulation of MnSOD, an effect partially blocked by a phosphatidylinositol 3-kinase inhibitor (LY-294002) and strongly inhibited by an antioxidant ( N-acetylcysteine). These pro-oxidant responses were suppressed in AGER1 overexpressing cells and reappeared when AGER1 expression was reduced by small interfering RNA (siRNA). These studies point to a new pathway for the induction of OS by AGEs involving FKHRL1 inactivation and MnSOD suppression via Ser-36 phosphorylation of p66 shc in human kidney cells. This represents a key mechanism by which AGER1 maintains cellular resistance against OS. Thus the decrease of AGER1 noted in aging and diabetes may further enhance OS and reduce innate antioxidant defenses.
Mutational analysis of predicted intracellular loop domains of human motilin receptor
Authors: Tokunaga Hitoo , Matsuura Bunzo , Dong Maoqing , Miller Laurence J. , Ueda Teruhisa , Furukawa Shinya , Hiasa Yoichi , Onji Morikazu
Published: November 2007

Motilin is an important endogenous regulator of gastrointestinal motor function, mediated by the class I G protein-coupled motilin receptor. Motilin and erythromycin, two chemically distinct full agonists of the motilin receptor, are known to bind to distinct regions of this receptor, based on previous systematic mutagenesis of extracellular regions that dissociated the effects on these two agents. In the present work, we examined the predicted intracellular loop regions of this receptor for effects on motilin- and erythromycin-stimulated activity. We prepared motilin receptor constructs that included sequential deletions throughout the predicted first, second, and third intracellular loops, as well as replacing the residues in key regions with alanine, phenylalanine, or histidine. Each construct was transiently expressed in COS cells and characterized for motilin- and erythromycin-stimulated intracellular calcium responses and for motilin binding. Deletions of receptor residues 63–66, 135–137, and 296–301 each resulted in substantial loss of intracellular calcium responses to stimulation by both motilin and erythromycin. Constructs with mutations of residues Tyr66, Arg136, and Val299 were responsible for the negative impact on biological activity stimulated by both agonists. These data suggest that action by different chemical classes of agonists that are known to interact with distinct regions of the motilin receptor likely yield a common activation state of the cytosolic face of this receptor that is responsible for interaction with its G protein. The identification of functionally important residues in the predicted cytosolic face provides strong candidates for playing roles in receptor-G protein interaction.
Transcriptional activation of the humanclaudin-18gene promoter through two AP-1 motifs in PMA-stimulated MKN45 gastric cancer cells
Authors: Yano Koichi , Imaeda Takashi , Niimi Tomoaki
Published: November 2007

Claudin-18 ( CLDN18), a member of the claudin family of proteins that are structural components of tight junctions, has two alternatively spliced variants, claudin-18a1 and claudin-18a2, which are highly expressed in lung and stomach, respectively. Downregulation of claudin-18a2 is associated with gastric cancers of an intestinal phenotype; however, the mechanisms regulating its expression have not been defined. Here, we found that phorbol 12-myristate 13-acetate (PMA) treatment of MKN45 human gastric cancer cell line increased claudin-18a2 expression. In addition, this study aimed to characterize the human CLDN18a2 promoter. Using reporter gene assays and deletion analysis, we mapped the critical promoter region of the PMA-stimulated claudin-18a2 expression to the −923/−286 region. Electrophoretic mobility shift assays and mutational analyses revealed that two activator protein (AP)-1 binding sites played an important role in the expression of claudin-18a2 in PMA-stimulated MKN45 cells. Protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) inhibitors suppressed the upregulation of claudin-18a2. These results indicate that the PKC/MAPK/AP-1 dependent pathway regulates claudin-18a2 expression in gastric cells.
Mice expressing ACE only in the heart show that increased cardiac angiotensin II is not associated with cardiac hypertrophy
Authors: Xiao Hong D. , Fuchs Sebastien , Bernstein Ellen A. , Li Ping , Campbell Duncan J. , Bernstein Kenneth E.
Published: November 2007

In the heart, angiotensin II has been suggested to regulate cardiac remodeling and promote cardiac hypertrophy. To examine this, we studied compound heterozygous mice, called angiotensin-converting enzyme (ACE) 1/8, in which one ACE allele is null, whereas the other ACE allele (the 8 allele) targets expression to the heart. In this model, cardiac ACE levels are about 15 times those of wild-type mice, and ACE expression is reduced or eliminated in other tissues. ACE 1/8 mice have 58% the cardiac ACE of a previous model, called ACE 8/8, but both ACE 1/8 and ACE 8/8 mice have ventricular angiotensin II levels about twofold those of wild-type controls. Despite equivalent levels of cardiac angiotensin II, ACE 1/8 mice do not develop the marked atrial enlargement or the conduction defects previously reported in the ACE 8/8 mice. Six-month-old ACE 1/8 mice have normal cardiac function, as determined by echocardiography and left ventricular catheterization, despite the elevated levels of angiotensin II. ACE 1/8 mice also have normal levels of connexin 43. Both wild-type and ACE 1/8 mice develop similar degrees of cardiac hypertrophy after aortic banding. These data suggest that a moderate increase of local angiotensin II production in the heart does not produce cardiac dysfunction, at least under basal conditions, and that, in response to aortic banding, cardiac hypertrophy is not augmented by a twofold increase of cardiac angiotensin II.
O2uptake kinetics, pyruvate dehydrogenase activity, and muscle deoxygenation in young and older adults during the transition to moderate-intensity exercise
Authors: Gurd B. J. , Peters S. J. , Heigenhauser G. J. F. , LeBlanc P. J. , Doherty T. J. , Paterson D. H. , Kowalchuk J. M.
Published: November 2007

The adaptation of pulmonary O2uptake (V̇o2p) kinetics is slowed in older compared with young adults during the transition to moderate-intensity exercise. In this study, we examined the relationship between V̇o2pkinetics and mitochondrial pyruvate dehydrogenase (PDH) activity in young ( n = 7) and older ( n = 6) adults. Subjects performed cycle exercise to a work rate corresponding to ∼90% of estimated lactate threshold. Phase 2 V̇o2pkinetics were slower ( P < 0.05) in older (τ = 40 ± 17 s) compared with young (τ = 21 ± 6 s) adults. Relative phosphocreatine (PCr) breakdown was greater ( P < 0.05) at 30 s in older compared with young adults. Absolute PCr breakdown at 6 min was greater ( P < 0.05) in older compared with young adults. In young adults, PDH activity increased ( P < 0.05) from baseline to 30 s, with no further change observed at 6 min. In older adults, PDH activity during baseline exercise was similar to that seen in young adults. During the exercise transition, PDH activity did not increase ( P > 0.05) at 30 s of exercise but was elevated ( P < 0.05) after 6 min. The change in deoxyhemoglobin (HHb) was greater for a given V̇o2pin older adults, and there was a similar time course of HHb accompanying the slower V̇o2pkinetics in the older adults, suggesting a slower adaptation of bulk O2delivery in older adults. In conclusion, the slower adaptation of V̇o2pin older adults is likely a result of both an increased metabolic inertia and lower O2availability.
Resistance training alters the response of fed state mixed muscle protein synthesis in young men
Authors: Tang Jason E. , Perco Jennifer G. , Moore Daniel R. , Wilkinson Sarah B. , Phillips Stuart M.
Published: November 2007

Ten healthy young men (21.0 ± 1.5 yr, 1.79 ± 0.1 m, 82.7 ± 14.7 kg, means ± SD) participated in 8 wk of intense unilateral resistance training (knee extension exercise) such that one leg was trained (T) and the other acted as an untrained (UT) control. After the 8 wk of unilateral training, infusions of l-[ring-d5]phenylalanine, l-[ring-13C6]phenylalanine, and d3-α-ketoisocaproic acid were used to measure mixed muscle protein synthesis in the T and UT legs by the direct incorporation method [fractional synthetic rate (FSR)]. Protein synthesis was determined at rest as well as 4 h and 28 h after an acute bout of resistance exercise performed at the same intensity relative to the gain in single repetition maximum before and after training. Training increased mean muscle fiber cross-sectional area only in the T leg (type I: 16 ± 10%; type II: 20 ± 19%, P < 0.05). Acute resistance exercise increased muscle protein FSR in both legs at 4 h (T: 162 ± 76%; UT: 108 ± 62%, P < 0.01 vs. rest) with the increase in the T leg being significantly higher than in the UT leg at this time ( P < 0.01). At 28 h postexercise, FSR in the T leg had returned to resting levels; however, the rate of protein synthesis in the UT leg remained elevated above resting (70 ± 49%, P < 0.01). We conclude that resistance training attenuates the protein synthetic response to acute resistance exercise, despite higher initial increases in FSR, by shortening the duration for which protein synthesis is elevated.
Role of nitric oxide deficiency in the development of hypertension in hydronephrotic animals
Authors: Carlström Mattias , Brown Russell D. , Edlund Jenny , Sällström Johan , Larsson Erik , Teerlink Tom , Palm Fredrik , Wåhlin Nils , Persson A. Erik G.
Published: November 2007

Hydronephrotic animals develop renal injury and hypertension, which is associated with an abnormal tubuloglomerular feedback (TGF). The TGF sensitivity is coupled to nitric oxide (NO) in the macula densa. The involvement of reduced NO availability in the development of hypertension in hydronephrosis was investigated. Hydronephrosis was induced by ureteral obstruction in young rats. Blood pressure and renal excretion were measured in adulthood, under different sodium conditions, and before and after chronic administration of either NG-nitro-l-arginine methyl ester (l-NAME) or l-arginine. Blood samples for ADMA, SDMA, and l-arginine analysis were taken and the renal tissue was used for histology and determination of NO synthase (NOS) proteins. TGF characteristics were determined by stop-flow pressure technique before and after administration of 7-nitroindazole (7-NI) or l-arginine. Hydronephrotic animals developed salt-sensitive hypertension, which was associated with pressure natriuresis and diuresis. The blood pressure response to l-NAME was attenuated and l-arginine supplementation decreased blood pressure in hydronephrotic animals, but not in the controls. Under control conditions, reactivity and sensitivity of the TGF response were greater in the hydronephrotic group. 7-NI administration increased TGF reactivity and sensitivity in control animals, whereas, in hydronephrotic animals, neuronal NOS (nNOS) inhibition had no effect. l-Arginine attenuated TGF response more in hydronephrotic kidneys than in controls. The hydronephrotic animals displayed various degrees of histopathological changes. ADMA and SDMA levels were higher and the renal expressions of nNOS and endothelial NOS proteins were lower in animals with hydronephrosis. Reduced NO availability in the diseased kidney in hydronephrosis, and subsequent resetting of the TGF mechanism, plays an important role in the development of hypertension.
Partial nephrectomy as a model for uremic cardiomyopathy in the mouse
Authors: Kennedy David J. , Elkareh Jihad , Shidyak Amjad , Shapiro Anna P. , Smaili Sleiman , Mutgi Krishna , Gupta Shalini , Tian Jiang , Morgan Eric , Khouri Samer , Cooper Christopher J. , Periyasamy Sankaridrug M. , Xie Zijian , Malhotra Deepak , Fedorova Olga V. , Bagrov Alexei Y. , Shapiro Joseph I.
Published: November 2007

Because of the plethora of genetic manipulations available in the mouse, we performed a partial nephrectomy in the mouse and examined whether the phenotypical features of uremic cardiomyopathy described in humans and rats were also present in the murine model. A nephrectomy was performed using a combination of electrocautory to decrease renal mass on the left kidney and right surgical nephrectomy. This procedure produced substantial and persistent hypertension as well as increases in circulating concentrations of marinobufagenin. Invasive physiological measurements of cardiac function demonstrated that the nephrectomy resulted in impairment of both active and passive left ventricular relaxation at 4 wk whereas tissue Doppler imaging detected changes in diastolic function after 6 wk. Morphologically, hearts demonstrated enlargement and progressive fibrosis, and biochemical measurements demonstrated downregulation of the sarcoplasmic reticulum calcium ATPase as well as increases in collagen-1, fibronectin, and vimentin expression. Our results suggest that partial nephrectomy in the mouse establishes a model of uremic cardiomyopathy which shares phenotypical features with the rat model as well as patients with chronic renal failure.
Creatine supplementation does not affect human skeletal muscle glycogen content in the absence of prior exercise
Authors: Sewell Dean A. , Robinson Tristan M. , Greenhaff Paul L.
Published: November 2007

Due to the current lack of clarity, we examined whether 5 days of dietary creatine (Cr) supplementation per se can influence the glycogen content of human skeletal muscle. Six healthy male volunteers participated in the study, reporting to the laboratory on four occasions to exercise to the point of volitional exhaustion, each after 3 days of a controlled normal habitual dietary intake. After a familiarization visit, participants cycled to exhaustion in the absence of any supplementation (N), and then 2 wk later again they cycled to exhaustion after 5 days of supplementation with simple sugars (CHO). Finally, after a further 2 wk, they again cycled to exhaustion after 5 days of Cr supplementation. Muscle samples were taken at rest before exercise, at the time point of exhaustion in visit 1, and at subsequent visit time of exhaustion. There was a treatment effect on muscle total Cr content in Cr compared with N and CHO supplementation ( P < 0.01). Resting muscle glycogen content was elevated above N following CHO ( P < 0.05) but not after Cr. At exhaustion following N, glycogen content was no different from CHO and Cr measured at the same time point during exercise. Cr supplementation under conditions of controlled habitual dietary intake had no effect on muscle glycogen content at rest or after exhaustive exercise. We suggest that any Cr-associated increases in muscle glycogen storage are the result of an interaction between Cr supplementation and other mediators of muscle glycogen storage.
Elucidation of spatially distinct compensatory mechanisms in diastole: radial compensation for impaired longitudinal filling in left ventricular hypertrophy
Authors: Riordan Matt M. , Kovács Sándor J.
Published: November 2007

Cardiac output maintenance is so fundamental that, when regional systolic function is impaired, as during ischemia, nonischemic segments compensate by becoming hypercontractile. By analogy, diastolic compensatory mechanisms that maintain filling volume must exist but remain to be fully elucidated. Viewing filling in spatially distinct (longitudinal, radial) mechanistic terms facilitates elucidation of diastolic compensatory mechanisms. Because impairment of longitudinal (long axis) diastolic function (DF) in left ventricular hypertrophy (LVH) is established, we hypothesized that to maintain filling volume, radial (short-axis) filling function would compensate. In 20 normal left ventricular ejection fraction (LVEF) subjects (10 with LVH, 10 without LVH), we analyzed longitudinal function via Doppler tissue imaging of mitral annular motion and radial function as change in short-axis endocardial dimension via M-mode. The spatial (long axis, short axis) endocardial LV dimensions and their changes allowed assignment of E-wave filling volume into (cylindrical geometry-based) longitudinal and radial components. Despite indistinguishable ( P = 0.70) E-wave velocity-time integrals (E-wave filling volume surrogate), systolic stroke volumes, and end-diastolic volumes in the LVH and control groups, longitudinal volume in absolute terms and the percent of E-wave volume accommodated longitudinally were reduced in the LVH group ( P < 0.05 and P < 0.01, respectively), whereas the percent of E-wave volume accommodated radially was enhanced ( P < 0.01). We conclude that, in normal LVEF (decreased longitudinal volume accommodation) LVH subjects vs. controls, spatially distinct compensatory mechanisms in diastole manifest as increased radial volume accommodation per unit of E-wave filling volume. Assessment of spatially distinct diastolic compensatory mechanisms in other pathophysiological subsets is warranted.