bluuebunny/crossref_metadata_2025 huggingface dataset:
The determinants of gene order conservation in yeasts
Authors: Poyatos Juan F , Hurst Laurence D
Published: November 2007

Background

Why do some groups of physically linked genes stay linked over long evolutionary periods? Although several factors are associated with the formation of gene clusters in eukaryotic genomes, the particular contribution of each feature to clustering maintenance remains unclear.

Results

We quantify the strength of the proposed factors in a yeast lineage. First we identify the magnitude of each variable to determine linkage conservation by using several comparator species at different distances to Saccharomyces cerevisiae. For adjacent gene pairs, in line with null simulations, intergenic distance acts as the strongest covariate. Which of the other covariates appear important depends on the comparator, although high co-expression is related to synteny conservation commonly, especially in the more distant comparisons, these being expected to reveal strong but relatively rare selection. We also analyze those pairs that are immediate neighbors through all the lineages considered. Current intergene distance is again the best predictor, followed by the local density of essential genes and co-regulation, with co-expression and recombination rate being the weakest predictors. The genome duplication seen in yeast leaves some mark on linkage conservation, as adjacent pairs resolved as single copy in all post-whole genome duplication species are more often found as adjacent in pre-duplication species.

Conclusion

Current intergene distance is consistently the strongest predictor of synteny conservation as expected under a simple null model. Other variables are of lesser importance and their relevance depends both on the species comparison in question and the fate of the duplicates following genome duplication.
IL-18 is a key proximal mediator of contact hypersensitivity and allergen-induced Langerhans cell migration in murine epidermis
Authors: Antonopoulos Christos , Cumberbatch Marie , Mee John B , Dearman Rebecca J , Wei Xiao-Qing , Liew Foo Y , Kimber Ian , Groves Richard W
Published: November 2007

Langerhans cells (LC) migrate rapidly from epidermis to lymph node following epicutaneous application of antigen. In this study, we have explored the role of IL-18, a cytokine with structural similarities to IL-1β, in murine LC migration and contact hypersensitivity (CHS), which to oxazolone (OX) and 2-4,dinitrofluorobenzene (DNFB) was suppressed significantly in IL-18 knockout (IL-18−/−) mice and could be rescued by local intradermal administration of IL-18 prior to sensitization, suggesting that the defect in these mice was in the afferent phase of CHS. To determine the effect of IL-18 on LC migration, mice were treated topically with OX or DNFB, and remaining LC numbers were assessed. A significant decline in remaining epidermal LC occurred in wild-type (WT) mice but did not occur in IL-18−/− mice. Sodium lauryl sulfate, a nonantigenic LC migratory stimulus, induced equivalent LC migration in IL-18−/− and WT mice. In IL-18−/− mice, IL-1β and TNF-α were equally able to mobilize LC from epidermis, indicating that migration in response to these cytokines is not dependent on IL-18 and suggesting that IL-18 acts upstream of these cytokines in the initiation of antigen-induced LC migration. Moreover, IL-1β but not IL-18 was able to rescue the defective CHS response observed in caspase-1−/− mice, which have no functional IL-1β or IL-18. These data indicate that IL-18 is a key proximal mediator of LC migration and CHS, acting upstream of IL-1β and TNF-α, and may play a central role in regulation of cutaneous immune responses.
Serum amyloid A mediates human neutrophil production of reactive oxygen species through a receptor independent of formyl peptide receptor like-1
Authors: Björkman Lena , Karlsson Jennie , Karlsson Anna , Rabiet Marie-Josèphe , Boulay Francois , Fu Huamei , Bylund Johan , Dahlgren Claes
Published: November 2007

Serum amyloid A (SAA) is one of the acute-phase reactants, a group of plasma proteins that increases immensely in concentration during microbial infections and inflammatory conditions, and a close relationship between SAA levels and disease activity in rheumatoid arthritis (RA) has been observed. RA is an inflammatory disease, where neutrophils play important roles, and SAA is thought to participate in the inflammatory reaction by being a neutrophil chemoattractant and inducer of proinflammatory cytokines. The biological effects of SAA are reportedly mediated mainly through formyl peptide receptor like-1 (FPRL1), a G protein-coupled receptor (GPCR) belonging to the formyl peptide receptor family. Here, we confirmed the affinity of SAA for FPRL1 by showing that stably transfected HL-60 cells expressing FPRL1 were activated by SAA and that the response was inhibited by the use of the FPRL1-specific antagonist WRWWWW (WRW4). We also show that SAA activates the neutrophil NADPH-oxidase and that a reserve pool of receptors is present in storage organelles mobilized by priming agents such as TNF-α and LPS from Gram-negative bacteria. The induced activity was inhibited by pertussis toxin, indicating the involvement of a GPCR. However, based on FPRL1-specific desensitization and use of FPRL1 antagonist WRW4, we found the SAA-mediated effects in neutrophils to be independent of FPRL1. Based on these findings, we conclude that SAA signaling in neutrophils is mediated through a GPCR, distinct from FPRL1. Future identification and characterization of the SAA receptor could lead to development of novel, therapeutic targets for treatment of RA.
Ray velocity and ray attenuation in homogeneous anisotropic viscoelastic media
Authors: Vavryčuk Václav
Published: November 2007

Asymptotic wave quantities such as ray velocity and ray attenuation are calculated in anisotropic viscoelastic media by using a stationary slowness vector. This vector generally is complex valued and inhomogeneous, and it predicts the complex energy velocity parallel to a ray. To compute the stationary slowness vector, one must find two independent, real-valued unit vectors that specify the directions of its real and imaginary parts. The slowness-vector inhomogeneity affects asymptotic wave quantities and complicates their computation. The critical quantities are attenuation and quality factor ([Formula: see text]-factor); these can vary significantly with the slowness-vector inhomogeneity. If the inhomogeneity is neglected, the attenuation and the [Formula: see text]-factor can be distorted distinctly by errors commensurate to the strength of the velocity anisotropy — as much as tens of percent for sedimentary rocks. The distortion applies to strongly as well as to weakly attenuative media. On the contrary, the ray velocity, which defines the wavefronts and physically corresponds to the energy velocity of a high-frequency signal propagating along a ray, is almost insensitive to the slowness-vector inhomogeneity. Hence, wavefronts can be calculated in a simplified way except for media with extremely strong anisotropy and attenuation.
A sensitivity analysis of DC resistivity prospecting on finite, homogeneous blocks and columns
Authors: Zhou Qi You
Published: November 2007

Besides field applications to geophysical prospecting and subsurface hydrology, electrical resistivity tomography can be applied to finite-scale blocks in the laboratory to characterize the resistivity structure of the blocks and to monitor internal physical and chemical processes. This requires a fast and accurate calculation of the sensitivity matrix to perform a successful resistivity inversion for such blocks. However, the complex geometric shape and boundary and the finite size of the block limit the application of field-suitable sensitivity calculation methods to these blocks. As blocks and finite columns are often used in the laboratory experiments, this paper develops practical analytic expressions, based on the method of image charges, for the sensitivity matrix for these two types of homogenous bodies. The corresponding formulae for the electric potential distribution and theelectrode array coefficient are also presented. As a result of the theory, the effects of placing limits on the sum index in the electric-potential calculation can be analyzed, and a comparison of the theoretical and the numerically simulated electric potential is shown. The results demonstrate the correctness of the theory and indicate that even the addition of only one set of mirror current sources greatly reduces the effects of the block boundary on the electric-potential calculation. Finally, several interesting sensitivity distributions for cross-surface arrays on blocks, and for circular and vertical arrays on columns, are given. Although the formulae developed here are only valid for homogeneous blocks and columns, and an element of relatively small volume is required to permit a good approximation to the sensitivity, the theory is useful in the verification of numerically simulated results, in sensitivity-analysis for optimum probing-scheme design, and in successful resistivity inversion calculation for finite bodies.
Translation invariant attributes for effective lithofacies discrimination
Authors: Singh Yesh Pal
Published: November 2007

This study introduces translation-invariant attributes using the Hadamard and Rapid transforms of seismic data to discriminate lithofacies. Unlike the Fourier transform, which projects the data onto a set of orthogonal sinusoidal waveforms, the Hadamard transform projects data onto a set of square waves called Walsh functions. The Hadamard transform is particularly good at finding repeating, stacked vertical sequences. Crossplot analysis indicates translation-invariant attributes for horizon-based time windows are less sensitive to horizon interpretation errors in the reservoir interval. Therefore, translation-invariant attributes can be used to find a particular geologic pattern of interest in a reservoir interval. These attributes have been applied successfully to discriminate the lithofacies in a reservoir interval of interest for a 3D seismic survey in the upper Assam basin of India. The sand-shale thickness ratio at the drilled locations within the reservoir interval is used to define the lithofacies categories. Using the discriminant function analysis of each of the conventional-seismic, principal-component, and translation-invariant sets of attributes, we create a corresponding discriminant score map. The probability density function (PDF) of the discriminant score at the drilled locations transforms the PDF to lithofacies categories. The comparative analysis presented in this study indicates that translation-invariant attributes are superior to conventional-seismic and principal-component attributes in discriminating the lithofacies.
An integrated geophysical approach for imaging subbasalt sedimentary basins: Case study of Jam River Basin, India
Authors: Chakravarthi V. , Shankar G. B. K. , Muralidharan D. , Harinarayana T. , Sundararajan N.
Published: November 2007

An integrated geophysical strategy comprising deep electrical resistivity and gravity data was devised to image subbasalt sedimentary basins. A 3D gravity inversion was used to determine the basement structure of the Permian sediments underlying the Cretaceous formation of the Jam River Basin in India. The thickness of the Cretaceous formation above the Permian sediments estimated from modeling 60 deep-electric-sounding data points agrees well with drilling information. The gravity effect of mass deficit between the Cretaceous and Permian formations was found using 3D forward modeling and subsequently removed from the Bouguer gravity anomaly along with the regional gravity field. The modified residual gravity field was then subjected to3D inversion to map the variations in depth of the basement beneath the Permian sediments. Inversion of gravity data resulted in two basement ridges, running almost east to west, dividing the basin into three independent depressions. It was found that the Katol and Kondhali faults were active even during post-Cretaceous time and were responsible for the development of the subsurface basement ridges in the basin. The inferred 3D basement configuration of the basin clearly brought out the listric nature of these two faults. Further, the extension of the Godavari Basin into the Deccan syneclise and the fact that the source-rock studies show the presence of hydrocarbons in the Sironcha block in the northern part of the Godavari Basin also shed some light on the hydrocarbon potential of the Jam River Basin.
Application of a linear finite-frequency theory to time-lapse crosswell tomography in ultrasonic and numerical experiments
Authors: Spetzler Jesper , Šijačić Danijela , Wolf Karl-Heinz
Published: November 2007

Time-lapse seismic monitoring is the geophysical discipline whereby multiple data sets recorded at the same location but at different times are used to locate and quantify temporal changes in the elastic parameters of the subsurface. We validate a time-lapse monitoring method by crosswell tomography using two types of wavefield-modeling experiments: (1) a 3D real ultrasonic waveform experiment and (2) 2D synthetic finite-difference wavefield simulations. For both wavefield experiments, a time-lapse structure simulating a fluid sweep in a reservoir layer is applied. The time-lapse tomographic monitoring approach is based on the standard ray theory and a finite-frequency wavefield theory, where the latter takes into account the finite-frequency properties of recorded wavefields. The inverted time-lapse models compiled with either the ray theory or the finite-frequency wavefield theory locate and correctly quantify the flooding zone in the simulated fluid sweep model. Both wavefield theories provide an adequate result because the flooding zone is comparable in size to the Fresnel volume.
Improving lateral and vertical resolution of seismic images by correcting for wavelet stretch in common-angle migration
Authors: Perez Gabriel , Marfurt Kurt J.
Published: November 2007

Long-offset or high-incident-angle seismic reflections provide us with improved velocity resolution, better leverage against multiples, less contamination by ground roll, and information that is often critical when estimating lithology and fluid product. Unfortunately, high-incident-angle seismic reflections suffer not only from nonhyperbolic moveout but also from wavelet stretch during imaging, resulting in lower-resolution images that mix the response from adjacent lithologies. For an arbitrary acoustic medium, wavelet stretch from prestack migration depends only on the cosine of the reflection angle, such that the amount of wavelet stretch will be the same for all samples of a common-reflection-angle migrated trace. Thus, we are able to implement a wavelet stretch correction by applying a simple stationary spectral shaping operation to common-angle migrated traces. We obtain such traces directly by a prestack Kirchhoff migration algorithm. Correcting for stretch effectively increases the fold of imaged data, far beyond that achieved in conventional migration, resulting in improved signal-to-noise ratio of the final stacked section. Increasing the fidelity of large incident angles results in images with improved vertical and lateral resolution and with increased angular illumination, valuable for amplitude variation with angle (AVA) and amplitude variation with offset (AVO) analysis. Finally, such large-angle images are more sensitive to and therefore provide increased leverage over errors in velocity and velocity anisotropy. These ideas were applied to prestack time migration on seismic data from the Fort Worth basin, in Texas.
The discrete prolate spheroidal sequences and a series expansion for seismic wavelets
Authors: Greene Michael
Published: November 2007

The discrete prolate spheroidal sequences (DPSSs) are a set of time-limited, band-limited, and mutually orthogonal sequences. I exploit their favorable properties to introduce a series expansion for seismic wavelets. By modifying the definition of the DPSSs, I generate new sequences that are tailored to the character of the seismic wavelet but retain the DPSSs’ favorable properties. I show that a series expansion composed of these new sequences can be thought of as a logical extension of a familiar practice, assuming the wavelet is a linear combination of a Ricker wavelet and its Hilbert transform ([Formula: see text] rotation). Two examples, one synthetic and one real, show how the series expansion can be used to tie well data to seismic data. This leads to a robust method to determine a wavelet. The examples also illustrate the properties of the series expansion, some of which can be related to familiar geophysical concepts such as thin-bed tuning. I conclude that this series expansion is a natural and useful way to describe the seismic wavelet.
Grid dispersion and stability criteria of some common finite-element methods for acoustic and elastic wave equations
Authors: De Basabe Jonás D. , Sen Mrinal K.
Published: November 2007

Purely numerical methods based on finite-element approximation of the acoustic or elastic wave equation are becoming increasingly popular for the generation of synthetic seismograms. We present formulas for the grid dispersion and stability criteria for some popular finite-element methods (FEM) for wave propagation, namely, classical and spectral FEM. We develop an approach based on a generalized eigenvalue formulation to analyze the dispersive behavior of these FEMs for acoustic or elastic wave propagation that overcomes difficulties caused by irregular node spacing within the element and the use of high-order polynomials, as is the case for spectral FEM. Analysis reveals that for spectral FEM of order four or greater, dispersion is less than 0.2% at four to five nodes per wavelength, and dispersion is not angle dependent. New results can be compared with grid-dispersion results of some classical finite-difference methods (FDM) used for acoustic or elastic wave propagation. Analysis reveals that FDM and classical FEM require a larger sampling ratio than a spectral FEM to obtain results with the same degree of accuracy. The staggered-grid FDM is an efficient scheme, but the dispersion is angle dependent with larger values along the grid axes. On the other hand, spectral FEM of order four or greater is isotropic with small dispersion, making it attractive for simulations with long propagation times.
Wide-angle FD and FFD migration using complex Padé approximations
Authors: Amazonas Daniela , Costa Jessé C. , Schleicher Jörg , Pestana Reynam
Published: November 2007

Seismic migration by downward continuation using the one-way wave-equation approximations has two shortcomings: imaging steep-dip reflectors and handling evanescent waves. Complex Padé approximations allow a better treatment of evanescent modes, stabilizing finite-difference migration without requiring special treatment for the migration domain boundaries. Imaging of steep-dip reflectors can be improved using several terms in the Padé expansion. We discuss the implementation and evaluation of wide-angle complex Padé approximations for finite-difference and Fourier finite-difference migration methods. The dispersion relation and the impulsive response of the migration operator provide criteria to select the number of terms and coefficients in the Padé expansion. This ensures stability for a prescribed maximum propagation direction. The implementations are validated on the Marmousi model data set and SEG/EAGE salt model data.
Asymptotic airwave modeling for marine controlled-source electromagnetic surveying
Authors: Nordskag Janniche Iren , Amundsen Lasse
Published: November 2007

Marine controlled-source electromagnetic (CSEM) surveying, also called seabed logging, is a technique for finding resistive layers in the subsurface, which can be hydrocarbon-saturated reservoirs. The EM signal from the horizontal electric dipole source induces an airwave along the air/sea surface that interferes with the signal from the subsurface and dominates at larger offsets. The airwave commonly denotes the energy that propagates from the source via the atmosphere to the receiver on the seabed. The airwave component is especially problematic in shallow waters, where it is less attenuated during its up-and-down propagation in the water column than for deeper waters. An asymptotically derived space-domain equation that describes the airwavecomponent in a water half-space bounded by air is well known from the EM literature. We demonstrate that by taking into account the reflections and reverberations of the airwave component in the water column between the seabed and the sea surface at both the source side and the receiver side, this equation can be generalized to a water layer. The new model we present can serve as an integrity check for other modeling schemes. Our airwave model shows how the airwave component depends on water depth, source-receiver range, frequency, and seabed resistivity. The model is verified by extensive numerical testing. Finally, we show how the source-induced airwave may affect the marine CSEM recordings and how the airwave component in principle can be suppressed by a modeling-and-subtraction approach.
Modified imaging principle: An alternative to preserved-amplitude least-squares wave-equation migration
Authors: Kiyashchenko Denis , Plessix René-Edouard , Kashtan Boris
Published: November 2007

Impedance contrast images can result from a least-squares migration or from a modified imaging principle. Theoretically, the two approaches should give similar results, but in practice they lead to different estimates of the impedance contrasts because of limited acquisition geometry, difficulty in computing exact weights for least-squares migration, and small contrast approximation. To analyze those differences, we compare the two approaches based on 2D synthetics. Forward modeling is either a finite-difference solver of the full acoustic wave equation or a one-way wave-equation solver that correctly models the amplitudes. The modified imaging principle provides better amplitude estimates of the impedance contrasts and does not suffer from the artifacts at-tributable to diving waves, which can be seen in two-way, least-squares migrated sections. However, because of the shot-based formulation, artifacts appear in the modified imaging principle results in shadow zones where energy is defocused. Those artifacts do not exist with the least-squares migration algorithm because all shots are processed simultane-ously.
Shallow 3D seismic-reflection imaging of fracture zones in crystalline rock
Authors: Schmelzbach Cedric , Horstmeyer Heinrich , Juhlin Christopher
Published: November 2007

A limited 3D seismic-reflection data set was used to map fracture zones in crystalline rock for a nuclear waste disposal site study. Seismic-reflection data simultaneously recorded along two roughly perpendicular profiles (1850 and [Formula: see text] long) and with a [Formula: see text] receiver array centered at the intersection of the lines sampled a [Formula: see text] area in three dimensions. High levels of source-generated noise required a processing sequence involving surface-consistent deconvolution, which effectively increased the strength of reflected signals, and a linear [Formula: see text] filtering scheme to suppress any remaining direct [Formula: see text]-wave energy. A flexible-binning scheme significantly balanced and increased the CMP fold, but the offset and azimuth distributions remain irregular; a wide azimuth range and offsets [Formula: see text] are concentrated in the center of the survey area although long offsets [Formula: see text] are only found at the edges of the site. Three-dimensional dip moveout and 3D poststack migration were necessary to image events with conflicting dips up to about 40°. Despite the irregular acquisition geometry and the high level of source-generated noise, we obtained images rich in structural detail. Seven continuous to semicontinuous reflection events were traced through the final data volume to a maximum depth of around [Formula: see text]. Previous 2D seismic-reflection studies and borehole data indicate that fracture zones are the most likely cause of the reflections.
Combining an Antioxidant‐Fortified Diet with Behavioral Enrichment Leads to Cognitive Improvement and Reduced Brain Pathology in Aging Canines
Authors: HEAD ELIZABETH
Published: November 2007

Abstract:  The number of elderly individuals in our population is rapidly rising and age‐associated neurodegenerative disease is becoming more prevalent. Thus, identifying ways by which we can promote healthy aging are becoming more critical. Lifestyle factors, such as engaging in physical, intellectual, and social activities, are protective against dementia in aged individuals. Similarly, there is some evidence to suggest that antioxidants are beneficial. Observational studies in humans have been confirmed and extended in rodent model systems. We present additional evidence that, in a canine model of aging, combining an antioxidant‐enriched diet and behavioral enrichment (including social, physical, and cognitive components) can lead to substantial improvements in cognition and reduced brain pathology. These results suggest that modifying lifestyle factors can have a beneficial impact on the aging process, even in aged individuals with existing cognitive decline and brain pathology.
Healthy Aging
Authors: BELL ERICA
Published: November 2007

Abstract: The potential of a transdisciplinary research method—Quali‐Quantitative Analysis (QQA)—for delivering better evidence for healthy aging is explored. Illustrative reviews from the literature on healthy aging are summarized, as are papers on methodology by Charles Ragin and colleagues. The evidence needs for healthy aging are explored, particularly in relation to the ability of randomized controlled trials (RCTs) to deliver rich, diversity‐oriented evidence. The techniques of QQA, which involves treating cases as configurations, are described. The QQA method has potential value for healthy aging research in that: (a) it could provide evidence in combinatorial forms useful to holistic practice; (b) it could enrich the evidence for practice by providing more rigorous information from small‐Ngroups, within RCTs and where RCTs cannot be used; and (c) it could add to the ability of RCTs to generate theoretical advances.
Effects of Old Age on Hepatocyte Oxygenation
Authors: CHELUVAPPA RAJKUMAR , HILMER SARAH N. , KWUN SUN YOUNG , COGGER VICTORIA C. , Le COUTEUR DAVID G.
Published: November 2007

Abstract:  Hepatic phase I drug metabolism is diminished in old age. It has been suggested that hepatocyte hypoxia and impaired bioenergetics in old age may contribute to this aging change. Therefore, we sought to determine whether old age was associated with in vivo hypoxia in the aged rat liver. Immunohistochemical studies with the nitroimidazole hypoxia marker, pimonidazole, were carried out in livers from young and old rats. Preliminary studies were performed on four young (4‐month‐old) and six old (2‐year‐old) F344 rats to directly visualize the distribution and intensity of pimonidazole staining. There were no significant differences in the distribution or in the intensity of pimonidazole immunohistochemical staining between young and aged rat livers. In conclusion, no major changes in hepatocyte oxygenation were seen in the aged rat liver, and the ATP changes are unlikely to be secondary to hepatocyte hypoxia or impaired oxygen diffusion into the liver. It is thus more likely that age‐related reduction in liver ATP is attributable to mitochondrial dysfunction.
Independence, Well‐being, and Social Participation in an Aging Population
Authors: ALPASS FIONA , TOWERS ANDY , STEPHENS CHRISTINE , FITZGERALD ELJON , STEVENSON BRENDAN , DAVEY JUDITH
Published: November 2007

Abstract:  In 2005 the Health, Work, and Retirement (HWR) Longitudinal Study was established at Massey University in order to identify the later‐midlife factors that lay the basis for community participation, independence, and health in later life. Information was collected via postal questionnaire on physical and mental health, psychosocial factors, work and retirement attitudes, and socioeconomic and demographic indicators of a sample of 6662 community‐dwelling adults aged 55–70 years. This report provides an overview of these results, and highlights the impact that the transition from work to retirement has on the health and retirement adjustment of older people with respect to independence, well‐being, and social participation.
Comparative Analysis of Mitochondrial Genotype and Aging
Authors: BALLARD J. WILLIAM O. , KATEWA SUBHASH D. , MELVIN RICHARD G. , CHAN GRACE
Published: November 2007

Abstract:  A common feature across all animals, including humans, is that mitochondrial bioenergetics is linked to oxidative stress, but the nature of these relationships with survival is yet to be properly defined. In this study we included 12 Drosophila simulans isofemale lines: four of each distinct mtDNA haplogroup (siI, ‐II, and ‐III). First, we investigated sequence variation in six mtDNA and 13 nuclear encoded genes (nine nuclear‐encoded subunits, and the four known isoforms, of complex IV of the electron transport chain). As expected we observed high divergence among the three distinct mitotypes and greatest mtDNA variability in siII‐harboring flies. In the nuclear encoded genes, no fixed amino acid differences were observed and levels of polymorphism did not differ significantly among flies harboring distinct mtDNA types. Second, 15,456 flies were included in mortality studies. We observed that mtDNA type influenced survival (siII ≈ siIII > siI), flies harboring siII mtDNA had the greatest variation in mortality rates, and in all cases males were longer lived than females. We also assayed maximal rates of hydrogen peroxide (H2O2) production from complex III of the electron transport chain in mitochondria isolated from 11‐day‐old flies. Contrary to our prediction, rates of H2O2 production tended to increase with mean survival. This result suggests that higher rates of H2O2 production in younger flies may lead to an upregulation of antioxidants, age‐dependent increase in the rate of H2O2 production differ, and/or flies vary in their mitochondrial uncoupling. Alternatively, the whole organism may not regularly, if ever, experience maximal H2O2 production rates.
Mechanisms of Action of TGF‐β in Cancer
Authors: LI HE , LIU JUN‐PING
Published: November 2007

Abstract:  Transforming growth factor‐β (TGF‐β) induces cell differentiation and suppresses cell proliferation, but the mechanisms underlying the actions of TGF‐β remain to be fully elucidated. Recent studies suggest that TGF‐β suppresses neoplastic cell development by employing Smad3 protein to repress the gene of human telomerase reverse transcriptase (hTERT). In human breast cancer cells, TGF‐β induces rapid phosphorylation and subsequent entry of Smad3 into the nucleus. In the nucleus, Smad3 binds to the hTERT gene promoter directly and inhibits hTERT gene transcription activity. By interacting with c‐myc, Smad3 also represses the c‐myc gene. Thus, TGF‐β prevents continuous cell proliferation by switching off telomerase activity through Smad3 repression of the hTERT gene and the action of c‐myc. Modulating the interface between Smad3 and the hTERT gene, and the potential feedback loop from telomeres to Smad3 via Smurf2, may represent a novel approach to regulate cell lifespan of proliferation.
Healthy Aging for Caregivers
Authors: WU TINA , LO KAREN
Published: November 2007

Abstract:  The aim of this study was to design a culture‐sensitive scale to measure caregiver's burden for the purpose of identifying their needs in Taiwan. In this study, four factors were identified as caregiver's top priority needs: “personal factors,”“relation factors,”“financial factors,” and “reward factors.” Definitions for each factor are also discussed. The total variances explained by the four factors are 34%, 13%, 9%, and 8%, respectively. The results show caregivers in Taiwan place more emphasis on their physical and emotional interaction with the care‐receivers than is found in other cultures. Policy recommendations inferred from these findings are made. It is necessary for the government or organizations to provide services to fulfill caregivers' needs to promote a healthy aging process of the caregivers themselves. Participants who cared for their elderly parents or relatives were selected randomly from the island of Taiwan. The total selected sample size of caregivers is 2524, who were caring for 3504 persons. Data were analyzed by univariate, bivariate, and multivariate methods. Maximum Likelihood Extraction Factors Analysis and LISREL for Structural Equation Modeling methods were used to confirm and make final the structure of the scale. Recommendations and suggestions are provided for further studies on culturally sensitive projects.
Involving Service Users and their Carers as Equal Partners in a Project Using Electronic Communication
Authors: ASHBY SUSAN M. , MASLIN‐PROTHERO SIAN E. , ROUT AMELIA C.
Published: November 2007

Abstract:  This paper presents a research team's experience using a virtual steering group to manage a research project. The main research project was concerned with the evaluation and development of interprofessional working among health and social care staff across primary and secondary care in the United Kingdom, with a focus on older people receiving intermediate care. Intermediate care is a service aimed at preventing unnecessary hospital admission; supporting early discharge from hospital; and reducing or delaying the need for residential care in the community. Intermediate care covers multi‐agency and interprofessional working across the continuum of care. We examine one aspect—the use of a virtual steering group, which is an innovative approach aimed at facilitating user and carer participation in the research in a supportive and less intimidating way. The research team includes academics, practitioners, older people and carers, and representatives from the voluntary sector—all are equal members. The team believes it is important to actively involve clients and their carers in the development and direction of research because they can provide a unique perspective ensuring that the research addresses issues of importance to them as service users. We examine and discuss the importance of preparation, support, and training to meaningfully engage in the virtual steering group and the direction of this research. The paper concludes by making recommendations about this model of involving service users in research.
Transcriptional Regulation of Telomerase Activity
Authors: DWYER JULIE , LI HE , XU DAKANG , LIU JUN‐PING
Published: November 2007

Abstract:  Telomerase maintains telomeres to preclude cell senescence. It remains elusive how telomerase activity is repressed in differentiated cells, but retained at high levels in stem cells and cancer. Recent studies suggest that the Ets transcription factor family, downstream of the mitogen signaling pathways of MAP kinase, regulates telomerase activity at the gene transcription level of human telomerase reverse transcriptase (hTERT). Several Ets transcription factors are involved in regulating hTERT gene expression, both directly and indirectly through the proto‐oncogene c‐myc. ER81 may mediate telomerase activation in telomerase‐negative fibroblasts stimulated by oncogenes Her2/Neu, Ras, and Raf. Ets2 may also play an important role in regulating the hTERT gene; but further studies are required to decipher the mechanisms in the regulation of telomerase activity.
Healthy Aging as an Intervention to Minimize Injury from Falls among Older People
Authors: PEEL NANCYE MAY , BARTLETT HELEN PATRICIA , McCLURE RODERICK JOHN
Published: November 2007

Abstract:  With global trends toward population aging, many countries are adopting healthy aging policies to minimize disability and increase quality in the extended years of life. Falls in older people are a major contributor to functional decline generally associated with aging. Based on a study quantifying the relationship between healthy aging factors and risk of fall‐related hip fracture in community‐dwelling older people, this paper discusses evidence for the promotion of healthy aging as a population‐based intervention for prevention of injuries from falls. To examine the protective effect of healthy aging on the risk of fall‐related hip fractures, a case–control study was conducted with 387 participants. Persons aged 65 and over hospitalized with a fall‐related hip fracture were matched with community‐based controls recruited via electoral roll sampling. A questionnaire designed to assess lifestyle risk factors, identified as determinants of healthy aging, was administered during face‐to‐face interviews. After adjustment for health status and demographic factors, a number of lifestyle factors were seen to have a significant independent protective effect on the risk of hip fracture. These included never smoking, moderate alcohol consumption, being active, maintaining normal weight, and being proactive in preventive health care. Psychosocial factors included having supportive environments and personal resources to cope with stress. This study identified a range of modifiable lifestyle factors associated with fall‐related hip fracture, suggesting that the “healthy aging” paradigm offers a comprehensive approach to falls injury prevention, and thus supports the adoption of healthy aging policies to extend years of quality life among older persons.
Dietary Influences on Cognitive Function with Aging
Authors: PARROTT MATTHEW D. , GREENWOOD CAROL E.
Published: November 2007

Abstract:  Human epidemiologic studies provide convincing evidence that dietary patterns practiced during adulthood are important contributors to age‐related cognitive decline and dementia risk. Diets high in fat, especially trans and saturated fats, adversely affect cognition, while those high in fruits, vegetables, cereals, and fish are associated with better cognitive function and lower risk of dementia. While the precise physiologic mechanisms underlying these dietary influences are not completely understood, modulation of brain insulin activity and neuroinflammation likely contribute. Not surprisingly, deficits in cognitive functions, especially those dependent on the medial temporal lobes, are apparent in type 2 diabetes mellitus (T2DM). Special care in food selection at meals should be exercised by those with T2DM since ingestion of rapidly absorbed, high–glycemic index carbohydrate foods further impairs medial temporal lobe function, with food‐induced increases in oxidative stress and cytokine release likely explaining the association between food ingestion and reduction in cognitive function in those with T2DM.
The Human Mosaic
Authors: ROSICH ROSELLEN M.
Published: November 2007

Abstract:  Developing culturally competent healthcare service must incorporate the needs of ethnic elders as well as the types of services provided. The question arises as to how to define optimal ways of teaching cultural diversity to the future healthcare professionals who will be treating older adults of indigenous heritage. Basing its work on an ethnogeriatric approach developed by the Stanford Geriatric Education Center, the Alaska Geriatric Education Center adapted the tool and utilized it with indigenous populations within Alaska. The reformatted approach examined and charted historical events (by cohort analysis) that have influenced Alaska's Native Elder's healthcare belief system over generations. Historical profiles produced from this approach may be used in studying and treating seniors from diverse ethnic backgrounds and provide an educational tool in training gerontology or geriatric healthcare professionals. The approach may also be used for organizing individuals' perceptions of the historical events in their lives within clinical health and mental health settings.
“Grey Nomads” in Australia
Authors: HIGGS PAUL F. D. , QUIRK FRANCES
Published: November 2007

Abstract:  Lifestyle factors have been identified as being very important in determining health in later life. Nutrition, exercise, and social environment all interact to promote, or to limit, opportunities for an active and healthy post‐working life. Not only are rates of chronic illness and disability reduced through the promotion of healthy lifestyles, but also quality of life is maintained through the compression of morbidity. Governments in Australia, as in the European Union and North America, have highlighted the importance of behavioral change in health promotion strategies with the aim of having an impact on the health‐related lifestyles of their populations. This paper examines the example of a group of older Australians, the “grey nomads,” who may present opportunities for examining health‐related lifestyle changes. The term grey nomad refers to a portion of the older population in Australia who choose to use their later years and retirement as opportunities for travel and leisure, mainly within the confines of the Australian continent. As such, they are similar to groups in North America, such as the “snow birds,” who travel to the southern United States to escape the colder winters of more northerly latitudes. Similar seasonal migrations occur from Northern to Southern Europe. What all share in common is an active culture/lifestyle of attempting to “age successfully.” Grey nomads also participate in the creation of what can be termed postmodern communities, where they and other regular travelers may develop a sense of community feeling with others who are also regularly returning to the same spot year after year. Social support is highly predictive of health outcomes and such mobile communities may prove a positive factor in promoting good health. In this paper we examine whether the “grey nomads” represent a good model for improving health‐related lifestyles in later life.
Intermittent Dietary Restriction as a Practical Intervention in Aging
Authors: SHARMA SANDEEP , KAUR GURCHARAN
Published: November 2007

Abstract:  Recent studies on the effects of dietary restriction (DR) in rodents and primates have shown that even late‐onset short‐term regimens can bring about comparable beneficial changes seen in animals subjected to life‐long DR. We examined the effect of 3 months of DR on the expression of antioxidant enzymes and antioxidants, heat‐shock protein 70 (HSP‐70), neural cell adhesion molecule (NCAM) and its polysialylated form, PSA‐NCAM, as well as astrocytic marker glial fibrillary acidic protein (GFAP) in 18‐month‐old middle‐aged rats. The present study shows that DR initiated in late adulthood confers beneficial effects, such as attenuation of oxidative stress, enhanced expression of HSP‐70, neural plasticity markers NCAM, and PSA‐NCAM, and reduced levels of GFAP.
Well for Life: A Way of Life
Authors: KRUGER WENDI A. , THOMPSON CATHERINE E. , McKENZIE ROSEMARY A. , NACCARELLA LUCIO
Published: November 2007

Abstract:  Well for Life is an innovative public program in Victoria, Australia that focuses on improving nutrition and increasing physical activity to promote healthy aging. For more than 4 years Aged Care has funded projects for frail older people who live in Public Sector Residential Aged Care (PSRAC) facilities or attend Home and Community Care (HACC) Planned Activity Groups (PAGs). Many stereotypes exist around what frail older people can or cannot do. Well for Life challenges many of these through organizational culture and policy change and workforce development. A person‐centered approach to care is adopted that emphasizes improving participants' activities of daily living and encouraging exercise and involvement. An external provider used a participatory evaluation approach to support the first phase of Well for Life. This approach enabled funded agencies to plan, implement, and monitor progress in their projects and assist them to embed Well for Life into policy and practice. The evaluation not only revealed insight into the delivery and adoption of Well for Life, but also assisted management and staff to make Well for Life a reality. Many PSRAC residents and PAG participants have reported significant gains from their involvement in Well for Life. These achievements reflect staff enthusiasm and organizational commitment to Well for Life principles. Evidence supports the benefit of improved nutrition and physical activity for people of any age and Well for Life is adding to the evidence‐base for frail older people.
Caloric Restriction, the Traditional Okinawan Diet, and Healthy Aging
Authors: WILLCOX BRADLEY J. , WILLCOX D. CRAIG , TODORIKI HIDEMI , FUJIYOSHI AKIRA , YANO KATSUHIKO , HE QIMEI , CURB J. DAVID , SUZUKI MAKOTO
Published: November 2007

Abstract:  Long‐term caloric restriction (CR) is a robust means of reducing age‐related diseases and extending life span in multiple species, but the effects in humans are unknown. The low caloric intake, long life expectancy, and the high prevalence of centenarians in Okinawa have been used as an argument to support the CR hypothesis in humans. However, no long‐term, epidemiologic analysis has been conducted on traditional dietary patterns, energy balance, and potential CR phenotypes for the specific cohort of Okinawans who are purported to have had a calorically restricted diet. Nor has this cohort's subsequent mortality experience been rigorously studied. Therefore, we investigated six decades of archived population data on the elderly cohort of Okinawans (aged 65‐plus) for evidence of CR. Analyses included traditional diet composition, energy intake, energy expenditure, anthropometry, plasma DHEA, mortality from age‐related diseases, and current survival patterns. Findings include low caloric intake and negative energy balance at younger ages, little weight gain with age, life‐long low BMI, relatively high plasma DHEA levels at older ages, low risk for mortality from age‐related diseases, and survival patterns consistent with extended mean and maximum life span. This study lends epidemiologic support for phenotypic benefits of CR in humans and is consistent with the well‐known literature on animals with regard to CR phenotypes and healthy aging.
Evidence‐Based Practice
Authors: NAY RHONDA , FETHERSTONHAUGH DEIRDRE
Published: November 2007

Abstract:  Evidence‐based practice (EBP) has been heralded as the most appropriate way of ensuring that patients receive the most effective care possible. It does, however, have several limitations. It is also not enough just to locate and evaluate the evidence without implementing it. This paper discusses EBP and its limitations and potential barriers; it also suggests strategies for changing current practices to more evidence‐based ones according to an accurate understanding of the concept of EBP.
Debating the Influence of Self‐Reports by People Living with Chronic Disease on Healthy Aging and Longevity
Authors: PRICE KAY
Published: November 2007

Abstract:  For people living with chronic disease, decision‐making in relation to their health and lifestyle choices is an integral aspect to managing the complexity that living with chronic disease brings into their lives. Research findings reveal that people living with chronic disease can self‐report what may seem to be appropriate explanations for their health status and seem to be in control of their health in their efforts to master the constraints imposed by their life situation. Precisely because ignoring disease‐related changes may actually contribute to disease progression, it is imperative to know whether self‐reports are made linking biomedical understandings of their disease with the person's social situation and life events. To understand how to influence choices made by people living with chronic disease to promote healthy aging and longevity, it is imperative for health and social care professionals to learn how to question people's self‐reports, given that self‐reports are often used as evidence in practice and research to inform clinical solutions.