bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation between intraretinal changes in diabetic macular oedema seen in fluorescein angiography and optical coherence tomography
Authors: Soliman Wael , Sander Birgit , Hasler Pascal W. , Larsen Michael
Published: July 2007

Purpose:  To study the relationship between intraretinal optical coherence tomography (OCT) and fluorescein angiography (FA) findings in eyes with diabetic macular oedema (DMO).

Methods:  We carried out a retrospective observational case series. Thirty eyes with previously untreated DMO underwent FA and OCT. The same ETDRS template was overlaid on the FA images in order to compare OCT and FA. Transfoveal linear high‐resolution OCT scans (at the 0‐ and 90‐degree meridians) and FA pictures were compared according to the ETDRS rings.

Results:  Six distinct patterns of intraretinal changes in OCT correlated with changes in FA: (a) focal angiographic leakage did not correspond to any obvious intraretinal abnormality in OCT in four eyes; (b) localized thickening of the outer nuclear layer in OCT corresponded to focal leaking microaneurysm (focal oedema) in FA in 11 eyes; (c) diffuse thickening of the outer nuclear layer in OCT corresponded to diffuse angiographic leakage in 21 eyes; (d) cystoid expansion of the outer nuclear layer was found in seven eyes with a petaloid angiographic pattern of leakage; (e) cystoid expansion of the inner nuclear layer was found in relation to honeycomb angiographic oedema in five eyes, and (f) serous detachment of the fovea in OCT did not correspond to any distinct finding in FA in four eyes.

Conclusions:  Intraretinal abnormalities found in OCT correlate systemically with changes in FA. Very early DMO morphological changes may be seen better with FA than with OCT. Serous detachment of the fovea is seen in OCT, but not in FA. The combination of OCT and FA is useful in facilitating understanding of the pathophysiological changes that occur in DMO.
Mineral trioxide aggregate as a root canal filling material in reimplanted teeth. Microscopic analysis in monkeys
Authors: Panzarini Sônia Regina , Holland Roberto , De Souza Valdir , Poi Wilson Roberto , Sonoda Celso Koogi , Pedrini Denise
Published: July 2007

Abstract –  This study analyzed mineral trioxide aggregate (MTA) as a root canal filling material for the immediate reimplantation of monkey teeth. Four adult capuchin monkeys Cebus apella were used, which had their maxillary and mandibular lateral incisors on both sides extracted and reimplanted after 15 min. During the extra‐alveolar period, the teeth were kept in saline solution and after reimplantation retention was performed with a stainless steel wire and composite resin for 14 days. After 7 days, the reimplanted teeth were submitted to endodontic treatment with biomechanics up to file n. 30 and irrigation with a saturated solution of calcium hydroxide [Ca(OH)2], and then divided into two study groups: group I – root canal filled with a Ca(OH)2 paste, and group II – root canal filled with MTA. Radiographic follow up was performed at 30, 60 and 90 days postoperatively, and after 180 days the animals were killed and specimens were processed for histomorphological analysis. The results revealed that most specimens of both groups presented organized periodontal ligament with no inflammation. The resorptions observed were surface resorptions and were repaired by cementum. Both MTA and Ca(OH)2 were good root canal filling materials for immediately reimplanted teeth, providing good repair and also allowing biological sealing of some lateral canals. There was no significant difference between the study groups (α = 29.60%).
Comparison of acidic fibroblast growth factor on collagen carrier with calcium hydroxide as pulp capping agents in monkeys
Authors: Li Zhimei , Sae‐Lim Varawan
Published: July 2007

Abstract –  Acidic fibroblast growth factor (aFGF) has been shown to facilitate wound healing by stimulating fibroblast proliferation and angiogenesis. It has also been reported to possess a powerful anti‐apoptotic function This study compared the histological pulp responses to aFGF on collagen carrier and Ca(OH)2 placed on the mechanically exposed dental pulp in monkeys at two observation periods. Thirty‐six teeth with pulp exposures were distributed into three groups according to the capping agents used prior to application of the coronal seal: collagen‐based matrix carrier (group 1), aFGF on the collagen‐based matrix carrier (group 2) and aqueous calcium hydroxide [Ca(OH)2] paste (group 3). Specimens were harvested at 6 and 13 weeks postoperatively and prepared for hematoxylin and eosin, and Gram staining. Histological qualitative evaluation of pulp responses were performed under the light microscope following criteria modified from Cox et al. (17) and Hu et al. (18). Semi‐quantitative analysis was also carried out using Kruskal–Wallis and Mann–Whitney U‐tests. There was neither negligible inflammatory infiltrates with no bacteria present in the three groups at both timings, nor was there any significant difference in the soft tissue organization among the three groups at or between the 6‐ and 13‐week observation periods. At 6 weeks, the hard tissue barrier produced by Ca(OH)2 group (1.040 ± 0.089) was significantly more superior than aFGF/collagen carrier group (1.930 ± 0.825) (P = 0.030) as well as collagen carrier group (3.142 ± 1.069, P = 0.018). At 13 weeks, both aFGF/collagen carrier group (1.214 ± 0.485) and the collagen carrier group (1.457 ± 0.814) produced significantly better hard tissue barrier (P = 0.040 and P = 0.017, respectively) than earlier timing. However, these two groups did not induce significantly improved hard tissue barrier compared to that produced by aqueous Ca(OH)2 paste which stimulated matrix secretion in a polar tubular dentin‐like pattern.
An experimentally calibrated finite element study of maxillary trauma
Authors: Casas Michael J , Krimbalis Peter P , Morris Alan R , Behdinan Kamran , Kenny David J
Published: July 2007

Abstract –  A baseball injury to an instrumented human cadaver maxillae was simulated with a regulation (142 g) baseball traveling at 14 m s−1. Measurements of strain were obtained with three‐axis strain gauge rosettes located at the medial palate and both canine fossae. A three‐dimensional finite element (FE) model of a dentate human maxilla was constructed from computed tomography scans of the skull of an adolescent. This three‐dimensional mathematical model of the maxilla was deemed geometrically accurate by convergence testing when the model's degrees of freedom approximated 74 000. The simulated load case involved a transient dynamic impact to the medial maxilla with boundary conditions imposed at skeletal buttresses of the model. The model was calibrated through direct comparison with the displacements and principal strains gathered from experimental and epidemiological data. The comparison of experimental and calculated principal strains as a result of the simulated impacts revealed a 1.7–11.4% difference.
Conservative treatment of an ankylosed tooth after delayed replantation: a case report
Authors: Díaz Jaime Andrés , Sandoval Hector Paulo , Pineda Patricia Irene , Junod Pablo Antonio
Published: July 2007

Abstract –  An 8‐year‐old boy sustained avulsion of his upper right maxillary central incisor and lateral luxation of his upper left maxillary incisors. Subsequently, the upper right maxillary central incisor developed replacement resorption, and both upper left maxillary incisors developed pulpal canal obliteration. In the ankylosed tooth, decoronation procedure was performed, and in the 44‐month follow‐up period the involved alveolar site showed vertical apposition of bone and continuing replacement resorption. Decoronation is a surgical procedure that allows preservation of the bone volume for the future, avoiding aesthetic disturbances and more aggressive treatments in cases where other therapeutic alternatives are not feasible.
General health of elderly institutionalised and community‐dwelling Brazilians
Authors: Deco Camila Porto de , Santos Jarbas Francisco Fernandes do , Cunha Vicente de Paula Prisco da , Marchini Leonardo
Published: July 2007

Objective:  To evaluate the heart rate, blood pressure, blood glucose and other important indicators of the general health of an elderly population of São José dos Campos, Brazil.

Materials and methods:  A cross‐sectional study was conducted among 150 institutionalised and 150 community‐dwelling individuals aged 60 years or more. The parameters evaluated were heart rate, blood pressure and blood glucose. The elderly also answered a questionnaire about osteoporosis, falls, physical exercising, participation in social events, type of foods ingested, Alzheimer and Parkinson’s diseases and medication.

Results:  The institutionalised elderly showed an average heart rate of 75.1, while that of the community‐dwelling elderly was 76.7. The percentage of systolic hypertension in the institutionalised and community‐dwelling groups was 36% and 30% respectively, while diastolic hypertension showed a percentage of 40% and 57%, and diabetes was 32% and 30%. Among the institutionalised and community‐dwelling groups, 13.3% and 21.3% respectively, reported osteoporosis, 31.3% and 42.7% falls, 7.3% and 24% exercised regularly, 4% and 69.3% participated regularly in social events, 58.7% and 51.3% reported eating solid foods, and 13.3% and 2%, respectively, suffered from Alzheimer’s disease. Parkinson’s disease was reported by 2% in both groups. The institutionalised elderly reported taking an average of 3.2 medications, while among community‐dwelling elderly this number was 1.8.

Conclusion:  The entire sample presented a high prevalence of hypertension, diabetes and osteoporosis. No significant differences were found in the systemic health of the elderly institutionalised and community‐dwelling groups. However, the latter group reported more frequent falls, participation in social events and exercised regularly.
Expression studies of the core+1 protein of the hepatitis C virus 1a in mammalian cells
Authors: Vassilaki Niki , Boleti Haralabia , Mavromara Penelope
Published: July 2007

Recent studies have suggested the existence of a novel protein of hepatitis C virus (HCV) encoded by an ORF overlapping the core gene in the +1 frame (core+1 ORF). Two alternative translation mechanisms have been proposed for expression of the core+1 ORF of HCV‐1a in cultured cells; a frameshift mechanism within codons 8–11, yielding a protein known as core+1/F, and/or translation initiation from internal codons in the core+1 ORF, yielding a shorter protein known as core+1/S. To date, the main evidence for the expression of this protein in vivo has been the specific humoral and cellular immune responses against the protein in HCV‐infected patients, inasmuch as its detection in biopsies or the HCV infectious system remains elusive. In this study, we characterized the expression properties of the HCV‐1a core+1 protein in mammalian cells in order to identify conditions that facilitate its detection. We showed that core+1/S is a very unstable protein, and that expression of the core protein in addition to proteosome activity can downregulate its intracellular levels. Also, we showed that in the Huh‐7/T7 cytoplasmic expression system the core+1 ORF from the HCV‐1 isolate supports the synthesis of both the core+1/S and core+1/F proteins. Finally, immunofluorescence and subcellular fractionation analyses indicated that core+1/S and core+1/F are cytoplasmic proteins with partial endoplasmic reticulum distribution in interphase cells, whereas in dividing cells they also localize to the microtubules of the mitotic spindle.
Calcium‐binding to lens βB2‐ and βA3‐crystallins suggests that all β‐crystallins are calcium‐binding proteins
Authors: Jobby Maroor K. , Sharma Yogendra
Published: July 2007

Crystallins are the major proteins of a mammalian eye lens. The topologically similar eye lens proteins, β‐ and γ‐crystallins, are the prototype and founding members of the βγ‐crystallin superfamily. βγ‐Crystallins have until recently been regarded as structural proteins. However, the calcium‐binding properties of a few members and the potential role of βγ‐crystallins in fertility are being investigated. Because the calcium‐binding elements of other member proteins, such as spherulin 3a, are not present in βB2‐crystallin and other βγ‐crystallins from fish and mammalian genomes, it was argued that lens βγ‐crystallins should not bind calcium. In order to probe whether β‐crystallins can bind calcium, we selected one basic (βB2) and one acidic (βA3) β‐crystallin for calcium‐binding studies. Using calcium‐binding assays such as 45Ca overlay, terbium binding, Stains‐All and isothermal titration calorimetry, we established that both βB2‐ and βA3‐crystallin bind calcium with moderate affinity. There was no significant change in their conformation upon binding calcium as monitored by fluorescence and circular dichroism spectroscopy. However, 15N‐1H heteronuclear single quantum correlation NMR spectroscopy revealed that amide environment of several residues underwent changes indicating calcium ligation. With the corroboration of calcium‐binding to βB2‐ and βA3‐crystallins, we suggest that all β‐crystallins bind calcium. Our results have important implications for understanding the calcium‐related cataractogenesis and maintenance of ionic homeostasis in the lens.
Functional interaction of diphenols with polyphenol oxidase
Authors: Kanade Santosh R. , Suhas V. L. , Chandra Nagasuma , Gowda Lalitha R.
Published: July 2007

Polyphenol oxidase (PPO) catalyzes the oxidation of o‐diphenols to their respective quinones. The quinones autopolymerize to form dark pigments, an undesired effect. PPO is therefore the target for the development of antibrowning and antimelanization agents. A series of phenolic compounds experimentally evaluated for their binding affinity and inhibition constants were computationally docked to the active site of catechol oxidase. Docking studies suggested two distinct modes of binding, dividing the docked ligands into two groups. Remarkably, the first group corresponds to ligands determined to be substrates and the second group corresponds to reversible inhibitors. Analyses of the complexes provide structural explanations for correlating subtle changes in the position and nature of the substitutions on diphenols to their functional properties as substrates and inhibitors. Higher reaction rates and binding are reckoned by additional interactions of the substrates with key residues that line the hydrophobic cavity. The docking results suggest that inhibition of oxidation stems from an interaction between the aromatic carboxylic acid group and the apical His109 of the four coordinates of the trigonal pyramidal coordination polyhedron of CuA. The spatial orientation of the hydroxyl in relation to the carboxylic group either allows a perfect fit in the substrate cavity, leading to inhibition, or because of a steric clash flips the molecule vertically, facilitating oxidation. This is the first study to explain, at the molecular level, the determinants of substrate and inhibitor specificity of a catechol oxidase, thereby providing a platform for the design of selective inhibitors useful to both the food and pharmaceutical industries.
Regulation of dCTP deaminase from Escherichia coli by nonallosteric dTTP binding to an inactive form of the enzyme
Authors: Johansson Eva , Thymark Majbritt , Bynck Julie H. , Fanø Mathias , Larsen Sine , Willemoës Martin
Published: July 2007

The trimeric dCTP deaminase produces dUTP that is hydrolysed to dUMP by the structurally closely related dUTPase. This pathway provides 70–80% of the total dUMP as a precursor for dTTP. Accordingly, dCTP deaminase is regulated by dTTP, which increases the substrate concentration for half‐maximal activity and the cooperativity of dCTP saturation. Likewise, increasing concentrations of dCTP increase the cooperativity of dTTP inhibition. Previous structural studies showed that the complexes of inactive mutant protein, E138A, with dUTP or dCTP bound, and wild‐type enzyme with dUTP bound were all highly similar and characterized by having an ordered C‐terminal. When comparing with a new structure in which dTTP is bound to the active site of E138A, the region between Val120 and His125 was found to be in a new conformation. This and the previous conformation were mutually exclusive within the trimer. Also, the dCTP complex of the inactive H121A was found to have residues 120–125 in this new conformation, indicating that it renders the enzyme inactive. The C‐terminal fold was found to be disordered for both new complexes. We suggest that the cooperative kinetics are imposed by a dTTP‐dependent lag of product formation observed in presteady‐state kinetics. This lag may be derived from a slow equilibration between an inactive and an active conformation of dCTP deaminase represented by the dTTP complex and the dUTP/dCTP complex, respectively. The dCTP deaminase then resembles a simple concerted system subjected to effector binding, but without the use of an allosteric site.
Eukaryotic class 1 translation termination factor eRF1 − the NMR structure and dynamics of the middle domain involved in triggering ribosome‐dependent peptidyl‐tRNA hydrolysis
Authors: Ivanova Elena V. , Kolosov Peter M. , Birdsall Berry , Kelly Geoff , Pastore Annalisa , Kisselev Lev L. , Polshakov Vladimir I.
Published: July 2007

The eukaryotic class 1 polypeptide chain release factor is a three‐domain protein involved in the termination of translation, the final stage of polypeptide biosynthesis. In attempts to understand the roles of the middle domain of the eukaryotic class 1 polypeptide chain release factor in the transduction of the termination signal from the small to the large ribosomal subunit and in peptidyl‐tRNA hydrolysis, its high‐resolution NMR structure has been obtained. The overall fold and the structure of the β‐strand core of the protein in solution are similar to those found in the crystal. However, the orientation of the functionally critical GGQ loop and neighboring α‐helices has genuine and noticeable differences in solution and in the crystal. Backbone amide protons of most of the residues in the GGQ loop undergo fast exchange with water. However, in the AGQ mutant, where functional activity is abolished, a significant reduction in the exchange rate of the amide protons has been observed without a noticeable change in the loop conformation, providing evidence for the GGQ loop interaction with water molecule(s) that may serve as a substrate for the hydrolytic cleavage of the peptidyl‐tRNA in the ribosome. The protein backbone dynamics, studied using 15N relaxation experiments, showed that the GGQ loop is the most flexible part of the middle domain. The conformational flexibility of the GGQ and 215–223 loops, which are situated at opposite ends of the longest α‐helix, could be a determinant of the functional activity of the eukaryotic class 1 polypeptide chain release factor, with that helix acting as the trigger to transmit the signals from one loop to the other.
Interference with the citrulline‐based nitric oxide synthase assay by argininosuccinate lyase activity in Arabidopsis extracts
Authors: Tischner Rudolf , Galli Mary , Heimer Yair M. , Bielefeld Sarah , Okamoto Mamoru , Mack Alyson , Crawford Nigel M.
Published: July 2007

There are many reports of an arginine‐dependent nitric oxide synthase activity in plants; however, the gene(s) or protein(s) responsible for this activity have yet to be convincingly identified. To measure nitric oxide synthase activity, many studies have relied on a citrulline‐based assay that measures the formation of l‐citrulline from l‐arginine using ion exchange chromatography. In this article, we report that when such assays are used with protein extracts from Arabidopsis, an arginine‐dependent activity was observed, but it produced a product other than citrulline. TLC analysis identified the product as argininosuccinate. The reaction was stimulated by fumarate (> 500 µm), implicating the urea cycle enzyme argininosuccinate lyase (EC 4.3.2.1), which reversibly converts arginine and fumarate to argininosuccinate. These results indicate that caution is needed when using standard citrulline‐based assays to measure nitric oxide synthase activity in plant extracts, and highlight the importance of verifying the identity of the product as citrulline.
The glycosaminoglycan chain of decorin plays an important role in collagen fibril formation at the early stages of fibrillogenesis
Authors: Rühland Claus , Schönherr Elke , Robenek Horst , Hansen Uwe , Iozzo Renato V. , Bruckner Peter , Seidler Daniela G.
Published: July 2007

Decorin is a multifunctional small leucine‐rich proteoglycan involved in the regulation of collagen fibrillogenesis. In patients with a variant of Ehlers–Danlos syndrome, about half of the secreted decorin lacks the single glycosaminoglycan side chain. Notably, these patients have a skin‐fragility phenotype that resembles that of decorin null mice. In this study, we investigated the role of glycanated and unglycanated decorin on collagen fibrillogenesis. Glycosaminoglycan‐free decorin, generated by mutating Ser4 of the mature protein core into Ala (DCN‐S4A), showed reduced inhibition of fibrillogenesis compared with the decorin proteoglycan. Interestingly, using a 3D matrix generated by decorin‐null fibroblasts, an increase in fibril diameter was found after the addition of decorin, and even greater effects were observed with DCN‐S4A. To avoid potential side effects of artificial tags, adenoviruses containing decorin and DCN‐S4A were used to transduce decorin‐null fibroblasts prior to matrix formation. Both molecules were efficiently incorporated into the matrix, with no changes in collagen composition and network formation, or altered expression of the related proteoglycan biglycan. Both decorin and DCN‐S4A mutants increased the collagen fibril diameter, with the latter showing the most prominent effects. These data show that at early stages of fibrillogenesis, the glycosaminoglycan chain of decorin has a reducing effect on collagen fibril diameter.
Biochemical characterization of USP7 reveals post‐translational modification sites and structural requirements for substrate processing and subcellular localization
Authors: Fernández‐Montalván Amaury , Bouwmeester Tewis , Joberty Gerard , Mader Robert , Mahnke Marion , Pierrat Benoit , Schlaeppi Jean‐Marc , Worpenberg Susanne , Gerhartz Bernd
Published: July 2007

Ubiquitin specific protease 7 (USP7) belongs to the family of deubiquitinating enzymes. Among other functions, USP7 is involved in the regulation of stress response pathways, epigenetic silencing and the progress of infections by DNA viruses. USP7 is a 130‐kDa protein with a cysteine peptidase core, N‐ and C‐terminal domains required for protein–protein interactions. In the present study, recombinant USP7 full length, along with several variants corresponding to domain deletions, were expressed in different hosts in order to analyze post‐translational modifications, oligomerization state, enzymatic properties and subcellular localization patterns of the enzyme. USP7 is phosphorylated at S18 and S963, and ubiquitinated at K869 in mammalian cells. In in vitro activity assays, N‐ and C‐terminal truncations affected the catalytic efficiency of the enzyme different. Both the protease core alone and in combination with the N‐terminal domain are over 100‐fold less active than the full length enzyme, whereas a construct including the C‐terminal region displays a rather small decrease in catalytic efficiency. Limited proteolysis experiments revealed that USP7 variants containing the C‐terminal domain interact more tightly with ubiquitin. Besides playing an important role in substrate recognition and processing, this region might be involved in enzyme dimerization. USP7 constructs lacking the N‐terminal domain failed to localize in the cell nucleus, but no nuclear localization signal could be mapped within the enzyme's first 70 amino acids. Instead, the tumor necrosis factor receptor associated factor‐like region (amino acids 70–205) was sufficient to achieve the nuclear localization of the enzyme, suggesting that interaction partners might be required for USP7 nuclear import.
Analysis of the vacuolar luminal proteome of Saccharomyces cerevisiae
Authors: Sarry Jean‐Emmanuel , Chen Sixue , Collum Richard P. , Liang Shun , Peng Mingsheng , Lang Albert , Naumann Bianca , Dzierszinski Florence , Yuan Chao‐Xing , Hippler Michael , Rea Philip A.
Published: July 2007

Despite its large size and the numerous processes in which it is implicated, neither the identity nor the functions of the proteins targeted to the yeast vacuole have been defined comprehensively. In order to establish a methodological platform and protein inventory to address this shortfall, we refined techniques for the purification of ‘proteomics‐grade’ intact vacuoles. As confirmed by retention of the preloaded fluorescent conjugate glutathione–bimane throughout the fractionation procedure, the resistance of soluble proteins that copurify with this fraction to digestion by exogenous extravacuolar proteinase K, and the results of flow cytometric, western and marker enzyme activity analyses, vacuoles prepared in this way retain most of their protein content and are of high purity and integrity. Using this material, 360 polypeptides species associated with the soluble fraction of the vacuolar isolates were resolved reproducibly by 2D gel electrophoresis. Of these, 260 were identified by peptide mass fingerprinting and peptide sequencing by MALDI‐MS and liquid chromatography coupled to ion trap or quadrupole TOF tandem MS, respectively. The polypeptides identified in this way, many of which correspond to alternate size and charge states of the same parent translation product, can be assigned to 117 unique ORFs. Most of the proteins identified are canonical vacuolar proteases, glycosidases, phosphohydrolases, lipid‐binding proteins or established vacuolar proteins of unknown function, or other proteases, glycosidases, lipid‐binding proteins, regulatory proteins or proteins involved in intermediary metabolism, protein synthesis, folding or targeting, or the alleviation of oxidative stress. On the basis of the high purity of the vacuolar preparations, the electrophoretic properties of the proteins identified and the results of quantitative proteinase K protection measurements, many of the noncanonical vacuolar proteins identified are concluded to have entered this compartment for breakdown, processing and/or salvage purposes.
Shock heating by Fanaroff–Riley type I radio sources in galaxy clusters
Authors: Brüggen M. , Heinz S. , Roediger E. , Ruszkowski M. , Simionescu A.
Published: July 2007

Feedback by active galactic nuclei (AGN) is frequently invoked to explain the cut-off of the galaxy luminosity function at the bright end and the absence of cooling flows in galaxy clusters. Meanwhile, there are recent observations of shock fronts around radio-loud AGN. Using realistic 3D simulations of jets in a galaxy cluster, we address the question what of fraction of AGN energy is dissipated in shocks. We find that weak shocks that encompass the AGN have Mach numbers of 1.1–1.2 and dissipate at least 2 per cent of the mechanical luminosity of the AGN. In a realistic cluster medium, even a continuous jet can lead to multiple shock structures, which may lead to an overestimate of the AGN duty cycles inferred from the spatial distribution of waves.
Phase analysis of the cosmic microwave background from incomplete sky coverage
Authors: Chiang Lung-Yih , Naselsky Pavel D.
Published: July 2007

Phases of the spherical harmonic analysis of full-sky cosmic microwave background (CMB) temperature data contain useful information complementary to the ubiquitous angular power spectrum. In this Letter we present a new method of phase analysis on incomplete sky maps. It is based on Fourier phases of equal-latitude pixel rings of the map, which are related to the mean angle of the trigonometric moments from the full-sky phases. It has an advantage for probing regions of interest without tapping polluted Galactic plane area, and can localize non-Gaussian features. This method is therefore very useful for detection of departure from Gaussianity and statistical isotropy in the CMB.
Multiple dynamical components in Local Group dwarf spheroidals
Authors: McConnachie Alan W. , Peñarrubia Jorge , Navarro Julio F.
Published: July 2007

The dwarf spheroidal (dSph) satellites of the Local Group have long been thought to be simple spheroids of stars embedded within extended dark matter haloes. Recently, however, evidence for the presence of spatially and kinematically distinct stellar populations has been accumulating. Here, we examine the influence of such components on dynamical models of dwarf galaxies embedded in cold dark matter haloes. We begin by constructing a model of Andromeda II, a dSph satellite of M31 which shows evidence for spatially distinct stellar components. We find that the two-component model predicts an overall velocity dispersion profile that remains approximately constant at ∼10−11 km s−1 out to ∼1 kpc from the centre; this is despite wide kinematic and spatial differences between the two individual components. This prediction can be validated by detailed spectroscopic analysis of this galaxy. The presence of two components may also help to explain oddities in the velocity dispersion profiles of other dSphs; we show that velocity dispersion profiles which appear to rise from the centre outwards before levelling off – such as those of Leo I, Draco, and Fornax – can result from the gradual transition from a dynamically cold, concentrated component to a second, hotter, and more spatially extended one, both in equilibrium within the same dark halo. Dwarf galaxies with two stellar components generally have a leptokurtic line-of-sight velocity distribution which is well described by a double Maxwellian. This may be contrasted with other dynamical explanations such as a radially dependent anisotropy in the stars' orbits. Interestingly, we find that multiple equilibrium components could also provide a potential alternative origin for ‘extra-tidal’ stars (normally ascribed to tidal effects) in situations where corroborating evidence for tides – such as elongation of the main body of the dwarf in the orbital direction or velocity gradients across its face driven by protruding tidal tails – may be lacking.
Studying Ancient Israelite Ritual: Methodological Considerations
Authors: Bergen Wesley
Published: July 2007

Any adequate account of ancient Israel and its texts must include a study of its ritual practices. Most of what we would term ‘religion’ in that society was made up of regular events and the rituals that accompanied them. Harvest was celebrated with festivals, the slaughter of animals for food became sacrifice rituals, death was accompanied by mourning rituals, etc. Studying these rituals is necessary yet difficult. Using recent theory from anthropology and textual study, numerous new studies have taken up these challenges. Using the study of animal sacrifice as its primary example, this essay explores the problems and prospects of the study of Israel's rituals.
Identification and Experimental Validation of Damping Ratios of Different Human Body Segments Through Anthropometric Vibratory Model in Standing Posture
Authors: Gupta T. C.
Published: July 2007

A 15degrees of freedom lumped parameter vibratory model of human body is developed, for vertical mode vibrations, using anthropometric data of the 50th percentile US male. The mass and stiffness of various segments are determined from the elastic modulii of bones and tissues and from the anthropometric data available, assuming the shape of all the segments is ellipsoidal. The damping ratio of each segment is estimated on the basis of the physical structure of the body in a particular posture. Damping constants of various segments are calculated from these damping ratios. The human body is modeled as a linear spring-mass-damper system. The optimal values of the damping ratios of the body segments are estimated, for the 15degrees of freedom model of the 50th percentile US male, by comparing the response of the model with the experimental response. Formulating a similar vibratory model of the 50th percentile Indian male and comparing the frequency response of the model with the experimental response of the same group of subjects validate the modeling procedure. A range of damping ratios has been considered to develop a vibratory model, which can predict the vertical harmonic response of the human body.
A Mechanical Composite Spheres Analysis of Engineered Cartilage Dynamics
Authors: Kohles Sean S. , Wilson Christopher G. , Bonassar Lawrence J.
Published: July 2007

In the preparation of bioengineered reparative strategies for damaged or diseased tissues, the processes of biomaterial degradation and neotissue synthesis combine to affect the developing mechanical state of multiphase, composite engineered tissues. Here, cell-polymer constructs for engineered cartilage have been fabricated by seeding chondrocytes within three-dimensional scaffolds of biodegradable polymers. During culture, synthetic scaffolds degraded passively as the cells assembled an extracellular matrix (ECM) composed primarily of glycosaminoglycan and collagen. Biochemical and biomechanical assessment of the composite (cells, ECM, and polymer scaffold) were modeled at a unit-cell level to mathematically solve stress-strain relationships and thus construct elastic properties (n=4 samples per seven time points). This approach employed a composite spheres, micromechanical analysis to determine bulk moduli of: (1) the cellular-ECM inclusion within the supporting scaffold structure; and (2) the cellular inclusion within its ECM. Results indicate a dependence of constituent volume fractions with culture time (p<0.05). Overall mean bulk moduli were variably influenced by culture, as noted for the cell-ECM inclusion (Kc‐m=29.7kPa, p=0.1439), the cellular inclusion (Kc=5.5kPa, p=0.0067), and its surrounding ECM (Km=373.9kPa, p=0.0748), as well as the overall engineered construct (K=165.0kPa, p=0.6899). This analytical technique provides a framework to describe the time-dependent contribution of cells, accumulating ECM, and a degrading scaffold affecting bioengineered construct mechanical properties.
A Model for Prediction of Bone Stiffness Using a Mechanical Approach of Composite Materials
Authors: Perreux Dominique M. , Steven Johnson W.
Published: July 2007

A model to predict the bone stiffness is presented in this paper. The objective is to obtain a description of bone stiffness of a representative elementary volume (REV) based on a small set of physical parameters. The main idea is to use measurable information related to the orientation and the density of a basic elementary submicrostructure (ESMS). This ESMS is the first arrangement of the basic components. A simple rule-of-mixtures approach is used to provide the elastic properties for the ESMS. The basic properties are dependent on the volume fraction of the mineralized phase. The orientation and the density of the ESMS is described by a tensor and a scalar, respectively. The model is used to obtain the elastic properties of both the cortical and trabecular bones. Data from femoral bone are used to verify this approach.
Axon Kinematics Change During Growth and Development
Authors: Hao Hailing , Shreiber David I.
Published: July 2007

The microkinematic response of axons to mechanical stretch was examined in the developing chick embryo spinal cord during a period of rapid growth and myelination. Spinal cords were isolated at different days of embryonic (E) development post-fertilization (E12, E14, E16, and E18) and stretched 0%, 5%, 10%, 15%, and 20%, respectively. During this period, the spinal cord grew ∼55% in length, and white matter tracts were myelinated significantly. The spinal cords were fixed with paraformaldehyde at the stretched length, sectioned, stained immunohistochemically for neurofilament proteins, and imaged with epifluorescence microscopy. Axons in unstretched spinal cords were undulated, or tortuous, to varying degrees, and appeared to straighten with stretch. The degree of tortuosity (ratio of the segment’s pathlength to its end-to-end length) was quantified in each spinal cord by tracing several hundred randomly selected axons. The change in tortuosity distributions with stretch indicated that axons switched from non-affine, uncoupled behavior at low stretch levels to affine, coupled behavior at high stretch levels, which was consistent with previous reports of axon behavior in the adult guinea pig optic nerve (Bain, Shreiber, and Meaney, J. Biomech. Eng., 125(6), pp. 798–804). A mathematical model previously proposed by Bain et al. was applied to quantify the transition in kinematic behavior. The results indicated that significant percentages of axons demonstrated purely non-affine behavior at each stage, but that this percentage decreased from 64% at E12 to 30% at E18. The decrease correlated negatively to increases in both length and myelination with development, but the change in axon kinematics could not be explained by stretch applied during physical growth of the spinal cord. The relationship between tissue-level and axonal-level deformation changes with development, which can have important implications in the response to physiological forces experienced during growth and trauma.
Cyclic Mechanical Compression Increases Mineralization of Cell-Seeded Polymer Scaffolds In Vivo
Authors: Duty Angel O. , Oest Megan E. , Guldberg Robert E.
Published: July 2007

Despite considerable documentation of the ability of normal bone to adapt to its mechanical environment, very little is known about the response of bone grafts or their substitutes to mechanical loading even though many bone defects are located in load-bearing sites. The goal of this research was to quantify the effects of controlled in vivo mechanical stimulation on the mineralization of a tissue-engineered bone replacement and identify the tissue level stresses and strains associated with the applied loading. A novel subcutaneous implant system was designed capable of intermittent cyclic compression of tissue-engineered constructs in vivo. Mesenchymal stem cell-seeded polymeric scaffolds with 8 weeks of in vitro preculture were placed within the loading system and implanted subcutaneously in male Fisher rats. Constructs were subjected to 2 weeks of loading (3 treatments per week for 30min each, 13.3N at 1Hz) and harvested after 6 weeks of in vivo growth for histological examination and quantification of mineral content. Mineralization significantly increased by approximately threefold in the loaded constructs. The finite element method was used to predict tissue level stresses and strains within the construct resulting from the applied in vivo load. The largest principal strains in the polymer were distributed about a modal value of −0.24% with strains in the interstitial space being about five times greater. Von Mises stresses in the polymer were distributed about a modal value of 1.6MPa, while stresses in the interstitial tissue were about three orders of magnitude smaller. This research demonstrates the ability of controlled in vivo mechanical stimulation to enhance mineralized matrix production on a polymeric scaffold seeded with osteogenic cells and suggests that interactions with the local mechanical environment should be considered in the design of constructs for functional bone repair.
Nonhomogeneous Strain From Sparse Marker Arrays for Analysis of Transmural Myocardial Mechanics
Authors: Kindberg K. , Karlsson M. , Ingels N. B. , Criscione J. C.
Published: July 2007

Background: Knowledge of normal cardiac kinematics is important when attempting to understand the mechanisms that impair the contractile function of the heart during disease. The complex kinematics of the heart can be studied by inserting radiopaque markers in the cardiac wall and study the pumping heart with biplane cineradiography. In order to study the local strain, the bead array was developed where small radiopaque beads are inserted along three columns transmurally in the left ventricle. Method: This paper suggests a straightforward method for strain computation, based on polynomial least-squares fitting and tailored for combined marker and bead array analyses. Results: This polynomial method gives small errors for a realistic bead array on an analytical test case. The method delivers an explicit expression of the Lagrangian strain tensor as a polynomial function of the coordinates of material points in the reference configuration. The method suggested in this paper is validated with analytical strains on a deforming cylinder resembling the heart, compared to a previously suggested finite element method, and applied to in vivo ovine data. The errors in the estimated strain components are shown to remain unchanged on an analytical test case when evaluating the effects of one missing bead. In conclusion, the proposed strain computation method is accurate and robust, with errors smaller or comparable to the current gold standard when applied on an analytical test case.
Multiscale, Structure-Based Modeling for the Elastic Mechanical Behavior of Arterial Walls
Authors: Stylianopoulos Triantafyllos , Barocas Victor H.
Published: July 2007

Passive elastic behavior of arterial wall remains difficult to model. Although phenomenological and structural models exist, the question of how the three-dimensional network structure of the collagen in the artery determines its mechanical properties is still open. A model is presented that incorporates a collagen network as well as the noncollagenous material that comprise the artery. The collagen architecture is represented as a network of interconnected fibers, and a neo-Hookean constitutive equation is used to describe the contribution of the noncollagenous matrix. The model is multiscale in that volume-averaging theory is applied to the collagen network, and it is structural in that parameters of the microstructure of the collagen network were considered instead of a macroscopic constitutive law. The computational results provided a good fit to published experimental data for decellularized porcine carotid arteries. The model predicted increased circumferential compliance for increased axial stretch, consistent with previously published reports, and a relatively small sensitivity to open angle. Even at large extensions, the model predicted that the noncollagenous matrix would be in compression, preventing collapse of the collagen network. The incorporation of fiber-fiber interactions led to an accurate model of artery wall behavior with relatively few parameters. The counterintuitive result that the noncollagenous component is in compression during extension and inflation of the tissue suggests that the collagen is important even at small strains, with the noncollagenous components supporting the network, but not resisting the load directly. More accurate representation of the microstructure of the artery wall is needed to explore this issue further.
A NUMERICAL SOLUTION METHOD FOR AN INFINITESIMAL ELASTO-PLASTIC COSSERAT MODEL
Authors: NEFF PATRIZIO , CHEŁMIŃSKI KRZYSZTOF , MÜLLER WOLFGANG , WIENERS CHRISTIAN
Published: July 2007

We present a finite element implementation of a Cosserat elasto-plastic model and provide a rigorous numerical analysis of the introduced time-incremental algorithm. The model allows the use of standard tools from convex analysis as known from classical Prandtl–Reuss plasticity. We derive the dual stress formulation and prove that for vanishing Cosserat couple modulus μc → 0 the classical problem is approximated. Our numerical results show the robustness of the approximation. Notably, for positive couple modulus μc > 0 there is no need for a safe-load assumption. For small μc the response is numerically indistinguishable from the classical response.
A FREE BOUNDARY PROBLEM MODELLING CANCER RADIOVIROTHERAPY
Authors: TAO YOUSHAN , GUO QIAN
Published: July 2007

This paper deals with a procedure for cancer radiovirotherapy which requires not only injection of replication-competent viruses but also administration of radioiodide. The viruses infect tumor cells, replicate inside them and eventually cause their death. As infected cells die, the viruses inside them are released and then proceed to infect adjacent tumor cells. Radioiodide is in a continuous state of flux between the tumor and the remaining part. Iodide undergoes beta particle decay and the emitted beta particles have a significant effect on tumor cells. The combination of virotherapy with radiotherapy has recently been shown to be significantly more effective than treatment with virotherapy alone. Cancer radiovirotherapy can be described by a free boundary problem for a nonlinear system of partial differential equations, where the free boundary is the surface of a tumor. Global existence and uniqueness of solutions to this free boundary problem is proved, and a new explicit parameter condition corresponding to the success of therapy is also found. Furthermore, numerical simulations are given to show that there is an optimal timing for radio-iodine administration, and that there is an optimal dose for the radioactive iodide.
SHOCK PROPAGATION IN A FLOW THROUGH DEFORMABLE POROUS MEDIA: ASYMPTOTIC BEHAVIOUR AS THE POROSITY APPROXIMATES A CONSTANT
Authors: COMPARINI ELENA , UGHI MAURA
Published: July 2007

We consider a one-dimensional incompressible flow through a porous medium undergoing deformations such that the porosity and the hydraulic conductivity can be considered as functions of the flux intensity. We prove that if one approximates the porosity with a constant then the solution of the hyperbolic problem converges to the classical continuous Green–Ampt solution, also in the presence of shocks. In general, however, the shocks remain present in any approximating solution.
IMPROVED ACCURACY FOR ALTERNATING-DIRECTION METHODS FOR PARABOLIC EQUATIONS BASED ON REGULAR AND MIXED FINITE ELEMENTS
Authors: ARBOGAST TODD , HUANG CHIEH-SEN , YANG SONG-MING
Published: July 2007

An efficient modification by Douglas and Kim of the usual alternating directions method reduces the splitting error from [Formula: see text] to [Formula: see text] in time step k. We prove convergence of this modified alternating directions procedure, for the usual non-mixed Galerkin finite element and finite difference cases, under the restriction that k/h2 is sufficiently small, where h is the grid spacing. This improves the results of Douglas and Gunn, who require k/h4 to be sufficiently small, and Douglas and Kim, who require that the locally one-dimensional operators commute. We propose a similar and efficient modification of alternating directions for mixed finite element methods that reduces the splitting error to [Formula: see text], and we prove convergence in the noncommuting case, provided that k/h2 is sufficiently small. Numerical computations illustrating the mixed finite element results are also presented. They show that our proposed modification can lead to a significant reduction in the alternating direction splitting error.
NONUNIQUENESS FOR CRYSTALLINE CURVATURE FLOW
Authors: NOVAGA MATTEO , PAOLINI MAURIZIO
Published: July 2007

We discuss some examples of nonuniqueness for the crystalline curvature flow, when the Wulff shape is a square not centered at the origin.
ATP-sensitive K+ channels and disease: from molecule to malady
Authors: Ashcroft Frances M.
Published: July 2007

This essay is based on a lecture given to the American Physiological Society in honor of Walter B. Cannon, an advocate of homeostasis. It focuses on the role of the ATP-sensitive potassium K+ (KATP) channel in glucose homeostasis and, in particular, on its role in insulin secretion from pancreatic β-cells. The β-cell KATP channel comprises pore-forming Kir6.2 and regulatory SUR1 subunits, and mutations in either type of subunit can result in too little or too much insulin release. Here, I review the latest information on the relationship between KATP channel structure and function, and consider how mutations in the KATP channel genes lead to neonatal diabetes or congenital hyperinsulinism.