bluuebunny/crossref_metadata_2025 huggingface dataset:
Structures of cyclic, antimicrobial peptides in a membrane‐mimicking environment define requirements for activity
Authors: Appelt Christian , Wessolowski Axel , Dathe Margitta , Schmieder Peter
Published: November 2007

New antimicrobial compounds are of major importance because of the growing problem of bacterial resistance. In this context, antimicrobial peptides have received a lot of attention. Their mechanism of action, however, is often obscure. Here, the structures of two cyclic, antimicrobial peptides from the family of arginine‐ and tryptophan‐rich peptides determined in a membrane‐mimicking environment are described. The sequence of the peptides has been obtained from a cyclic parent peptide by scrambling the amino acids. While the activity of the peptides is similar to that of the parent peptide, the structures are not. The peptides do, however, all adopt an amphiphilic structure. A comparison between the structures helps to define the requirements for the activity of these peptides. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
A minor β‐structured conformation is the active state of a fusion peptide of vesicular stomatitis virus glycoprotein
Authors: Sarzedas Carolina G. , Lima Carla S. , Juliano Maria A. , Juliano Luiz , Valente Ana Paula , Da Poian Andrea T. , Almeida Fabio C. L.
Published: November 2007

Entry of enveloped animal viruses into their host cells always depends on a step of membrane fusion triggered by conformational changes in viral envelope glycoproteins. Vesicular stomatitis virus (VSV) infection is mediated by virus spike glycoprotein G, which induces membrane fusion at the acidic environment of the endosomal compartment. In a previous work, we identified a specific sequence in the VSV G protein, comprising the residues 145–164, directly involved in membrane interaction and fusion. In the present work we studied the interaction of pep[145–164] with membranes using NMR to solve the structure of the peptide in two membrane‐mimetic systems: SDS micelles and liposomes composed of phosphatidylcholine and phosphatidylserine (PC:PS vesicles). The presence of medium‐range NOEs showed that the peptide has a tendency to form N‐ and C‐terminal helical segments in the presence of SDS micelles. Analysis of the chemical shift index indicated helix–coil equilibrium for the C‐terminal helix under all conditions studied. At pH 7.0, the N‐terminal helix also displayed a helix–coil equilibrium when pep[145‐164] was free in solution or in the presence of PC:PS. Remarkably, at the fusogenic pH, the region of the N‐terminal helix in the presence of SDS or PC:PS presented a third conformational species that was in equilibrium with the helix and random coil. The N‐terminal helix content decreases pH and the minor β‐structured conformation becomes more prevalent at the fusogenic pH. These data point to a β‐conformation as the fusogenic active structure‐which is in agreement with the X‐ray structure, which shows a β‐hairpin for the region corresponding to pep[145‐164]. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Cellular uptake of cell‐penetrating peptides pVEC and transportan in plants
Authors: Chugh Archana , Eudes François
Published: November 2007

Internalization of fluorescently labeled CPPs, pVEC, transportan and scrambled pVEC, in a range of plant cells was investigated. Cellular uptake of the peptides was found to be tissue dependent. pVEC and transportan were distinctly internalized in triticale mesophyll protoplasts, onion epidermal cells, leaf bases and root tips of seven‐day old triticale seedlings but showed negligible florescence in coleoptile and leaf tips as observed under a fluorescence microscope. Further, pVEC and transportan uptake studies were focused on mesophyll protoplasts as a system of investigation. In fluorimetric studies transportan showed 2.3 times higher cellular internalization than pVEC in protoplasts, whereas scrambled pVEC failed to show any significant fluorescence. Effect of various factors on cellular internalization of pVEC and transportan in protoplasts was also investigated. The cellular uptake of both the peptides was concentration dependent and nonsaturable. The cellular uptake of pVEC and transportan was enhanced at low temperature (4 °C). The presence of endocytic/macropinocytosis inhibitors did not reduce the cellular uptake of the peptides, suggesting direct cell penetration, receptor‐independent internalization of pVEC and transportan into the plant cells. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Time‐resolved ultrafast carrier dynamics in as‐grown nanocrystalline silicon films: the effect of film thickness and grain boundaries
Authors: Lioudakis Emmanouil , Othonos Andreas
Published: November 2007

In this letter, we have studied transient photoinduced absorption in as‐grown nanocrystalline silicon films with thickness varied from 5 to 30 nm. Effects of quantum confinement (QC) in z ‐direction and grain boundary distortions alter the carrier dynamics of these films considerably. Based on the determination of critical points in the first Brillouin zone of the band structure of materials, we have time‐resolved the relaxation times of surface‐related states and indirect valleys. When decreasing the film thickness down to the QC limit (∼10 nm) new ultrafast relaxation mechanisms start to play a dominant role in carrier dynamics due to the topological disordering of these ultrathin films. These relaxation mechanisms seem to be related with the traping/de‐traping of the excited carriers prior to recombination. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and analysis of disease and risk factors through learning Bayesian networks from observational data
Authors: Li Jing , Shi Jianjun , Satz Devin
Published: November 2007

This paper focuses on identification of the relationships between a disease and its potential risk factors using Bayesian networks in an epidemiologic study, with the emphasis on integrating medical domain knowledge and statistical data analysis. An integrated approach is developed to identify the risk factors associated with patients' occupational histories and is demonstrated using real‐world data. This approach includes several steps. First, raw data are preprocessed into a format that is acceptable to the learning algorithms of Bayesian networks. Some important considerations are discussed to address the uniqueness of the data and the challenges of the learning. Second, a Bayesian network is learned from the preprocessed data set by integrating medical domain knowledge and generic learning algorithms. Third, the relationships revealed by the Bayesian network are used for risk factor analysis, including identification of a group of people who share certain common characteristics and have a relatively high probability of developing the disease, and prediction of a person's risk of developing the disease given information on his/her occupational history. Copyright © 2007 John Wiley & Sons, Ltd.
Copper Catalyzed Azide‐Alkyne Cycloadditions on Solid Surfaces: Applications and Future Directions
Authors: Devaraj Neal K. , Collman James P.
Published: November 2007

The Copper Catalyzed Azide‐Alkyne Cycloaddition (CuAAC), a paradigm of “click” chemistry has found numerous applications in the field of surface chemistry. This minireview discusses the reaction from a surface chemist's perspective. Specific advantages, limitations, and surface related concerns are discussed. We review the types of solid surfaces that have been modified via click chemistry and conclude with several elegant applications.
Growth of Gold Bipyramids with Improved Yield and Their Curvature‐Directed Oxidation
Authors: Kou Xiaoshan , Ni Weihai , Tsung Chia‐Kuang , Chan Kong , Lin Hai‐Qing , Stucky Galen D. , Wang Jianfang
Published: November 2007

The surface‐plasmon properties of Au bipyramids are investigated using the finite‐difference time‐domain method. It is found that both the extinction cross sections and local electric‐field enhancements of Au bipyramids are larger than those of Au nanorods that have longitudinal surface plasmon (LSP) wavelengths close to those of Au bipyramids. Following this result the growth of Au bipyramids using cationic surfactants of variously sized headgroups as stabilizing agents is carried out. It is found that the growth using cetyltributylammonium bromide (CTBAB) produces Au bipyramids with tunable LSP wavelengths in high yields. The oxidation behaviour of Au bipyramids using hydrogen peroxide as the oxidizing agent is fully explored and the oxidation is found to occur preferentially at highly curved surface sites. It is further demonstrated that the oxidation rate can be controlled by varying the amounts of hydrogen peroxide and hydrochloric acid. This oxidation approach can be used in conjunction with the seed‐mediated growth in CTBAB solutions to produce Au bipyramids, the LSP wavelengths of which are finely tunable from 650 to 1300 nm.
Fast, frequency‐based, integrated register allocation and instruction scheduling
Authors: Cutcutache Ioana , Wong Weng‐Fai
Published: November 2007

Instruction scheduling and register allocation are two of the most important optimization phases in modern compilers as they have a significant impact on the quality of the generated code. Unfortunately, the objectives of these two optimizations are in conflict with one another. The instruction scheduler attempts to exploit instruction‐level parallelism and requires many operands to be available in registers. On the other hand, the register allocator wants register pressure to be kept low so that the amount of spill code can be minimized. Currently these two phases are done separately, typically in three passes: prepass scheduling, register allocation and postpass scheduling. But this separation can lead to poor results. Previous works attempted to solve the phase‐ordering problem by combining the instruction scheduler with graph‐coloring‐based register allocators. The latter tend to be computationally expensive. Linear‐scan register allocators, on the other hand, are simple, fast and efficient. In this paper, we describe our effort to integrate instruction scheduling with a linear‐scan allocator. Furthermore, our integrated optimizer is able to take advantage of execution frequencies obtained through profiling. Our integrated register allocator and instruction scheduler achieved good code quality with significantly reduced compilation times. On the SPEC2000 benchmarks running on a 900 MHz ItaniumII, compared with OpenIMPACT, we halved the time spent in instruction scheduling and register allocation with negligible impact on execution times. Copyright © 2007 John Wiley & Sons, Ltd.
Verformungsbezogene mittragende Breite niedriger Verbundträger
Authors: Rieg Andreas , Kuhlmann Ulrike
Published: November 2007

Aufgrund der vergleichsweise großen Schlankheit niedriger Verbundträger wird bei diesen Trägern in sehr vielen Fällen die Einhaltung von Verformungsgrenzwerten querschnittsbestimmend. Das Verformungsverhalten dieser Träger wird dabei wesentlich durch die große Biegesteifigkeit des Betongurts und dessen Rissbildung bestimmt. Einer der maßgebenden Einflüsse auf die rechnerischen Verformungen ist die mittragende Breite des Betongurts.

Neue Untersuchungen, die das Verformungsverhalten niedriger Verbundträger unter Berücksichtigung der Biegetragwirkung und Rissbildung des Betongurts betrachten, zeigen unter anderem, dass für die Spannungs‐ und die Verformungsberechnung unterschiedliche Werte der mittragenden Breite anzusetzen sind. Anhand umfangreicher experimenteller, analytischer und numerischer Untersuchungen konnten die Einflüsse auf die mittragende Breite analysiert werden. Auf Basis der Ergebnisse einer ausführlichen Parameterstudie wird ein Berechnungsansatz für die verformungsbezogene mittragende Breite entwickelt und ein Vorschlag zur quasi‐elastischen Verformungsberechnung niedriger Verbundträger gemacht. Es zeigt sich, dass die verformungsbezogene mittragende Breite im Besonderen von der Biegetragwirkung des Betongurts, dessen Rissbildung, dem Verhältnis von Gurtbreite zu Trägerlänge, der Steifigkeitsverteilung im Verbundträger und der Belastungshöhe abhängt.

Mit dem entwickelten Berechungsansatz sind eine realistische Verformungsberechnung und eine wirtschaftliche Dimensionierung niedriger Verbundträger möglich.
Zur Verbundsicherung von kammerbetonierten Verbundträgern
Authors: Goralski Claus , Hegger Josef
Published: November 2007

In einem von der Deutschen Forschungsgemeinschaft geförderten Projekt [1] wurde das Trag‐ und Verformungsverhalten kammerbetonierter Verbundträger aus hochfestem Beton und hochfestem Stahl untersucht. Die rechnerische Erfassung des Kammerbetons erfordert die Beschreibung der Verbundmechanismen zwischen Kammerbeton und Stahlprofil. Hierzu wurde die Übertragung der Längsschubkraft zwischen Kammerbeton und Stahlprofil in Modell‐ und Biegeträgerversuchen unter positiver und negativer Momentenbeanspruchung untersucht. Durch die Entwicklung eines neuen Abscherversuchs konnte die Wirkungsweise von Kopfbolzendübeln sowohl bei druck‐ als auch bei zugbeanspruchtem Kammerbeton bestimmt werden. Die Verbundmechanismen am Biegeträger wurden anhand experimenteller Untersuchungen und dreidimensionaler nicht‐linearer Finite‐Elemente‐Modelle lokalisiert und quantifiziert.
Zur plastischen Bemessung hochfester kammerbetonierter Verbundträger
Authors: Hegger Josef , Goralski Claus
Published: November 2007

Die traglaststeigernde Wirkung des Kammerbetons wurde bisher im Verbundträgerbau aufgrund fehlender mechanischer Modelle und Bemessungsregeln insbesondere bei hochfesten Baustoffen häufig nicht genutzt. Dieser Beitrag gibt einen Einblick in die Lastabtragungsmechanismen kammerbetonierter Verbundträger und beschreibt Bemessungsansätze zum wirtschaftlichen und sicheren Einsatz von hochfesten Baustoffen. Anhand einer Parameteruntersuchung zum Einfluss von hochfestem Kammerbeton und hochfestem Stahl auf die Querschnittstragfähigkeit des Verbundträgers wird ein plastisches Bemessungsverfahren für kammerbetonierte Verbundträger im positiven und negativen Momentenbereich hergeleitet. Die vorgestellten Ergebnisse sind Teil eines DFG‐Forschungsvorhabens, das in [1] und [2] ausführlich beschrieben ist.
Neue Untersuchungen zum Ermüdungsverhalten von Verbundträgern aus hochfesten Werkstoffen mit Kopfbolzendübeln und Puzzleleiste
Authors: Feldmann Markus , Hechler Oliver , Hegger Josef , Rauscher Sabine
Published: November 2007

Neue Ergebnisse sind bei der Erforschung von Verbundträgern mit hochfestem Werkstoffen angefallen [1]. Unter anderem wurde das Ermüdungsverhalten verschiedener Verbundmittel (Kopfbolzendübel ∅︁ 22 mm und puzzleförmige Dübelleisten) bei Einsatz hochfester Werkstoffe (Stahl S 460 und Beton C 80/95) untersucht. Sowohl für die Kopfbolzendübel als auch für die Dübelleisten wurden zyklische Push‐Out‐Tests und Versuche an zyklisch belasteten Verbundträgern durchgeführt.

Die Ergebnisse der zyklischen Push‐Out‐Tests mit Kopfbolzendübeln und hochfesten Werkstoffen deuten darauf hin, dass höhere Lastwechselzahlen ertragen werden können, ihre statische Resttragfähigkeiten waren nach ca. 1,0 Mio. Lastwechseln (ähnlich wie bei normalfesten Werkstoffen) um 25% reduziert. Bei den kontinuierlichen Verbundmitteln (Puzzleleiste) sind unter zyklischer Belastung zwar Anrisse aufgetreten, jedoch wurde hier keine Beeinträchtigung des Last‐Verformungsverhaltens oder der statischen Resttragfähigkeit festgestellt.

Die zyklischen Trägerversuche mit Kopfbolzendübeln zeigen, dass die Vorhersage der Ermüdung mit den Regeln der aktuellen Normung – wie bei der Verwendung mit normalfesten Werkstoffen – nicht geeignet ist. Vielmehr gelingt eine gute Vorhersage des Risswachstums (und damit des Ermüdungsverhaltens) auf Grundlage der in [6] vorgestellten Verknüpfung des Dübelrisswachstums mit dem Schlupf in der Trägerverbundfuge. Für Verbundfugen mit Dübelleisten lässt sich über bruchmechanische Berechnungen ein theoretischer Grenzwert angeben, unterhalb dessen kein Risswachstum mehr auftritt. Allerdings hängt dies in Wirklichkeit stark von der gewählten Brennschnittqualität ab.
Mechanical and Structural Properties of Expanded Extrudates Produced from Blends of Native Starches and Natural Fibers of Henequen and Coconut
Authors: Aguilar‐Palazuelos E. , Zazueta‐Morales José de Jesús , Jiménez‐Arévalo Omar A. , Martínez‐Bustos Fernando
Published: November 2007

The aim of this research was to evaluate the effects of barrel temperature (130‐180ºC), feed moisture (14.6‐24.5%) and fiber content (0.0‐15.0%) on the physicochemical and structural properties of starch‐derived loose‐fill packaging materials (LFPM). Two blends were analyzed: one of corn starch and henequen fiber (Agave americana) (CS‐HF), and the other of potato starch and coconut fiber (PS‐CF). An experimental laboratory extruder with a 2.9 mm internal diameter die‐nozzle was used, and a hybrid central composite design was employed to study the LFPM, and the influence of some extrusion variables on mechanical properties, i.e. tensile strength (ϵ),stress (σ), flexion modulus (Ef), and structural properties; expansion index (EI), water absorption capacity (WAC), crystallinity by X‐ray diffraction, viscosity profiles and scanning electronic microscopy (SEM). In both extruded blends feed moisture was the most significant variable, increasing the values of EI and ϵ, and decreasing the values of σ and Ef when the feed moisture was decreased. The blend of PS‐CF had the highest values of EI, ϵ, σ and Ef,, and is the more appropriate for the preparation of LFPM. X‐ray diffraction analysis of the LFPM samples suggested the formation of almost completely amorphous structures, similar to those of commercial LFPM prepared from polystyrene. This research indicated that blends from natural sources like corn starch with henequen, and potato starch with coconut fibers have the potential to be used in the preparation of LFPM with similar characteristics to commercial LFPM, with the additional advantage of being biodegradable.
Visual Observation of Hydrolyzed Potato Starch Granules by α‐Amylase with Confocal Laser Scanning Microscopy
Authors: Apinan Soottitantawat , Yujiro Ikuta , Hidefumi Yoshii , Takeshi Furuta , Myllärinen Päivi , Forssell Pirkko , Poutanen Kaisa
Published: November 2007

Porous starch was produced by digestion of freeze‐dried potato starch with α‐amylase from Bacillus sp. The surface structure of the granules became perforated and in the interior of the granules a capsule‐like cavity was formed, i.e. the hydrolyzed starch can be used as an encapsulant. The structure change of the granules was observed with confocal laser scanning microscopy and scanning electron microscopy. The degree of starch hydrolysis could be correlated with the Avrami equation. The activation energy of starch hydrolysis by α‐amylase was 83 kJ/mol.
Arguing to learn and learning to argue: Case studies of how students' argumentation relates to their scientific knowledge
Authors: von Aufschnaiter Claudia , Erduran Sibel , Osborne Jonathan , Simon Shirley
Published: November 2007

In this study we investigated junior high school students' processes of argumentation and cognitive development in science and socioscientific lessons. Detailed studies of the relationship between argumentation and the development of scientific knowledge are rare. Using video and audio documents of small group and classroom discussions, the quality and frequency of students' argumentation was analyzed using a schema based on the work of Toulmin (1958). In parallel, students' development and use of scientific knowledge was also investigated, drawing on a schema for determining the content and level of abstraction of students' meaning‐making. These two complementary analyses enabled an exploration of their impact on each other. The microanalysis of student discourse showed that: (a) when engaging in argumentation students draw on their prior experiences and knowledge; (b) such activity enables students to consolidate their existing knowledge and elaborate their science understanding at relatively high levels of abstraction. The results also suggest that students can acquire a higher quality of argumentation that consists of well‐grounded knowledge with a relatively low level of abstraction. The findings further suggest that the main indicator of whether or not a high quality of argument is likely to be attained is students' familiarity and understanding of the content of the task. The major implication of this work for developing argumentation in the classroom is the need to consider the nature and extent of students' content‐specific experiences and knowledge prior to asking them to engage in argumentation. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 101–131, 2008
A virtual link routing scheme in the wireless home network architecture supporting end‐to‐end seamless connectivity
Authors: Kim Byounghoon , Park E. K. , Tak Sungwoo
Published: November 2007

This paper presents a communication framework for end‐to‐end seamless connectivity improvement in IEEE802.11‐based wireless home networks. The proposed communication framework incorporates the following two things: a new concept of wireless home network architecture and a new routing technique in an effort to improve wireless communication coverage and end‐to‐end seamless packet delivery respectively. First, the proposed wireless home network architecture based on the End‐to‐end Seamless multi‐hop COnnectivity based on Dual‐mode (ESCOD) integrates infrastructure and ad hoc modes in an IEEE 802.11‐based wireless home network. Second, the Virtual Link Routing (VLR) technique, a kind of ad hoc routing protocols working on the layer 2.5, provides mobile nodes with end‐to‐end seamless connectivity and packet delivery. We compare the performance of VLR with two prominent on‐demand routing protocols for Mobile Ad hoc Networks (MANET), Dynamic Source Routing (DSR) and Ad hoc On demand Distance Vector (AODV), in the ESCOD‐based wireless home network. Experiments show that our communication framework incorporating the VLR technique in the ESCOD‐based wireless home network architecture yields efficient performance in terms of the low failure rate of packet transmission, fast packet transmission time, network throughput, and a wider coverage area of wireless home networks. Copyright © 2007 John Wiley & Sons, Ltd.
In vivo x‐ray fluorescence measurements of lead, cadmium and mercury in occupational and environmental studies: a review of work conducted in Sweden 1970–2005
Authors: Börjesson Jimmy , Mattsson Sören
Published: November 2007

Lead, cadmium and mercury are toxic elements capable of causing temporary or permanent damage to human organs and tissues. An adequate control of these elements necessitates measurements in humans, on samples from man and the environment. This applies to both occupationally exposed subjects and to members of the general public including patients. The present paper will review the in vivo x‐ray fluorescence (XRF) technique for non‐invasive estimation of element levels directly in humans. Focus is on work conducted by researchers in Sweden between 1970 and 2005.

Results from studies made with in vivo XRF on occupationally lead and cadmium exposed groups of workers have revealed very high levels of these elements in bone and kidneys, respectively. The development of the cadmium in vivo XRF technique implies usefilness even for measuring the low levels found in subjects of the general public, e.g. the detection limit for cadmium in kidney cortex allows for groups of smokers and non‐smokers to be separated. Retired lead workers show a clear association between bone lead and blood lead due to the endogenous lead excretion from bone. Longitudinal studies of retired workers show biological half‐lives for bone lead of several years. A study of mercury in vivo showed that the technique is capable of detecting the element in the kidneys of the most heavily exposed workers. In vivo XRF in oncology and rheumatology subjects, administered with therapeutic compounds containing platinum and gold, respectively, helps to understand the retention of these compounds in the human body. Copyright © 2007 John Wiley & Sons, Ltd.
Spectrometry methods for in vivo bone strontium measurements
Authors: Zamburlini M. , Pejović‐Milić A. , Chettle D. R.
Published: November 2007

In vivo x‐ray fluorescence (XRF) and dual‐photon absorptiometry (DPA) are two widely accepted radiation‐based measurement techniques. The first one is mainly used for the measurement of toxic elements in the human body, while the second one is clinically used to measure bone density. In this paper we present a literature review of the application of these two techniques to in vivo strontium measurements. Strontium is a natural constituent of the human skeleton, where it may exert beneficial or detrimental effects depending on the dietary intake and other factors. Recently, several medical publications have focused on the beneficial effects on bone of pharmacological dosages of strontium, especially with regard to its anti‐osteoporotic effects. However, the mechanism by which strontium exerts its therapeutic action is still not known. XRF and DPA have the potential of providing unique information on bone strontium concentration, retention and elimination that cannot be gained at the moment in any other way. Copyright © 2007 John Wiley & Sons, Ltd.
Muscle wasting in chronic kidney disease: the role of the ubiquitin proteasome system and its clinical impact
Authors: Rajan Vik R. , Mitch William E.
Published: November 2007

Muscle wasting in chronic kidney disease (CKD) and other catabolic diseases (e.g. sepsis, diabetes, cancer) can occur despite adequate nutritional intake. It is now known that complications of these various disorders, including acidosis, insulin resistance, inflammation, and increased glucocorticoid and angiotensin II production, all activate the ubiquitin–proteasome system (UPS) to degrade muscle proteins. The initial step in this process is activation of caspase-3 to cleave the myofibril into its components (actin, myosin, troponin, and tropomyosin). Caspase-3 is required because the UPS minimally degrades the myofibril but rapidly degrades its component proteins. Caspase-3 activity is easily detected because it leaves a characteristic 14kD actin fragment in muscle samples. Preliminary evidence from several experimental models of catabolic diseases, as well as from studies in patients, indicates that this fragment could be a useful biomarker because it correlates well with the degree of muscle degradation in dialysis patients and in other catabolic conditions.
Total Hip Arthroplasty is Less Painful at 12 Months Compared with Hemiarthroplasty in Treatment of Displaced Femoral Neck Fracture
Authors: Macaulay William , Nellans Kate W. , Iorio Richard , Garvin Kevin L. , Healy William L. , Rosenwasser Melvin P.
Published: November 2007

Objectives

The Displaced Femoral (neck fracture) Arthroplasty Consortium for Treatment and Outcomes (DFACTO) study compared total hip arthroplasty (THA) to hemiarthroplasty in the treatment of displaced femoral neck fractures.

Design

This study was designed as a prospective, randomized clinical trial.

Setting

The study was conducted in five US academic and private medical centers.

Patients

Patients were composed of independent, mentally competent individuals, >50 years old who suffered a displaced femoral neck fracture without existing arthritis at the hip. Forty-one patients were enrolled.

Main outcome measures

Functional outcomes and quality of life were assessed at 6 and 12 months post-fracture using the SF-36, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), the Harris Hip Score, and the Timed “Up & Go” Test (TUG test).

Results

Groups were equivalent at baseline in terms of age, comorbid conditions, and functional status. At 6 months, there were no significant differences between the groups using the outcome measures or overall rates of complications. There was one dislocation in the THA group (5.8% of patients). At 12 months, the THA group reported significantly less pain (53.2 ± 10.2) than the hemiarthroplasty group (42.4 ± 11.5) using the SF-36 ( p = 0.02). Using the TUG Test, we observed a greater proportion of THA patients remain functionally independent 1 year after surgery compared the hemiarthroplasty group ( p = 0.08, controlling for age and sex).

Conclusions

These differences in pain and functional outcomes suggest THA is a viable treatment option for the active elderly displaced femoral neck fracture population.
Voltage‐dependent potassium channels are involved in staurosporine‐induced apoptosis of rat mesenchymal stem cells
Authors: Wang Shaoping , Wang Jian‐an , Li Jun , Zhou Jinghong , Wang Hai
Published: November 2007

The strategy of mesenchymal stem cells (MSCs) transplantation is limited by the inability to deliver a large number of grafted cells that resist peri‐transplantation apoptosis in ischemic tissues, and this led us to investigate methods of improving the viability of these cells. We demonstrate the presence of voltage‐gated potassium channels in rat MSCs that can be activated by staurosporine (ST). MSCs exposed to ST underwent apoptotic cell changes. Tetraethylammonium (TEA), a classic blocker of K+ channels, blocked the ST‐induced augmentation of K+ currents, and reduced ST‐induced apoptosis. Furthermore, we found that TEA prevented the ST‐induced increase in expression of the pro‐apoptotic protein Bax and decrease of the anti‐apoptotic protein Bcl‐2. Taken together, our findings suggest that voltage‐gated potassium is involved in ST‐induced apoptosis of rat MSCs. TEA blocks the ST‐induced augmentation of K+ currents, alters the expression of Bcl‐2 family proteins induced by ST, and attenuates the apoptosis of rat MSCs.
Aqueous extract of the Chinese medicine, Danggui‐Shaoyao‐San, inhibits apoptosis in hydrogen peroxide‐induced PC12 cells by preventing cytochrome c release and inactivating of caspase cascade
Authors: Qian Yun‐fei , Wang Hua , Yao Wen‐bing , Gao Xiang‐dong
Published: November 2007

Danggui‐Shaoyao‐San (DSS), a traditional Chinese medicine used for centuries for the enhancement of women's health, has been shown to display therapeutic efficacy on senile dementia. In the present study, using a rat pheochromocytoma (PC12) cell line, the effect of DSS on hydrogen peroxide (H2O2) induced apoptosis was studied. The apoptosis in H2O2‐induced PC12 cells was accompanied by downregulation of Bcl‐2, upregulation of Bax, the release of mitochondrial cytochrome c into cytosol, and sequential activation of caspase‐9 and −3. DSS was able to suppress all these changes and eventually protected against H2O2‐induced apoptosis. Taken together, these results suggest that treatment of PC12 cells with DSS can block H2O2‐induced apoptosis by the regulation of Bcl‐2 family members, as well as suppression of cytochrome c release and caspase cascade activation.
Cyclic AMP‐dependent proteolysis of GATA‐6 expressed on the intracellular membrane
Authors: Tsuge Takeshi , Uetani Kae , Sato Ryuichiro , Ohashi‐Kobayashi Ayako , Maeda Masatomo
Published: November 2007

Cyclic AMP‐dependent proteolysis of GATA‐6 was characterized by fusing GATA‐6 with the carboxyl‐terminal membrane domain of SREBP‐2. When the fusion protein was stably expressed in CHO‐K1 cells, it was recovered in the ER membrane. This protein was processed in a similar manner to SREBP‐2 upon cholesterol starvation, and the GATA‐6 moiety moved into the nucleus. The GATA‐6 moiety on the membrane became undetectable in the presence of dbcAMP or cholera toxin. However, H‐89, K‐252a, MG115 and lactacystin inhibited this decrease, suggesting that the cytoplasmic GATA‐6 moiety of the fusion protein was degraded by proteasomes though A‐kinase upon elevation of the cellular cAMP concentration.
Celecoxib, a cyclooxygenase‐2 inhibitor, induces apoptosis in human osteosarcoma cell line MG‐63 via down‐regulation of PI3K/Akt
Authors: Liu Bing , Shi Zhong‐li , Feng Jie , Tao Hui‐min
Published: November 2007

Cyclooxygenase‐2 (COX‐2), involved in the inhibition of apoptosis and, the potentiation of cell growth, is frequently overexpressed in human malignancies including osteosarcoma (OS). We have attempted to identify the anti‐proliferation of celecoxib, a selective COX‐2 inhibitor, and the combination of celecoxib and cisplatin in MG‐63 cells, and to explore the potential molecular mechanisms involved. MG‐63 cells were treated with the combination of celecoxib and cisplatin or either agent alone for 48 h in serum‐supplemented medium. Celecoxib caused G1 phase arrest and significantly inhibited cell growth, as well as potentiating cisplatin‐induced apoptosis. The effect was dose‐dependent, and apoptotic changes such as DNA fragments and apoptotic bodies were observed. However, downregulation of COX‐2 did not occur in cells treated with celecoxib. Phosphoinositide‐3‐kinase (PI3K)/Akt, survivin, bcl‐2 were significantly downregulated in cells treated with the combination of celecoxib and cisplatin, and decreased survivin and bcl‐2 levels were found in cells with wortmannin, a specific PI3K inhibitor. Moreover, the decreased expressions of procaspase‐9, procaspase‐3 and cleaved PARP‐1 were detected by Western blot analysis. Therefore, celecoxib exerts its anti‐tumor activities through COX‐2‐independent mechanisms, which may be PI3K/Akt‐dependent, and survivin and bcl‐2‐related. PI3K may be at the center of the celecoxib effects, which play an essential role in the regulation of survivin and Bcl‐2.
Loss of putative tumor suppressor EI24/PIG8 confers resistance to etoposide
Authors: Mork Christina N. , Faller Douglas V. , Spanjaard Remco A.
Published: November 2007

Expression of p53‐target gene EI24/PIG8 is lost in invasive breast cancers, suggesting that EI24/PIG8 is a tumor suppressor that prevents tumor spreading, and partially mediates p53‐attributed tumor suppressor activity. EI24/PIG8 also has pro‐apoptotic activity indicating that loss of EI24/PIG8 may modulate sensitivity to chemotherapy. Here it is demonstrated that suppression of EI24/PIG8 in fibroblasts and breast cancer cells significantly inhibits the apoptotic response to etoposide treatment. These findings suggest that loss of EI24/PIG8 contributes significantly to resistance of cells to chemotherapeutic agents that function through p53, and identify the EI24/PIG8 status as a potentially new prognostic marker of chemotherapy responsiveness.
Structural basis of mercury‐ and zinc‐conjugated complexes as SARS‐CoV 3C‐like protease inhibitors
Authors: Lee Cheng-Chung , Kuo Chih-Jung , Hsu Min-Feng , Liang Po-Huang , Fang Jim-Min , Shie Jiun-Jie , Wang Andrew H.-J.
Published: November 2007

Five active metal‐conjugated inhibitors (PMA, TDT, EPDTC, JMF1586 and JMF1600) bound with the 3C‐like protease of severe acute respiratory syndrome (SARS)‐associated coronavirus were analyzed crystallographically. The complex structures reveal two major inhibition modes: Hg2+‐PMA is coordinated to C44, M49 and Y54 with a square planar geometry at the S3 pocket, whereas each Zn2+ of the four zinc‐inhibitors is tetrahedrally coordinated to the H41–C145 catalytic dyad. For anti‐SARS drug design, this Zn2+‐centered coordination pattern would serve as a starting platform for inhibitor optimization.
Transcending Race? Schoolteachers and Political Militancy in Andean Peru, 1970–2000
Authors: WILSON FIONA
Published: November 2007

Using accounts by militant schoolteachers from a province in the central sierra of Peru, this article attempts to show how and why concepts of race and political commitment among teachers changed at three critical moments in Peruvian history: agrarian reform, mass unionisation, and Maoist insurgency. The article explores how binary representations of race as mestizo or Indian, mestizo or cholo, were both formed and challenged by the everyday experience of teachers as well as their political action. Their reactions to, and negotiation of, racial ascription are framed within three fields of power: racialised social identities, processes of state formation, and opportunities and repertoire of contestatory politics.
Néstor Kirchner, Santa Cruz, and the Hielos Continentales Controversy 1991–1999
Authors: ALLAN LAURENCE
Published: November 2007

This article traces the development of the political controversy in Argentina over the resolution of border issues between Argentina and Chile during the 1990s, examining provincial opposition to the Menem government's proposals for the Hielos Continentales zone in the far southern Andes. It argues that territorial perceptions held by Argentine opponents of the proposals, whilst highly significant, are insufficient to explain domestic opposition to the territorial accords. Instead it suggests that the sensitivity and longevity of the controversy reflected both specific territorial perceptions and anti-Menem dynamics in Argentina. Whilst the article highlights citizen opposition to government policy, it also points to the key role of Néstor Kirchner, at the time governor of the province of Santa Cruz, and subsequently Argentina's president. Kirchner's role in the decade-long controversy highlights two key factors. First, the potential utility of foreign policy issues, and particularly those centred on territory, as a resource in the domestic political environment, and, second, the fact that Kirchner's opposition itself responded at least in part to disputes within Peronism during the 1990s.
The Dilemmas of Male Consumption in Nineteenth-Century Argentina: Fashion, Consumerism, and Darwinism in Domingo Sarmiento and Juan B. Alberdi
Authors: NOVOA ADRIANA
Published: November 2007

This article explores how the relationship between luxury, consumption and gender in Argentina changed in response to the introduction of Darwinian ideas. Ideas surrounding consumerism were transformed by the 1870s, influenced by a scientific revolution that gave new meaning to gender categories. The introduction of Darwinism at a time of extreme ideological confusion about how to organise the nation only enhanced the perceived dangers about how economic changes and the expansion of markets would affect elites' ability to govern. The article focuses specifically on changing perceptions of gender and consumerism between 1830 and 1880, paying particular attention to the work of two of the most important intellectuals of the Generación del '37, Juan B. Alberdi and Domingo F. Sarmiento. By closely examining their reflections on the expansion of markets and accumulation of luxury goods, it reveals the nature of the cultural changes introduced by the Darwinian revolution.
Enganche and Exports in Chiapas, Mexico: a Comparison of Plantation Labour in the Districts of Soconusco and Palenque, 1876–1911
Authors: WASHBROOK SARAH
Published: November 2007

This article examines the internal structure and dynamics of the coffee economy in two districts of the southern Mexican state of Chiapas during the presidency of Porfirio Díaz (1876–1911). In both Palenque, in the northern highlands, and Soconusco, on the Pacific coast, production was oriented to international markets, direct foreign investment was a key aspect of coffee plantation development, and workers were recruited by the payment of wage advances (enganche), which they were then expected to pay off by labouring on coffee plantations. Yet, despite these similarities, the social relations that characterised coffee production in the two districts differed considerably. This article analyses those differences by comparing and contrasting the demographic factors, processes of land privatisation and the relationship between foreign investors, the national regime and local elites that influenced the nature and purpose of debt peonage in each district.
The Crisis of the Estado docente and the Critical Education Movement: the Escuelas Obreras Federales Racionalistas in Chile (1921–1926)
Authors: REYES-JEDLICKI LEONORA
Published: November 2007

Inspired by recent critical pedagogic and social movement theory, this article explores the cultural production of social movements in Chile at the beginning of the twentieth century. Questioning the belief that the Estado docente was the sole mechanism of social democratisation, it explores the pedagogic proposals developed by workers and their associations during what is referred to as the period of the ‘Social Question’. The article concludes by analyzing the factors which led to the demise of these alternative pedagogic experiments.
Ambulatory Assessment - Monitoring Behavior in Daily Life Settings
Authors: Fahrenberg Jochen , Myrtek Michael , Pawlik Kurt , Perrez Meinrad
Published: November 2007

Abstract. Ambulatory assessment refers to the use of computer-assisted methodology for self-reports, behavior records, or physiological measurements, while the participant undergoes normal daily activities. Since the 1980s, portable microcomputer systems and physiological recorders/analyzers have been developed for this purpose. In contrast to their use in medicine, these new methods have hardly entered the domain of psychology. Questionnaire methods are still preferred, in spite of the known deficiencies of retrospective self-reports. Assessment strategies include: continuous monitoring, monitoring with time- and event-sampling methods, in-field psychological testing, field experimentation, interactive assessment, symptom monitoring, and self-management. These approaches are innovative and address ecological validity, context specificity, and are suitable for practical applications. The advantages of this methodology, as well as issues of acceptance, compliance, and reactivity are discussed. Many technical developments and research contributions have come from the German-speaking countries and the Netherlands. Nonetheless, the current Decade of Behavior (APA) calls for a more widespread use of such techniques and developments in assessment. This position paper seeks to make the case for this approach by demonstrating the advantages - and in some domains - necessities of ambulatory monitoring methodology for a behavioral science orientation in psychology.
Psychological and Psychophysiological Ambulatory Monitoring
Authors: Ebner-Priemer Ulrich W. , Kubiak Thomas
Published: November 2007

Abstract. Ambulatory assessment targets capturing psychological, behavioral, and physiological data in “real time” using in-field data acquisition systems. Although ambulatory assessment research has flourished particularly in the last decades, overviews on hardware and software solutions for monitoring are scarce, and - if found - are often outdated. In this review, we give an overview of current software and hardware solutions, focusing on multichannel systems for physiological data acquisition and hand-held computer based “experience sampling” systems. We aim at offering the reader guidance with regard to their choice of psychological and physiological monitoring solutions, giving special emphasis to key features relevant for different research questions.
Ambulatory Assessment of Affective Instability in Borderline Personality Disorder
Authors: Ebner-Priemer Ulrich W. , Sawitzki Günther
Published: November 2007

Abstract. Affective instability is an essential criterion for borderline personality disorder (BPD) but studies using diaries have rendered conflicting results. Discrepant findings may be caused by differences in the time-based design, especially in the diverse length of the time intervals between self-reports. Even though there is consensus that the time-based design should fit the temporal dynamics of the processes of interest, no general conventions exist. We used 24 h ambulatory monitoring to repeatedly assess subjective ratings of distress in 50 BPD-patients and in 50 healthy controls. We investigated if the chosen time-based design with a time interval of 15 min between self-reports (1) reveals within subject variability in BPD-patients and (2) taps the process of interest. Using graphical and statistical evaluation, we demonstrate that the time-based design (15 min/24 h) does catch within-person variability in the BPD-patients. Comparison of the original data with randomly distributed data (simulation) and autocorrelation analyses prove that we tapped a specific process and did not randomly pick states of distress. Using increasing lags between self-reports reveals that short intervals, especially, (15 min, 30 min) tap a specific process. We recommend using short time intervals to study temporal dynamics of affective instability.
Assessing Mood in Daily Life
Authors: Wilhelm Peter , Schoebi Dominik
Published: November 2007

Abstract. The repeated measurement of moods in everyday life, as is common in ambulatory monitoring, requires parsimonious scales, which may challenge the reliability of the measures. The current paper evaluates the factor structure, the reliability, and the sensitivity to change of a six-item mood scale designed for momentary assessment in daily life. We analyzed data from 187 participants who reported their current mood four times per day during seven consecutive days using a multilevel approach. The results suggest that the proposed three factors Calmness, Valence, and Energetic arousal are appropriate to assess fluctuations within persons over time. However, calmness and valence are not distinguishable at the between-person level. Furthermore, the analyses showed that two-item scales provide measures that are reliable at the different levels and highly sensitive to change.
The Learning Affect Monitor (LAM)
Authors: Reicherts Michael , Salamin Virginie , Maggiori Christian , Pauls Karl
Published: November 2007

Abstract. The Learning Affect Monitor (LAM) is a new computer-based assessment system integrating basic dimensional evaluation and discrete description of affective states in daily life, based on an autonomous adapting system. Subjects evaluate their affective states according to a tridimensional space (valence and activation circumplex as well as global intensity) and then qualify it using up to 30 adjective descriptors chosen from a list. The system gradually adapts to the user, enabling the affect descriptors it presents to be increasingly relevant. An initial study with 51 subjects, using a 1 week time-sampling with 8 to 10 randomized signals per day, produced n = 2,813 records with good reliability measures (e.g., response rate of 88.8%, mean split-half reliability of .86), user acceptance, and usability. Multilevel analyses show circadian and hebdomadal patterns, and significant individual and situational variance components of the basic dimension evaluations. Validity analyses indicate sound assignment of qualitative affect descriptors in the bidimensional semantic space according to the circumplex model of basic affect dimensions. The LAM assessment module can be implemented on different platforms (palm, desk, mobile phone) and provides very rapid and meaningful data collection, preserving complex and interindividually comparable information in the domain of emotion and well-being.