bluuebunny/crossref_metadata_2025 huggingface dataset:
Criteria for Defining Polycystic Ovary Syndrome as a Predominantly Hyperandrogenic Syndrome: An Androgen Excess Society Guideline
Authors: Azziz Ricardo , Carmina Enrico , Dewailly Didier , Diamanti-Kandarakis Evanthia , Escobar-Morreale Hector F. , Futterweit Walter , Janssen Onno E. , Legro Richard S. , Norman Robert J. , Taylor Ann E. , Witchel Selma F.
Published: August 2006

Objective: The Androgen Excess Society (AES) charged a task force to review all available data and recommend an evidence-based definition for polycystic ovary syndrome (PCOS), whether already in use or not, to guide clinical diagnosis and future research.

Participants: Participants included expert investigators in the field.

Evidence: Based on a systematic review of the published peer-reviewed medical literature, by querying MEDLINE databases, we tried to identify studies evaluating the epidemiology or phenotypic aspects of PCOS.

Consensus Process: The task force drafted the initial report, following a consensus process via electronic communication, which was then reviewed and critiqued by the AES Board of Directors. No section was finalized until all members were satisfied with the contents and minority opinions noted. Statements that were not supported by peer-reviewed evidence were not included.

Conclusions: Based on the available data, it is the view of the AES Task Force on the Phenotype of PCOS that there should be acceptance of the original 1990 National Institutes of Health criteria with some modifications, taking into consideration the concerns expressed in the proceedings of the 2003 Rotterdam conference. A principal conclusion was that PCOS should be first considered a disorder of androgen excess or hyperandrogenism, although a minority considered the possibility that there may be forms of PCOS without overt evidence of hyperandrogenism but recognized that more data are required before validating this supposition. Finally, the task force recognized, and fully expects, that the definition of this syndrome will evolve over time to incorporate new research findings.
Improved Triglycerides and Insulin Sensitivity with 3 Months of Acipimox in Human Immunodeficiency Virus-infected Patients with Hypertriglyceridemia
Authors: Hadigan Colleen , Liebau James , Torriani Martin , Andersen Rebecca , Grinspoon Steven
Published: August 2006

Context: Metabolic abnormalities such as hypertriglyceridemia remain a challenge for optimizing long-term health in HIV-infected patients.

Objective: Elevation of free fatty acids (FFAs) may contribute to hyperlipidemia and insulin resistance in HIV. We evaluated the efficacy and safety of chronic inhibition of lipolysis in HIV-infected men and women with hypertrigyceridemia. We hypothesized that acipimox would lead to significant reductions in triglycerides and improved insulin sensitivity, compared with placebo.

Design: A 3-month, randomized, double-blind, controlled trial of acipimox (250 mg thrice daily) vs. placebo was conducted in 23 HIV-infected men and women with hypertriglyceridemia (>150 mg/dl), abnormal fat distribution, and no current lipid-lowering therapy. The primary outcome variable was triglyceride concentration, and insulin sensitivity measured by hyperinsulinemic euglycemic clamp was a secondary outcome.

Setting: The study was conducted at an academic medical center.

Results: Acipimox resulted in significant reductions in FFAs [mean change −0.38 (0.06) vs. 0.08 (0.06) mEq/liter with placebo, −68 vs. +17% change from mean baseline, P < 0.0001], decreased rates of lipolysis (P < 0.0001), and a median triglyceride decrease from 238 mg/dl at baseline to 190 mg/dl, compared with an increase from 290 to 348 mg/dl in the placebo group (P = 0.01). Acipimox improved insulin sensitivity [acipimox +2.31 (0.74) vs. placebo −0.21 (0.90) mg glucose per kilogram lean body mass per minute, or +31 vs. −2% change from mean baseline values, P = 0.04]. Improvements in insulin sensitivity were significantly correlated with reductions in FFAs (r = −0.62, P = 0.003) and lipolysis (r = −0.59, P = 0.005).

Conclusions: Acipimox resulted in significant sustained reductions in lipolysis, improved glucose homeostasis, and significant but modest reductions in triglycerides in HIV-infected individuals with abnormal fat distribution and hypertriglyceridemia. Improvement in overall metabolic profile with acipimox suggests a potential clinical utility for this agent that requires further investigation.
Testosterone Gel Combined with Depomedroxyprogesterone Acetate Is an Effective Male Hormonal Contraceptive Regimen and Is Not Enhanced by the Addition of a GnRH Antagonist
Authors: Page Stephanie T. , Amory John K. , Anawalt Bradley D. , Irwig Michael S. , Brockenbrough Andrew T. , Matsumoto Alvin M. , Bremner William J.
Published: August 2006

Introduction: Exogenous androgens plus progestins can be used to suppress spermatogenesis, resulting in effective male hormonal contraception; however, induction of azoospermia can require 3–6 months, and these methods require injectable or implantable androgens. We hypothesized that testosterone (T) transdermal gel (T gel) could be combined with a depot formulation of the progestin, depomedroxyprogesterone acetate (DMPA), with or without the potent GnRH antagonist, acyline, to suppress spermatogenesis conveniently, rapidly, and reversibly.

Objectives: The objectives of the study were: 1) to determine the rate of severe oligospermia (≤1 million sperm/ml) using T gel+DMPA; and 2) to determine whether the addition of acyline to T gel+DMPA during the first 12 wk of the regimen would accelerate and improve suppression of spermatogenesis.

Methods: Forty-four healthy men, ages 18–55 yr, were randomized to T gel (100 mg daily)+DMPA (300 mg/3 months) or acyline (300 μg/kg·2 wk × 12 wk)+T gel+DMPA. Thirty-eight men completed the 24-wk treatment protocol.

Results: All men had dramatic suppression of spermatogenesis; 90% of the subjects became severely oligospermic, a rate comparable to implantable and injectable T+progestin combinations. The addition of acyline did not significantly accelerate spermatogenic suppression or improve rates of severe oligospermia. There were no serious adverse events, and there were minimal changes in weight, serum lipids, and prostate-specific antigen.

Conclusions: The combination of T gel+DMPA is a promising new regimen in male contraception. The addition of the GnRH antagonist acyline, as part of an induction phase in a male contraception regimen, has limited clinical utility. Additional studies using T gel for male contraception are warranted.
Uncertainty about nest position influences systematic search strategies in desert ants
Authors: Merkle Tobias , Knaden Markus , Wehner Rüdiger
Published: August 2006

Foraging desert ants return to their starting point, the nest, by means of path integration. If the path-integration vector has been run off but the nest has not yet been reached, the ants engage in systematic search behavior. This behavior results in a system of search loops of ever increasing size and finally leads to a search density profile peaking at the location where the path integration system has been reset to zero. In this study we investigate whether this systematic search behavior is adapted to the uncertainty resulting from the preceding foraging run. We show first that the longer the distances of the foraging excursions, the larger the errors occurring during path integration, and second that the ants adapt their systematic search strategy to their increasing uncertainty by extending their search pattern. Hence, the density of the systematic search pattern is correlated with the ants' confidence in their path integrator. This confidence decreases with increasing foraging distances.
Size discrimination of hollow hemispheres by echolocation in a nectar feeding bat
Authors: Simon Ralph , Holderied Marc W. , von Helversen Otto
Published: August 2006

Nectar feeding bats use echolocation to find their flowers in the dense growth of tropical rainforests, and such flowers have evolved acoustic features that make their echo more conspicuous to their pollinators. To shed light on the sensory and cognitive basis of echoacoustic object recognition we conducted a size discrimination experiment with the nectarivorous bat Glossophaga soricina and compared the bats' behavioural performance with the echoic features of the training objects.

We chose a simple geometric form, the hollow hemisphere, as the training object because of its resemblance to the bell-shaped concave form of many bat flowers, as well as its special acoustic qualities. The hemispheres showed a characteristic echo pattern, which was constant over a wide range of angles of sound incidence. We found systematic size-dependent changes in the echo's temporal and spectral pattern as well as in amplitude.

Bats were simultaneously confronted with seven different sizes of hollow hemispheres presented from their concave sides. Visits to one particular size were rewarded with sugar water, while we recorded the frequency of visits to the unrewarded hemispheres. We found that: (1) bats learned to discriminate between hemispheres of different size with ease; (2) the minimum size difference for discrimination was a constant percentage of the hemisphere's size (Weber fraction: approximately 16% of the radius); (3) the comparison of behavioural data and impulse response measurements of the objects' echoes yielded discrimination thresholds for mean intensity differences (1.3 dB), the temporal pattern (3-22 μs) and the change of spectral notch frequency(approximately 16%). We discuss the advantages of discrimination in the frequency and/or time domain.
Efficiency of antlion trap construction
Authors: Fertin Arnold , Casas Jérôme
Published: August 2006

Assessing the architectural optimality of animal constructions is in most cases extremely difficult, but is feasible for antlion larvae, which dig simple pits in sand to catch ants. Slope angle, conicity and the distance between the head and the trap bottom, known as off-centring, were measured using a precise scanning device. Complete attack sequences in the same pits were then quantified, with predation cost related to the number of behavioural items before capture. Off-centring leads to a loss of architectural efficiency that is compensated by complex attack behaviour. Off-centring happened in half of the cases and corresponded to post-construction movements. In the absence of off-centring, the trap is perfectly conical and the angle is significantly smaller than the crater angle, a physical constant of sand that defines the steepest possible slope. Antlions produce efficient traps, with slopes steep enough to guide preys to their mouths without any attack, and shallow enough to avoid the likelihood of avalanches typical of crater angles. The reasons for the paucity of simplest and most efficient traps such as theses in the animal kingdom are discussed.
Modeling the electric field of weakly electric fish
Authors: Babineau David , Longtin André , Lewis John E.
Published: August 2006

Weakly electric fish characterize the environment in which they live by sensing distortions in their self-generated electric field. These distortions result in electric images forming across their skin. In order to better understand electric field generation and image formation in one particular species of electric fish, Apteronotus leptorhynchus, we have developed three different numerical models of a two-dimensional cross-section of the fish's body and its surroundings. One of these models mimics the real contour of the fish; two other geometrically simple models allow for an independent study of the effects of the fish's body geometry and conductivity on electric field and image formation. Using these models, we show that the fish's tapered body shape is mainly responsible for the smooth, uniform field in the rostral region, where most electroreceptors are located. The fish's narrowing body geometry is also responsible for the relatively large electric potential in the caudal region. Numerical tests also confirm the previous hypothesis that the electric fish body acts approximately like an ideal voltage divider; this is true especially for the tail region. Next, we calculate electric images produced by simple objects and find they vary according to the current density profile assigned to the fish's electric organ. This explains some of the qualitative differences previously reported for different modeling approaches. The variation of the electric image's shape as a function of different object locations is explained in terms of the fish's geometrical and electrical parameters. Lastly, we discuss novel cues for determining an object's rostro-caudal location and lateral distance using these electric images.
Dolphin continuous auditory vigilance for five days
Authors: Ridgway Sam , Carder Don , Finneran James , Keogh Mandy , Kamolnick Tricia , Todd Mark , Goldblatt Allen
Published: August 2006

The present report describes the first study of continuous vigilance in dolphins. Two adult bottlenose dolphins (Tursiops truncatus), WEN(male) and SAY (female), maintained a very high detection rate of randomly presented, infrequent, 1.5-s target tones in a background of frequent 0.5-s equal-amplitude tones over five continuous 120-h sessions. The animals were able to maintain high levels (WEN 97, 87, 99%; SAY 93, 96%) of target detection without signs of sleep deprivation as indicated by behavior, blood indices or marked sleep rebound during 24 h of continuous post-experiment observation. Target response time overall (F=0.384; P=0.816)did not change between day 1 and day 5. However, response time was significantly slower (F=21.566, P=0.019) during the night(21.00-04.00 h) when the dolphins would have ordinarily been resting or asleep.
Effect of host kairomones and oviposition experience on the arrestment behavior of an egg parasitoid
Authors: Peri Ezio , Sole Mery Angelica , Wajnberg Eric , Colazza Stefano
Published: August 2006

Chemical residues left by walking adults of the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae) induce arrestment behavior in the egg parasitoid Trissolcus basalis (Wollaston)(Hymenoptera: Scelionidae) leading to prolonged periods of walking on contaminated areas and to systematic return to the stimulus after encountering the treatment borders. In this study, we quantified how the hierarchical value of residues from host adults and oviposition experience can influence the arrestment behavior of T. basalis females. Our results showed that:(1) female wasps perceived host residues at different hierarchical levels depending on the host gender, with a clear preference for the chemical residues deposited by host females rather then host males; (2) wasps'arrestment response to chemical residues of host females became weaker when wasps were not rewarded by an oviposition experience, and stronger following successful oviposition; (3) repeated encounters with host male chemical residues, followed or not by oviposition experience, did not cause wasps to change their innate arrestment response; (4) in the unrewarded condition,arrestment responses of wasps varied according to the time elapsed between successive visits to areas contaminated by host females: responses were weak with a short interval (less than 24 h) and stronger with a long interval (more than 72 h), suggesting that this unrewarded experience, i.e. encounter with female traces not followed by host egg location, fade within a few hours. The potential significance of these results to the host location behavior of T. basalis in the field is discussed.
Noradrenergic modulation of respiratory motor output during tadpole development: role of α-adrenoceptors
Authors: Fournier Stéphanie , Kinkead Richard
Published: August 2006

Noradrenaline (NA) is an important modulator of respiratory activity. Results from in vitro studies using immature rodents suggest that the effects exerted by NA change during development, but these investigations have been limited to neonatal stages. To address this issue, we used in vitro brainstem preparations of an ectotherm, Rana catesbeiana,at three developmental stages: pre-metamorphic tadpoles, metamorphic tadpoles and fully mature adult bullfrogs. We first compared the effects of NA bath application (0.02-10 μmol l-1) on brainstem preparations from both pre-metamorphic (Taylor-Köllros stages VII-XI) and metamorphic tadpoles (TK stages XVIII-XXIII) and adult frogs. The fictive lung ventilation frequency response to NA application was both dose- and stage-dependent. Although no net change was observed in the pre-metamorphic group, NA application decreased fictive lung burst frequency in preparations from more mature animals. These effects were attenuated by application ofα-adrenoceptor antagonists. Conversely, NA application elicited dose-and stage-dependent increases in fictive buccal ventilation frequency. We then assessed the contribution of α-adrenoceptors towards these responses by applying specific agonists (α1: phenylephrine;α 2: clonidine; concentration range from 10 to 200 μmol l-1 for both). Of the two agonists used, only phenylephrine application consistently mimicked the lung burst frequency response observed during NA application in each stage group. However, both agonists decreased buccal burst frequency, thus suggesting that other (β) adrenoceptor types mediate this response. We conclude that modulation of both buccal and lung-related motor outputs change during development. NA modulation affects both types of respiratory activities in a distinct fashion, owing to the different adrenoceptor type involved.
Molecular characterization of sodium/proton exchanger 3 (NHE3) from the yellow fever vector,Aedes aegypti
Authors: Pullikuth Ashok K. , Aimanova Karlygash , Kang'ethe Wanyoike , Sanders Heather R. , Gill Sarjeet S.
Published: August 2006

Transport across insect epithelia is thought to depend on the activity of a vacuolar-type proton ATPase (V-ATPase) that energizes ion transport through a secondary proton/cation exchanger. Although several of the subunits of the V-ATPase have been cloned, the molecular identity of the exchanger has not been elucidated. Here, we present the identification of sodium/proton exchanger isoform 3 (NHE3) from yellow fever mosquito, Aedes aegypti(AeNHE3). AeNHE3 localizes to the basal plasma membrane of Malpighian tubule, midgut and the ion-transporting sector of gastric caeca. Midgut expression of NHE3 shows a different pattern of enrichment between larval and adult stages, implicating it in the maintenance of regional pH in the midgut during the life cycle. In all tissues examined, NHE3 predominantly localizes to the basal membrane. In addition the limited expression in intracellular vesicles in the median Malpighian tubules may reflect a potential functional versatility of NHE3 in a tissue-specific manner. The localization of V-ATPase and NHE3, and exclusion of Na+/K+-ATPase from the distal ion-transporting sector of caeca, indicate that the role of NHE3 in ion and pH regulation is intricately associated with functions of V-ATPase. The AeNHE3 complements yeast mutants deficient in yeast NHEs, NHA1 and NHX1. To further examine the functional property of AeNHE3, we expressed it in NHE-deficient fibroblast cells. AeNHE3 expressing cells were capable of recovering intracellular pH following an acid load. The recovery was independent of the large cytoplasmic region of AeNHE3, implying this domain to be dispensable for NHE3 ion transport function. 22Na+uptake studies indicated that AeNHE3 is relatively insensitive to amiloride and EIPA and is capable of Na+ transport in the absence of the cytoplasmic tail. Thus, the core domain containing the transmembrane regions of NHE3 is sufficient for pH recovery and ion transport. The present data facilitate refinement of the prevailing models of insect epithelial transport by incorporating basal amiloride-insensitive NHE3 as a critical mediator of transepithelial ion and fluid transport and likely in the maintenance of intracellular pH.
Frictional adhesion: a new angle on gecko attachment
Authors: Autumn K. , Dittmore A. , Santos D. , Spenko M. , Cutkosky M.
Published: August 2006

Directional arrays of branched microscopic setae constitute a dry adhesive on the toes of pad-bearing geckos, nature's supreme climbers. Geckos are easily and rapidly able to detach their toes as they climb. There are two known mechanisms of detachment: (1) on the microscale, the seta detaches when the shaft reaches a critical angle with the substrate, and (2) on the macroscale, geckos hyperextend their toes, apparently peeling like tape. This raises the question of how geckos prevent detachment while inverted on the ceiling, where body weight should cause toes to peel and setal angles to increase. Geckos use opposing feet and toes while inverted, possibly to maintain shear forces that prevent detachment of setae or peeling of toes. If detachment occurs by macroscale peeling of toes, the peel angle should monotonically decrease with applied force. In contrast, if adhesive force is limited by microscale detachment of setae at a critical angle, the toe detachment angle should be independent of applied force. We tested the hypothesis that adhesion is increased by shear force in isolated setal arrays and live gecko toes. We also tested the corollary hypotheses that (1) adhesion in toes and arrays is limited as on the microscale by a critical angle, or (2)on the macroscale by adhesive strength as predicted for adhesive tapes. We found that adhesion depended directly on shear force, and was independent of detachment angle. Therefore we reject the hypothesis that gecko toes peel like tape. The linear relation between adhesion and shear force is consistent with a critical angle of release in live gecko toes and isolated setal arrays, and also with our prior observations of single setae. We introduced a new model,frictional adhesion, for gecko pad attachment and compared it to existing models of adhesive contacts. In an analysis of clinging stability of a gecko on an inclined plane each adhesive model predicted a different force control strategy. The frictional adhesion model provides an explanation for the very low detachment forces observed in climbing geckos that does not depend on toe peeling.
Down-regulation of endogenes mediated by a transitive silencing signal
Authors: Bleys Annick , Van Houdt Helena , Depicker Anna
Published: August 2006

Some RNA silencing systems in plants, nematodes, and fungi show spreading of silencing along target sequences, termed transitive silencing. Here, we address the question of whether endogenous targets can be silenced by a transitive silencing signal in plants. In transgenic Arabidopsis thaliana plants that harbored a silencing-inducing locus and a transgenic chimeric primary target, silencing of a secondary transgenic target occurred and the expression of the endogenous catalase genes was down-regulated, coinciding with a knock-down phenotype. Strikingly, the efficiency of the catalase silencing appeared to be correlated with the zygosity of the primary target locus and, to a lesser extent, with that of the silencing-inducing locus. These data suggest that silencing of an endogene induced by transgenic secondary small interfering RNAs (siRNAs) might depend on the amount of primary target transcripts that can act as template for the production of an efficient transitive silencing signal.
RNA editing level in the mouse is determined by the genomic repeat repertoire
Authors: Neeman Yossef , Levanon Erez Y. , Jantsch Michael F. , Eisenberg Eli
Published: August 2006

A-to-I RNA editing is the conversion of adenosine to inosine in double-stranded cellular and viral RNAs. Recently, abundant editing of human transcripts affecting thousands of genes has been reported. Most editing sites are confined to the primate-specific Alu repeats. Notably, the editing level in mouse was shown to be much lower. In order to find the reason for this dramatic difference, here we identify editing sites within mouse repeats and analyze the sequence properties required for RNA editing. Our results show that the overall rate of RNA editing is determined by specific properties of different repeat families such as abundance, length, and divergence. We show that the striking difference in editing levels between human and mouse is mostly due to the higher divergence of the different mouse repeats.
RNA aptamers to mammalian initiation factor 4G inhibit cap-dependent translation by blocking the formation of initiation factor complexes
Authors: Miyakawa Shin , Oguro Akihiro , Ohtsu Takashi , Imataka Hiroaki , Sonenberg Nahum , Nakamura Yoshikazu
Published: August 2006

Eukaryotic translation initiation factor 4G (eIF4G) plays a crucial multimodulatory role in mRNA translation and decay by interacting with other translation factors and mRNA-associated proteins. In this study, we isolated eight different RNA aptamers with high affinity to mammalian eIF4G by in vitro RNA selection amplification. Of these, three aptamers (apt3, apt4, and apt5) inhibited the cap-dependent translation of two independent mRNAs in a rabbit reticulocyte lysate system. The cap-independent translation directed by an HCV internal ribosome entry site was not affected. Addition of exogenous eIF4G reversed the aptamer-mediated inhibition of translation. Even though apt3 and apt4 were selected independently, they differ only by two nucleotides. The use of truncated eIF4G variants in binding experiments indicated that apt4 (and probably apt3) bind to both the middle and C-terminal domains of eIF4G, while apt5 binds only to the middle domain of eIF4G. Corresponding to the difference in the binding sites in eIF4G, apt4, but not apt5, hindered eIF4G from binding to eIF4A and eIF3, in a purified protein solution system as well as in a crude lysate system. Therefore, the inhibition of translation by apt4 (and apt3) is due to the inhibition of formation of initiation factor complexes involving eIF4A and eIF3. On the other hand, apt5 had a much weaker affinity to eIF4G than apt4, but inhibited translation much more efficiently by an unknown mechanism. The five additional aptamers have sequences and predicted secondary structures that are largely different from each other and from apt3 through apt5. Therefore, we speculate that these seven sets of aptamers may bind to different regions in eIF4G in different fashions.
Translation-independent inhibition of mRNA deadenylation during stress in Saccharomyces cerevisiae
Authors: Hilgers Valérie , Teixeira Daniela , Parker Roy
Published: August 2006

Post-transcriptional control mechanisms play an important role in regulating gene expression during cellular responses to stress. For example, many stresses inhibit translation, and at least some stresses inhibit mRNA turnover in yeast and mammalian cells. We show that hyperosmolarity, heat shock, and glucose deprivation stabilize multiple mRNAs in yeast, primarily through inhibition of deadenylation. Although these stresses inhibit translation and promote the movement of mRNAs into P-bodies, we also observed inhibition of deadenylation in cycloheximide-treated cells as well as in a mutant strain where translation initiation is impaired. This argues that inhibition of poly(A)-shortening is independent of the translational state of the mRNAs and can occur when mRNAs are localized in polysomes or are not engaged in translation. Analysis of pan2Δ or ccr4Δ strains indicates that stress inhibits the function of both the Ccr4p/Pop2p/Notp and the Pan2p/Pan3p deadenylases. We suggest that under stress, simultaneous repression of translation and deadenylation allows cells to selectively translate mRNAs specific to the stress response, while retaining the majority of the cytoplasmic pool of mRNAs for later reuse and recovery from stress. Moreover, because various cellular stresses also inhibit deadenylation in mammalian cells, this mechanism is likely to be a conserved aspect of the stress response.
The Effects of Trust-Assuring Arguments on Consumer Trust in Internet Stores: Application of Toulmin's Model of Argumentation
Authors: Kim Dongmin , Benbasat Izak
Published: August 2006

A trust-assuring argument refers to “a claim and its supporting statements used in an Internet store to address trust-related issues.” Although trust-assuring arguments often appear in Internet stores, little research has been conducted to understand their effects on consumer trust in an Internet store. The goals of this study are (1) to investigate whether or not the provision of trust-assuring arguments on the website of an Internet store increase consumer trust in that Internet store and (2) to identify the most effective form of trust-assuring arguments to provide guidelines for their implementation.

Toulmin's (1958) model of argumentation is proposed as a basis to identify the elements of an argument and to strengthen the effects of trust-assuring arguments on consumer trust in an Internet store. Based on Toulmin's (1958) model of argumentation, three elements of arguments that commonly appear in daily communication; namely, claim, data, and backing, are identified. Data refers to the grounds for a claim, while backing is used for providing reasons for why the data should be accepted. By combining these three elements, three forms of trust-assuring arguments (claim only, claim plus data, and claim plus data and backing) are developed. The effects of these three forms of trust-assuring arguments on consumer trust in an Internet store are tested by comparing them to a no trust-assuring argument condition in a laboratory experiment with 112 participants.

The results indicate (1) providing trust-assuring arguments that consist of claim plus data or claim plus data and backing increases consumers' trusting belief but displaying arguments that contain claim only does not and (2) trust-assuring arguments that include claim plus data and backing lead to the highest level of trusting belief among the three forms of arguments examined in this study. Based on the results, we argue that Toulmin's (1958) model of argumentation is an effective basis for website designers to develop convincing trust-assuring arguments and to improve existing trust-assuring arguments in Internet stores.
From IT Leveraging Competence to Competitive Advantage in Turbulent Environments: The Case of New Product Development
Authors: Pavlou Paul A. , El Sawy Omar A.
Published: August 2006

A burning question for information systems (IS) researchers and practitioners is whether and how IT can build a competitive advantage in turbulent environments. To address this question, this study focuses on the business process level of analysis and introduces the construct of IT leveraging competence—the ability to effectively use IT functionalities. This construct is conceptualized in the context of new product development (NPD). IT leveraging competence is shown to indirectly influence competitive advantage in NPD through two key mediating links: functional competencies (the ability to effectively execute operational NPD processes) and dynamic capabilities (the ability to reconfigure functional competencies to address turbulent environments). Environmental turbulence is also shown to moderate the process by which IT leveraging competence influences competitive advantage in NPD. Empirical data were collected from 180 NPD managers.

Through the construct of IT leveraging competence, the study shows that the effective use of IT functionalities, even generic functionalities, by business units can help build a competitive advantage. The study also shows that the strategic effect of IT leveraging competence is more pronounced in higher levels of environmental turbulence. This effect is not direct: It is fully mediated by both dynamic capabilities and functional competencies. Taken together, these findings suggest that IS researchers should look beyond the direct effects of firm-level IT infrastructures and focus their attention on how business units can leverage IT functionalities to better reconfigure and execute business processes. In turbulent environments, focusing on these aspects is even more vital.
Privacy Protection in Data Mining: A Perturbation Approach for Categorical Data
Authors: Li Xiao-Bai , Sarkar Sumit
Published: August 2006

To respond to growing concerns about privacy of personal information, organizations that use their customers' records in data-mining activities are forced to take actions to protect the privacy of the individuals involved. A common practice for many organizations today is to remove identity-related attributes from the customer records before releasing them to data miners or analysts. We investigate the effect of this practice and demonstrate that many records in a data set could be uniquely identified even after identity-related attributes are removed. We propose a perturbation method for categorical data that can be used by organizations to prevent or limit disclosure of confidential data for identifiable records when the data are provided to analysts for classification, a common data-mining task. The proposed method attempts to preserve the statistical properties of the data based on privacy protection parameters specified by the organization. We show that the problem can be solved in two phases, with a linear programming formulation in Phase I (to preserve the first-order marginal distribution), followed by a simple Bayes-based swapping procedure in Phase II (to preserve the joint distribution). Experiments conducted on several real-world data sets demonstrate the effectiveness of the proposed method.
The Effectiveness of Knowledge Transfer Portfolios in Software Process Improvement: A Field Study
Authors: Slaughter Sandra A. , Kirsch Laurie J.
Published: August 2006

Because of challenges often experienced when deploying software, many firms have embarked on software process improvement (SPI) initiatives. Critical to the success of these initiatives is the transfer of knowledge across individuals who occupy a range of roles in various organizational units involved in software production. Prior research suggests that a portfolio of different mechanisms, employed frequently, can be required for effective knowledge transfer. However, little research exists that examines under what situations differing portfolios of mechanisms are selected. Further, it is not clear how effective different portfolio designs are. In this study, we conceptualize knowledge transfer portfolios in terms of their composition (the types of mechanisms used) and their intensity (the frequency with which the mechanisms are utilized). We hypothesize the influence of organizational design decisions on the composition and intensity of knowledge transfer portfolios for SPI. We then posit how the composition and intensity of knowledge transfer portfolios affect performance improvement. Our findings indicate that a more intense portfolio of knowledge transfer mechanisms is used when the source and recipient are proximate, when they are in a hierarchical relationship, or when they work in different units. Further, a source and recipient select direction-based portfolios when they are farther apart, in a hierarchical relationship, or work in different units. In terms of performance, our results reveal that the fit between the composition and intensity of the knowledge transfer portfolio influences the recipient's performance improvement. At lower levels of intensity direction-based portfolios are more effective, while at higher levels of intensity routine-based portfolios yield the highest performance improvement. We discuss the implications of our findings for researchers and for managers who want to promote knowledge transfer to improve software processes in their organizations.
The epidemiology and aetiology of Perthes’ disease in Norway
Authors: Wiig O. , Terjesen T. , Svenningsen S. , Lie S. A.
Published: August 2006

A nationwide study of Perthes’ disease in Norway was undertaken over a five-year period from January 1996. There were 425 patients registered, which represents a mean annual incidence of 9.2 per 100 000 in subjects under 15 years of age, and an occurrence rate of 1:714 for the country as a whole. There were marked regional variations. The lowest incidence was found in the northern region (5.4 per 100 000 per year) and the highest in the central and western regions (10.8 and 11.3 per 100 000 per year, respectively). There was a trend towards a higher incidence in urban (9.5 per 100 000 per year) compared with rural areas (8.9 per 100 000 per year). The mean age at onset was 5.8 years (1.3 to 15.2) and the male:female ratio was 3.3:1.

We compared 402 patients with a matched control group of non-affected children (n = 1 025 952) from the Norwegian Medical Birth Registry and analysed maternal data (age at delivery, parity, duration of pregnancy), birth length and weight, birth presentation, head circumference, ponderal index and the presence of congenital anomalies. Children with Perthes’ disease were significantly shorter at birth and had an increased frequency of congenital anomalies.

Applying Sartwell’s log-normal model of incubation periods to the distribution of age at onset of Perthes’ disease showed a good fit to the log-normal curve. Our findings point toward a single cause, either genetic or environmental, acting prenatally in the aetiology of Perthes’ disease.
Continuous interscalene infusion and single injection using levobupivacaine for analgesia after surgery of the shoulder
Authors: Kean J. , Wigderowitz C. A. , Coventry D. M.
Published: August 2006

We performed a double-blind, randomised controlled trial to assess the effectiveness of a continuous-infusion brachial plexus block with levobupivacaine compared with that of a standard single injection for the management of post-operative pain after surgery on the shoulder.

Eight patients were randomised to receive a pre-operative brachial plexus block using 30 ml of levobupivacaine 0.5% with adrenaline 1:200 000 followed by insertion of a 20-gauge polyamide catheter. This was connected to a disposable elastometric pump, set immediately after surgery to administer a continuous flow of levobupivacaine 0.25% at a rate of 5 ml per hour. The other eight patients were randomised to receive only the initial injection of 30 ml. The study was double-blinded with the aid of sham catheters and clamped pumps.

All patients were given regular paracetamol and were prescribed morphine through a patient-controlled analgesia pump. Motor and sensory block assessments, visual analogue scale pain scores and consumption of morphine were recorded after the operation and then at 6, 12 and 24 hours after administration of the block.

Satisfactory motor and sensory block was achieved in all patients. The mean visual analogue scale pain score at 12 hours and consumption of morphine at 24 hours after injection were significantly lower (p < 0.05) in the continuous-infusion group. This group also took longer to request their first additional analgesia and reported a significantly higher overall level of satisfaction.

Our study has shown that continuous interscalene infusion of levobupivacaine is an effective method of post-operative analgesia after major surgery of the shoulder.
Use of freeze-dried bone allograft with platelet-derived growth factor for revision of a glenoid component
Authors: Peidro L. , Segur J. M. , Poggio D. , de Retana P. Fernandez
Published: August 2006

Glenoid replacement is technically challenging. Removal of a cemented glenoid component often results in a large osseous defect which makes the immediate introduction of a revision prosthesis almost impossible. We describe a two-stage revision procedure using a reversed shoulder prosthesis. Freeze-dried allograft with platelet-derived growth factor was used to fill the glenoid defect. Radiological incorporation of the allograft was seen and its consistency allowed the placement of a screwed glenoid component. There were no signs of new mature bone formation on histological examination.

The addition of platelet-derived growth factor to the allograft seems to contribute to an increase in incorporation and hardness, but does not promote the growth of new bone.
Uncompromised quality of the cement mantle in Exeter femoral components implanted through a minimally-invasive direct anterior approach
Authors: Mayr E. , Krismer M. , Ertl M. , Kessler O. , Thaler M. , Nogler M.
Published: August 2006

A complete cement mantle is important for the longevity of a total hip replacement. In the minimally-invasive direct anterior approach used at the Innsbruck University hospital, the femoral component has to be inserted into the femoral canal by an angulated movement. In a cadaver study, the quality and the extent of the cement mantle surrounding 13 Exeter femoral components implanted straight through a standard anterolateral transgluteal approach were compared with those of 13 similar femoral components implanted in an angulated fashion through a direct anterior approach. A third-generation cementing technique was used. The inner and outer contours of the cement mantles was traced from CT scans and the thickness and cross-sectional area determined.

In no case was the cement mantle incomplete. The total mean thickness of the cement mantle was 3.62 mm (95% confidence interval 3.59 to 3.65). The mean thickness in the group using the minimally-invasive approach was 0.16 mm less than that in the anterolateral group. The distribution of the thickness was similar in the two groups. The mean thickness was less on the anteromedial and anterolateral aspect than on the posterior aspect of the femur.

There is no evidence that the angulated introduction of Exeter femoral components in the direct anterior approach in cadavers compromises the quality, extent or thickness of the cement mantle.
Outcome of surgery for reconstruction of fractures of the acetabulum
Authors: Madhu R. , Kotnis R. , Al-Mousawi A. , Barlow N. , Deo S. , Worlock P. , Willett K.
Published: August 2006

This is a retrospective case review of 237 patients with displaced fractures of the acetabulum presenting over a ten-year period, with a minimum follow-up of two years, who were studied to test the hypothesis that the time to surgery was predictive of radiological and functional outcome and varied with the pattern of fracture. Patients were divided into two groups based on the fracture pattern: elementary or associated. The time to surgery was analysed as both a continuous and a categorical variable. The primary outcome measures were the quality of reduction and functional outcome. Logistic regression analysis was used to test our hypothesis, while controlling for potential confounding variables.

For elementary fractures, an increase in the time to surgery of one day reduced the odds of an excellent/good functional result by 15% (p = 0.001) and of an anatomical reduction by 18% (p = 0.0001). For associated fractures, the odds of obtaining an excellent/good result were reduced by 19% (p = 0.0001) and an anatomical reduction by 18% (p = 0.0001) per day.

When time was measured as a categorical variable, an anatomical reduction was more likely if surgery was performed within 15 days (elementary) and five days (associated). An excellent/good functional outcome was more likely when surgery was performed within 15 days (elementary) and ten days (associated).

The time to surgery is a significant predictor of radiological and functional outcome for both elementary and associated displaced fractures of the acetabulum. The organisation of regional trauma services must be capable of satisfying these time-dependent requirements to achieve optimal patient outcomes.
Combined reconstruction of chronic posterior cruciate ligament and posterolateral corner deficiency
Authors: Khanduja V. , Somayaji H. S. , Harnett P. , Utukuri M. , Dowd G. S. E.
Published: August 2006

We report a retrospective analysis of the results of combined arthroscopically-assisted posterior cruciate ligament reconstruction and open reconstruction of the posterolateral corner in 19 patients with chronic (three or more months) symptomatic instability and pain in the knee.

All the operations were performed between 1996 and 2003 and all the patients were assessed pre- and post-operatively by physical examination and by applying three different ligament rating scores. All also had weight-bearing radiographs, MR scans and an examination under anaesthesia and arthroscopy pre-operatively. The posterior cruciate ligament reconstruction was performed using an arthroscopically-assisted single anterolateral bundle technique and the posterolateral corner structures were reconstructed using an open Larson type of tenodesis.

The mean follow up was 66.8 months (24 to 110). Pre-operatively, all the patients had a grade III posterior sag according to Clancy and demonstrated more than 20° of external rotation compared with the opposite normal knee on the Dial test. Post-operatively, seven patients (37%) had no residual posterior sag, 11 (58%) had a grade I posterior sag and one (5%) had a grade II posterior sag. In five patients (26%) there was persistent minimal posterolateral laxity. The Lysholm score improved from a mean of 41.2 (28 to 53) to 76.5 (57 to 100) (p = 0.0001) and the Tegner score from a mean of 2.6 (1 to 4) to 6.4 (4 to 9) (p = 0.0001).

We conclude that while a combined reconstruction of chronic posterior cruciate ligament and posterolateral corner instability improves the function of the knee, it does not restore complete stability.
Surgical biopsy with intra-operative frozen section
Authors: Ashford R. U. , McCarthy S. W. , Scolyer R. A. , Bonar S. F. , Karim R. Z. , Stalley P. D.
Published: August 2006

The most appropriate protocol for the biopsy of musculoskeletal tumours is controversial, with some authors advocating CT-guided core biopsy. At our hospital the initial biopsies of most musculoskeletal tumours has been by operative core biopsy with evaluation by frozen section which determines whether diagnostic tissue has been obtained and, if possible, gives the definitive diagnosis. In order to determine the accuracy and cost-effectiveness of this protocol we have undertaken a retrospective audit of biopsies of musculoskeletal tumours performed over a period of two years.

A total of 104 patients had biopsies according to this regime. All gave the diagnosis apart from one minor error which did not alter the management of the patient. There was no requirement for re-biopsy. This protocol was more labour-intensive and 38% more costly than CT-guided core biopsy (AU$1804 vs AU$1308). However, the accuracy and avoidance of the anxiety associated with repeat biopsy outweighed these disadvantages.
MRI study of the lumbar spine in achondroplasia
Authors: Jeong S.-T. , Song H.-R. , Keny S. M. , Telang S. S. , Suh S.-W. , Hong S.-J.
Published: August 2006

We carried out an MRI study of the lumbar spine in 15 patients with achondroplasia to evaluate the degree of stenosis of the canal. They were divided into asymptomatic and symptomatic groups. We measured the sagittal canal diameter, the sagittal cord diameter, the interpedicular distance at the mid-pedicle level and the cross-sectional area of the canal and spinal cord at mid-body and mid-disc levels.

The MRI findings showed that in achondroplasia there was a significant difference between the groups in the cross-sectional area of the body canal at the upper lumbar levels. Patients with a narrower canal are more likely to develop symptoms of spinal stenosis than others.