bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma ghrelin concentrations are positively associated with carotid artery atherosclerosis in males
Authors: PÖYKKÖ S. M. , KELLOKOSKI E. , UKKOLA O. , KAUMA H. , PÄIVÄNSALO M. , KESÄNIEMI Y. A. , HÖRKKÖ S.
Published: June 2006

Background.  Ghrelin, a peptide hormone from stomach, stimulates food intake and decreases fat utilization. Ghrelin binds to growth hormone secretagogue receptor (GHSR). GHSR density has been shown to be upregulated in atherosclerotic lesions, but the relationship between ghrelin concentration and atherosclerosis has not yet been studied. We, therefore, characterized the association between ghrelin concentration and carotid artery intima‐media thickness (IMT) in a population‐based cohort of 1024 middle‐aged (40–60 years) men and women.

Methods.  Intima‐media thickness and the number of atherosclerotic plaques were determined ultrasonographically. Fasting plasma ghrelin concentrations were analysed using RIA‐kit (PhoenixPeptide).

Results.  There was a positive association between mean IMT and ghrelin concentration in the analysis of males before and after adjustments for the traditional risk factors of atherosclerosis [age, systolic blood pressure, LDL cholesterol, body mass index (BMI), and smoking (ancova, P = 0.004 and P = 0.007, respectively)]. However, no such association was found in females (P = 0.985 and P = 0.915). There was no correlation between ghrelin and CRP concentrations or ghrelin and smoking.

Conclusion.  Ghrelin concentrations and carotid artery atherosclerosis are positively associated in males even after adjustment for the commonly recognized risk factors of atherosclerosis. Experimental and prospective studies are warranted to elucidate the role of ghrelin in atherosclerosis.
Fracture risk associated with the use of morphine and opiates
Authors: VESTERGAARD P. , REJNMARK L. , MOSEKILDE L.
Published: June 2006

Objectives.  To study the effect of morphine and opiates on fracture risk.

Design.  Case–control study.

Setting.  Nationwide register‐based study.

Subjects.  Cases were all subjects with any fracture sustained during the year 2000 (n = 124 655). For each case, three controls (n = 373 962) matched on age and gender were randomly drawn from the background population. The primary exposure variables were use of morphine and opiates. Morphine and other opiates had been used by 10 015 (8.0%) of the case subjects and 12 108 (3.2%) of the controls. Adjustments were made for several confounders including prior fracture, and use of weak analgesics [nonsteroidal anti‐inflammatory drugs, acetylsalicylic acid (ASA) and acetaminophene]. The effect of dose was examined by stratifying for cumulated dose (defined daily dose).

Main outcome measure.  Fracture.

Results.  Morphine (1.47, 95% CI 1.37–1.58), fentanyl (2.23, 95% CI 1.89–2.64), methadone (1.39, 95% CI 1.05–1.83), oxycodone (1.36, 95% CI 1.08–1.69), nicomorphine (1.57, 95% CI 1.38–1.78), ketobemidone (1.07, 95% CI 1.02–1.13), tramadol (1.54, 95% CI 1.49–1.58) and codeine (1.16, 95% CI 1.12–1.20) were all associated with an increase in overall fracture risk. No increase was present for buprenorphine (0.86, 95% CI 0.79–0.95), pethidine (0.98, 95% CI 0.89–1.08), dextropropoxiphene (1.02, 95% CI 0.90–1.16), and combinations of ASA and codeine (0.94, 95% CI 0.88–1.01).

Conclusions.  An increased fracture risk is seen in users of morphine and opiates. The reason for this may be related to the risk of falls due to central nervous system effects such as dizziness.
Use of a marker plasmid to examine differential rates of growth and death between clinical and environmental strains of Vibrio vulnificus in experimentally infected mice
Authors: Starks Angela M. , Bourdage Keri L. , Thiaville Patrick C. , Gulig Paul A.
Published: June 2006

Vibrio vulnificus is Gram‐negative bacterium that contaminates oysters, causing highly lethal sepsis after consumption of raw oysters and wound infection. We previously described two sets of V. vulnificus strains with different levels of virulence in subcutaneously inoculated iron dextran‐treated mice. Both virulent, clinical strains and attenuated, environmental strains could be recovered in high numbers from skin lesions and livers; however, the attenuated environmental strains required significantly higher numbers of colony‐forming units (cfu) in the inoculum to produce lethal infection. Using some of these strains and an additional clinical strain, we presently asked if the different abilities to cause infection between the clinical and environmental strains were due to differences in rates of growth or death of the bacteria in the mouse host. We therefore constructed a marker plasmid, pGTR902, that functions as a replicon only in the presence of arabinose, which is not present in significant levels in animal tissues. V. vulnificus strains containing pGTR902 were inoculated into iron dextran‐treated and untreated mice. Measuring the proportion of bacteria that had maintained the marker plasmid recovered from mice enabled us to monitor the number of in vivo divisions, hence growth rate; whereas measuring the number of marker plasmid‐containing bacteria recovered enabled the measurement of death of the vibrios in the mice. The numbers of bacterial divisions in vivo for all of the strains over a 12–15 h infection period were not significantly different in iron dextran‐treated mice; however, the rate of death of one environmental strain was significantly higher compared with the clinical strains. Infection of non‐iron dextran‐treated mice with clinical strains demonstrated that the greatest effect of iron dextran‐treatment was increased growth rate, while one clinical strain also experienced increased death in untreated mice. V. vulnificus inoculated into iron dextran‐treated mice replicated extremely rapidly over the first 4 h of infection with doubling times of approximately 15–28 min. In contrast, one of the environmental strains exhibited a reduced early growth rate. These results demonstrate that differences in virulence among naturally occurring V. vulnificus can be explained by diverse abilities to replicate rapidly in or resist defences of the host. The marker plasmid pGTR902 should be useful for examining virulence of bacteria in terms of differentiating growth verses death in animal hosts for most Gram‐negative bacteria.
RA domain‐mediated interaction of Cdc35 with Ras1 is essential for increasing cellular cAMP level for Candida albicans hyphal development
Authors: Fang Hao‐Ming , Wang Yue
Published: June 2006

Many Ras GTPases activate their effectors through binding at a conserved Ras association (RA) domain. An example is the activation of the budding yeast adenylate cyclase Cyr1 by Ras1 and Ras2. Candida albicans Ras1 is speculated to similarly activate Cdc35, the orthologue of Cyr1, for hyphal development. Here, we have investigated whether the RA domain mediates Ras1–Cdc35 interaction and how this interaction regulates cAMP levels and morphogenesis. Yeast two‐hybrid assays suggested that Ras1 interacts only with the RA but not any other identifiable domains of Cdc35. The Ras1–RA interaction was further confirmed by in vitro binding assays of purified RA domain and Ras1 and by co‐immunoprecipitation of Ras1 and Cdc35 from cell lysates. Substituting Ala for the conserved residue K338 or L349 in the RA domain or deleting the RA domain abolished the Ras1–RA or Ras1–Cdc35 interactions. cdc35 mutants with the RA domain deleted or carrying K388A or L349A mutation exhibited rather normal yeast growth but were completely defective in hyphal morphogenesis. Further, the mutants contained nearly wild‐type levels of cAMP during yeast growth but were unable to increase it upon hyphal induction. These results suggest an essential role for the RA‐mediated Ras1–Cdc35 interaction in raising cellular cAMP levels for hyphal morphogenesis.
Promiscuity in multidrug recognition and transport:  the bacterial MFS Mdr transporters
Authors: Lewinson Oded , Adler Julia , Sigal Nadejda , Bibi Eitan
Published: June 2006

Multidrug (Mdr) transport is an obstacle to the successful treatment of cancer and infectious diseases, and it is mediated by Mdr transporters that recognize and export an unusually broad spectrum of chemically dissimilar toxic compounds. Therefore, in addition to its clinical significance, the Mdr transport phenomenon presents intriguing and challenging mechanistic queries. Recent studies of secondary Mdr transporters of the major facilitator superfamily (MFS) have revealed that they are promiscuous not only regarding their substrate recognition profile, but also with respect to matters of energy utilization, electrical and chemical flexibility in the Mdr recognition pocket, and surprisingly, also in their physiological functions.
The atypical amino‐terminal LPNTG‐containing domain of the pneumococcal human IgA1‐specific protease is required for proper enzyme localization and function
Authors: Bender Matthew H. , Weiser Jeffrey N.
Published: June 2006

Streptococcus pneumoniae produces a zinc metalloproteinase, Iga, which cleaves human immunoglobulin A1 (IgA1), and whose activity is predominantly localized to the bacterial surface. However, proper surface localization is not predicted using current models, as the LPNTG sorting motif is located atypically near the amino‐ rather than the carboxy‐terminus. The cell‐associated form of Iga was confirmed to be external to the bacterial membrane, and while bound tightly, its attachment to the cell wall is non‐covalent, but dependent on both a complete LPNTG sequence and sortase activity. Disruption of the region between the signal peptidase cleavage site and the LPNTG domain resulted in a localization defect, premature degradation, and an alteration of the ability of the enzyme to act on a monoclonal human IgA1 substrate and to enhance bacterial adherence, linking localization to enzyme function. Edman sequencing of cell‐associated Iga determined that the enzyme is processed at an unexpected site downstream of the sorting signal yet still associates with the bacterial surface. Our results indicate a non‐covalent re‐association between the carboxy‐terminal enzymatic domain and the cleaved, sorted amino‐terminal localization domain. This amino‐terminal motif is shared among the other zinc metalloproteinases in streptococci and suggests a novel conserved mechanism for the surface localization of protease activity.
The Zn(II)2Cys6 putative transcription factor NosA controls fruiting body formation in Aspergillus nidulans
Authors: Vienken Kay , Fischer Reinhard
Published: June 2006

The filamentous fungus Aspergillus nidulans reproduces asexually with conidiospores and sexually with ascospores, both of which are the result of complex morphogenetic pathways. The developmental decisions for both ways of reproduction largely depend on the action of stage‐specific transcription factors. Here we have characterized the putative Zn(II)2Cys6 transcription factor NosA (number of sexual spores), a protein of 675 aa, which shares 44% sequence identity to Pro1 from Sordaria macrospora and 43% identity to A. nidulans RosA, a second protein of that class. The nosA gene was constitutively expressed during the life cycle of A. nidulans and was upregulated during late asexual development and upon carbon starvation. The NosA protein localized to nuclei. Both, NosA and RosA, regulate sexual development. Whereas RosA plays a role in early decisions and represses sexual development, NosA activity is required for primordium maturation. Interestingly, the two factors are genetically linked, because RosA repressed NosA expression. This illustrates that the balance of these two Zn(II)2Cys6 proteins determines the fate of vegetative hyphae to undergo sexual development.
Acetyl phosphate‐sensitive regulation of flagellar biogenesis and capsular biosynthesis depends on the Rcs phosphorelay
Authors: Fredericks Christine E. , Shibata Satoshi , Aizawa Shin‐Ichi , Reimann Sylvia A. , Wolfe Alan J.
Published: June 2006

As part of our attempt to map the impact of acetyl phosphate (acetyl∼P) on the entire network of two‐component signal transduction pathways in Escherichia coli, we asked whether the influence of acetyl∼P on capsular biosynthesis and flagellar biogenesis depends on the Rcs phosphorelay. To do so, we performed a series of epistasis experiments: mutations in the components of the pathway that controls acetyl∼P levels were combined with mutations in components of the Rcs phosphorelay. Cells that did not synthesize acetyl∼P produced no capsule under normally permissive conditions, while those that accumulated acetyl∼P synthesized capsule under conditions previously considered to be non‐permissive. Acetyl∼P‐dependent capsular biosynthesis required both RcsB and RcsA, while the lack of RcsC restored capsular biosynthesis to acetyl∼P‐deficient cells. Similarly, acetyl∼P‐sensitive repression of flagellar biogenesis was suppressed by the loss of RcsB (but not of RcsA), while it was enhanced by the lack of RcsC. Taken together, these results show that both acetyl∼P‐sensitive activation of capsular biosynthesis and acetyl∼P‐sensitive repression of flagellar biogenesis require the Rcs phosphorelay. Moreover, they provide strong genetic support for the hypothesis that RcsC can function as either a kinase or a phosphatase dependent on environmental conditions. Finally, we learned that RcsB and RcsC inversely regulated the timing of flagellar biogenesis: rcsB mutants elaborated flagella prematurely, while rcsC mutants delayed their display of flagella. Temporal control of flagella biogenesis implicates the Rcs phosphorelay (and, by extension, acetyl∼P) in the transition of motile, planktonic individuals into sessile biofilm communities.
Aragonite cycles: diagenesis caught in the act
Authors: REUNING LARS , REIJMER JOHN J.G. , MATTIOLI EMANUELA
Published: June 2006

Organic biomarker and nannofossil assemblages are used in combination with sedimentary petrology to identify the role of diagenesis for the formation of a rhythmic calcareous succession. A record from the Early Pliocene of the Maldives (Ocean Drilling Program, ODP Leg 115) is presented containing precession and eccentricity cycles expressed as variable aragonite content. Additional sub‐Milankovitch cycles are caused by rhythmic precipitation of calcite cement in the lower part of the interval. Comparison with palaeo‐productivity indicators (nannofossils, chlorin, total organic carbon) suggests that cementation occurs preferentially in intervals characterized by increasing or decreasing productivity. The coupled variability in productivity and carbonate diagenesis is attributed to the effect of organic matter degradation in the sediment. The observed combination of primary and diagenetic factors hampers the interpretation of the cyclicity on Milankovitch and sub‐Milankovitch scales. Diagenetically stable proxies for palaeo‐productivity, such as nannofossil assemblage data, were used to distinguish between palaeoclimate and diagenetic influences.
Rapid increase in cuckoo egg matching in a recently parasitized reed warbler population
Authors: Avilés J. M. , Stokke B. G. , Moksnes A. , Røskaft E. , Åsmul M. , Møller A. P.
Published: June 2006

Parasitic cuckoos lay eggs that mimic those of their hosts, and such close phenotypic matching may arise from coevolutionary interactions between parasite and host. However, cuckoos may also explicitly choose hosts in a way that increases degree of matching between eggs of cuckoos and parasites, with female preference for specific host phenotypes increasing the degree of matching. We tested for temporal change in degree of matching between eggs of the parasitic European cuckoo (Cuculus canorus) and its reed warbler (Acrocephalus scirpaceus) host during 24 consecutive years in a recently parasitized reed warbler population. Cuckoo–host egg matching in an ultraviolet-brownness component yielding most of the chromatic variance of eggs improved during the study period. Improved matching was not due to changes in cuckoo egg phenotype. Cuckoo eggs matched host eggs for ultraviolet-brownness within nests irrespective of duration of sympatry. Ultraviolet-brownness of cuckoo eggs was similar to that of reed warbler eggs at parasitized nests, but differed from that of reed warbler eggs at unparasitized nests. These findings provide tentative support for the cuckoo preference hypothesis suggesting that cuckoo-host egg matching could partially be due to cuckoo females selecting host nests based on the appearance of their eggs.
Phenotypic plasticity in two marine snails: constraints superseding life history
Authors: Hollander J. , Collyer M. L. , Adams D. C. , Johannesson K.
Published: June 2006

In organisms encountering predictable environments, fixed development is expected, whereas in organisms that cannot predict their future environment, phenotypic plasticity would be optimal to increase local adaptation. To test this prediction we experimentally compared phenotypic plasticity in two rocky-shore snail species; Littorina saxatilis releasing miniature snails on the shore, and Littorina littorea releasing drifting larvae settling on various shores, expecting L. littorea to show more phenotypic plasticity than L. saxatilis. We compared magnitude and direction of vectors of phenotypic difference in juvenile shell traits after 3 months exposure to different stimuli simulating sheltered and crab-rich shores, or wave-exposed and crab-free shores. Both species showed similar direction and magnitude of vectors of phenotypic difference with minor differences only between ecotypes of the nondispersing species, indicating that plasticity is an evolving trait in L. saxatilis. The lack of a strong plastic response in L. littorea might be explained by limits rather than costs to plasticity.
Ultrastructural Morphometry of Mammary Gland in Transgenic and Non‐transgenic Rabbits
Authors: Dragin S. , Pivko J. , Massanyi P. , Lukac N. , Makarevich A. V. , Paleyanda R. K. , Chrenek P.
Published: June 2006

The mammary gland of transgenic animals has been used for the production of recombinant proteins of therapeutic and nutraceutical use. The objective of this study was to compare the ultrastructure of transgenic and non‐transgenic rabbit mammary gland tissue. New Zealand White transgenic rabbits were obtained by breeding non‐transgenic rabbits with transgenic founder rabbits containing a whey acidic protein‐human factor VIII (WAP‐hFVIII) transgene integrated into their genome. Samples of mammary gland tissue from lactating rabbit females were isolated by surgical procedures. These samples were examined by optical and electron microscopy and photographs were taken. Measurements of ultrastructural organelles were made from digital images of the mammary cells. No differences were found in the cellular structure of mammary tissue, but significant differences t(0.001) in the relative volume of mitochondria and vacuoles between transgenic and non‐transgenic mammary gland epithelium were observed.
Morphometrical Characteristics of Age‐Associated Changes in the Thymus of Old Male Wistar Rats
Authors: Plećaš‐Solarović B. , Pešić V. , Radojević K. , Leposavić G.
Published: June 2006

In order to provide a morphometrical description of the changes in the aged rat thymus and to relate them to apoptotic and proliferative activity of thymocytes, the thymuses from 3‐ and 18‐month‐old male Wistar rats and the percentages of bromodeoxyuridine‐incorporating and apoptotic cells in cultures of thymocytes were assessed by stereological analysis and flow cytometry, respectively. In old rats the volume of lymphoepithelial thymic tissue is markedly reduced, reflecting a sharp decrease in the total number of thymocytes. A reduction in the proliferative capacity of thymocytes and increase in their susceptibility to apoptosis are, most likely, primarily responsible for a 7‐fold reduction in thymic cellularity in old animals. Furthermore, only the volume of cortical compartment was affected by aging, while that of medulla, despite of reduced cellularity, was not significantly altered. The loss of functional tissue in aged thymus is compensated by a substantial increase in the volume of inter‐lobular connective and adipose tissue, so the thymic weight remained unaltered in old rats. These results suggest that thymus of aged Wistar rats exhibits morphological characteristics similar to those found in aged human thymus and thus may serve as an animal model for further investigations of thymus‐related changes in immunological aging.
Social Context Influences the Antipredator Behaviour of Fathead Minnows to Chemical Alarm Cues
Authors: Pollock M. S. , Pollock R. J. , Chivers D. P.
Published: June 2006

Prey fishes, like many organisms under fluctuating predation threat, rely on multiple sources of information to accurately gauge current risk. This includes the use of chemical cues such as alarm cues from damaged conspecifics or familiar heterospecifics, as well as the odour of known predators. While each fish is well equipped with its own array of sensory abilities, they should also be alert to the behaviours of nearby neighbours who may have information they lack. In the present study, we tested the ability of fathead minnows to use social cues in combination with the odour of damaged conspecifics and heterospecifics to mediate the assessment of predation risk. Specifically, we tested whether the presence of a shoal of conspecifics or familiar heterospecifics would significantly change a minnow's antipredator behaviour when exposed to the odour of a damage‐release cue from a conspecific or ecologically similar heterospecific. The results of our study showed a significant interaction between the damage‐release cues to which the minnows were exposed and the presence/absence of shoalmates. These findings have important implications for the design of future investigations of antipredator responses because most studies of group‐living prey have been conducted on solitary subjects.
Exact Linearization and Invariant Solutions of the Generalized Burgers Equation with Linear Damping and Variable Viscosity
Authors: Vaganan B. Mayil , Kumaran M. Senthil
Published: June 2006

The generalized Burgers equation with linear damping and variable viscosity is subjected to Lie's classical method. Five distinct expressions for the variable viscosity are identified. Both the reduced ordinary differential equations and their corresponding Euler‐Painlevé transcendents admit first integrals in the form of Bernoulli's equation and are linearized to obtain solutions in closed form.
MODEL UNCERTAINTY AND ITS IMPACT ON THE PRICING OF DERIVATIVE INSTRUMENTS
Authors: Cont Rama
Published: June 2006

Uncertainty on the choice of an option pricing model can lead to “model risk” in the valuation of portfolios of options. After discussing some properties which a quantitative measure of model uncertainty should verify in order to be useful and relevant in the context of risk management of derivative instruments, we introduce a quantitative framework for measuring model uncertainty in the context of derivative pricing. Two methods are proposed: the first method is based on a coherent risk measure compatible with market prices of derivatives, while the second method is based on a convex risk measure. Our measures of model risk lead to a premium for model uncertainty which is comparable to other risk measures and compatible with observations of market prices of a set of benchmark derivatives. Finally, we discuss some implications for the management of “model risk.”
NO ARBITRAGE UNDER TRANSACTION COSTS, WITH FRACTIONAL BROWNIAN MOTION AND BEYOND
Authors: Guasoni Paolo
Published: June 2006

We establish a simple no‐arbitrage criterion that reduces the absence of arbitrage opportunities under proportional transaction costs to the condition that the asset price process may move arbitrarily little over arbitrarily large time intervals.

We show that this criterion is satisfied when the return process is either a strong Markov process with regular points, or a continuous process with full support on the space of continuous functions. In particular, we prove that proportional transaction costs of any positive size eliminate arbitrage opportunities from geometric fractional Brownian motion for H∈ (0, 1) and with an arbitrary continuous deterministic drift.
The Effects of Employment Protection for Obese People
Authors: CARPENTER CHRISTOPHER S.
Published: June 2006

This paper uses a 1993 court case, Cook v. Rhode Island, in conjunction with the implementation of the Americans with Disabilities Act (ADA) to estimate the impact of employment protection on the labor market outcomes of obese people. In Cook, a federal appeals court ruled for the first time that obesity can be covered under the ADA. Using data from 1988 to 1999, I estimate that Cook increased employment for obese women and men relative to those whose weight was in the recommended range on the order of four and two percentage points, respectively. The results provide new evidence that obesity has important labor market implications.
Changing Regimes of Workplace Governance, Shifting Axes of Social Mobilization, and the Challenge to Industrial Relations Theory
Authors: PIORE MICHAEL J. , SAFFORD SEAN
Published: June 2006

This article challenges prevailing views about the collapse of the New Deal industrial relations system and the role of the market. It argues that the old system has been replaced not by the market but by an employment rights regime, in which the rules of the workplace are imposed by law, judicial opinions, and administrative rulings, supplemented by mechanisms at the enterprise level that are responsive to the law but also are susceptible to employee pressures, both individual and collective. The emergence of this regime is the product of a shift in the axes of social and political mobilization from mobilization around economic identities rooted in class, industry, occupation, and enterprise to identities rooted in the society outside the workplace: sex, race, ethnicity, age, disability, and sexual orientation. The shift in the axes of mobilization in turn reflects the collapse of the underlying model of social and economic organization upon which the collective bargaining regime was built and more fundamentally a shift in our understanding of the nature of industrial society and its direction of evolution in history. This interpretation poses a challenge to the conceptual tools used in industrial relations to understand the issues of work and to frame the public policy debate. We conclude with some suggestions as to the direction in which we might move to provide an alternative conceptual framework.
Influence of income and capital on reproduction in a viviparous snake: direct and indirect effects
Authors: Gregory P. T.
Published: June 2006

A central issue in life‐history studies is the extent to which organisms are ‘capital’ versus ‘income’ breeders (i.e. using stored resources vs. current food intake). Snakes are primarily capital breeders, but income during vitellogenesis can also contribute to reproductive output. In Manitoba, the garter snake Thamnophis sirtalis has a short active season, with mating occurring upon emergence from hibernation and vitellogenesis shortly thereafter. Given the brevity of this sequence, animals in these populations should be almost exclusively capital breeders. Consistent with this prediction, in this experiment the reproductive output of recently mated snakes was influenced by mass of the mother at the time of mating but not by her food intake shortly after mating. Food eaten during pregnancy contributed significantly to postpartum mass but not to litter mass. However, the initial mass of snakes influenced both postpartum and litter mass. For snakes given a high ration of food, a female's relative mass (i.e. adjusted for body length) significantly influenced the actual amount she consumed (relatively lighter snakes ate more). Perhaps most important, among pregnant snakes, those that were initially relatively heavier gave birth substantially and significantly earlier. Thus, snakes that are relatively heavy when they mate may gain further fitness benefits following pregnancy (e.g. more time to acquire resources and for offspring to grow before winter), which can also be interpreted as indirect effects on reproduction. These life‐history variations may be relevant to population dynamics.
Personality traits in early phases of panic disorder: implications on the presence of agoraphobia, clinical severity and short‐term outcome
Authors: Carrera M. , Herrán A. , Ramírez M. L. , Ayestarán A. , Sierra‐Biddle D. , Hoyuela F. , Rodríguez‐Cabo B. , Vázquez‐Barquero J. L.
Published: June 2006

Objective:  To explore the relations between personality traits using the Big Five model and presence of agoraphobia, clinical severity and short‐term outcome in an unbiased clinical sample of never‐treated panic disorder patients.

Method:  Panic disorder (PD) patients (n = 103) in the first stages of their illness were evaluated using the Neuroticism‐Extraversion‐Openness Five Factor Inventory of Personality (NEO‐FFI) and were compared with a sample of healthy subjects. Severity was assessed by the Panic Disorder Severity Scale and the Clinical Global Impression Scales. Patients were evaluated after 8 weeks of naturalistic pharmacologic treatment with Selective Serotonin Reuptake Inhibitors.

Results:  Panic disorder patients show more neuroticism than healthy subjects. Patients suffering from agoraphobia are more introverted than controls. Extraversion, in addition to gender and distress, during panic attacks allows to correctly classifying 72% of the cases of agoraphobia.

Conclusion:  Low scores in extraversion contribute to explain the presence of agoraphobia in panic disorder. Personality traits are neither related to clinical severity nor to short‐term response to pharmacological treatment.
Trapezius activity and intramuscular balance during isokinetic exercise in overhead athletes with impingement symptoms
Authors: Cools A. M. , Declercq G. A. , Cambier D. C. , Mahieu N. N. , Witvrouw E. E.
Published: June 2006

We compared normalized trapezius muscle activity and intramuscular balance ratios between overhead athletes with impingement symptoms and non‐injured athletes during isokinetic abduction and external rotation movements. Thirty‐nine overhead athletes with chronic impingement symptoms and 30 non‐injured athletes participated in the study. Electromyographic activity of upper, middle, and lower trapezius was measured during isokinetic abduction and external rotation, using surface electrodes. The results show a significant increase of upper trapezius activity during both movements in the patient group, with decreased activity in the lower trapezius during abduction, and in the middle trapezius during external rotation. Analysis of the intramuscular activity ratios revealed muscle imbalance on the injured side of the patient group for upper/middle trapezius and upper/lower trapezius during abduction, and for all three muscle activity ratios during external rotation. These results confirm the presence of scapular muscle imbalances in patients with impingement symptoms and emphasize the relevance of restoration of scapular muscle balance in shoulder rehabilitation.
Early Complete Failures of Fixed Implant‐Supported Prostheses in the Edentulous Maxilla: A 3‐Year Analysis of 17 Consecutive Cluster Failure Patients
Authors: Jemt Torsten , Häger Per
Published: June 2006

Background  Clusters of implant failures in the edentulous maxilla seem to occur in some patients. To create groups for analysis with higher numbers of these patients implies large original groups for inclusion.

Purpose  The aim of this study was to retrospectively describe and compare a group of “cluster failure patients” with randomly selected patients treated in the edentulous maxilla.

Materials and Methods  From a group of 1,267 consecutively treated patients in one clinic, all patients presenting failing fixed implant‐supported prostheses within the first 3 years of follow‐up were included. All patients were treated with turned titanium implants using two‐stage surgery. A control group of equal number of patients were created for comparison. Data on patients were retrospectively retrieved from their records, and compared.

Results  Seventeen patients (1.3%) met the inclusion criteria in the entire group. The bone resorption index revealed less bone quantity in the study group (p < .05) during implant placement, but there was no difference regarding primary implant stability at first‐stage surgery. The distribution of short and long implants showed relatively higher number of short implants in the study group (p < .05), and more patients had a presurgical discussion on the risk of implant failure prior to treatment in this group (p < .05). Only 5 out of 102 implants (4.9%) were lost before prosthesis placement as compared to 38 and 25 lost implants during the following two years in the study group. Smoking habits and signs of bone loss related to periodontitis in the lower dentition were more frequent in the study group, but did not reach a significant level (p > .05).

Conclusion  The results indicate that bone quantity, reflected in fixture length, has a significant impact on increased implant failure risk. Other factors of interest as predictors for implant failures could be smoking habits and also possibly signs of periodontitis in the opposing dentition.
Analysis of oxidative events induced by expanded polyglutamine huntingtin exon 1 that are differentially restored by expression of heat shock proteins or treatment with an antioxidant
Authors: Firdaus Wance J. J. , Wyttenbach Andreas , Diaz‐Latoud Chantal , Currie R. W. , Arrigo André‐Patrick
Published: June 2006

We recently reported that the transient expression of polyglutamine tracts of various size in exon 1 of the huntingtin polypeptide (httEx1) generated abnormally high levels of intracellular reactive oxygen species that directly contributed to cell death. Here, we compared the protection generated by heat shock proteins to that provided by the antioxidant agent N‐acetyl‐l‐cysteine. In cells expressing httEx1 with 72 glutamine repeats (httEx1‐72Q), the overexpression of Hsp27 or Hsp70 plus Hdj‐1(Hsp40) or treatment of the cells with N‐acetyl‐l‐cysteine inhibited not only mitochondrial membrane potential disruption but also the increase in reactive oxygen species, nitric oxide and protein oxidation. However, only heat shock proteins and not N‐acetyl‐l‐cysteine reduced the size of the inclusion bodies formed by httEx1‐72Q. In cells expressing httEx1 polypeptide with 103 glutamine repeats (httEx1‐103Q), heat shock proteins neither decreased oxidative damage nor reduced the size of the inclusions. In contrast, N‐acetyl‐l‐cysteine still efficiently decreased the oxidative damage induced by httEx1‐103Q polypeptide without altering the inclusions. N‐Acetyl‐l‐cysteine was inactive with regard to proteasome inhibition, whereas heat shock proteins partially restored the caspase‐like activity of this protease. These observations suggest some relationships between the presence of inclusion bodies and the oxidative damage induced by httEx1‐polyQ.
Structure/function analysis of spinalin, a spine protein of Hydra nematocysts
Authors: Hellstern Simon , Stetefeld Jörg , Fauser Charlotte , Lustig Ariel , Engel Jürgen , Holstein Thomas W. , Özbek Suat
Published: June 2006

The nematocyst capsules of the cnidarians are specialized explosive organelles that withstand high osmotic pressures of ≈ 15 MPa (150 bar). A tight disulfide network involving cysteine‐rich capsule wall proteins, like minicollagens and nematocyst outer wall antigen, characterizes their molecular composition. Nematocyst discharge leads to the expulsion of a long inverted tubule that was coiled inside the capsule matrix before activation. Spinalin has been characterized as a glycine‐rich, histidine‐rich protein associated with spine structures on the surface of everted tubules. Here, we show that full‐length Hydra spinalin can be expressed recombinantly in HEK293 cells and has the property to form disulfide‐linked oligomers, reflecting its state in mature capsules. Furthermore, spinalin showed a high tendency to associate into dimers in vitro and in vivo. Our data, which show incomplete disulfide connectivity in recombinant spinalin, suggest a possible mechanism by which the spine structure may be linked to the overall capsule polymer.
INFORMATION TECHNOLOGY, PRODUCTIVITY GROWTH, AND REDUCED LEISURE: REVISITING “END OF HISTORY”
Authors: Banerjee Debdas
Published: June 2006

The highly productive Information and Communications Technology industry has sharply divided the opinions between those who believe that it represents a radical transformation of the capitalist order and those who believe that it is just more of the same. This study draws attention to a critical indicator: The balance of work and leisure in the daily life of a worker that has gradually evolved in the course of capitalist development is now tilting significantly against leisure despite productivity growth. Here, this paradox is explained by the quality composition of knowledge workers as well as—in contrast to what neoliberalism makes us believe—the growing hegemony of business organizations over that of market.
Phytoplasma from little leaf disease affected sweetpotato in Western Australia: detection and phylogeny
Authors: Tairo F. , Jones R.A.C. , Valkonen J.P.T.
Published: June 2006

Symptoms of leaf and stem chlorosis and plant stunting were common in sweetpotato plants (Ipomoea batatas) in farmers’ fields in two widely separated locations, Kununurra and Broome, in the tropical Kimberley region in the state of Western Australia in 2003 and 2004. In the glasshouse, progeny plants developed similar symptoms characteristic of phytoplasma infection, consisting of chlorosis and a stunted, bushy appearance as a result of proliferation of axillary shoots. The same symptoms were reproduced in the African sweetpotato cv. Tanzania grafted with scions from the plant Aus1 with symptoms and in which no viruses were detected. PCR amplification with phytoplasma‐specific primers and sequencing of the 16S‐23S rRNA gene region from two plants with symptoms, Aus1 (Broome) and Aus142A (Kununurra), revealed highly identical sequences. Phylogenetic analysis of the 16S rRNA gene sequences obtained from previously described sweetpotato phytoplasma and inclusion of other selected phytoplasma for comparison indicated that Aus1 and Aus142A belonged to the Candidatus Phytoplasma aurantifolia species (16SrII). The 16S genes of Aus1 and Aus142A were almost identical to those of sweet potato little leaf (SPLL‐V4) phytoplasma from Australia (99.3%–99.4%) but different from those of the sweetpotato phytoplasma from Taiwan (95.5%–95.6%) and Uganda (SPLL‐UG, 90.0%–90.1%). Phylogenetically, Aus1, Aus142A and a phytoplasma previously described from sweetpotato in the Northern Territory of Australia formed a group distinctly different from other isolates within Ca. Phytoplasma aurantifolia species. These findings indicate that novel isolates of the 16SrII‐type phytoplasma pose a potential threat to sustainable sweetpotato production in northern Australia.
Poly‐Detect for Quantifying the Degree of Multidimensionality of Item Response Data
Authors: Yu Feng , Nandakumar Ratna
Published: June 2006

This study investigated the validity of the Poly‐Detect procedure to determine the approximate simple dimensionality structure and to quantify the degree of multidimensionality present in polytomous data through simulation and real data analysis. Both unidimensional and two‐dimensional data were generated in the simulation study for the complete and the BIB data. The simulation results showed that the dimensionality structures were similar between the corresponding complete data and the BIB data as identified by the Poly‐Detect procedure. Also, the simulation results indicated that the number of response categories of items did not affect the performance of the Poly‐Detect procedure in quantifying the degree of multidimensionality of polytomous data. Based on the simulation results, a subjective scale of the degree of multidimensionality of a data set was developed. Application of the Poly‐Detect procedure on the 1992 NAEP eighth‐grade reading data indicated that the degree of multidimensionality of the entire 1992 NAEP eighth‐grade reading item pool was moderate at most.
The Effect of Computer‐Based Tests on Racial‐Ethnic and Gender Groups
Authors: Gallagher Ann , Bridgeman Brent , Cahalan Cara
Published: June 2006

In this study data were examined from several national testing programs to determine whether the change from paper‐based administration to computer‐based tests (CBTs) influences group differences in performance. Performances by gender, racial, and ethnic groups on the Graduate Record Examination General Test, Graduate Management Admissions Test, SAT I: Reasoning Test, and Praxis: Professional Assessment for Beginning Teachers, were analyzed to determine whether the shift in testing format from paper‐and‐pencil tests to CBTs posed a disadvantage to any of these subgroups, beyond that already identified for paper‐based tests. Although all differences were quite small, some consistent patterns were found for some racial‐ethnic and gender groups. African‐American examinees and, to a lesser degree, Hispanic examinees appear to benefit from the CBT format. On some tests, female examinees' performance was relatively lower on the CBT version.
Multivariate Generalizability Analysis of the Impact of Training and Examinee Performance Information on Judgments Made in an Angoff‐Style Standard‐Setting Procedure
Authors: Clauser Brian E. , Swanson David B. , Harik Polina
Published: June 2006

Cut scores, estimated using the Angoff procedure, are routinely used to make high‐stakes classification decisions based on examinee scores. Precision is necessary in estimation of cut scores because of the importance of these decisions. Although much has been written about how these procedures should be implemented, there is relatively little literature providing empirical support for specific approaches to providing training and feedback to standard‐setting judges. This article presents a multivariate generalizability analysis designed to examine the impact of training and feedback on various sources of error in estimation of cut scores for a standard‐setting procedure in which multiple independent groups completed the judgments. The results indicate that after training, there was little improvement in the ability of judges to rank order items by difficulty but there was a substantial improvement in inter‐judge consistency in centering ratings. The results also show a substantial group effect. Consistent with this result, the direction of change for the estimated cut score was shown to be group dependent.
Identification and Evaluation of Local Item Dependencies in the Medical College Admissions Test
Authors: Zenisky April L. , Hambleton Ronald K. , Sired Stephen G.
Published: June 2006

Measurement specialists routinely assume examinee responses to test items are independent of one another. However, previous research has shown that many contemporary tests contain item dependencies and not accounting for these dependencies leads to misleading estimates of item, test, and ability parameters. The goals of the study were (a) to review methods for detecting local item dependence (LID), (b) to discuss the use of testlets to account for LID in context‐dependent item sets, (c) to apply LID detection methods and testlet‐based item calibrations to data from a large‐scale, high‐stakes admissions test, and (d) to evaluate the results with respect to test score reliability and examinee proficiency estimation. Item dependencies were found in the test and these were due to test speededness or context dependence (related to passage structure). Also, the results highlight that steps taken to correct for the presence of LID and obtain less biased reliability estimates may impact on the estimation of examinee proficiency. The practical effects of the presence of LID on passage‐based tests are discussed, as are issues regarding how to calibrate context‐dependent item sets using item response theory.
Can Examinees Use Judgments of Item Difficulty to Improve Proficiency Estimates on Computerized Adaptive Vocabulary Tests?
Authors: Vispoel Walter P. , Clough Sara J. , Bleiler Timothy , Hendrickson Amy B. , Ihrig Damien
Published: June 2006

Recent simulation studies indicate that there are occasions when examinees can use judgments of relative item difficulty to obtain positively biased proficiency estimates on computerized adaptive tests (CATs) that permit item review and answer change. Our purpose in the study reported here was to evaluate examinees' success in using these strategies while taking CATs in a live testing setting. We taught examinees two item difficulty judgment strategies designed to increase proficiency estimates. Examinees who were taught each strategy and examinees who were taught neither strategy were assigned at random to complete vocabulary CATs under conditions in which review was allowed after completing all items and when review was allowed only within successive blocks of items. We found that proficiency estimate changes following review were significantly higher in the regular review conditions than in the strategy conditions. Failure to obtain systematically higher scores in the strategy conditions was due in large part to errors examinees made in judging the relative difficulty of CAT items.
Alternative Missing Data Techniques to Grade Point Average: Imputing Unavailable Grades
Authors: Smits Niels , Mellenbergh Gideon J. , Vorst Harrie C. M.
Published: June 2006

In this article, grade point average (GPA) is considered a missing data technique for unavailable grades in school grade records. In Study 1, theoretical and empirical differences between GPA and seven alternative missing grade techniques were considered. These seven techniques are subject mean substitution, corrected subject mean, subject correlation substitution, regression imputation, expectation maximization algorithm imputation and two multiple imputation methods‐stochastic regression imputation and data augmentation., The missing grade techniques differ greatly. Data augmentation and stochastic regression imputation appear to be superior as missing grade techniques. In Study 2, the completed grade records (observed and imputed values) were used in two prediction analyses of academic achievement. One analysis was based on unweighed grades, the other on weighed grades. In both analyses, alternative missing grade methods produced better and more consistent predictions. It is concluded that some alternative missing grade methods are superior to GPA.
Data Sparseness and On‐Line Pretest Item Calibration‐Scaling Methods in CAT
Authors: Ban Jae‐Chun , Hanson Bradley A. , Yi Qing , Harris Deborah J.
Published: June 2006

The purpose of this study was to compare and evaluate three on‐line pretest item calibration‐scaling methods (the marginal maximum likelihood estimate with one expectation maximization [EM] cycle [OEM] method, the marginal maximum likelihood estimate with multiple EM cycles [MEM] method, and Stocking's Method B) in terms of itern parameter recovery when the item responses to the pretest items in the pool are sparse. Simulations of computerized adaptive tests were used to evaluate the results yielded by the three methods. The MEM method produced the smallest average total error in parameter estimation, and the OEM method yielded the largest total error.