bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture load and marginal fit of shrinkage‐free ZrSiO4 all‐ceramic crowns after chewing simulation
Authors: OKUTAN M. , HEYDECKE G. , BUTZ F. , STRUB J. R.
Published: June 2006

summary  The aim of this in vitro study was to evaluate the fracture load and marginal accuracy of crowns made from a shrinkage‐free ZrSiO4 ceramic cemented with glass–ionomer or composite cement after chewing simulation. Thirty‐two human mandibular molars were randomly divided into two groups. All teeth were prepared for and restored with shrinkage‐free ZrSiO4 ceramic crowns (Everest HPC®, KaVo). The crowns of group A (N = 16) were luted to the teeth using KetacCem® and group B (N = 16) were adhesively cemented using Panavia®21EX. Measurements of the marginal accuracy before and after cementation were made using replicas and an image analysis system. All specimens were exposed to 1·2 million cycles of thermo‐mechanical fatigue in a chewing simulator. Surviving specimens were subsequently loaded until fracture in a static testing device. Fracture loads (N) were recorded. All specimens survived chewing simulation. The mean fracture loads (±s.d.) were Group A, 1622 N (±433); group B, 1957 N (±806). There was no significant difference between the two groups (P > 0·05). The marginal gap values before cementation were (mean ± s.d.): Group A, 32·7 μm (±6·8); group B, 33·0 μm (±6·7).The mean marginal gap values after cementation were (±s.d.): Group A, 44·6 μm (±6·7); group B, 46·6 μm (±7·7). The marginal openings were significantly higher after cementation for both groups (P < 0·05). All test groups demonstrated fracture load and marginal accuracy values within the range of clinical acceptability.
Microsatellites provide insight into contrasting mating patterns in arribada vs. non‐arribada olive ridley sea turtle rookeries
Authors: JENSEN M. P. , ABREU‐GROBOIS F. A. , FRYDENBERG J. , LOESCHCKE V.
Published: June 2006

Molecular studies of sea turtles have shown that the frequency of multiple paternity (MP) varies between species, and between rookeries of the same species. This study uses nuclear microsatellite markers to compare the incidence of MP in two neighbouring olive ridley rookeries on the Pacific coast of Costa Rica, with contrasting nesting behaviours — the ‘arribada’ population nesting at Ostional and the solitary nesters of Playa Hermosa. Using two highly polymorphic microsatellite markers, we tested 13 nests from each location and found a significant difference (P < 0.001) between the level of MP of the arribada rookery (92%— the highest found for marine turtles) and that of the solitary nesting rookery (30%). Additional analyses based on six microsatellite loci revealed no genetic differentiation between nesting females from the two locations, or between nesting females and attendant males from the Ostional breeding area. Sixty‐nine per cent of the nests with MP were fathered by a minimum of three different males, and three nests showed evidence of at least four fathers. The results suggest that the differences observed in levels of MP between arribada and solitary rookeries are due to an effect of abundance of individuals on the mating system. This is supported by a regression analysis combining other paternity studies on sea turtles which shows that levels of MP increase with increasing abundance of nesting females.
Choroid plexus transplants in the treatment of brain diseases
Authors: Skinner Stephen J.M. , Geaney Marilyn S. , Rush Robert , Rogers Mary‐Louise , Emerich Dwaine F. , Thanos Christopher G. , Vasconcellos Alfred V. , Tan Paul L.J. , Elliott Robert B.
Published: June 2006

Abstract:  The choroid plexus (CP) produces and secretes numerous biologically active neurotrophic factors into the cerebrospinal fluid (CSF). These circulate throughout the brain and spinal cord, maintaining neuronal networks and associated cells. In neurodegenerative disease and in acute brain injury there is local up‐regulation of neurotrophin production close to the site of the lesion. Treatment by direct injection of neurotrophins and growth factors close to these lesion sites has repeatedly been demonstrated to improve recovery. It has therefore been proposed that transplanting viable choroid plexus cells close to the lesion might provide a novel means for continuous delivery of these molecules directly to the site of injury. Recent publications describe how transplanted CP, either free or in an immunoprotected encapsulated form, deliver therapeutic molecules to the desired site. This review briefly describes the accumulated evidence that CP cells support neuronal cells in vitro and have therapeutic properties when transplanted to treat acute and chronic brain disease and injury in animal models.
Allosensitized humans are at no greater risk of humoral rejection of GT‐KO pig organs than other humans
Authors: Hara Hidetaka , Ezzelarab Mohamed , Rood Pleunie P. M. , Lin Yih Jyh , Busch Jamie , Ibrahim Zuhaib , Zhu Xiaocheng , Ball Suyapa , Ayares David , Zeevi Adriana , Awwad Michel , Cooper David K. C.
Published: June 2006

Abstract:  Background:  The availability of pigs homozygous for α1,3‐galactosyltransferase gene‐knockout (GT‐KO) has enabled study of the incidence and cytotoxicity of primate antibodies directed to antigens other than Galα1,3Gal (Gal), termed non‐Gal antigens.

Methods:  Sera from 27 healthy humans and 31 patients awaiting renal allotransplantation, who were either unsensitized [panel reactive antibodies (PRA) < 10%] or allosensitized (PRA > 70%), were tested by flow cytometry for binding of immunoglobulin M (IgM) and IgG to peripheral blood mononuclear cells (PBMC) from both wild‐type (WT) and GT‐KO pigs. Complement‐dependent cytotoxicity to WT and GT‐KO PBMC was also measured.

Results:  IgM and IgG from all 27 (100%) healthy human sera bound to WT PBMC, while 78% and 63% of these sera had IgM and IgG that bound to GT‐KO PBMC, respectively. Mean binding to WT PBMC was significantly greater than GT‐KO PBMC. Whereas 100% of sera were cytotoxic to WT PBMC, only 61% were cytotoxic to GT‐KO PBMC, and the extent of lysis was significantly less. Neither mean binding of IgM and IgG nor cytotoxicity of unsensitized and allosensitized sera to WT and GT‐KO PBMC was significantly different to that of healthy sera.

Conclusions:  More than half of the healthy humans tested had cytotoxic antibodies to GT‐KO PBMC, but allosensitized patients will be at no greater risk of rejecting a pig xenograft by a humoral mechanism.
Cope's rule in cryptodiran turtles: do the body sizes of extant species reflect a trend of phyletic size increase?
Authors: Moen D. S.
Published: June 2006

Cope's rule of phyletic size increase is questioned as a general pattern of body size evolution. Most studies of Cope's rule have examined trends in the paleontological record. However, neontological approaches are now possible due to the development of model-based comparative methods, as well as the availability of an abundance of phylogenetic data. I examined whether the phylogenetic distribution of body sizes in extant cryptodiran turtles is consistent with Cope's rule. To do this, I examined body size evolution in each of six major clades of cryptodiran turtles and also across the whole tree of cryptodirans (n = 201 taxa). Extant cryptodiran turtles do not appear to follow Cope's rule, as no clade showed a significant phyletic body size trend. Previous analyses in other extant vertebrates have also found no evidence for phyletic size increase, which is in contrast to the paleontological data that support the rule in a number of extinct vertebrate taxa.
Parasite-mediated selection and the role of sex and diapause in Daphnia
Authors: Duncan A.B. , Mitchell S. E. , Little T.J.
Published: June 2006

To gain insight into parasite-mediated natural selection, we studied a natural population of the crustacean Daphnia magna during a severe epidemic of the bacterial parasite Pasteuria ramosa. We also investigated the relationship between susceptibility and the production of resting eggs, which are only produced during the sexual phase of reproduction. Live host samples were taken before and after this epidemic and resistance to P. ramosa was examined in the laboratory. Host clones collected after the epidemic were more resistant to P. ramosa than were those collected pre-epidemic, which is consistent with parasite-mediated selection. In our study population, asexually reproducing females were observed across the entire study period, but females carrying resting eggs were observed only prior to the epidemic. For hosts isolated in this pre-epidemic period, we found evidence that those carrying resting eggs (at the time of collection) were more susceptible than those that were reproducing asexually. This was especially apparent for measures of parasite growth, although not all measures of infection success conclusively supported this pattern. Nevertheless, the data suggest that some genotypes invest heavily in diapause at the expense of immunocompetence. Sex could therefore inhibit the evolution of resistance because each spring new genotypes will hatch from resting eggs that are relatively susceptible as they were not exposed to the previous years bout of parasite-mediated selection.
Do operational sex ratios influence sex allocation in viviparous lizards with temperature-dependent sex determination?
Authors: Allsop D. J. , Warner D. A. , Langkilde T. , Du W. , Shine R.
Published: June 2006

Under certain environmental situations, selection may favour the ability of females to adjust the sex ratio of their offspring. Two recent studies have suggested that viviparous scincid lizards can modify the sex ratio of the offspring they produce in response to the operational sex ratio (OSR). Both of the species in question belong to genera that have also recently been shown to exhibit temperature-dependent sex determination (TSD). Here we test whether pregnant montane water skinks (Eulamprus tympanum) utilise TSD to select offspring sex in response to population wide imbalances in the OSR, by means of active thermoregulation. We use a combination of laboratory and field-based experiments, and conduct the first field-based test of this hypothesis by maintaining females in outdoor enclosures of varying OSR treatments throughout pregnancy. Although maternal body temperature during pregnancy was influenced by OSR, the variation in temperature was not great enough to affect litter sex ratios or any other phenotypic traits of the offspring.
Imbalanced genomic imprinting in brain development: an evolutionary basis for the aetiology of autism
Authors: Badcock C. , Crespi B.
Published: June 2006

We describe a new hypothesis for the development of autism, that it is driven by imbalances in brain development involving enhanced effects of paternally expressed imprinted genes, deficits of effects from maternally expressed genes, or both. This hypothesis is supported by: (1) the strong genomic-imprinting component to the genetic and developmental mechanisms of autism, Angelman syndrome, Rett syndrome and Turner syndrome; (2) the core behavioural features of autism, such as self-focused behaviour, altered social interactions and language, and enhanced spatial and mechanistic cognition and abilities, and (3) the degree to which relevant brain functions and structures are altered in autism and related disorders. The imprinted brain theory of autism has important implications for understanding the genetic, epigenetic, neurological and cognitive bases of autism, as ultimately due to imbalances in the outcomes of intragenomic conflict between effects of maternally vs. paternally expressed genes.
Selection on body size and sexual size dimorphism differs between host species in a seed-feeding beetle
Authors: Fox C. W. , Czesak M. E.
Published: June 2006

Sexual size dimorphism varies substantially among populations and species but we have little understanding of the sources of selection generating this variation. We used path analysis to study how oviposition host affects selection on body size in a seed-feeding beetle (Stator limbatus) in which males contribute large ejaculates (nuptial gifts) to females. Females use nutrients in these ejaculates for egg production. Male body size, which affects ejaculate size, affects female fecundity and is thus under fecundity selection similar in magnitude to the fecundity selection on female body size. We show that when eggs are laid on a host on which larval mortality is low (seeds of Acacia greggii) fecundity predicts fitness very well and fecundity selection is the major source of selection on both male and female adult size. In contrast, when eggs are laid on a host on which larval mortality is high (seeds of Parkinsonia florida) fecundity poorly predicts fitness such that fecundity selection is relaxed on both male and female size. However, because egg size affects larval mortality on this poor host (P. florida) there is selection on female size via the female size → egg size → fitness path; this selection via egg size offsets the reduction in fecundity selection on female, but not male, body size. Thus, differences in host suitability (due to differences in larval mortality) affect the relative importance of two sources of selection on adult body size; fecundity selection on both male and female body size is lower on the poor quality host (P. florida) relative to the high quality host (A. greggii) whereas selection on female body size via effects of egg size on offspring survival (body size → egg size → fitness) is greater on the poor quality host relative to the high quality host. Because selection via the egg size path affects only females the difference in larval survival between hosts shifts the relative magnitude of selection on female vs. male size. Researchers working on other study systems should be alerted to the possible importance of subtle, but consequential, indirect selection on their study organisms.
Fitness effects of X chromosome drive in the stalk-eyed fly, Cyrtodiopsis dalmanni
Authors: Wilkinson G. S. , Johns P. M. , Kelleher E. S. , Muscedere M. L. , Lorsong A.
Published: June 2006

Sex-ratio (SR) males produce predominantly female progeny because most Y chromosome sperm are rendered nonfunctional. The resulting transmission advantage of XSR chromosomes should eventually cause population extinction unless segregation distortion is masked by suppressors or balanced by selection. By screening male stalk-eyed flies, Cyrtodiopsis dalmanni, for brood sex ratio we found unique SR alleles at three X-linked microsatellite loci and used them to determine if SR persists as a balanced polymorphism. We found that XSR/XST females produced more offspring than other genotypes and that SR males had lower sperm precedence and exhibited lower fertility when mating eight females in 24 h. Adult survival was independent of SR genotype but positively correlated with eye span. We infer that the SR polymorphism is likely maintained by a combination of weak overdominance for female fecundity and frequency dependent selection acting on male fertility. Our discovery of two SR haplotypes in the same population in a 10-year period further suggests that this SR polymorphism may be evolving rapidly.
Postzygotic incompatibilities between the pupfishes,Cyprinodon elegansandCyprinodon variegatus
Authors: Tech C.
Published: June 2006

I examined the intrinsic postzygotic incompatibilities between two pupfishes, Cyprinodon elegans and Cyprinodon variegatus. Laboratory hybridization experiments revealed evidence of strong postzygotic isolation. Male hybrids have very low fertility, and the survival of backcrosses into C. elegans was substantially reduced. In addition, several crosses produced female-biased sex ratios. Crosses involving C. elegans females and C. variegatus males produced only females, and in backcrosses involving hybrid females and C. elegans males, males made up approximately 25% of the offspring. All other crosses produced approximately 50% males. These sex ratios could be explained by genetic incompatibilities that occur, at least in part, on sex chromosomes. Thus, these results provide strong albeit indirect evidence that pupfish have XY chromosomal sex determination. The results of this study provide insight on the evolution of reproductive isolating mechanisms, particularly the role of Haldane's rule and the ‘faster-male’ theory in taxa lacking well-differentiated sex chromosomes.
Projection of the Grüneberg ganglion to the mouse olfactory bulb
Authors: Roppolo Daniele , Ribaud Virginie , Jungo Véronique Pauli , Lüscher Christian , Rodriguez Ivan
Published: June 2006

In mammals, sensory neurons from the main olfactory and vomeronasal systems project their axons to the olfactory bulbs in the brain. We here report that a cluster of neurons, distinct from these two systems, located at the very tip of the mouse nose and called the Grüneberg ganglion expresses the mature olfactory‐sensory neuron‐specific marker olfactory marker protein (OMP), but is unlikely to express known odorant or pheromone receptors. The ganglion is present at birth and maintained during adult life. Tracing experiments indicate that these neurons target ipsilaterally to a specific set of glomeruli located on the caudal part of the olfactory bulb, and that this connection is necessary for the survival of the ganglion. The glomerular targets are structures previously proposed to be associated with suckling behaviour. These observations strongly suggest that this peculiar olfactory neuronal population plays a sensory role, possibly linked to chemoperception.
Contribution of the corpus callosum to bilateral representation of the trunk midline in the human brain: an fMRI study of callosotomized patients
Authors: Fabri M. , Polonara G. , Mascioli G. , Paggi A. , Salvolini U. , Manzoni T.
Published: June 2006

Human brain studies have shown that the cutaneous receptors of trunk regions close to the midline are represented in the first somatosensory cortex (SI) of both hemispheres. The present study aims to establish whether in humans, as in non‐human primates, the bilateral representation of the trunk midline in area SI depends on the corpus callosum. Data were obtained from eight callosotomized patients: three with complete callosal resection, one with a partial posterior resection including the splenium and the callosal trunk, and four with partial anterior resections sparing the splenium and in one case also the posterior part of the callosal trunk. The investigation was carried out with functional magnetic resonance imaging. Unilateral tactile stimulation was applied by rubbing ventral trunk regions close to the midline (about 20 × 10 cm in width) with a soft cotton pad (frequency 1 Hz). Cortical activation foci elicited by unilateral stimulation of cutaneous regions adjacent to the midline were detected in the contralateral post‐central gyrus (PCG), in a region corresponding to the trunk ventral midline representation zone of area SI, as described in a previous study of intact subjects. In most patients, activation foci were also found in the ipsilateral PCG, again as in subjects with an intact corpus callosum. The data confirm that the skin regions adjacent to the trunk midline are represented bilaterally in SI, and indicate that ipsilateral activation is at least partially independent of the corpus callosum.
Regulation of NMDA receptor trafficking and function by striatal‐enriched tyrosine phosphatase (STEP)
Authors: Braithwaite Steven P. , Adkisson Michael , Leung John , Nava Adrian , Masterson Brett , Urfer Roman , Oksenberg Donna , Nikolich Karoly
Published: June 2006

Regulation ofN‐methyl‐d‐aspartate (NMDA) receptors is critical for the normal functioning of the central nervous system. There must be precise mechanisms to allow for changes in receptor function required for learning and normal synaptic transmission, but within tight constraints to prevent pathology. Tyrosine phosphorylation is a major means by which NMDA receptors are regulated through the equilibrium between activity of Src family kinases and tyrosine phosphatases. Identification of NMDA receptor phosphatases has been difficult, the best candidate being striatal‐enriched tyrosine phosphatase (STEP). Here we demonstrate that STEP is a critical regulator of NMDA receptors and reveal that the action of this tyrosine phosphatase controls the constitutive trafficking of NMDA receptors and leads to changes in NMDA receptor activity at the neuronal surface. We show that STEP binds directly to NMDA receptors in the absence of other synaptic proteins. The activity of STEP selectively affects the expression of NMDA receptors at the neuronal plasma membrane. The result of STEP's action upon the NMDA receptor affects the functional properties of the receptor and its downstream signaling. These effects are evident when STEP levels are chronically reduced, indicating that there is no redundancy amongst phosphatases to compensate for altered STEP function in the CNS. STEP may have evolved specifically to fill a pivotal role as the NMDA receptor phosphatase, having a distinct and restricted localization and compartmentalization, and unique activity towards the NMDA receptor and its signaling pathway.
Adult large pine weevils Hylobius abietis feed on silver birch Betula pendula even in the presence of conifer seedlings
Authors: Toivonen Riitta , Viiri Heli
Published: June 2006

1 The feeding preference of the adult pine weevil Hylobius abietis (L.) (Coleoptera: Curculionidae) for Betula pendula Roth was studied in no‐choice and paired‐choice feeding experiments.

2 In the first no‐choice test, large quantities of silver birch bark in Petri dishes were consumed; on average, the daily consumption of each weevil was 67 mm2.

3 In the second no‐choice test, the weevils were offered 1‐year‐old silver birch seedlings for 6 days. Initially, the weevils fed mostly on the stem bases; later, they moved upward to feed on other parts of the stems. In addition to the main shoots, scars caused by gnawing were also found on leaf bases, blades, veins and petioles. Feeding resulted in the death of the main stems in 15% of the seedlings.

4 In the paired‐choice tests, the conifers were preferred to silver birch, even though a large amount of silver birch was also consumed in the presence of conifers.

5 In the paired‐choice tests, equal amounts of Scots pine and Norway spruce were always consumed. When hybrid aspen was offered, only small amounts were gnawed.
White pine weevil performances in relation to budburst phenology and traumatic resin duct formation in Norway spruce
Authors: Poulin Julie , Lavallée Robert , Mauffette Yves , Rioux Danny
Published: June 2006

1 As the phenological window hypothesis was reported to be significant in influencing the fitness of many herbivores feeding on tree foliage, could it also explain the performance of an insect such as the white pine weevil Pissodes strobi mainly attacking the bark phloem of conifers?

2 Under field conditions, adult weevils were caged on Norway spruce trees presenting a natural variation in their shoot growth phenology.

3 We evaluated white pine weevil biological performances, including oviposition, the number of emerged insects, survival, adult mean weight and tree defense responses as reflected by the production of induced resin canals.

4 None of the white pine weevil biological parameters was significantly affected by Norway spruce phenology.

5 The number of eggs per hole, the number of oviposition holes per leader, the number of emerged adults and their mean weight were not affected by host phenology.

6 The intensity of the traumatic response observed was variable and not correlated with budburst phenology.

7 Trees with higher traumatic responses, forming two or more layers of traumatic ducts, had lower adult emergence and estimated survival.

8 The distance between the first layer of traumatic resin ducts and the start of the annual ring was not correlated with the number of emerged weevils.

9 Norway spruce, which is an exotic tree in North America and a relatively recent host for the white pine weevil, might not possess the defense mechanisms necessary to fight off the white pine weevil.
Assessment of psychological aspects during systemic provocation tests in patients with pseudoallergic drug reactions
Authors: Hermes B , Hein UR , Henz BM
Published: June 2006

Background  Basic mechanisms of pseudoallergic drug reactions as well as a possible role of the psyche are currently unknown.

Objective  Examination of psychological status and reactions during diagnostic provocation tests in patients with previous pseudoallergic reactions to drugs.

Subjects and methods  Ten inpatients, admitted for provocation tests, were studied in a double‐blind, placebo‐controlled setting, with inventories of anxiety and depression being measured at baseline and psychological reactions and symptoms being recorded daily by patients and the attending physician.

Results  Patients reported more than twice as many symptoms as the physician, independent of the type of exposure. While the basic psychological profile of the patients was normal, anxiety trait and state values were high during testing, with a significant increase depending on whether the patients thought they had received a drug or a placebo. Similarly, frequency of symptoms was dependent on the patients’ perception of the type of exposure.

Conclusion  These findings demonstrate a high level of anxiety during systemic provocation tests in patients with previous pseudoallergic drug reactions, raising serious questions as to the diagnostic validity of the routine application of this testing.
Odontogenic myxoma: a diagnosis to add to the list of facial tumours in infants
Authors: Boussault P , Boralevi F , Raux‐Rakotomalala F , Chauvel A , Taïeb A , Léauté‐Labrèze C
Published: June 2006

The differential diagnosis of a midfacial mass in a child includes a great variety of tumours. Odontogenic myxoma is a benign tumour arising from the mesenchymal portion of the odontogenic apparatus that is usually seen in adolescents and adults.
Nicaraguan Sign Language and Theory of Mind: the issue of critical periods and abilities
Authors: Morgan Gary , Kegl Judy
Published: June 2006

Background: Previous studies in the literature report that deaf individuals who experience late access to language perform poorly on false belief tests of Theory of Mind (ToM) compared with age‐matched deaf and hearing controls exposed to language early.

Methods: A group of 22 deaf Nicaraguans (aged 7 to 39 years) who learned Nicaraguan Sign Language (ISN) at different ages were tested on a false belief and a nonverbal cartoon retell task designed to elicit talk about the contents of character's mental states.

Results: Access to sign language by 10 years of age with possible advantages in language fluency was a strong predictor of performance on both the false belief task and mental state narrative task. However, a comparison of performance on the two tests indicated that children and adults who learned sign after the age of 10 were still able to demonstrate a more general ability to use mental state expressions in narratives. Results are discussed in terms of late access to language and critical periods for the parallel development of Theory of Mind and language.

Conclusions: The findings point to age 10 years as a crucial period when lack of language exposure can lead to long‐lasting deficits in false belief abilities. Late exposure to sign language does not, however, rule out all aspects of the ability to consider others’ mental states. This paper also highlights the need to take into consideration a variety of communication responses when evaluating deaf children's ToM reasoning.
Psychosocial outcomes at 15 years of children with a preschool history of speech‐language impairment
Authors: Snowling Margaret J. , Bishop D.V.M. , Stothard Susan E. , Chipchase Barry , Kaplan Carole
Published: June 2006

Background:  Evidence suggests there is a heightened risk of psychiatric disorder in children with speech‐language impairments. However, not all forms of language impairment are strongly associated with psychosocial difficulty, and some psychiatric disorders (e.g., attention deficit/hyperactivity disorder (ADHD)) are more prevalent than others in language‐impaired populations. The present study assessed the psychosocial adjustment in adolescence of young people with history of speech‐language impairment, and investigated specific relationships between language deficits and psychiatric disorders.

Methods:  Seventy‐one young people (aged 15–16 years) with a preschool history of speech‐language impairment were assessed using a psychiatric interview (K‐SADS) supplemented by questionnaires probing social encounters and parental reports of behaviour and attention. Their psycho‐social adjustment was compared with that of a cross‐sectional control group of age‐matched controls.

Results:  Overall the rate of psychiatric disorder was low in the clinical sample and children whose language delay had resolved by 5.5 years had a good outcome. For those whose language difficulties persisted through the school years, there was a raised incidence of attention and social difficulties. These difficulties were partially independent and associated with different language profiles. The group with attention problems showed a profile of specific expressive language difficulties; the group with social difficulties had receptive and expressive language difficulties; and the group with both attention and social difficulties was of low IQ with global language difficulties.

Conclusions:  Amongst children with speech‐language delays at 5.5 years, those with more severe and persistent language difficulties and low nonverbal IQ are at higher risk of psychiatric morbidity in adolescence.
On the problems of responsibility and accountability in referendums
Authors: SETÄLÄ MAIJA
Published: June 2006

Abstract. Supporters of representative democracy tend to be critical of referendums. They argue that referendums give citizens more responsibility for political decisions than they have either the capacity or the competence to take. Moreover, they argue that referendums may undermine representatives' accountability. In this article, these arguments about responsibility and accountability are analyzed in the light of normative theories of democracy, especially the theory of deliberative democracy. Furthermore, different institutional forms of referendum are analyzed. Particular attention is paid to the following aspects: the extent to which governments control the use of referendums, how referendums interact with parliamentary decision making, and whether referendums are advisory or binding. It is argued that sometimes governments indeed use their control over referendums to avoid taking stands on difficult issues. More importantly, however, current forms of government‐initiated referendums tend to weaken the accountability of the representatives, at least when interpreted in terms of liberal and deliberative democracy, and to distort parliamentary deliberations. Since delegation is a necessity in modern democracies, referendums should not undermine the mechanisms of representative democracy. In addition to the issues of citizens' capacity and competence, this viewpoint should be taken into account when designing referendum institutions.
The portfolio allocation paradox: An investigation into the nature of a very strong but puzzling relationship
Authors: WARWICK PAUL V. , DRUCKMAN JAMES N.
Published: June 2006

Abstract. Perhaps the strongest empirical finding in political science is ‘Gamson's Law’: the near‐perfect relationship that exists in parliamentary systems between a coalition party's seat contribution to the government and its quantitative allocation of cabinet portfolios. Nevertheless, doubts remain. What would happen if the salience or importance of the various portfolios was also taken into account? Should it not be the case that payoffs correspond with bargaining power rather than seat contributions? And perhaps most significantly, would addressing these issues produce evidence that the parties designated to form governments extract disproportionately large payoffs for themselves, as predicted by ‘proposer’ models of bargaining? Utilizing the results of a new expert survey of portfolio salience in 14 Western European countries, the authors of this article explore each of these questions. Their basic finding is that salience‐weighted portfolios payoffs overwhelmingly mirror seat contributions,contraproposer models and any other models based on bargaining power. The article concludes with a discussion of the implications for formal models of bargaining.
Sensemaking of Patient Safety Risks and Hazards
Authors: Battles James B. , Dixon Nancy M. , Borotkanics Robert J. , Rabin‐Fastmen Barbara , Kaplan Harold S.
Published: June 2006

In order for organizations to become learning organizations, they must make sense of their environment and learn from safety events. Sensemaking, as described by Weick (1995), literally means making sense of events. The ultimate goal of sensemaking is to build the understanding that can inform and direct actions to eliminate risk and hazards that are a threat to patient safety. True sensemaking in patient safety must use both retrospective and prospective approach to learning. Sensemaking is as an essential part of the design process leading to risk informed design. Sensemaking serves as a conceptual framework to bring together well established approaches to assessment of risk and hazards: (1) at the single event level using root cause analysis (RCA), (2) at the processes level using failure modes effects analysis (FMEA) and (3) at the system level using probabilistic risk assessment (PRA). The results of these separate or combined approaches are most effective when end users in conversation‐based meetings add their expertise and knowledge to the data produced by the RCA, FMEA, and/or PRA in order to make sense of the risks and hazards. Without ownership engendered by such conversations, the possibility of effective action to eliminate or minimize them is greatly reduced.
Enhancing Patient Safety through Organizational Learning: Are Patient Safety Indicators a Step in the Right Direction?
Authors: Rivard Peter E. , Rosen Amy K. , Carroll John S.
Published: June 2006

Objective. To assess the potential contribution of the Agency for Healthcare Research and Quality Patient Safety Indicators (PSIs) to organizational learning for patient safety improvement.

Principal Findings. Patient safety improvement requires organizational learning at the system level, which entails changes in organizational routines that cut across divisions, professions, and levels of hierarchy. This learning depends on data that are varied along a number of dimensions, including structure‐process‐outcome and from granular to high‐level; and it depends on integration of those varied data. PSIs are inexpensive, easy to use, less subject to bias than some other sources of patient safety data, and they provide reliable estimates of rates of preventable adverse events.

Conclusions. From an organizational learning perspective, PSIs have both limitations and potential contributions as sources of patient safety data. While they are not detailed or timely enough when used alone, their simplicity and reliability make them valuable as a higher‐level safety performance measure. They offer one means for coordination and integration of patient safety data and activity within and across organizations.
Improving Patient Safety in Hospitals: Contributions of High‐Reliability Theory and Normal Accident Theory
Authors: Tamuz Michal , Harrison Michael I.
Published: June 2006

Objective. To identify the distinctive contributions of high‐reliability theory (HRT) and normal accident theory (NAT) as frameworks for examining five patient safety practices.

Data Sources/Study Setting. We reviewed and drew examples from studies of organization theory and health services research.

Study Design. After highlighting key differences between HRT and NAT, we applied the frames to five popular safety practices: double‐checking medications, crew resource management (CRM), computerized physician order entry (CPOE), incident reporting, and root cause analysis (RCA).

Principal Findings. HRT highlights how double checking, which is designed to prevent errors, can undermine mindfulness of risk. NAT emphasizes that social redundancy can diffuse and reduce responsibility for locating mistakes. CRM promotes high reliability organizations by fostering deference to expertise, rather than rank. However, HRT also suggests that effective CRM depends on fundamental changes in organizational culture. NAT directs attention to an underinvestigated feature of CPOE: it tightens the coupling of the medication ordering process, and tight coupling increases the chances of a rapid and hard‐to‐contain spread of infrequent, but harmful errors.

Conclusions. Each frame can make a valuable contribution to improving patient safety. By applying the HRT and NAT frames, health care researchers and administrators can identify health care settings in which new and existing patient safety interventions are likely to be effective. Furthermore, they can learn how to improve patient safety, not only from analyzing mishaps, but also by studying the organizational consequences of implementing safety measures.
Fair and Just Culture, Team Behavior, and Leadership Engagement: The Tools to Achieve High Reliability
Authors: Frankel Allan S. , Leonard Michael W. , Denham Charles R.
Published: June 2006

Background.Disparate health care provider attitudes about autonomy, teamwork, and administrative operations have added to the complexity of health care delivery and are a central factor in medicine's unacceptably high rate of errors. Other industries have improved their reliability by applying innovative concepts to interpersonal relationships and administrative hierarchical structures (Chandler 1962). In the last 10 years the science of patient safety has become more sophisticated, with practical concepts identified and tested to improve the safety and reliability of care.

Objective.Three initiatives stand out as worthy regarding interpersonal relationships and the application of provider concerns to shape operational change: The development and implementation of Fair and Just Culture principles, the broad use of Teamwork Training and Communication, and tools like WalkRounds that promote the alignment of leadership and frontline provider perspectives through effective use of adverse event data and provider comments.

Methods.Fair and Just Culture, Teamwork Training, and WalkRounds are described, and implementation examples provided. The argument is made that they must be systematically and consistently implemented in an integrated fashion.

Conclusions.There are excellent examples of institutions applying Just Culture principles, Teamwork Training, and Leadership WalkRounds—but to date, they have not been comprehensively instituted in health care organizations in a cohesive and interdependent manner. To achieve reliability, organizations need to begin thinking about the relationship between these efforts and linking them conceptually.
Addressing Measurement Error Bias in Nurse Staffing Research
Authors: Harless David W. , Mark Barbara A.
Published: June 2006

Objective. To assess the extent of measurement error bias due to methods used to allocate nursing staff to the acute care inpatient setting and to recommend estimation methods designed to overcome this bias.

Data Sources/Study Setting. Secondary data obtained from the California Office of Statewide Health Planning and Development (OSHPD) and the Centers for Medicare and Medicaid Services' Healthcare Cost Report Information System for 279 general acute care hospitals from 1996 to 2001.

Study Design. California OSHPD provides detailed nurse staffing data for acute care inpatients. We estimate the measurement error and the resulting bias from applying different staffing allocation methods. Estimates of the measurement errors also allow insights into the best choices for alternate estimation strategies.

Principal Findings. The bias induced by the adjusted patient days method (and its modification) is smaller than for other methods, but the bias is still substantial: in the benchmark simple regression model, the estimated coefficient for staffing level on quality of care is expected to be one‐third smaller than its true value (and the bias is larger in a multiple regression model). Instrumental variable estimation, using one staffing allocation measure as an instrument for another, addresses this bias, but only particular choices of staffing allocation measures and instruments are suitable.

Conclusions. Staffing allocation methods induce substantial attenuation bias, but there are easily implemented estimation methods that overcome this bias.
Effect of Dialysis Center Profit‐Status on Patient Survival: A Comparison of Risk‐Adjustment and Instrumental Variable Approaches
Authors: Brooks John M. , Irwin Christopher P. , Hunsicker Lawrence G. , Flanigan Michael J. , Chrischilles Elizabeth A. , Pendergast Jane F.
Published: June 2006

Objective. To compare the estimated effects of dialysis center profit status on patient survival using alternative estimation strategies with retrospective data.

Data Sources/Study Setting. Patient and provider‐level retrospective data from the United States Renal Data System (USRDS), 1996–1999.

Study Design. Observational risk adjustment and instrumental variable methods.

Data Collection/Extraction Methods. Study collected measures from various USRDS files describing clinical characteristics, survival, and the profit status of the initial dialysis center for incident end‐stage renal disease (ESRD) patients aged 67+. USRDS facility files were used to assess dialysis center profit status and measure patient distances to dialysis centers.

Principal Findings. Found survival effect related to profit status in the range of previous research using risk‐adjusting covariates similar to those used in previous models. Adding further risk‐adjusting covariates halved this effect. The relative proximity of for‐profit and nonprofit dialysis centers to the patient residence was the strongest determinant of the profit status of the patient's initial dialysis center. The effect of profit status on survival was eliminated using the two‐stage least squares variant of instrumental variable estimation with the relative proximity of for‐profit and nonprofit dialysis centers to the patient's residence as the instrument.

Conclusions. Using only the variation in initial dialysis center profit status that was related to the relative proximity of for‐profit and nonprofit dialysis centers to the patient, we found no relationship between dialysis center profit status and patient survival. These results are in contrast to results obtained using risk‐adjustment methods with a limited set of risk‐adjusting covariates.
Implementing the Institute of Medicine Definition of Disparities: An Application to Mental Health Care
Authors: McGuire Thomas G. , Alegria Margarita , Cook Benjamin L. , Wells Kenneth B. , Zaslavsky Alan M.
Published: June 2006

Objective. In a recent report, the Institute of Medicine (IOM) defines a health service disparity between population groups to be the difference in treatment or access not justified by the differences in health status or preferences of the groups. This paper proposes an implementation of this definition, and applies it to disparities in outpatient mental health care.

Data Sources. Health Care for Communities (HCC) reinterviewed 9,585 respondents from the Community Tracking Study in 1997–1998, oversampling individuals with psychological distress, alcohol abuse, drug abuse, or mental health treatment. The HCC is designed to make national estimates of service use.

Study Design. Expenditures are modeled using generalized linear models with a log link for quantity and a probit model for any utilization. We adjust for group differences in health status by transforming the entire distribution of health status for minority populations to approximate the white distribution. We compare disparities according to the IOM definition to other methods commonly used to assess health services disparities.

Principal Findings. Our method finds significant service disparities between whites and both blacks and Latinos. Estimated disparities from this method exceed those for competing approaches, because of the inclusion of effects of mediating factors (such as income) in the IOM approach.

Conclusions. A rigorous definition of disparities is needed to monitor progress against disparities and to compare their magnitude across studies. With such a definition, disparities can be estimated by adjusting for group differences in models for expenditures and access to mental health services.
Near Fatal Arrhythmia Induction by An Implantable Cardioverter Defibrillator
Authors: WOLLMANN CHRISTIAN G. , GÖTTKER ULRICH , BÖCKER DIRK , GRADAUS RAINER
Published: June 2006

Sudden death among implantable cardioverter defibrillator (ICD) recipients is well known. The underlying mechanism remains unclear in most cases. One possible mechanism is an accidentally induced arrhythmia by the ICD itself. This report describes for the first time a case of a life‐threatening ventricular arrhythmia induced by a specific algorithm for ventricular arrhythmia reconfirmation before shock delivery in a fourth‐generation ICD.
Clinical Factors Associated with Quality of Life in Patients with Transient Loss of Consciousness
Authors: VAN DIJK NYNKE , SPRANGERS MIRJAM A. , COLMAN NANCY , BOER KIMBERLY R. , WIELING WOUTER , LINZER MARK
Published: June 2006

Introduction: Transient loss of consciousness (TLOC) is common and can be lethal. Although the patients with the most prevalent causes of TLOC have a benign prognosis, morbidity is considerable. Aim of this article, therefore, was to compare the generic quality of life (QoL) of patients presenting with TLOC with that of the general population, to compare the disease‐specific QoL with that of an American referral sample, and to examine which sociodemographic and clinical factors are associated with QoL in these patients.

Methods: This study was part of the fainting assessment study (FAST), which assessed diagnostic strategies for adult patients presenting with TLOC to the Academic Medical Center Amsterdam, between February 2000 and May 2002. The generic short form‐36 (SF‐36) health survey and the disease‐specific syncope functional status questionnaire (SFSQ) were used to assess QoL.

Results: Of 468 included patients, 82% completed the questionnaires. Patients with TLOC scored poorer on all scales of the SF‐36 than the Dutch population, with effect sizes ranging from 0.43 to 1.11 (>0.5 = moderate effect; >0.8 = large effect). The SFSQ indicated mean impairment in 33% of the listed activities (such as driving). Female gender, higher level of comorbidity, shorter duration of complaints, having had more than one syncopal episode, and the presence of presyncopal episodes were associated with poorer QoL.

Conclusion: TLOC seriously affects QoL, especially in patients with a recent onset of clinical symptoms and those suffering from both syncopal and presyncopal episodes.
Post‐spawn movements and habitat use by greater redhorse, Moxostoma valenciennesi
Authors: Bunt C. M. , Cooke S. J.
Published: June 2006

Abstract
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A combination of radio telemetry and surface observations were used to characterize the movements and habitats of greater redhorse, Moxostoma valenciennesi, after spawning in the Grand River, Ontario, Canada. This river supports a large population of greater redhorse that migrate upstream in the spring to spawn on riffles. After spawning, greater redhorse moved as far as 15.2 km downstream of spawning areas and maintained summer home ranges in low velocity runs. Mean (±SE) water depth used by greater redhorse was 46.3±0.9 cm, and water velocities were less than 5 cm/s. Greater redhorse were usually located over cobble/gravel substrates that were covered with Cladophora. Although interspecific associations with golden redhorse, M. erythrurum, common carp, Cyprinus carpio, smallmouth bass, Micropterus dolomieu, and northern hog sucker, Hypentelium nigricans, were observed, most greater redhorse associated with conspecifics. Areas and habitat types used throughout the summer did not change, until relocation to overwintering areas occurred in early autumn.