Structural equation analysis of the California verbal learning test‐children's version in the standardization sample

Maximum‐likelihood confirmatory factor analysis was applied to 13 qualitative and quantitative variables that were selected on the basis of specific theoretical and practical criteria from the California Verbal Learning Test‐Children's Version (CVLT‐C) standardization sample. Analyses were designed to determine which of 6 hypothetical, oblique factor solutions could best explain learning and memory as measured by the CVLT‐C. Competing latent‐variable models were identified on the basis of previous studies, as well as distinctions suggested by the CVLT‐C format. The findings suggested that a 5‐factor model (composed of Attention Span, Learning Efficiency, Free Delayed Recall, Cued Delayed Recall, and Inaccurate Recall) fit the data relatively best in terms of superior fit and acceptable parsimony. I conclude that this 5‐factor model is a useful and valid predictor of CVLT‐C performance variability.     

Two large-scale surveys on community attitudes toward an opt-out biobank

Although US research regulations allow for de-identified biorepositories to be developed without formal informed consent from the patients whose samples are included, it is unknown whether this model will be well-received by community members. Based on early evidence that such a biobank could be successful if patients who object have the opportunity to opt-out, Vanderbilt University developed a biorepository named BioVU that follows this model. This study reports the findings from two large-scale surveys among communities important to this biorepository. In the first, a population-based phone survey of Nashville residents, we found that approval for BioVU is high (93.9%) and that this approval is similar among all population groups. A hypothetical biobank that does not obtain some form of written permission is much less well received. In the second, an online survey of Vanderbilt University faculty and staff, we found a higher level of support for BioVU (94.5%) among faculty and staff working throughout the university. In this survey, employees least likely to approve of BioVU are those employees who prefer not to receive medical care at Vanderbilt University. These surveys demonstrate the highest level of approval for a genomic biobank ever reported in the literature, even among groups traditionally cautious about such research. This high level of approval may reflect increasing comfort with genomic research over time combined with the effect that trust in a specific institution can have on approval for an operating biobank compared with approval of a hypothetical biobank.     

Hypothetical and factual willingness to participate in biobank research

In the debate on biobank regulation, arguments often draw upon findings in surveys on public attitudes. However, surveys on willingness to participate in research may not always predict actual participation rates. We compared hypothetical willingness as estimated in 11 surveys conducted in Sweden, Iceland, United Kingdom, Ireland, United States and Singapore to factual participation rates in 12 biobank studies. Studies were matched by country and approximate time frame. Of 22 pairwise comparisons, 12 suggest that factual willingness to participate in biobank research is greater than hypothetical, six indicate the converse relationship, and four are inconclusive. Factual donors, in particular when recruited in health care or otherwise face-to-face with the researcher, are possibly motivated by factors that are less influential in a hypothetical context, such as altruism, trust, and sense of duty. The value of surveys in assessing factual willingness may thus be limited.     

Neuroticism and common mental disorders: Meaning and utility of a complex relationship

Neuroticism's prospective association with common mental disorders (CMDs) has fueled the assumption that neuroticism is an independent etiologically informative risk factor. This vulnerability model postulates that neuroticism sets in motion processes that lead to CMDs. However, four other models seek to explain the association, including the spectrum model (manifestations of the same process), common cause model (shared determinants), state and scar models (CMD episode adds temporary/permanent neuroticism). To examine their validity we reviewed literature on confounding, operational overlap, stability and change, determinants, and treatment effects. None of the models is able to account for (virtually) all findings. The state and scar model cannot explain the prospective association. The spectrum model has some relevance, especially for internalizing disorders. Common causes are most important but the vulnerability model cannot be excluded although confounding of the prospective association by baseline symptoms and psychiatric history is substantial. In fact, some of the findings, such as interactions with stress and the small decay of neuroticism's effect over time, are consistent with the vulnerability model. We describe research designs that discriminate the remaining models and plea for deconstruction of neuroticism. Neuroticism is etiologically not informative yet but useful as an efficient marker of non-specified general risk.     

The role of internalizing and externalizing liability factors in accounting for gender differences in the prevalence of common psychopathological syndromes

BACKGROUND: We hypothesized that gender differences in average levels on the internalizing and externalizing factors that account for co-morbidity among common psychopathological syndromes in both men and women account for gender differences in the prevalence of specific syndromes. METHOD: The latent structure of 11 syndromes was examined in a middle-aged (mean age=52.66 years, s.d.=5.82) sample of 2992 (37% men) members of the community-based Minnesota Twin Registry (MTR) assessed using 10 scales of the Psychiatric Diagnostic Screening Questionnaire (PDSQ) and an adult antisocial behavior scale. Confirmatory factorial invariance models were applied to a best-fitting, internalizing-externalizing model. RESULTS: A 'strong gender invariance model' fit best, indicating that gender differences in the means of individual syndromes were well accounted for by gender differences in mean levels of internalizing and externalizing. Women exhibited higher mean levels of internalizing (d=0.23) and lower mean levels of externalizing (d=-0.52) than men. CONCLUSIONS: These findings suggest that risk factors for common mental disorders exhibiting gender differences may influence prevalence at the latent factor level. Future research may benefit from focusing on both the latent factor and individual syndrome levels in explaining gender differences in psychopathology.     

Excess hospital admissions for pneumonia, chronic obstructive pulmonary disease, and heart failure during influenza seasons in Hong Kong

It is widely held that Southern China is a hypothetical influenza epicentre for the emergence of pandemic influenza viruses. However, influenza is perceived as a relatively unimportant infection in this part of the world compared with western countries. Hong Kong is situated within the hypothetical epicentre and serves as a sentinel post for the region. In a retrospective study, the influenza-associated excess hospitalisations in a regional hospital for pneumonia, chronic obstructive pulmonary disease (COPD), heart failure, and asthma in persons aged > or = 65 years from 1998 to 2001 were each estimated by a model taking into consideration the confounding effect of other respiratory viral infections, seasonal factors, time trends, and weather and pollution indices. In the regression models, influenza activity is an independent significant factor affecting admission rates for pneumonia, COPD, and heart failure but not that for asthma. The variations in hospital admissions for pneumonia, COPD, and heart failure explained by influenza activity were 38.9, 7.5, and 45.6%, respectively. The adjusted rates of excess influenza-associated hospital admissions for the three diagnoses combined amounted to 58.5, 20.0, 29.2, and 13.4 per 10,000 populations aged > or = 65 years in 1998, 1999, 2000, and 2001, respectively. In conclusion, influenza activity is associated significant excess hospital admissions among elderly aged 65 or above in Hong Kong, comparable to the data reported in Western countries. The findings support a wider application of annual influenza vaccination in this region.     

Determinant factors of community-based disaster preparedness: a case study of flood prone area

This study examined the determinants of willingness to participate in a community-based disaster preparedness scheme. The theory of reasoned action (Ajzen & Fishbein, 1977, 1980; Fishbein & Ajzen, 1975) was applied as a basic model and was complemented by the factor of concern about disaster. A structural equation modeling was performed to validate this model. The hypothetical model was supported for the data from the residents (N = 3 036) of an area with a high risk of flood damage. It was clarified that the subjective norm and concern about flood positively contributed to the intention of participating in a community-based disaster preparedness scheme. The perceived cost of preparedness was the inhibitory factor of participating in such a scheme.     

The role of anxiety sensitivity and drinking motives in predicting alcohol use: a critical review

Anxiety sensitivity (AS) is a cognitive, individual difference variable that refers to the fear of arousal-related bodily sensations. Persons with high AS fear these sensations because they believe the sensations are signs of impending catastrophic events. AS has been linked to increased alcohol consumption and also risky drinking motives, including coping and conformity motives. This paper summarizes statistical modeling studies and experimental research on the functional relationships between AS and drinking motives and alcohol consumption. AS functions as a risk factor that sets the stage for negative reinforcement by alcohol use. Whether alcohol use becomes a method of coping with AS depends on multiple risk factors and motivations. We propose an integrated model to account for the observed relationships and to guide future research. In addition, we identify key methodological limitations and directions for future research.     

Extinction is not a natural consequence of unilateral spatial neglect: evidence from contrast detection experiments

To investigate whether the expression of visual extinction is dependent upon the contralesional low saliency existing in neglect, we tested stroke patients with neglect and extinction, as well as normal controls, on detection of a peripheral Gabor patch, while a competing patch was presented simultaneously on the other side. To compensate for uneven saliency we set the contrast level relative to the detection threshold on each side. Patients showed contralesional extinction even for stimuli set at threshold level. They differed from controls in their sensitivity to changes in relative contrast between sides, showing stronger tendency for extinction and requiring much higher contrast increments in the target patch in order to eliminate extinction. The differences between normal and pathological extinction, shown despite compensation for contralesional perceptual attenuation due to neglect, suggest an additional extinction-specific deficit related to an abnormal interplay between the bilaterally presented stimuli. These findings have important theoretical implications concerning the relationship between neglect and extinction. They demonstrate that the hypothetical ‘attentional gradient’, taken to explain reduced saliency of stimuli in the neglected side, cannot fully account for the phenomenon of extinction.     

单钉固定股骨颈骨折的应力分析

本文对单钉同定股骨颈骨折的模型进行应力计算,考虑中空钉和股骨之间的接触以及摩擦作用,分析了不同摩擦系数的影响.有限元计算结果表明:摩擦系数对计算结果有一定的影响,采用不同的摩擦系数,计算结果最大相差7.16%;中空钉和股骨之间按接触计算,计算的结果更精确;如果是进行定性的分析,为了节省计算时间,可以用节点位移耦合代替接触,二者计算结果最大相差8.58%.     

Disclosing incidental findings in genetics contexts: A review of the empirical ethical research

The disclosure of incidental findings, also called unsolicited findings, unexpected results, and secondary variants, is increasingly recognised as an issue in clinical and research genetics contexts. The rise of next generation sequencing methods has only intensified the issue, increasing the likelihood of incidental findings appearing. This review focuses on empirical research on the ethical issues involved. Electronic databases were searched for articles covering quantitative and qualitative research on the ethical issues involved in the disclosure of incidental findings in clinical and research genetics contexts. 16 articles were ultimately accepted for review. Data was extracted and synthesised on the factors that should be taken into account during the decision-making process surrounding the disclosure of an incidental finding in a genetics context. These factors include the possibility of disclosure, various practical and technical factors, and various ethical factors. We suggest the development of a decision-making tree, involving an exploration of the practical and ethical concerns raised by the studies. This is in our view the best way of handling the wide variety of both possible incidental findings and parties interested in the disclosure of incidental findings.     

Maternal social support predicts birth weight and fetal growth in human pregnancy

OBJECTIVE: Low birth weight is a primary cause of infant mortality and morbidity. Results of previous studies suggest that social support may be related to higher birth weight through fetal growth processes, although the findings have been inconsistent. The purpose of this investigation was to test a model of the association between a latent prenatal social support factor and fetal growth while taking into account relations between sociodemographic and obstetric risk factors and birth weight. METHOD: A prospective study was conducted among 247 women with a singleton, intrauterine pregnancy receiving care in two university-affiliated prenatal clinics. Measures of support included support from family, support from the baby's father, and general functional support. Sociodemographic characteristics were also assessed. Birth outcome and obstetric risk information were abstracted from patients' medical charts after delivery. RESULTS: Structural equation modeling analyses showed that a latent social support factor significantly predicted fetal growth (birth weight adjusted for length of gestation) with infant sex, obstetric risk, and ethnicity in the model. Marital status and education were indirectly related to fetal growth through social support. The final model with social support and other variables accounted for 31% of the variance in fetal growth. CONCLUSIONS: These findings suggest that prenatal social support is associated with infant birth weight through processes involving fetal growth rather than those involving timing of delivery. Biological and behavioral factors may contribute to the association between support and fetal growth, although these mechanisms need to be further explored. These results pave the way for additional research on fetal growth mechanisms and provide a basis for support intervention research.     

High-resolution ERP mapping of cortical activation related to implicit object-location memory

High-density event-related potentials (ERPs) were recorded during an object recognition task which involved task-irrelevant changes in the location of studied objects. Participants categorised objects as studied or novel while data were analysed to ascertain the effect of the location changes on performance and waveform topography. Our results indicate that humans can classify objects faster and more accurately when using implicit spatial memory. Individual differences observed in object recognition proficiency were absent if objects were presented in their ‘correct’ location. In a second experiment we replicated the behavioural findings while manipulating viewpoint to discount scene recognition as an underlying factor. We propose a model which includes activation of the right medial temporal lobe prior to P300 elicitation to account for the prophylactic effect of implicit processing on object recognition. Hemispheric differences in parietal componentry dependant on sex of participant were also observed and are discussed in relation to differential strategies.     

High-resolution ERP mapping of cortical activation related to implicit object-location memory

High-density event-related potentials (ERPs) were recorded during an object recognition task which involved task-irrelevant changes in the location of studied objects. Participants categorised objects as studied or novel while data were analysed to ascertain the effect of the location changes on performance and waveform topography. Our results indicate that humans can classify objects faster and more accurately when using implicit spatial memory. Individual differences observed in object recognition proficiency were absent if objects were presented in their ‘correct’ location. In a second experiment we replicated the behavioural findings while manipulating viewpoint to discount scene recognition as an underlying factor. We propose a model which includes activation of the right medial temporal lobe prior to P300 elicitation to account for the prophylactic effect of implicit processing on object recognition. Hemispheric differences in parietal componentry dependant on sex of participant were also observed and are discussed in relation to differential strategies.     

Development of a structural model explaining medication compliance of persons with schizophrenia

The purpose of this study was to develop and test a structural model explaining medication compliance of schizophrenia. From a review of the literature, a hypothetical model was developed based on the conceptual framework of the Health Belief Model with medication knowledge, symptom severity and social support as the exogenous variables, and perceived benefits, perceived barriers, substance use and medication compliance as the endogenous variables. Data was collected at various mental health facilities, including psychiatric outpatient clinics of general hospitals and community mental health centers, between March and May, 2001. A structured questionnaire was used by one- on- one interviews to collect data on 208 schizophrenic patients. Well established measurement instruments, with confirmed reliability, were used to assess each method variable. As a result of covariance structural analysis, the hypothetical model was found not to fit the empirical data well, so a parsimonious model was adopted after modifying the model. The final model was able to explain the 33 % medication compliance. Medication knowledge, social support and perceived benefits had significant effects on medication compliance. The findings of this study address the importance of medication education and social support to promote medication compliance. It is also suggested that various education programs and support groups are needed to enhance medication compliance.     

Exploring the role of external criticism in Obsessive Compulsive Disorder: a narrative review

The concept of external criticism has been associated with different aspects of Obsessive Compulsive phenomena. The various threads of evidence highlight the potential role of criticism within different areas of the cognitive model of Obsessive Compulsive Disorder (OCD) with often overlapping ideas. However, the fragmented nature of the findings makes it difficult to identify how or why criticism impacts on OCD. This review collates the existing findings and maps these onto the cognitive model of OCD to provide a better understanding of the potential role of criticism. It proposes criticism could play a role in OCD as a vulnerability factor, but also as a perpetuating factor. Furthermore potential research questions have been generated which could help inform future understanding. Future research should consider the complexity of the concept when defining criticism as well as developing methodological designs which could answer questions of causality.     

The protective role of Langerhans' cells and sunlight in multiple sclerosis

The low prevalence of multiple sclerosis in equatorial areas may be the consequence of a physiological immunosuppression induced by ultraviolet radiation on the epidermal Langerhans' cells, which are the antigen-presenting cells. Multiple sclerosis appears to be the consequence of an immune response to an environmental antigen during childhood in the absence of two protective factors: a genetic factor conferred by the HLA haplotypes of Langerhans' cells, and an environmental factor conferred by ultraviolet radiation in sunlight. In the presence of these two factors, T lymphocytes are physiologically immunosuppressed. Their association may play a key role in protection against multiple sclerosis. The varying combinations of these two factors may provide an explanation for the differences in incidence and prevalence of the disease noted within a single region or from one region to another throughout the globe. The hypothetical pathogenic mechanism developed in this article opens up new fields of research, particularly those concerning its therapeutic applications.     

Molecular aspects of polycythemia vera (review)

Polycythemia vera (PV) is a rare, progressive myeloproliferative disorder thought to originate from the clonal expansion of a multipotent haemopoietic stem cell. This disease is characterised by hyperproliferation of the erythroid, myeloid and megakaryocyte lineages in the early phase, anaemia and fibrosis in the spent phase, and with a significant number of patients developing acute myeloid leukaemia (AML) in the final phase. Studies investigating the growth factor requirements of committed progenitors have shown hypersensitivity to a number of haemopoietic growth factors (HGF) in vitro and several HGF receptor and signalling molecule alterations have been reported. The findings to date, however, are unable to account for the transformation of a primitive stem cell and the many alterations to growth factor responses seen in PV progenitors. Identification of the primary lesion that leads to the pathogenesis of PV is of major importance given the profound effects on regulation of the haemopoietic stem cell compartment. In this article we focus on characteristics of the disease, research findings to date and possible mechanisms to explain altered growth factor responses, receptor alterations and signalling abnormalities in PV.     

Modifications to central neural circuitry during heart failure

AIM: During heart failure (HF), excess sodium retention is triggered by increased plasma renin-angiotensin-aldosterone activity and increased basal sympathetic nerve discharge (SND). Enhanced basal SND in the renal nerves plays a role in sodium retention. Therefore, as a hypothetical model for the central sympathetic control pathways that are dysregulated as a consequence of HF, the central neural pathways regulating the sympathetic motor output to the kidney are reviewed in the context of their role during HF. CONCLUSION: From these findings, a model of the neuroanatomical circuitry that may be affected during HF is constructed.