Examination of the Construct Validity of Impact™ Computerized Test,Traditional, and Experimental Neuropsychological Measures

Although computerized neuropsychological screening is becoming a standard for sports concussion identification and management, convergent validity studies are limited. Such studies are important for several reasons: reference to established measures is needed to establish validity; examination of the computerized battery relative to a more traditional comprehensive battery will help understand the strengths and limitations of the computer battery; and such an examination will help inform the output of the computerized battery. We compared scores on the ImPACT? battery to a comprehensive battery of traditional neuropsychological measures and several experimental measures used in the assessment of sports-related concussion in 54 healthy male athletes. Convergent validity was demonstrated for four of the five ImPACT? domain scores. Two cognitive domains often compromised as a result of mild TBI were not directly identified by the ImPACT? battery: sustained attention and auditory working memory. Affective symptoms correlated with performance on measures of attention and working memory. In this healthy sample the correlations between the domains covered by ImPACT? and the neuropsychological battery supports ImPACT? as a useful screening tool for assessing many of the cognitive factors related to mTBI. However, the data suggest other sources of data need to be considered when identifying and managing concussions.     

In vitro characterization of the human recombinant soluble granulocyte- macrophage colony-stimulating factor receptor

We have cloned, expressed, and partially purified a naturally occurring, truncated, soluble form of the human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor alpha subunit to investigate its biochemical and biologic properties. The soluble receptor species lacks the transmembrane and cytoplasmic domains that are presumably removed from the intact receptor cDNA by a mechanism of alternative splicing. The resulting soluble 55- to 60-kD glycosylated receptor species binds GM-CSF with a dissociation constant (kd) of 3.8 nmol/L. The soluble GM-CSF receptor successfully competes for GM-CSF binding not only with the transmembrane-anchored GM-CSF receptor alpha subunit but also with the native oligomeric high-affinity receptor complex. In addition, in human bone marrow colony-forming assays, the soluble GM-CSF receptor species can antagonize the activity of GM-CSF. Our data suggest that the soluble GM-CSF receptor may be capable of acting in vivo as a modulator of the biologic activity of GM-CSF.     

A prospective study on defecation frequency, stool weight, and consistency

It has been commonly believed that children in developing countries pass stools that are very different from those of developed countries. A community based study on defecation frequency, stool weight, and consistency was conducted in a cohort of 300 Myanmar (Burmese) children aged 1 to 4 years. Most (80.3%) children opened their bowels daily and none passed more than three stools a day. The mean (SD) defecation frequency was 6.98 (1.94) times a week and total stool weight was 596 (221) g a week. The majority (61%) of children passed soft stools. At all ages, there was no significant difference in the defecation frequency, stool weight, and consistency between boys and girls, those on adult style diet and those partially weaned, and between age groups.     

The need for microsimulation to evaluate osteoporosis interventions

Simulations play an increasingly important role in the evaluation of osteoporosis interventions. Existing evaluations have been based on reduced-form cohort simulations that do not reflect the complexity and heterogeneity of osteoporosis and its outcomes. Such simplified models offer parsimony and ease of use, but they also are limited in their ability to explain and extrapolate outcomes in a way that is most useful for both clinical and health policy decision makers. Alternatively, evaluations could be based on structural microsimulations, which explicitly model the underlying biology of osteoporosis at the individual level. The structural approach presents technical challenges, including the need to obtain more-detailed data and the requirement that underlying biological models be validated. However, evaluations based on structural microsimulation may ultimately provide substantially more useful information, resulting in improved decision making.     

Electromagnetic breast imaging: average tissue property values in women with negative clinical findings

Representative data are provided for three electromagnetic breast imaging techniques-near-infrared spectroscopy, electrical impedance spectroscopy, and microwave imaging spectroscopy-to serve as potential benchmarks for future investigation. The breasts of 23 women without clinical or mammographic findings of disease were imaged in the coronal plane with nonionizing radiation of varying frequencies. Average electromagnetic property values were reconstructed at each frequency on the basis of computational models of light diffusion, current flow, and microwave propagation. Electromagnetic properties were correlated with subject characteristics and between techniques. Each technique yielded information on breast tissue features (eg, conductivity, permittivity, light scattering, and absorption) that had not previously all been measured in the same individuals.     

Predictors of difficulty when discontinuing postmenopausal hormone therapy

OBJECTIVE: To describe the experiences of postmenopausal women who try to stop hormone therapy and to identify characteristics associated with inability to stop. METHODS: We conducted telephone interviews with 377 randomly selected female members of the Kaiser Foundation Health Plan, aged 50-69 years, who regularly used hormone therapy for at least 1 year before July 1, 2002 and had attempted to stop between July 2002 and March 2003. RESULTS: Of the 377 women, 280 (74%) successfully stopped and 97 (26%) resumed taking hormone therapy. The major predictor of resuming hormone therapy use was the development of troublesome withdrawal symptoms (odds ratio 8.8; 95% confidence interval 4.9, 16.0). Report of hysterectomy, hormone therapy prescribed by a nongynecologist, and perception of high risk of hip or spine fracture were independently associated with a higher likelihood of unsuccessful stopping. Women with a hysterectomy who had used hormone therapy for 10 or more years and who started hormone therapy mainly for reasons other than health promotion were more likely (P <.001) to be unsuccessful in quitting (44%) compared with those with one or two (25%) or none (9%) of these three characteristics. Most successful stoppers (71%) stopped hormone therapy abruptly, but 29% tapered off hormone therapy; there was no difference in the incidence of troublesome withdrawal symptoms or successful quitting between these two groups. CONCLUSION: Approximately one quarter of women who try to stop report that they are unable to discontinue postmenopausal hormone therapy, primarily because they develop troublesome withdrawal symptoms. Effective approaches to reducing hormone therapy withdrawal symptoms should be a priority for future research.