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UNLABELLED: In this study, we determined that operator positioning precision contributes significant measurement error in high-resolution peripheral quantitative computed tomography (HR-pQCT). Moreover, we developed software to quantify intra- and inter-operator variability and demonstrated that standard positioning training (now available as a web-based application) can significantly reduce inter-operator variability. INTRODUCTION: HR-pQCT is increasingly used to assess bone quality, fracture risk, and anti-fracture interventions. The contribution of the operator has not been adequately accounted in measurement precision. Operators acquire a 2D projection (scout view image) and define the region to be scanned by positioning a reference line on a standard anatomical landmark. In this study, we (i) evaluated the contribution of positioning variability to in vivo measurement precision, (ii) measured intra- and inter-operator positioning variability, and (iii) tested if custom training software led to superior reproducibility in new operators compared to experienced operators. METHODS: To evaluate the operator in vivo measurement precision, we compared precision errors calculated in 64 co-registered and non-co-registered scan-rescan images. To quantify operator variability, we developed software that simulates the positioning process of the scanners software. Eight experienced operators positioned reference lines on scout view images designed to test intra- and inter-operator reproducibility. Finally, we developed modules for training and evaluation of reference line positioning. We enrolled six new operators to participate in a common training, followed by the same reproducibility experiments performed by the experienced group. RESULTS: In vivo precision errors were up to threefold greater (Tt.BMD and Ct.Th) when variability in scan positioning was included. The inter-operator precision errors were significantly greater than the short-term intra-operator precision (p

Body mass index is a common proxy for proportion of body fat. However, body mass index may not classify youth similarly across ages and ethnicities. We used sex- and ethnic-specific receiver operating characteristic curves to determine how obesity classifications compared between body mass index and dual energy x-ray absorptiometry-based body fat percent. Male and female participants 9- to 18-years-old (n = 944; 487 female) were measured 1 to 13 times (1999-2012; 4,411 observations). Body mass index identified < 50% of those classified as obese from body fat percent. Specificity was 99.7%, and sensitivity was 35.8%. Using area under the curve and standard error values, body mass index performed significantly better for: Male versus female at 10 years, Asian versus European female except at 13-, 15-, and 16-years-old, Asian female versus male except at 10- and 15-years-old, and for European male versus female, 9- to 11-years-old (p < 0.05). Our findings provide evidence that users of body mass index should use caution when comparing body mass index across age, sex, and ethnicity.

Neurogenesis has been described in various regions of the CNS throughout life. We examined the extent of natural cell division and replacement from 7 weeks to 7 months after cervical spinal cord injury in four adult rhesus monkeys. Bromodeoxyuridine ( BrdU) injections revealed an increase of > 80-fold in the number of newly divided cells in the primate spinal cord after injury, with an average of 725,000 BrdU-labeled cells identified per monkey in the immediate injury zone. By 7 months after injury, 15% of these new cells expressed mature markers of oligodendrocytes and 12% expressed mature astrocytic markers. Newly born oligodendrocytes were present in zones of injury-induced demyelination and appeared to ensheath or remyelinate host axons. Thus, cell replacement is an extensive natural compensatory response to injury in the primate spinal cord that contributes to neural repair and is a potential target for therapeutic enhancement.

Mechanisms of cognitive decline with aging remain primarily unknown. We determined whether localized cell loss occurred in brain regions associated with age-related cognitive decline in primates. On a task requiring the prefrontal cortex, aged monkeys were impaired in maintaining representations in working memory. Stereological quantification in area 8A, a prefrontal region associated with working memory, demonstrated a significant 32 +/- 11% reduction in the number of Nissl-stained neurons compared with young monkeys. Furthermore, the number of immunolabeled cholinergic neurons projecting to this region of cortex from the nucleus basalis was also reduced by 50 +/- 6%. In contrast, neuronal number was strikingly preserved in an adjoining prefrontal cortical region also associated with working memory, area 46, and in the component of the nucleus basalis projecting to this region. These findings demonstrate extensive but highly localized loss of neocortical neurons in aged, cognitively impaired monkeys that likely contributes to cognitive decline. Cell degeneration, when present, extends transneuronally.

Background Concurrent with their enrollment in Web-based Randomized Controlled Trials (RCTs), participants can easily choose to use treatment programs that are not assigned in the study. The prevalence of using non-assigned treatments is largely unknown although it is likely to be related to the extent to which non-assigned treatments are: (a) easy to find and use, (b) low in cost, (c) well publicized, and (d) available from trusted sources. The impact of using other programs—both beneficial and detrimental—warrants additional research investigation. Objective The aim of this report is to explore the extent to which participants enrolled in a Web-based intervention for smoking cessation used treatment methods that were not explicitly assigned (“non-assigned treatment”). In addition to describing the relation between using non-assigned treatments and smoking cessation outcomes, we also explore the broader issue of non-assigned program use by RCT participants in Web-based behavioral interventions, generally. Methods We describe the use of other programs (as measured by self-report at the 3-month follow-up assessment) by 1028 participants who were randomized to the Web-based SHIP (Smokers’ Health Improvement Program) RCT which compared the Quit Smoking Network (QSN) treatment program and the Active Lives control condition. We examine the extent to which pharmacotherapy products were used by participants in the QSN condition (which explicitly recommended their use) and the Active Lives condition (which purposefully omitted mention of the use of pharmacotherapy). We also test for any between-condition impact of using non-assigned treatments and pharmacotherapy products on smoking cessation outcomes. Results A total of 24.1% (248/1028) participants reported using one or more smoking cessation treatment programs that were not explicitly recommended or assigned in their treatment protocol. Types of non-assigned treatments used in this manner included individual counseling (1.7%), group counseling (2.3%), hypnotherapy/acupuncture (4.5%), pamphlets/books (12.6%), and other Web-based smoking cessation programs (9.0%). Participants who used non-assigned treatments were more likely to be female and have at least a high school education. Use of non-assigned Web programs was related to greater levels of self-reported smoking cessation measured at the 3-month assessment (OR = 2.63, CI = 1.67 - 4.14, P < .001) as well as the combined 3- and 6-month assessments (OR = 2.09, CI = 1.11 - 3.91, P = .022). In terms of reported medication use, there were no differences between conditions in the number of pharmacotherapy products used. However, more participants in the QSN condition used at least one pharmacotherapy product: 50.0% (262/524) vs 43.8% (221/504); χ2 (1, N = 1028) = 3.90, P = .048. The use of pharmacotherapy and non-assigned treatment types showed a small but marginally significant correlation: r1028 = .061, P = .05. Conclusions A noteworthy proportion of individuals recruited via the Internet to participate in a Web-based intervention used treatment programs and tools not formally assigned as a part of their research protocol. We consider factors likely to influence using non-assigned treatments and suggest ways that future research can begin to study more fully this important phenomenon which is likely to be found in any type of research, but may be particularly pronounced in minimal contact, Web-based intervention trials.

Background Smoking cessation remains a significant public health problem. Innovative interventions that use the Internet have begun to emerge that offer great promise in reaching large numbers of participants and encouraging widespread behavior change. To date, the relatively few controlled trials of Web-based smoking cessation programs have been limited by short follow-up intervals. Objective We describe the 6-month follow-up results of a randomized controlled trial in which participants recruited online were randomly assigned to either a Web-based smoking cessation program (Quit Smoking Network; QSN) or a Web-based exercise enhancement program (Active Lives) adapted somewhat to encourage smoking cessation. Methods The study was a two-arm randomized controlled trial that compared two Web-based smoking cessation programs: (1) the QSN intervention condition presented cognitive-behavioral strategies, and (2) the Active Lives control condition provided participants with guidance in developing a physical activity program to assist them with quitting. The QSN condition provided smoking cessation information and behavior change strategies while the Active Lives condition provided participants with physical activity recommendations and goal setting. The QSN condition was designed to be more engaging (eg, it included multimedia components) and to present much greater content than is typically found in smoking cessation programs. Results Contrary to our hypotheses, no between-condition differences in smoking abstinence were found at 3- and 6-month follow-up assessments. While participants in the QSN intervention condition spent more time than controls visiting the online program, the median number of 1.0 visit in each condition and the substantial attrition (60.8% at the 6-month follow-up) indicate that participants were not as engaged as we had expected. Conclusions Contrary to our hypothesis, our test of two Web-based smoking cessation conditions, an intervention and an attention placebo control, failed to show differences at 3- and 6-month assessments. We explored possible reasons for this finding, including limited engagement of participants and simplifying program content and architecture. Future research needs to address methods to improve participant engagement in online smoking cessation programs. Possible approaches in this regard can include new informed consent procedures that better explain the roles and responsibilities of being a research participant, new program designs that add more vitality (changing content from visit to visit), and new types of reminders pushed out to participants to encourage return visits. Simplifying program content through a combination of enhanced tailoring and information architecture also merits further research attention.