Using Ecological Momentary Assessment to Examine Antecedents and Correlates of Physical Activity Bouts in Adults Age 50+ Years: A Pilot Study

Background  

National recommendations supporting the promotion of multiple short (10+ minute) physical activity bouts each day to increase overall physical activity levels in middle-aged and older adults underscore the need to identify antecedents and correlates of such daily physical activity episodes.     

Inhibitory dendrite dynamics as a general feature of the adult cortical microcircuit

The mammalian neocortex is functionally subdivided into architectonically distinct regions that process various types of information based on their source of afferent input. Yet, the modularity of neocortical organization in terms of cell type and intrinsic circuitry allows afferent drive to continuously reassign cortical map space. New aspects of cortical map plasticity include dynamic turnover of dendritic spines on pyramidal neurons and remodeling of interneuron dendritic arbors. While spine remodeling occurs in multiple cortical regions, it is not yet known whether interneuron dendrite remodeling is common across primary sensory and higher-level cortices. It is also unknown whether, like pyramidal dendrites, inhibitory dendrites respect functional domain boundaries. Given the importance of the inhibitory circuitry to adult cortical plasticity and the reorganization of cortical maps, we sought to address these questions by using two-photon microscopy to monitor interneuron dendritic arbors of thy1-GFP-S transgenic mice expressing GFP in neurons sparsely distributed across the superficial layers of the neocortex. We find that interneuron dendritic branch tip remodeling is a general feature of the adult cortical microcircuit, and that remodeling rates are similar across primary sensory regions of different modalities, but may differ in magnitude between primary sensory versus higher cortical areas. We also show that branch tip remodeling occurs in bursts and respects functional domain boundaries.     

Angiotensin-converting enzyme (CD143) marks hematopoietic stem cells in human embryonic, fetal, and adult hematopoietic tissues

Previous studies revealed that mAb BB9 reacts with a subset of CD34(+) human BM cells with hematopoietic stem cell (HSC) characteristics. Here we map BB9 expression throughout hematopoietic development and show that the earliest definitive HSCs that arise at the ventral wall of the aorta and surrounding endothelial cells are BB9(+). Thereafter, BB9 is expressed by primitive hematopoietic cells in fetal liver and in umbilical cord blood (UCB). BB9(+)CD34(+) UCB cells transplanted into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice contribute 10-fold higher numbers of multilineage blood cells than their CD34(+)BB9(-) counterparts and contain a significantly higher incidence of SCID-repopulating cells than the unfractionated CD34(+) population. Protein microsequencing of the 160-kDa band corresponding to the BB9 protein established its identity as that of somatic angiotensin-converting enzyme (ACE). Although the role of ACE on human HSCs remains to be determined, these studies designate ACE as a hitherto unrecognized marker of human HSCs throughout hematopoietic ontogeny and adulthood.     

Making meaning: the creative component in qualitative research

Findings in qualitative research are often wondrous and exciting, expounding new knowledge and perceptions previously unknown. Qualitative research requires the researcher to ponder and reflect on the data collected so as to find the meaning within. Helping researchers learn how to perform this step is not well discussed in the qualitative literature, yet this is one of the more crucial components of this type of research. In this article, the incubation, the meaning-making phase of qualitative research, is discussed in relation to the experiences of five researchers who have used traditional processes, models, metaphors, plays, pastiche, poetry, and quilt making and design to help them make meaning.     

Event-related potentials reflect individual differences in age-invariant auditory skills

Previous work has found that auditory event-related potentials show maturational changes, with latency and amplitude of late components (N1 and P2) decreasing and increasing with age respectively. Our goal was to test the hypothesis that these changes reflect increased speed of neural processing in the auditory system. Thirty-three listeners, aged 10-50 years, were tested on a frequency discrimination task and an auditory backward recognition masking task. P1 and N1b event-related potential components were measured to tones. The N1b became larger and earlier with age, and the latency of P1 decreased with age. However, thresholds on the behavioural tasks did not change with age. Nevertheless, individual differences in the peak amplitude of N1b were independently related to frequency discrimination and degree of masking. Thus, the relationship that does exist between individual differences in psychoacoustic performance and the auditory N1b reflect a stable characteristic of the individual rather than a maturational change.     

Growth phase-dependent expression of ICAD-L/DFF45 modulates the pattern of apoptosis in human colonic cancer cells

The inhibitor of caspase-3-activated DNase (ICAD) is a caspase-3 substrate that controls nuclear apoptosis. ICAD has two isoforms: a functional isoform of M(r) 45,000, ICAD-L/DNA fragmentation factor (DFF) 45; and a M(r) 35,000 isoform, ICAD-S/DFF35. ICAD-deficient murine cells display resistance to apoptotic stimuli and absence of typical nuclear changes of apoptosis. Our aim was to: (a) characterize the ICAD expression in several human colonic cancer cell lines compared with human normal colonocytes; and (b) correlate the phenotypic features of apoptosis to the level of ICAD expression. ICAD expression was assessed by immunoblot analysis. Early markers of apoptosis of cultured cells included lactate dehydrogenase retention in dying cells, cytokeratin 18 cleavage, and caspase-3 activation. Nuclear markers of apoptosis were assessed by Hoechst staining of nuclei, electron microscopy, and DNA electrophoresis. Inhibition of caspases was performed using a broad-spectrum caspase inhibitor, z-Val-Ala-Asp-fluoromethyl ketone. ICAD expression was restricted to the functional ICAD-L/DFF45 isoform in colonic cancer cells as well as in human normal colonocytes. In a clonal derivative of HT29 cells (HT29-Cl.16E cells), ICAD expression was found to be down-regulated during the exponential phase of growth, and the cell death triggered by IFN-gamma, anti-Fas antibody plus Adriamycin was characterized by the expression of early markers of apoptosis, whereas the key nuclear features of apoptosis were absent. In contrast, exposure of confluent cells to this treatment led to a typical apoptotic nuclear fragmentation. Both forms of apoptosis, in exponentially growing and confluent cells, were sensitive to the broad spectrum inhibitor of caspases, z-Val-Ala-Asp-fluoromethyl ketone. Our findings support the concept that the expression of ICAD is essential to the execution of full-blown apoptosis in colonic cancer cells. Altogether, our results point to ICAD as a potential target for restoring a normal apoptotic signal transduction pathway in colonic cancer cells.     

Breast cancer mortality among female radiologic technologists in the United States

We evaluated breast cancer mortality through 1997 among 69 525 female radiologic technologists who were certified in the United States from 1926 through 1982 and who responded to our questionnaire. Risk of breast cancer mortality was examined according to work history and practices and was adjusted for known risk factors. Breast cancer mortality risk was highest among women who were first employed as radiologic technologists prior to 1940 (relative risk [RR] = 2.92, 95% confidence interval [CI] = 1.22 to 7.00) compared with risk of those first employed in 1960 or later and declined with more recent calendar year of first employment (P for trend =.002). Breast cancer mortality risk increased with increasing number of years of employment as a technologist prior to 1950 (P for trend =.018). However, risk was not associated with the total number of years a woman worked as a technologist. Technologists who first performed fluoroscopy (RR = 1.69, 95% CI = 1.02 to 3.11) and multifilm procedures (RR = 1.87, 95% CI = 1.04 to 3.34) before 1950 had statistically significantly elevated risks compared with technologists who first performed these procedures in 1960 or later. The high risks of breast cancer mortality for women exposed to occupational radiation prior to 1950 and the subsequent decline in risk are consistent with the dramatic reduction in recommended radiation exposure limits over time.