Relationships Between Neighbourhood Physical Environmental Attributes and Older Adults' Leisure-Time Physical Activity: A Systematic Review and Meta-Analysis.

BACKGROUND: Activity-friendly neighbourhood physical environments with access to recreational facilities are hypothesised to facilitate leisure-time physical activity (LTPA) among older adults (≥ 65 years old). The aim of the current study was to systematically review and quantitatively summarise study findings on the relationships between physical environmental attributes and LTPA among older adults. METHODS: An extensive search of literature, including grey literature, yielded 72 articles eligible for inclusion. The reported associations between seven categories of environmental attributes and six LTPA outcomes were extracted, weighted by sample size and study quality, and quantitatively summarised. Reported moderating effects of individual and environmental characteristics and neighbourhood definition were also examined. RESULTS: We observed positive associations for walkability (p = 0.01), land-use mix-access (p = 0.02) and aesthetically pleasing scenery (p < 0.001) with leisure-time walking. For leisure-time walking within the neighbourhood, evidence was found for positive associations with land-use mix-access (p = 0.03) and access to public transit (p = 0.05), and a negative association with barriers to walking/cycling (p = 0.03). Evidence for positive relationships between overall LTPA and access to recreational facilities (p = 0.01) and parks/open space (p = 0.04) was found. Several environmental attribute-LTPA outcome combinations were insufficiently studied to draw conclusions. No consistent moderating effects were observed for individual and environmental characteristics and neighbourhood definition. CONCLUSIONS: The observed significant relationships can be used to inform policy makers and planners on how to (re-)design neighbourhoods that promote LTPA among older adults. Many environmental attribute-LTPA outcome relationships have been studied insufficiently and several methodological issues remain to be addressed. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO 2016:CRD42016051180.

Built environmental correlates of older adults' total physical activity and walking: a systematic review and meta-analysis.

BACKGROUND: Identifying attributes of the built environment associated with health-enhancing levels of physical activity (PA) in older adults (≥65 years old) has the potential to inform interventions supporting healthy and active ageing. The aim of this study was to first systematically review and quantify findings on built environmental correlates of older adults' PA, and second, investigate differences by type of PA and environmental attribute measurement. METHODS: One hundred articles from peer-reviewed and grey literature examining built environmental attributes related to total PA met inclusion criteria and relevant information was extracted. Findings were meta-analysed and weighted by article quality and sample size and then stratified by PA and environmental measurement method. Associations (p < .05) were found in relation to 26 individual built environmental attributes across six categories (walkability, residential density/urbanisation, street connectivity, access to/availability of destinations and services, infrastructure and streetscape, and safety) and total PA and walking specifically. Reported individual- and environmental-level moderators were also examined. RESULTS: Positive environmental correlates of PA, ranked by strength of evidence, were: walkability (p < .001), safety from crime (p < .001), overall access to destinations and services (p < .001), recreational facilities (p < .001), parks/public open space (p = .002) and shops/commercial destinations (p = .006), greenery and aesthetically pleasing scenery (p = .004), walk-friendly infrastructure (p = .009), and access to public transport (p = .016). There were 26 individual differences in the number of significant associations when the type of PA and environmental measurement method was considered. No consistent moderating effects on the association between built environmental attributes and PA were found. CONCLUSIONS: Safe, walkable, and aesthetically pleasing neighbourhoods, with access to overall and specific destinations and services positively influenced older adults' PA participation. However, when considering the environmental attributes that were sufficiently studied (i.e., in ≥5 separate findings), the strength of evidence of associations of specific categories of environment attributes with PA differed across PA and environmental measurement types. Future research should be mindful of these differences in findings and identify the underlying mechanisms. Higher quality research is also needed.

The neighbourhood physical environment and active travel in older adults: a systematic review and meta-analysis.

BACKGROUND: Perceived and objectively-assessed aspects of the neighbourhood physical environment have been postulated to be key contributors to regular engagement in active travel (AT) in older adults. We systematically reviewed the literature on neighbourhood physical environmental correlates of AT in older adults and applied a novel meta-analytic approach to statistically quantify the strength of evidence for environment-AT associations. METHODS: Forty two quantitative studies that estimated associations of aspects of the neighbourhood built environment with AT in older adults (aged ≥ 65 years) and met selection criteria were reviewed and meta-analysed. Findings were analysed according to five AT outcomes (total walking for transport, within-neighbourhood walking for transport, combined walking and cycling for transport, cycling for transport, and all AT outcomes combined) and seven categories of the neighbourhood physical environment (residential density/urbanisation, walkability, street connectivity, access to/availability of services/destinations, pedestrian and cycling infrastructure, aesthetics and cleanliness/order, and safety and traffic). RESULTS: Most studies examined correlates of total walking for transport. A sufficient amount of evidence of positive associations with total walking for transport was found for residential density/urbanisation, walkability, street connectivity, overall access to destinations/services, land use mix, pedestrian-friendly features and access to several types of destinations. Littering/vandalism/decay was negatively related to total walking for transport. Limited evidence was available on correlates of cycling and combined walking and cycling for transport, while sufficient evidence emerged for a positive association of within-neighbourhood walking with pedestrian-friendly features and availability of benches/sitting facilities. Correlates of all AT combined mirrored those of walking for transport. Positive associations were also observed with food outlets, business/institutional/industrial destinations, availability of street lights, easy access to building entrance and human and motorised traffic volume. Several but inconsistent individual- and environmental-level moderators of associations were identified. CONCLUSIONS: Results support strong links between the neighbourhood physical environment and older adults' AT. Future research should focus on the identification of types and mixes of destinations that support AT in older adults and how these interact with individual characteristics and other environmental factors. Future research should also aim to clarify dose-response relationships through multi-country investigations and data-pooling from diverse geographical regions.

Effects of power frequency electromagnetic fields on melatonin and sleep in the rat.

BACKGROUND: Studies investigating the effect of power frequency (50-60 Hz) electromagnetic fields (EMF) on melatonin synthesis in rats have been inconsistent with several showing suppression of melatonin synthesis, others showing no effect and a few actually demonstrating small increases. Scant research has focused on the ensuing sleep patterns of EMF exposed rats. The present study was designed to examine the effects of extremely low power frequency electromagnetic fields (EMF) on the production of melatonin and the subsequent sleep structure in rats. METHODS: Eighteen male Sprague-Dawley rats were exposed to a 1000 milligauss (mG) magnetic field for 1 month. Urine was collected for the final 3 days of the exposure period for analysis of 6-sulphatoxymelatonin, the major catabolic product of melatonin found in urine. Subsequent sleep was analyzed over a 24-hour period. RESULTS: Melatonin production was mildly increased in exposed animals. Although there were no statistically significant changes in sleep structure, exposed animals showed slight decreases in REM (rapid eye movement) sleep as compared to sham (non-exposed) animals. CONCLUSIONS: Power frequency magnetic fields induced a marginally statistically significant increase in melatonin levels in exposed rats compared to control. Subsequent sleep analysis indicated little effect on the sleep architecture of rats, at least not within the first day after 1 month's continuous exposure. Varying results in the literature are discussed and future research suggested.

Ruptured intracranial dermoid cyst.

Rupture of an intracranial dermoid cyst is a rare event with considerable associated morbidity and potential mortality. We present a case of intracranial rupture of a dermoid cystic tumor with consequent dissemination of subarachnoid fat droplets resulting in acute aseptic chemical meningitis. Radiographic findings, operative treatment, and pathologic features are described.

Fiducial marker placement for intraoperative spine localization.

In recent years, there has been a great increase in the number of cases of image-guided fiducial marker placement for the purposes of stereotactic radiosurgery. At the authors' parent institution, a tertiary referral academic medical center, the placement of fiducial markers has also been used for the purposes of localization before spine surgery. Given the reported prevalence of "wrong-site" surgical intervention documented in the medical literature, particularly involving spinal surgery, the neurosurgical department at the authors' institution has requested the expertise of interventional radiology for assistance in preoperative spine localization. Therefore, there are medicolegal, medical cost, and patient care implications of image-guided fiducial marker placement.

Electrical activity and exocytotic correlates of biphasic insulin secretion from beta-cells of canine islets of Langerhans: contribution of tuning two modes of Ca2+ entry-dependent exocytosis to two modes of glucose-induced electrical activity.

Biphasic insulin secretion in response to glucose, consisting of a transient first phase followed by a progressive second phase, is well described in pancreatic islets. Using single canine beta-cells we have compared the time courses of electrical activity and insulin granule exocytosis to biphasic insulin secretion. Short trains of action potentials, similar those found during first phase insulin secretion, trigger phasic exocytosis from a small pool of insulin granules, likely an immediately releasable pool docked near voltage activated Ca(2+) channels. In contrast, plateau depolarizations to between -35 and -20 mV resembling those during second phase insulin secretion, trigger tonic exocytosis from a larger pool of insulin granules, likely a highly Ca(2+)-sensitive pool farther from Ca(2+) channels. Both phasic and tonic modes of exocytosis are enhanced by glucose, via its metabolism. Hence, in canine beta-cells two distinct components of exocytosis, tuned to two components of electrical activity, may contribute significantly to biphasic insulin secretion.

Ion channels underlying stimulus-exocytosis coupling and its cell-to-cell heterogeneity in beta-cells of transplantable porcine islets of Langerhans.

Given the growing interest in porcine islets as model tissue for studying the pathogenesis of human diabetes mellitus and its treatment by transplantation, we investigated stimulus-exocytosis coupling in single porcine beta-cells using patch clamp electrophysiology, Ca2+ imaging, capacitance tracking and amperometry. We establish that porcine beta-cells display several features prominently seen in beta-cells from human islets of Langerhans. These include: (i) wide heterogeneity of electrical responsiveness to glucose; (ii) dependence of action potential activity on voltage-dependent Na(+) as well as high voltage activated Ca2+ current; (iii) heterogeneity of time course of depolarization-evoked insulin granule exocytosis; and (iv) the dependence of vigorous single cell electrical activity and insulin granule exocytosis on the presence of agents that enhance cytosolic cAMP concentration. These findings promote the usefulness of porcine beta-cells as a model for studying beta-cell function in large mammals, including humans, as well as an appropriate source of tissue for xenotransplantation.

Multidisciplinary treatment of a large cerebral dural arteriovenous fistula using embolization, surgery, and radiosurgery.

Dural arteriovenous fistulae are rare lesions composed of abnormal connections between meningeal arteries and the dural sinuses or lepto-meningeal veins. Treatment is challenging because of the small size and wide distribution of the myriad sites of fistulous connection. We present a case of a dural arteriovenous fistula presenting with visual deterioration, pulsatile tinnitus, and intracranial hypertension that was successfully treated with a multidisciplinary approach combining angiographic, surgical, and radiosurgical intervention. This is one of the largest of these formidable lesions treated in this fashion that has been reported.

Sleep-stage scoring in the rat using a support vector machine.

Analysis and classification of sleep stages is a fundamental part of basic sleep research. Rat sleep stages are scored based on electrocorticographic (ECoG) signals recorded from electrodes implanted epidurally and electromyographic (EMG) signals from the temporalis or nuchal muscle. An automated sleep scoring system was developed using a support vector machine (SVM) to discriminate among waking, nonrapid eye movement sleep, and paradoxical sleep. Two experts scored retrospective data obtained from six Sprague-Dawley rodents to provide the training sets and subsequent comparison data used to assess the effectiveness of the SVM. Numerous time-domain and frequency-domain features were extracted for each epoch and selectively reduced using statistical analyses. The SVM kernel function was chosen to be a Gaussian radial basis function and kernel parameters were varied to examine the effectiveness of optimization methods. Tests indicated that a common set of features could be chosen resulted in an overall agreement between the automated scores and the expert consensus of greater than 96%.

Optimization of microelectrode design for cortical recording based on thermal noise considerations.

Intracortical microelectrode recordings of neural activity show great promise as control signals for neuroprosthetic applications. However, faithful, consistent recording of single unit spiking activity with chronically implanted silicon-substrate microelectrode arrays has proven difficult. Many approaches seek to enhance the long-term performance of microelectrode arrays by, for example, increasing electrode biocompatibility, decreasing electrode impedance, or improving electrode interface properties through application of small voltage pulses. The purpose of this study was to use computational models to optimize the design of microelectrodes. We coupled detailed models of the neural source signal, silicon-substrate microelectrodes, and thermal noise to define the electrode contact size that maximized the signal-to-noise ratio (SNR). Model analysis combined a multi-compartment cable model of a layer V cortical pyramidal neuron with a 3D finite element model of the head and microelectrode to define the amplitude and time course of the recorded signal. A spatially-lumped impedance model was parameterized with in vitro and in vivo spectroscopy data and used to define thermal noise as a function of electrode contact size. Our results suggest that intracortical microelectrodes with a contact size of ~380 microm2 will provide an increased SNR in vivo and improve the long-term recording capabilities of silicon-substrate microelectrode arrays.

Maintenance of stimulus-secretion coupling and single beta-cell function in cryopreserved-thawed human islets of Langerhans.

Studies of stimulus-secretion coupling in human beta-cells have been hampered by poor availability of tissue due to variability of the supply of cadaver pancreati and in the adequacy of enzymatic liberation of islets as well as by the shunting of isolates into transplant trials. Here we establish that aliquots of islets, several from high-quality but low-yield islet isolates (50,000-100,000 islets), cryopreserved and then thawed as needed, respond to glucose in a calcium- and metabolic-dependent fashion. Insulin secretion is modulated by blockers of voltage-dependent Na+ and Ca2+ channels, and paracrine hormones (glucagon and somatostatin) in manners indistinguishable from fresh tissue preparations. Using single-cell electrophysiological and electrochemical assays we demonstrate that single beta-cells from cryopreserved islets display (1) stimulus-depolarization coupling based on rapid closure of K+ (ATP) channels; (2) action potential electrogenesis with upstrokes based on voltage-dependent Na and Ca currents; and (3) Ca2+ entry-mediated depolarization-exocytosis coupling sustained over multiple bouts of stimulation and modulated by paracrine hormones. All of these features are indistinguishable from those seen in single cells from freshly harvested islets. These results support the utility of cryopreservation, even of low-yield but functional isolates, as a means of ensuring a steady source of repeatedly accessible tissue for research on normal and diabetic islets.

alpha-Latrotoxin increases spontaneous and depolarization-evoked exocytosis from pancreatic islet beta-cells.

alpha-Latrotoxin (alpha-LT), a potent excitatory neurotoxin, increases spontaneous, as well as action potential-evoked, quantal release at nerve terminals and increases hormone release from excitable endocrine cells. We have investigated the effects of alpha-LT on single human, mouse and canine beta-cells. In isolated and combined measurements, alpha-LT, at nanomolar concentrations, induces: (i) rises in cytosolic Ca(2+), into the micromolar range, that are dependent on extracellular Ca(2+); (ii) large conductance non-selective cation channels; and (iii) Ca(2+)-dependent insulin granule exocytosis, measured as increases in membrane capacitance and quantal release of preloaded serotonin. Furthermore, at picomolar concentrations, alpha-LT potentiates depolarization-induced exocytosis often without evidence of inducing channel activity or increasing cytosolic Ca(2+). These results strongly support the hypothesis that alpha-LT, after binding to specific receptors, has at least two complementary modes of action on excitable cells. (i) alpha-LT inserts into the plasma membrane to form Ca(2+) permeable channels and promote Ca(2+) entry thereby triggering Ca(2+)-dependent exocytosis in unstimulated cells. (ii) At lower concentrations, where its channel forming activity is hardly evident, alpha-LT augments depolarization-evoked exocytosis probably by second messenger-induced enhancement of the efficiency of the vesicle recruitment or vesicle fusion machinery. We suggest that both modes of action enhance exocytosis from a newly described highly Ca(2+)-sensitive pool of insulin granules activated by global cytosolic Ca(2+) concentrations in the range of approximately 1 microm.

Respiratory syncytial virus infection and the primary care physician.

Respiratory syncytial virus (RSV) infection is a common viral illness affecting almost all children within their first few years of life. In most young children, RSV results in a mild respiratory infection. It is, however, the single most important cause of bronchiolitis and pneumonitis in infancy and contributes to significant morbidity and even mortality in a subset of high-risk children. There are new developments in the diagnosis, treatment, and prevention of RSV infection in infants and children. Early recognition of young children at high risk for severe RSV infection and apnea can help to minimize the morbidity and mortality.