After brain damage such as stroke, topographically organized sensory and motor cortical representations remap onto adjacent surviving tissues. It is conceivable that cortical remapping is accomplished by changes in the temporal precision of sensory processing and regional connectivity in the cortex. To understand how the adult cortex remaps and processes sensory signals during stroke recovery, we performed in vivo imaging of sensory-evoked changes in membrane potential, as well as multiphoton imaging of dendrite structure and tract tracing. In control mice, forelimb stimulation evoked a brief depolarization in forelimb cortex that quickly propagated to, and dissipated within, adjacent motor/hindlimb areas (Ͻ100 ms). One week after forelimb cortex stroke, the cortex was virtually unresponsive to tactile forelimb stimulation. After 8 weeks recovery, forelimb-evoked depolarizations reemerged with a characteristic pattern in which responses began within surviving portions of forelimb cortex (Ͻ20 ms after stimulation) and then spread horizontally into neighboring peri-infarct motor/hindlimb areas in which depolarization persisted 300 -400% longer than controls. These uncharacteristically prolonged responses were not limited to the remapped peri-infarct zone and included distant posteromedial retrosplenial cortex, millimeters from the stroke. Structurally, the remapped peri-infarct area selectively exhibited high levels of dendritic spine turnover, shared more connections with retrosplenial cortex and striatum, and lost inputs from lateral somatosensory cortical regions. Our findings demonstrate that sensory remapping during stroke recovery is accompanied by the development of prolonged sensory responses and new structural circuits in both the peri-infarct zone as well as more distant sites.
Most processing of sensation involves the cortical hemisphere opposite (contralateral) to the stimulated limb. Stroke patients can exhibit changes in the interhemispheric balance of sensory signal processing. It is unclear whether these changes are the result of poststroke rewiring and experience, or whether they could result from the immediate effect of circuit loss. We evaluated the effect of mini-strokes over short timescales (<2 h) where cortical rewiring is unlikely by monitoring sensory-evoked activity throughout much of both cortical hemispheres using voltage-sensitive dye imaging. Blockade of a single pial arteriole within the C57BL6J mouse forelimb somatosensory cortex reduced the response evoked by stimulation of the limb contralateral to the stroke. However, after stroke, the ipsilateral (uncrossed) forelimb response within the unaffected hemisphere was spared and became independent of the contralateral forelimb cortex. Within the unaffected hemisphere, mini-strokes in the opposite hemisphere significantly enhanced sensory responses produced by stimulation of either contralateral or ipsilateral pathways within 30-50 min of stroke onset. Stroke-induced enhancement of responses within the spared hemisphere was not reproduced by inhibition of either cortex or thalamus using pharmacological agents in nonischemic animals. I/LnJ acallosal mice showed similar rapid interhemispheric redistribution of sensory processing after stroke, suggesting that subcortical connections and not transcallosal projections were mediating the novel activation patterns. Thalamic inactivation before stroke prevented the bilateral rearrangement of sensory responses. These findings suggest that acute stroke, and not merely loss of activity, activates unique pathways that can rapidly redistribute function within the spared cortical hemisphere.ischemia | plasticity | in vivo imaging | recovery of cortical function | thalamocortical circuit
A lthough obesity is a preventable condition, rates worldwide have doubled since 1980. 1 Being overweight or obese is the fifth leading risk factor for global deaths, 1 and excess weight significantly increases the risk of chronic illnesses such as cardiovascular disease, stroke, diabetes, and some cancers. 2,3 While it is perceived as a problem predominantly in industrialized nations, obesity is now a growing concern in developing countries 4 and poses a financial burden in many regions. In Canada, the estimated cost of obesity to the economy was $4.6 billion in 2008, up approximately 20% from the year 2000. 5 While province-specific Canadian data have been collected on an ongoing basis, and the epidemic rise in obesity has been noted in reports such as the recent Public Health Agency of Canada report, Obesity in Canada, 5 provincial obesity surveillance maps have not been published since 2002, when data from the 1995 to 1998 period were presented. 6 Our approach to data presentationusing colour-coded depictions of changes in obesity rates over time -is a graphic way to communicate the changing prevalence of obesity that is appropriate for both public and professional audiences. The purpose of this paper is to update Canada's obesity maps with data collected between 2000 and 2011 to more accurately reflect estimated obesity rates across Canada. METHODSSources of data were extracted from the Canadian Community Health Survey (CCHS); data included self-reported height and weight for 2000, 2003, 2005, and 2007-11. The data were drawn from annual health indicator profiles for each province as reported on the Statistics Canada website, 7 except for the year 2000, where data were provided in response to a request to Statistics Canada. 8 Body mass index (BMI) was calculated for all eligible respondents aged 18 and older based on their self-reported heights and weights,
The use of ureteral access sheaths (UAS) is common practice during routine flexible ureteroscopy procedures. However, debates and concerns continue amongst endourologists on routine UAS placement. UAS placement allows for multiple passages of the ureteroscope, decreases intrarenal pressure, and may improve stone-free rates. However, concerns for the UAS's effectiveness in these claimed benefits and complications related to UAS placement has been documented and investigated by many. In this review, we will discuss the controversies surrounding the placement of UAS during ureteroscopy.
Radical cystectomy (RC) with urinary diversion is considered the standard treatment for muscle invasive bladder cancer (MIBC). As one of the most challenging surgical techniques performed by urologists, RC was described many decades ago, and yet patient morbidity rates have remained stagnant over the years.This review outlines the most recent indications and techniques for RC and analyses the current landscape of complications after cystectomy. There is significant room for improvement with respect to both oncologic and functional outcomes after RC. Future efforts will need to focus on unifying reporting methodology, optimal patient selection criteria, enhanced surgical techniques and peri-operative care pathways, and technological advances to improve patient outcomes.
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