Translate this page to:
Choose Language…
In JoVE (1)
Other Publications (6)
Articles by D. Sesath Hewapathirane in JoVE
JoVE General
Single Cell Electroporation in vivo within the Intact Developing Brain
1Brain Research Centre, University of British Columbia - UBC, 2Department of Cellular and Physiological Sciences, University of British Columbia - UBC
Single-cell electroporation (SCE) is a specialized technique allowing delivery of DNA or other macromolecules into individual cells within intact tissue, including in vivo preparations. Here we detail the procedure for SCE of a fluorescent dye or plasmid DNA into neurons within the intact brain of the Xenopus laevis tadpole.
Other articles by D. Sesath Hewapathirane on PubMed
Propagation of Amygdala-kindled Seizures to the Hippocampus in the Rat: Electroencephalographic Features and Behavioural Correlates
The propagation of amygdala-kindled seizures to the dorsal and ventral hippocampus was examined, in rats. The relation of contralateral seizure propagation to the onset of generalized convulsions was also studied.
In Vivo Imaging of Seizure Activity in a Novel Developmental Seizure Model
The immature brain is exceptionally susceptible to seizures. However, it remains unclear whether seizures occurring during development affect critical processes underlying neural circuit formation, leading to long-term functional consequences. Here we characterize a novel in vivo model system of developmental seizures based on the transparent albino Xenopus laevis tadpole, which allows direct examination of seizure activity, and seizure-induced effects on neuronal development within the intact unanesthetized brain. Pentylenetetrazol (PTZ), kainic acid, bicuculline, picrotoxin, 4-aminopyridine, and pilocarpine were tested for their ability to induce behavioral seizures in freely swimming tadpoles when bath applied. All six chemoconvulsants consistently induced similar patterns of abnormal behavior in a dose-dependent manner, characterized by convulsive clonus-like motor patterns with periods of behavioral arrest. Extracellular field recordings demonstrated rhythmic synchronous epileptiform electrographic responses induced by convulsants irrespective of mechanism of action, that could be terminated by the anti-epileptic drug valproate. PTZ-induced seizures were further characterized using in vivo two-photon fluorescence imaging of neuronal calcium dynamics, in unanesthetized immobilized tadpoles. Imaging of calcium dynamics during PTZ-induced seizures revealed waves of neural activity propagating through large populations of neurons within the brain. Analysis of single-cell responses demonstrated distinct synchronized high-amplitude calcium spikes not observed under baseline conditions. Similar to other developmental seizure models, prolonged seizures failed to induce marked neuronal death within the brain, detected by cellular propidium iodide incorporation in vivo or TUNEL labeling. This novel developmental seizure model system has distinct advantages for controlled seizure induction, and direct visualization of both seizure activity and seizure-induced effects on individual developing neurons within the intact unanesthetized brain. Such a system is necessary to address important questions relating to the long-term impact of common perinatal seizures on developing neural circuits.
Dynamic Morphometrics Reveals Contributions of Dendritic Growth Cones and Filopodia to Dendritogenesis in the Intact and Awake Embryonic Brain
Using in vivo rapid and long-interval two-photon time-lapse imaging of brain neuronal growth within the intact and unanesthetized Xenopus laevis tadpole, we characterize dynamic dendritic growth behaviors of filopodia, branches, and dendritic growth cones (DGCs), and analyze their contribution to persistent arbor morphology. The maturational progression of dynamic dendritogenesis was captured by short-term, 5 min interval, imaging for 1h every day for 5 days, and the contribution of short-term growth to persistent structure was captured by imaging at 5 min intervals for 5h, and at 2h intervals for 10h during the height of arbor growth. We find that filopodia and branch stability increases with neuronal maturation, and while the vast majority of dendritic filopodia rapidly retract, 3-7% of interstitial filopodia transition into persistent branches with lifetimes greater than 90 min. Here, we provide the first characterization of DGC dynamics, including morphology and behavior, in the intact and awake developing vertebrate brain. We find that DGCs occur on all growing branches indicating an essential role in branch elongation, and that DGC morphology correlates with dendritic branch growth behavior and varies with maturation. These results demonstrate that dendritogenesis involves a remarkable amount of continuous remodeling, with distinct roles for filopodia and DGCs across neuronal maturation. © 2011 Wiley Periodicals, Inc. Develop Neurobiol, 2011.
Baseline Knowledge on Vehicle Safety and Head Restraints Among Fleet Managers in British Columbia Canada: a Pilot Study
Whiplash is the most common injury type arising from motor vehicle collisions, often leading to long-term suffering and disability. Prevention of such injuries is possible through the use of appropriate, correctly positioned, vehicular head restraints.
Does Obesity Increase the Risk of Injury or Mortality in Motor Vehicle Crashes? A Systematic Review and Meta-Analysis
OBJECTIVES: . The objective of this review was to assess the risk of obesity in injuries and fatalities resulting from motor vehicle crash (MVC), as compared with individuals with a normal-range body mass index. METHODS: . A systematic review of the literature was conducted yielding 824 potential studies. Nine of these studies met our inclusion criteria. Meta-analyses examining obesity as a risk factor for various injury types and risk of fatality were conducted using data from these studies. RESULTS: . Obesity was associated with higher fatality risk (odds ratio [OR] = 1.89, 95% confidence interval [CI] = 1.51-2.37, P = .0001; pooled estimate from 6 studies), and increased risk of lower extremity fractures (OR = 1.39, 95% CI = 1.18-1.65, P = .0001; pooled estimate from 2 studies). No significant differences were observed when considering abdominal injuries or pelvic fractures. Interestingly, for head injuries obesity was a protective factor (OR = 0.67, 95% CI = 0.46-0.97, P = .0001; pooled data from 3 studies). CONCLUSIONS: . Evidence strongly supports the association of obesity with higher fatality and fractures of the lower extremities in MVCs. Contrary to our hypothesis, 3 studies showed that obesity was a protective factor in reducing head injuries. Furthermore, the review shows that obesity was not a risk factor of MVC-related pelvic fractures and abdominal injuries.
Bull Bars and Vulnerable Road Users
Pedestrian injuries are a leading cause of the global death and injury burden, accounting for 65 percent of the 1.2 million annual road deaths. The purpose of this brief literature review is to examine whether bull bars, a rigid aftermarket accessory fitted to the front end of passenger vehicles, increase the risk of severe and fatal injuries to vulnerable road users in the event of a collision.
