BCIT Citations Collection | BCIT Institutional Repository

BCIT Citations Collection

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Collection of published works from BCIT researchers, faculty, and instructors.

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Protracted myelin clearance hinders central primary afferent regeneration following dorsal rhizotomy and delayed neurotrophin-3 treatment
Regeneration within or into the CNS is thwarted by glial inhibition at the site of a spinal cord injury and at the dorsal root entry zone (DREZ), respectively. At the DREZ, injured axons and their distal targets are separated by degenerating myelin and an astrocytic glia limitans. The different glial barriers to regeneration following dorsal rhizotomy are temporally and spatially distinct. The more peripheral astrocytic barrier develops first, and is surmountable by neurotrophin-3 (NT-3) treatment; the more central myelin-derived barrier, which prevents dorsal horn re-innervation by NT-3-treated axons, becomes significant only after the onset of myelin degeneration. Here we test the hypothesis that in the presence of NT-3, axonal regeneration is hindered by myelin degeneration products. To do so, we used the Long Evans Shaker (LES) rat, in which oligodendrocytes do not make CNS myelin, but do produce myelin-derived inhibitory proteins. We show that delaying NT-3 treatment for 1 week in normal (LE) rats, while allowing axonal penetration of the glia limitans and growth within degenerating myelin, results in misdirected regeneration with axons curling around presumptive degenerating myelin ovoids within the CNS compartment of the dorsal root. In contrast, delaying NT-3 treatment in LES rats resulted in straighter, centrally-directed regenerating axons. These results indicate that regeneration may be best optimized through a combination of neurotrophin treatment plus complete clearance of myelin debris., Peer-reviewed article, Published. Received 3 June 2006, Revised 8 September 2006, Accepted 8 September 2006, Available online 22 November 2006.
Quantification of pyrrolizidine alkaloids in North American plants and honey by LC-MS
Pyrrolizidine alkaloids (PAs) are a class of naturally occurring compounds produced by many flowering plants around the World. Their presence as contaminants in food systems has become a significant concern in recent years. For example, PAs are often found as contaminants in honey through pollen transfer. A validated method was developed for the quantification of four pyrrolizidine alkaloids and one pyrrolizidine alkaloidN-oxide in plants and honey grown and produced in British Columbia. The method was optimised for extraction efficiency from the plant materials and then subjected to a single-laboratory validation to assess repeatability, accuracy, selectivity, LOD, LOQ and method linearity. The PA content in plants ranged from1.0 to 307.8 µg/g with repeatability precision between 3.8 and 20.8% RSD. HorRat values were within acceptable limits and ranged from 0.62 to 1.63 for plant material and 0.56–1.82 for honey samples. Method accuracy was determined through spike studies with recoveries ranging from 84.6 to 108.2% from the raw material negative control and from 82.1–106.0 % for the pyrrolizidine alkaloids in corn syrup. Based on the findings in this single-laboratory validation, this method is suitable for the quantitation of lycopsamine, senecionine, senecionineN-oxide, heliosupine and echimidine in common comfrey (Symphytum officinale), tansy ragwort (Senecio jacobaea), blueweed (Echium vulgare) and hound’s tongue (Cynoglossum officinale)and for PA quantitation in honey and found that PA contaminants were present at low levels in BC honey., Peer-reviewed article, Published. Received 4 June 2015; accepted 20 September 2015.
A quantitative study of cotyledon positioning in conifer development
The number of cotyledons in angiosperm monocots and dicots is tightly constrained. But in the gymnosperm Pinaceae (pine family), which includes many of the conifers, cotyledon number ( nc) can vary widely, commonly from 2 to 12. Conifer cotyledons form in whorled rings on a domed embryo geometry. We measured the diameter of embryos and counted the cotyledons to determine the radial positioning of the whorl and the circumferential spacing between cotyledons. Results were similar between Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco), Sitka spruce ( Picea sitchensis (L.) H.Karst .), and larch ( Larix × leptoeuropaea, synonymous with L. × marschlinsii Coaz), indicating a common mechanism for cotyledon positioning in conifers. Disrupting transport of the growth regulator auxin (with 1- N-naphthylphthalamic acid (NPA)) led to cup-shaped embryos, indicating that whorl (ring) formation is separable from cotyledon patterning within the ring. NPA inhibits cotyledon outgrowth, but not the spacing (distance) between cotyledons. The NPA effect is direct; it does not operate indirectly on embryo size. These results support a hierarchical model for cotyledon positioning in conifers, in which a first stage (not requiring auxin transport) sets the whorl position, constraining the second stage (which requires auxin transport) to form cotyledons within this whorl. Similarly, recent studies in Arabidopsis have shown that different components of complex developmental patterns can have different transport properties; this aspect of patterning may be shared across plants., Peer-reviewed article, Published. Received 27 November 2015. Accepted 8 April 2016.
Raphe-spinal neurons display an age-dependent differential capacity for neurite outgrowth compared to other brainstem-spinal populations
Functional regeneration of brainstem–spinal pathways occurs in the developing chick when the spinal cord is severed prior to embryonic day (E) 13. Functional spinal cord regeneration is not observed in animals injured after E13. This developmental transition from a permissive to a restrictive repair period may be due to the formation of an extrinsic inhibitory environment preventing axonal growth, and/or an intrinsic inability of mature neurons to regenerate. Here, we investigated the capacity of specific populations of brainstem–spinal projection neurons to regrow neurites in vitro from young (E8) versus mature (E17) brainstem explants. A crystal of carbocyanine dye (DiI) was implanted in ovo into the E5 cervical spinal cord to retrogradely label brainstem–spinal projection neurons. Three or 12 days later, discrete regions of the brainstem containing DiI-labeled neurons were dissected to produce explant cultures grown in serum-free media on laminin substrates. The subsequent redistribution of DiI into regenerating processes permitted the study of in vitro neurite outgrowth from identified brainstem–spinal neurons. When explanted on E8, i.e., an age when brainstem–spinal neurons are normally elongating through the spinal cord and are capable of in vivo functional regeneration, robust neurite outgrowth was observed from all brainstem populations, including rubro-, reticulo-, vestibulo-, and raphe–spinal neurons. In contrast, when explanted on E17, robust neurite outgrowth was seen only from raphe-spinal neurons. Neurite outgrowth from raphe-spinal neurons was 5-hydroxy-tryptamine immunoreactive. This study demonstrates that in growth factor-free environments with permissive growth substrates, neurite outgrowth from brainstem–spinal neurons is dependent on both neuronal age and phenotype., Peer-reviewed article, Published. Received 22 February 2000; Accepted 25 May 2000; Available online 25 May 2002.
Real-time control of a video game with a direct brain-computer interface
Mason and Birch have developed a direct brain–computer interface for intermittent control of devices such as environmental control systems and neuroprotheses. This EEG-based brain switch, named the LF-ASD, has been used in several off-line studies, but little is known about its usability with real-world devices and computer applications. In this study, able-bodied individuals and people with high-level spinal injury used the LF-ASD brain switch to control a video game in real time. Both subject groups demonstrated switch activations varying from 30% to 78% and false-positive rates in the range of 0.5% to 2.2% over three 1-hour test sessions. These levels correspond to switch classification accuracies greater than 94% for all subjects. The results suggest that subjects with spinal cord injuries can operate the brain switch to the same ability as able-bodied subjects in a real-time control environment. These results support the findings of previous studies., Peer-reviewed article, Published.
Report on key points arising from visioning process on prosthetic and orthotic education done at the British Columbia Institute of Technology
The Prosthetics and Orthotics Department at the British Columbia Institute of Technology (BCIT) in Vancouver, Canada, has recently completed a visioning process which was done as part of a curriculum review. This report presents and discusses the key points emerging from the process. It is anticipated that the results of the visioning process will provide a basis for a major curriculum revision to the BCIT’s prosthetics and orthotics program. The intent of a curriculum review is to determine whether an educational program’s curriculum is current and relevant with respect to providing students with entry-level skills for the workforce. It involves examining the current scope of practice and competencies of the profession in question and then reflecting back on the curriculum to determine whether these competencies are being taught adequately. Visioning attempts to determine not what entry-level skills graduates require but, instead, what knowledge and skills students need to meet the challenges of the workplace approximately 10 to 15 years into the future., Peer-reviewed article, Published.
A review of the chemistry of the genus Crataegus
Since the 1800s, natural health products that contain hawthorn (Crataegus spp.) have been used in North America for the treatment of heart problems such as hypertension, angina, arrhythmia, and congestive heart failure. Traditionally, Native American tribes used hawthorn (Crataegus spp.) to treat gastrointestinal ailments and heart problems, and consumed the fruit as food. Hawthorn also has a long history of use in Europe and China for food, and in traditional medicine. Investigations of Crataegus spp. typically focus on the identification and quantification of flavonoids and anthocyanins, which have been shown to have pharmacological activity. The main flavonoids found in Crataegus spp. are hyperoside, vitexin, and additional glycosylated derivatives of these compounds. Reviewed herein are the botany, ethnobotany, and traditional use of hawthorn while focusing on the phytochemicals that have been reported in Crataegus species, and the variation in the described chemistry between individual species., Peer-reviewed article, Published. Received 4 July 2011; Revised 9 December 2011; Available online 17 May 2012.
Rho-kinase inhibition enhances axonal plasticity and attenuates cold hyperalgesia after dorsal rhizotomy
Dorsal rhizotomy results in primary deafferentation of the dorsal horn with concomitant sprouting of spared intraspinal monoaminergic axons. Because descending monoaminergic systems are thought to mitigate nociceptive transmission from the periphery and because dorsal rhizotomy can result in neuropathic pain, we sought to determine whether the rhizotomy-induced sprouting response could be further augmented. Because myelin-derived molecules mask endogenous plasticity of CNS axons and because myelin-inhibitory signaling occurs through the Rho-GTPase pathway, we inhibited Rho-pathway signaling after cervical dorsal rhizotomy in rats. An increase in the density of serotonergic- and tyrosine hydroxylase-positive fibers was seen in the dorsal horn 1 week after septuple rhizotomy, and axon density continued to increase for at least 1 month. One week after septuple rhizotomy, administration of intrathecal Y-27632, an antagonist of Rho-kinase (ROCK), increased the density of both fiber types over vehicle-treated controls. To examine behavioral effects of both cervical rhizotomy and ROCK inhibition, we examined responses to evoked pain: mechanical and thermal allodynia and cold hyperalgesia in the forepaw were examined after single, double, and quadruple rhizotomies of dorsal roots of the brachial plexus. The most notable behavioral outcome was the development of cold hyperalgesia in the affected forepaw after rhizotomies of the C7 and C8 dorsal roots. Application of Y-27632 both attenuated cold hyperalgesia and induced monoaminergic plasticity after C7/8 rhizotomy. Thus, inhibition of Rho-pathway signaling both promoted the sprouting of intact supraspinal monoaminergic fibers and alleviated pain after dorsal rhizotomy., Peer-reviewed article, Published. Received July 6, 2004; revised Oct. 3, 2004; accepted Oct. 18, 2004.
Schwann cells generated from neonatal skin-derived precursors or neonatal peripheral nerve improve functional recovery after acute transplantation into the partially injured cervical spinal cord of the rat
The transplantation of Schwann cells (SCs) holds considerable promise as a therapy for spinal cord injury, but the optimal source of these cells and the best timing for intervention remains debatable. Previously, we demonstrated that delayed transplantation of SCs generated from neonatal mouse skin-derived precursors (SKP-SCs) promoted repair and functional recovery in rats with thoracic contusions. Here, we conducted two experiments using neonatal rat cells and an incomplete cervical injury model to examine the efficacy of acute SKP-SC transplantation versus media control (Experiment 1) and versus nerve-derived SC or dermal fibroblast (Fibro) transplantation (Experiment 2). Despite limited graft survival, by 10 weeks after injury, rats that received SCs from either source showed improved functional recovery compared with media- or fibroblast-treated animals. Compared with media treatment, SKP-SC-transplanted rats showed enhanced rubrospinal tract (RST) sparing/plasticity in the gray matter (GM) rostral to injury, particularly in the absence of immunosuppression. The functional benefits of SC transplantations over fibroblast treatment correlated with the enhanced preservation of host tissue, reduced RST atrophy, and/or increased RST sparing/plasticity in the GM. In summary, our results indicate that: (1) early transplantation of neonatal SCs generated from skin or nerve promotes repair and functional recovery after incomplete cervical crush injury; (2) either of these cell types is preferable to Fibros for these purposes; and (3) age-matched SCs from these two sources do not differ in terms of their reparative effects or functional efficacy after transplantation into the injured cervical spinal cord., Peer-reviewed article, Published.Received March 17, 2014; revised March 18, 2015; accepted March 21, 2015.
Shaped 3D singular spectrum analysis for quantifying gene expression, with application to the early zebrafish embryo
Recent progress in microscopy technologies, biological markers, and automated processing methods is making possible the development of gene expression atlases at cellular-level resolution over whole embryos. Raw data on gene expression is usually very noisy. This noise comes from both experimental (technical/methodological) and true biological sources (from stochastic biochemical processes). In addition, the cells or nuclei being imaged are irregularly arranged in 3D space. This makes the processing, extraction, and study of expression signals and intrinsic biological noise a serious challenge for 3D data, requiring new computational approaches. Here, we present a new approach for studying gene expression in nuclei located in a thick layer around a spherical surface. The method includes depth equalization on the sphere, flattening, interpolation to a regular grid, pattern extraction by Shaped 3D singular spectrum analysis (SSA), and interpolation back to original nuclear positions. The approach is demonstrated on several examples of gene expression in the zebrafish egg (a model system in vertebrate development). The method is tested on several different data geometries (e.g., nuclear positions) and different forms of gene expression patterns. Fully 3D datasets for developmental gene expression are becoming increasingly available; we discuss the prospects of applying 3D-SSA to data processing and analysis in this growing field., Peer-reviewed article, Published. Received 8 February 2015; Accepted 1 May 2015.
Shaped singular spectrum analysis for quantifying gene expression, with application to the early drosophila embryo
In recent years, with the development of automated microscopy technologies, the volume and complexity of image data on gene expression have increased tremendously. The only way to analyze quantitatively and comprehensively such biological data is by developing and applying new sophisticated mathematical approaches. Here, we present extensions of 2D singular spectrum analysis (2D-SSA) for application to 2D and 3D datasets of embryo images. These extensions, circular and shaped 2D-SSA, are applied to gene expression in the nuclear layer just under the surface of the Drosophila (fruit fly) embryo. We consider the commonly used cylindrical projection of the ellipsoidal Drosophila embryo. We demonstrate how circular and shaped versions of 2D-SSA help to decompose expression data into identifiable components (such as trend and noise), as well as separating signals from different genes. Detection and improvement of under- and overcorrection in multichannel imaging is addressed, as well as the extraction and analysis of 3D features in 3D gene expression patterns., Peer-reviewed article, Published. Received 4 July 2014; Revised 10 September 2014; Accepted 10 September 2014.
Sharp borders from fuzzy gradients
Critical boundaries in the early Drosophila embryo are set by morphogenetic gradients. A new quantitative study shows that the placement of one such boundary is more accurate than the gradient thought to set it. Genetic analysis of the accuracy of the process implicates a gene not previously thought to be involved., Peer-reviewed article, Published.
Single-laboratory validation of a method for the detection and/or quantification of select alkaloids in goldenseal supplements and raw materials by reversed-phase high-performance liquid chromatography
Quality of botanical products and raw materials is important to manufacturers, regulators, researchers, and consumers. Many modern botanical quality-assurance schemes set specifications for select phytochemicals and measure against those specifications as one determinant of quality. While numerous publications describe procedures for determining compounds of interest in plant species, few methods have been systematically evaluated for accuracy, precision, or reliability, and often the analysis of finished products is not within the scope of the method. Hydrastis canadensis L., commonly referred to as Goldenseal, is an economically important North American medicinal plant that has been subject to adulteration in commerce. The phytochemicals of interest in the plant are the alkaloids hydrastine, berberine, and canadine. Of interest is also palmatine, an alkaloid found in potential adulterant species but not in goldenseal. In this study, goldenseal materials in raw, capsule, and tablet form, including an Echinacea/ Goldenseal combination product, were extracted with acidified water and acetonitrile and their hydrastine, berberine, canadine, and palmitine content determined by HPLC. The analytical method was optimized and evaluated in a single-laboratory validation study. Calibration curves for hydrastine and berberine were linear from 10 to 150 μ g/mL. The limits of detection for palmatine and canadine were determined to be 0.5 μ g/mL, which translates to detection of levels of 0.004% w/w in test samples. Chromatographic resolution was achieved for all analytes in an isocratic 12.5-min chromatographic run employing a binary mobile phase. Triplicate determinations performed on 10 test materials by two analysts on 3 days resulted in relative standard deviations ranging from 0.9% to 3.4%., Peer-reviewed article, Published.
The Smartphone Peer Physical Activity Counseling (SPPAC) program for manual wheelchair users
Physical activity (PA) must be performed regularly to accrue health benefits. However, the majority of manual wheelchair users do not meet PA recommendations. Existing community-based PA programs for manual wheelchair users appear to work, but effect sizes are small and retention is low. Existing PA programs may not fully implement some psychosocial factors that are strongly linked with PA (eg, autonomy). The use of peers and mobile phone technology in the Smartphone Peer PA Counseling (SPPAC) program represents a novel approach to cultivating a PA-supportive environment for manual wheelchair users., Peer-reviewed article, Published.
Spatial bistability generates hunchback expression sharpness in the drosophila embryo
During embryonic development, the positional information provided by concentration gradients of maternal factors directs pattern formation by providing spatially dependent cues for gene expression. In the fruit fly, Drosophila melanogaster, a classic example of this is the sharp on-off activation of the hunchback (hb) gene at midembryo, in response to local concentrations of the smooth anterior-posterior Bicoid (Bcd) gradient. The regulatory region for hb contains multiple binding sites for the Bcd protein as well as multiple binding sites for the Hb protein. Some previous studies have suggested that Bcd is sufficient for properly sharpened Hb expression, yet other evidence suggests a need for additional regulation. We experimentally quantified the dynamics of hb gene expression in flies that were wild-type, were mutant for hb self-regulation or Bcd binding, or contained an artificial promoter construct consisting of six Bcd and two Hb sites. In addition to these experiments, we developed a reaction-diffusion model of hb transcription, with Bcd cooperative binding and hb self-regulation, and used Zero Eigenvalue Analysis to look for multiple stationary states in the reaction network. Our model reproduces the hb developmental dynamics and correctly predicts the mutant patterns. Analysis of our model indicates that the Hb sharpness can be produced by spatial bistability, in which hb self-regulation produces two stable levels of expression. In the absence of self-regulation, the bistable behavior vanishes and Hb sharpness is disrupted. Bcd cooperative binding affects the position where bistability occurs but is not itself sufficient for a sharp Hb pattern. Our results show that the control of Hb sharpness and positioning, by hb self-regulation and Bcd cooperativity, respectively, are separate processes that can be altered independently. Our model, which matches the changes in Hb position and sharpness observed in different experiments, provides a theoretical framework for understanding the data and in particular indicates that spatial bistability can play a central role in threshold-dependent reading mechanisms of positional information., Peer-reviewed article, Published. Received October 16, 2007; Accepted August 13, 2008; Published September 26, 2008.
Spinal cord injury influences psychogenic as well as physical components of female sexual ability
Study Design: Secure, web-based survey. Objectives: Elicit specific information about sexual function from women with spinal cord injuries (SCI). Setting: World-wide web. Methods: Individuals 18 years or older living with SCI obtained a pass code to enter a secure website and then answered survey questions. Results: Bladder and/or bowel incontinence during sexual activity and/or sexual intercourse were significant concerns and prevented some women from seeking sexual activity. Autonomic dysreflexia (AD) during sexual activity was interpreted negatively by many and was found to interfere with sexual activity. Most subjects reported difficulty becoming psychologically aroused as well as physically aroused, which were both correlated with feeling that their SCI had altered their sexual sense of self. An inverse relationship existed between developing new areas of arousal above the level of lesion and not having sensation or movement below the lesion. The most commonly reported sexual stimulation leading to the best arousal involved stimulation of the head/neck and torso areas. The majority of subjects reported having experienced intercourse postinjury. Most participants reported difficulty with positioning during foreplay and intercourse, vaginal lubrication, and spasticity during intercourse. Almost half reported experiencing orgasm postinjury and this was positively associated with the presence of genital sensation. Conclusion: SCI significantly impairs psychological and physical aspects of female sexual arousal. In addition, bladder and bowel incontinence as well as AD negatively impact sexual activity and intercourse., Peer-reviewed article, Published.

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