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1.
Magn Reson Imaging ; 102: 151-163, 2023 10.
Article in English | MEDLINE | ID: mdl-37353180

ABSTRACT

PURPOSE: To develop a second-order and slice-specific linear shimming technique and investigate its efficiency in the mitigation of signal loss and distortions, and the increase of temporal signal-to-noise ratio (tSNR) within the spinal cord during functional Magnetic Resonance Imaging (fMRI) of the human cervical spinal cord. METHODS: All scans were performed on a General Electric Discovery MR750 3 T scanner, using a head, neck and spine coil and a neurovascular array. To improve B0 homogeneity, a field map was acquired, and second-order shims (SOS) were optimized over manually defined regions of interest (ROIs). Signal loss from dephasing by susceptibility-induced gradients was reduced by optimizing slice-specific x-, y- and z-shims to maximize signal within the spinal cord. Spectral-spatial excitation pulses were used in both the slice-specific linear shimming calibration scan and fMRI acquisitions. The shimming technique's efficiency was initially tested on eight healthy volunteers by comparing tSNR between images acquired with the manufacturer's standard linear shimming and with our SOS and xyz-shimming technique. Subsequently, using an increased spatial resolution as needed for fMRI of the spinal cord, tSNR measurements were performed on resting-state fMRI images from 14 healthy participants. RESULTS: Spinal fMRI images acquired with only the standard linear shimming suffered from severe signal loss below the C5 vertebral level. The developed shimming technique compensated for this loss especially at levels C6 and C7, while tSNR was significantly higher at all vertebral levels with SOS and xyz-shimming than without it. CONCLUSION: A comprehensive shimming approach which includes the use of spectral-spatial excitation pulses along with both second-order and slice-specific linear shim optimization reduces regional signal loss and increases tSNR along the c-spine (C3-C7), improving the ability to record functional signals from the human spinal cord.


Subject(s)
Brain , Magnetic Resonance Imaging , Humans , Magnetic Resonance Imaging/methods , Image Processing, Computer-Assisted/methods , Spinal Cord/diagnostic imaging
2.
J Invest Surg ; 34(4): 380-392, 2021 Apr.
Article in English | MEDLINE | ID: mdl-31304811

ABSTRACT

INTRODUCTION: We are developing ovine models of spinal cord injury to test novel neuromodulation-based methods on spasticity. The hemisection has been reported in a number of large animal studies. Our aim is to duplicate a hemisection injury in the sheep. Our effort is explored here. Methods and Results: Three sheep underwent hemi-sectioning of the spinal cord. Quantitative gait analysis was completed both pre- and post-injury. While measurable differences in most of the 20 gait metrics were observed, relatively few were above the predicted thresholds based on error levels expected from the data. Variations in severity of injury across the three sheep were observed. Conclusions: The hemisection ovine model of spinal cord injury shows promise as a large-animal platform for developing new therapies for treating spinal cord injuries. While variability in injury severity was observed across animals, as has been observed with weight drop-based SCI models, the hemi-section approach has the advantages of procedural ease and reduced technical complexity.


Subject(s)
Spinal Cord Injuries , Animals , Disease Models, Animal , Gait , Sheep , Spinal Cord
3.
J Invest Surg ; 33(3): 240-251, 2020 Mar.
Article in English | MEDLINE | ID: mdl-30380340

ABSTRACT

Introduction: Translating basic science research into a safe and effective therapy for spinal cord injury (SCI) requires suitable large animal models for testing both implantable devices and biologic approaches to better approximate human anatomy and function. Hemisection lesions, routinely used for investigational purposes in small animals, are less frequently described in large animals that might be appropriate for translational studies. Size constraints of small animals (mice and rats) limits the predictability of the findings when scaled up. Our goal is to review the status of hemisection SCI in large animals across species and time to prepare for the testing of a novel intradural spinal cord stimulation device for control of spasticity in an ovine model. Methods and Results: We surveyed the literature on hemisection in quadrupeds and nonhuman primates, and catalogued the species, protocols and outcomes of the experimental work in this field. Feline, lapine, canine, simian, porcine, ovine and bovine models were the primary focal points. There is a consistent body of literature reporting use of the hemisection approach in large animals, but with differences in surgical technique depending on the goals and nature of the individual studies. While the injuries are not always consistent, the experimental variability is generally lower than that of the contusion-based approach. In general, as the body size of the animal increases, animal care requirements and the associated costs follow. In most cases, this is inversely correlated with the number of animals used in hemisection models. Conclusions: The hemisection approach to modeling SCI is straightforward compared with other methods such as the contusive impact and enables the transection of isolated ascending and descending tracts and segment specific cell bodies. This has certain advantages in models investigating post-injury axonal regrowth. However, this approach is not generally in line with the patho-physiologies encountered in SCI patients. Even so, the ability to achieve more control over the level of injury makes it a useful adjunct to contusive and ischemic approaches, and suggests a useful role in future translational studies.


Subject(s)
Disease Models, Animal , Dissection/methods , Spinal Cord Injuries/etiology , Spinal Cord/surgery , Animals , Body Size , Cats , Cattle , Dogs , Humans , Macaca , Rabbits , Sheep , Spinal Cord/physiopathology , Spinal Cord Injuries/physiopathology , Swine
4.
Insects ; 10(9)2019 Sep 10.
Article in English | MEDLINE | ID: mdl-31510017

ABSTRACT

The advent of novel genetic methods has led to renewed interest in the sterile insect technique (SIT) for management of insect pests, owing to applications in mass rearing and in the production of sterile offspring without use of irradiation. An area-wide management programme for codling moth, Cydia pomonella, has employed the SIT and other management practices over a large area (3395 to 7331 ha) of orchards and neighbouring urban, public, or First Nations lands in British Columbia, Canada, for 25 years. This project is the first to employ the SIT for C. pomonella, and the longest-running application of area-wide techniques for its control, anywhere. It was derived from basic research and applied trials from the 1960s onwards. Many biological challenges were overcome, and lessons learnt, in transferring from small- to large-scale applications of mass rearing and the SIT, with particular regard to Lepidoptera. Research has proven essential to identifying, if not resolving, issues that threaten the implementation and success of any such programme. The major challenges encountered, and the resulting research, are reviewed, as well as future directions. Recommendations are given for application of the SIT as part of any area-wide management programme for C. pomonella.

5.
Environ Entomol ; 47(2): 221-232, 2018 04 05.
Article in English | MEDLINE | ID: mdl-29506136

ABSTRACT

Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was monitored from 2010 to 2014 in 314-828 sites located in interior fruit-growing regions of OR and WA, United States, and BC, Canada, using traps baited with apple cider vinegar or sugar-water-yeast. Seasonal population dynamics and sex ratios were summarized for berry, cherry, stone fruit, grape, non-crop host plants, non-host sites, and for conventional IPM, certified organic, backyard, and feral sites, by region and year. Overwintering was detected in all regions and years, despite winter temperatures below -17°C. A spatial analysis was conducted using a Geographic Information System (GIS), daily weather data, geomorphometric measures of terrain, distance to water, and other variables, at each site. Overwintering success at a site, measured as Julian week of first capture of D. suzukii, was significantly related (R2 = 0.49) in cherry habitats to year, agronomic treatment, and number of winter days with temperatures >-5°C. In berry, cherry, stone fruit and grape habitats, 2011-2014, it was significantly related (R2 = 0.42) to year, agronomic treatment, the logarithm of peak population of D. suzukii in the prior autumn, latitude, elevation, and topographic wetness index. The results show that D. suzukii has adapted to exploit a succession of irrigated crops and feral habitats in mixed landscapes of a semi-arid region with cold winters and hot dry summers, and are shaping strategies for pest management and for biological control.


Subject(s)
Agriculture , Climate , Drosophila , Seasons , Animals , Cold Temperature , Female , Male , Models, Statistical , Northwestern United States , Population Dynamics , Sex Ratio , Spatial Analysis
6.
Eur J Pain ; 22(7): 1245-1254, 2018 08.
Article in English | MEDLINE | ID: mdl-29520913

ABSTRACT

BACKGROUND: Traditional psychometric measures aimed at characterizing the pain experience often show considerable overlap, due to interlinked affective and modulatory processes under central nervous system control. Neuroimaging studies have been employed to investigate this complexity of pain processing, in an attempt to provide a quantifiable, adjunctive description of pain perception. In this exploratory study, we examine psychometric and neuroimaging data from 38 patients with painful osteoarthritis of the carpometacarpal joint. We had two aims: first, to utilize principal component analysis (PCA) as a dimension reduction strategy across multiple self-reported endpoints of pain, cognitive and affective functioning; second, to investigate the relationship between identified dimensions and regional cerebral blood flow (rCBF) as an indirect measure of brain activity underpinning their ongoing pain experiences. METHODS: Psychometric data were collected using validated questionnaires. Quantitative estimates of rCBF were acquired using pseudo-continuous arterial spin-labelled functional magnetic resonance imaging. RESULTS: Two principal components were identified that accounted for 73% of data variance; one related to pain scores and a second to psychological traits. Voxel-wise multiple regression analysis revealed a significant negative association between the 'pain score' component and rCBF to a right temporal lobe cluster, including the amygdala and the parahippocampal cortex. CONCLUSION: We suggest this association may represent a coping mechanism that aims to reduce fear-related pain-anxiety. Further investigation of central brain processing mechanisms in osteoarthritis-related pain may offer insights into more effective therapeutic strategies. SIGNIFICANCE: This study demonstrates that dimension reduction using PCA allows insight into pain perception and its affective components in relation to brain activation patterns in patients with painful hand osteoarthritis.


Subject(s)
Chronic Pain/physiopathology , Chronic Pain/psychology , Osteoarthritis/physiopathology , Osteoarthritis/psychology , Adult , Cerebrovascular Circulation/physiology , Chronic Pain/diagnostic imaging , Female , Humans , Magnetic Resonance Imaging , Middle Aged , Osteoarthritis/diagnostic imaging , Principal Component Analysis , Psychometrics
7.
J Med Eng Technol ; 40(3): 72-9, 2016.
Article in English | MEDLINE | ID: mdl-26785329

ABSTRACT

Our laboratories are developing treadmill-based gait analysis employing sheep to investigate potential efficacy of intra-dural spinal cord stimulation in the treatment of spinal cord injury and neuropathic pain. As part of efforts to establish the performance characteristics of the experimental arrangement, this study measured the treadmill speed via a tachometer, video belt-marker timing and ambulation-rate observations of the sheep. The data reveal a 0.1-0.3% residual drift in the baseline (unloaded) treadmill speed which increases with loading, but all three approaches agree on final speed to within 1.7%, at belt speeds of ≈ 4 km/h. Using the tachometer as the standard, the estimated upper limit on uncertainty in the video belt-marker approach is ± 0.18 km h(-1) and the measured uncertainty is ± 0.15 km h(-1). Employment of the latter method in determining timing differences between contralateral hoof strikes by the sheep suggests its utility in assessing severity of SCI and responses to therapeutic interventions.


Subject(s)
Exercise Test , Neuralgia/physiopathology , Spinal Cord Injuries/physiopathology , Walking/classification , Walking/physiology , Animals , Disease Models, Animal , Female , Sheep
8.
J Neuroendocrinol ; 28(4)2016 04.
Article in English | MEDLINE | ID: mdl-26660859

ABSTRACT

Oxytocin is a neuropeptide regulating social-affiliative and reproductive behaviour in mammals. Despite robust preclinical evidence for the antinociceptive effects and mechanisms of action of exogenous oxytocin, human studies have produced mixed results regarding the analgesic role of oxytocin and are yet to show a specific modulation of neural processes involved in pain perception. In the present study, we investigated the analgesic effects of 40 IU of intranasal oxytocin in 13 healthy male volunteers using a double-blind, placebo-controlled, cross-over design and brief radiant heat pulses generated by an infrared laser that selectively activate Aδ- and C-fibre nerve endings in the epidermis, at the same time as recording the ensuing laser-evoked potentials (LEPs). We predicted that oxytocin would reduce subjective pain ratings and attenuate the amplitude of the N1, N2 and P2 components. We observed that oxytocin attenuated perceived pain intensity and the local peak amplitude of the N1 and N2 (but not of P2) LEPs, and increased the latency of the N2 component. Importantly, for the first time, the present study reports an association between the analgesic effect of oxytocin (reduction in subjective pain ratings) and the oxytocin-induced modulation of cortical activity after noxious stimulation (attenuation of the N2 LEP). These effects indicate that oxytocin modulates neural processes contributing to pain perception. The present study reports preliminary evidence that is consistent with electrophysiological studies in rodents showing that oxytocin specifically modulates Aδ/C-fibre nociceptive afferent signalling at the spinal level and provides further specificity to evidence obtained in humans indicating that oxytocin may be modulating pain experience by modulating activity in the cortical areas involved in pain processing.


Subject(s)
Analgesics/therapeutic use , Laser-Evoked Potentials/physiology , Oxytocin/therapeutic use , Pain/drug therapy , Administration, Intranasal , Adult , Analgesics/administration & dosage , Analgesics/pharmacology , Cross-Over Studies , Double-Blind Method , Humans , Laser-Evoked Potentials/drug effects , Male , Oxytocin/administration & dosage , Oxytocin/pharmacology , Pain Measurement/methods , Young Adult
9.
J Plast Reconstr Aesthet Surg ; 67(10): 1345-51, 2014 Oct.
Article in English | MEDLINE | ID: mdl-24917371

ABSTRACT

Use of human acellular dermal matrix (ADM) during prosthetic breast reconstruction has increased. Several ADM products are available produced by differing manufacturing techniques. It is not known if outcomes vary with different products. This study reports the complication prevalence following use of a tutoplast-derived ADM (T-ADM) in prosthetic breast reconstruction. We performed a retrospective chart review of 203 patients (mean follow-up times 12.2 months) who underwent mastectomy and immediate prosthetic breast reconstruction utilizing T-ADM, recording demographic data, surgical indications and complication (infection, seroma, hematoma, wound healing exceeding three weeks and reconstruction failure). During a four-year period, 348 breast reconstructions were performed Complications occurred in 16.4% of reconstructed breasts. Infection occurred in 6.6% of breast reconstructions (3.7% - major infection, requiring intravenous antibiotics and 2.9% minor infection, requiring oral antibiotics only). Seromas occurred in 3.4% and reconstruction failure occurred in 0.6% of breast reconstructions. Analysis suggested that complication prevalence was significantly higher in patients with a BMI >30 (p = 0.03). The complication profile following T-ADM use is this series is comparable to that reported for with other ADM products. T-ADM appears to be a safe and acceptable option for use in ADM-assisted breast reconstruction.


Subject(s)
Acellular Dermis/adverse effects , Breast Implantation/adverse effects , Adult , Breast Implantation/methods , Cellulitis/epidemiology , Contracture/epidemiology , Female , Humans , Phthalazines , Retrospective Studies , Seroma/epidemiology , Tissue Expansion Devices
10.
J Med Eng Technol ; 38(5): 269-73, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24841845

ABSTRACT

The authors are developing a novel type of spinal cord stimulator, designed to be placed directly on the pial surface of the spinal cord, for more selective activation of target tissues within the dorsal columns. For pre-clinical testing of the device components, an ovine model has been implemented which utilizes the agility and flexibility of a sheep's cervical and upper thoracic regions, thus providing an optimal environment of accelerated stress-cycling on small gauge lead wires implanted along the dorsal spinal columns. The results are presented of representative biomechanical measurements of the angles of rotation and the angular velocities and accelerations associated with the relevant head, neck and upper back motions, and these findings are interpreted in terms of their impact on assessing the robustness of the stimulator implant systems.


Subject(s)
Spinal Cord Stimulation/instrumentation , Animals , Biomechanical Phenomena , Head/physiology , Male , Neck/physiology , Range of Motion, Articular , Sheep , Thorax/physiology
11.
J Med Eng Technol ; 38(1): 1-4, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24144117

ABSTRACT

This study develops a means of delivering electrical stimuli directly to the pial surface of the spinal cord for treatment of intractable pain. This intradural implant must remain in direct contact with the cord as it moves within the spinal canal. Therefore, magnetic resonance imaging was used to measure the movement of the spinal cord between neutral and flexed-back positions in a series of volunteers (n = 16). Following flexion of the back, the mean change in the pedicle-to-spinal cord dorsal root entry zone distance at the T10-11 level was (8.5 ± 6.0) mm, i.e. a 71% variation in the range of rostral-caudal movement of the spinal cord across all patients. There will be a large spectrum of spinal cord strains associated with this observed range of rostral-caudal motions, thus calling for suitable axial compliance within the electrode bearing portion of the intradural implant.


Subject(s)
Electric Stimulation Therapy/methods , Magnetic Resonance Imaging/methods , Spinal Cord/physiology , Adult , Humans , Lumbar Vertebrae/anatomy & histology , Middle Aged , Spinal Cord/anatomy & histology , Young Adult
12.
Rev Sci Instrum ; 84(11): 114303, 2013 Nov.
Article in English | MEDLINE | ID: mdl-24289414

ABSTRACT

We have designed, built, and tested an apparatus used for investigating the biomechanical response of a novel intradural spinal cord stimulator to the simulated physiological movement of the spinal cord within the thecal sac. In this apparatus, the rostral-caudal displacements of an anthropomorphic spinal cord surrogate can be controlled with a resolution of approximately 0.1% of a target value for up to 10(7) lateral movement cycles occurring at a repetition rate of 2 Hz. Using this system, we have been able to determine that the restoring force of the stimulator's suspension system works in concert with the frictional coupling between the electrode array and the surrogate to overcome the 0.42 µN inertial force associated with the lateral motion of the array. The result is a positional stability of the array on the surrogate (in air) of better than 0.2 mm over ~500,000 movement cycles. Design modifications that might lead to improved physiological performance are discussed.


Subject(s)
Electrodes, Implanted , Mechanical Phenomena , Spinal Cord Stimulation/instrumentation , Spinal Cord , Biomechanical Phenomena , Equipment Design , Humans
13.
J Neurosurg Sci ; 57(1): 81-6, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23584224

ABSTRACT

Brown-Séquard plus syndrome (BSPS) or incomplete spinal cord injuries from stab injury have been widely reported. However, only four detailed cases of pure Brown-Séquard syndrome (BSS) from stab injury have been previously reported. Here we present the case of an 18-year-old man who sustained a penetrating knife stab injury to the right side of his back resulting in a pure Brown-Séquard syndrome with left lower extremity hemiplegia. Imaging revealed right-sided soft tissue and ligamentous damage traveling in a right-to-left fashion as well as left-sided T2-weighted MRI cord signal change at the level of T9. Given concern for a cerebrospinal fluid leak (CSF) leak, the patient was taken for wound exploration, irrigation, laminectomy, dural closure and lumbar drain placement. At three years follow up, the patient was almost full strength. This is the first case in the literature demonstrating radiographic and correlative intraoperative imaging of a hemisection of the spinal cord resulting in a pure Brown-Séquard syndrome.


Subject(s)
Brown-Sequard Syndrome/surgery , Laminectomy/methods , Spinal Cord Injuries/surgery , Wounds, Stab/surgery , Adolescent , Brown-Sequard Syndrome/diagnostic imaging , Brown-Sequard Syndrome/physiopathology , Humans , Magnetic Resonance Imaging , Male , Spinal Cord Injuries/diagnostic imaging , Spinal Cord Injuries/etiology , Thoracic Vertebrae/diagnostic imaging , Thoracic Vertebrae/injuries , Thoracic Vertebrae/surgery , Tomography, X-Ray Computed , Treatment Outcome , Wounds, Stab/complications , Wounds, Stab/diagnostic imaging
14.
Cereb Cortex ; 23(10): 2309-21, 2013 Oct.
Article in English | MEDLINE | ID: mdl-22879355

ABSTRACT

The connection between auditory fields of the temporal lobe and prefrontal cortex has been well characterized in nonhuman primates. Little is known of temporofrontal connectivity in humans, however, due largely to the fact that invasive experimental approaches used so successfully to trace anatomical pathways in laboratory animals cannot be used in humans. Instead, we used a functional tract-tracing method in 12 neurosurgical patients with multicontact electrode arrays chronically implanted over the left (n = 7) or right (n = 5) perisylvian temporal auditory cortex (area PLST) and the ventrolateral prefrontal cortex (VLPFC) of the inferior frontal gyrus (IFG) for diagnosis and treatment of medically intractable epilepsy. Area PLST was identified by the distribution of average auditory-evoked potentials obtained in response to simple and complex sounds. The same sounds evoked little if there is any activity in VLPFC. A single bipolar electrical pulse (0.2 ms, charge-balanced) applied between contacts within physiologically identified PLST resulted in polyphasic evoked potentials clustered in VLPFC, with greatest activation being in pars triangularis of the IFG. The average peak latency of the earliest negative deflection of the evoked potential on VLPFC was 13.48 ms (range: 9.0-18.5 ms), providing evidence for a rapidly conducting pathway between area PLST and VLPFC.


Subject(s)
Auditory Cortex/physiology , Evoked Potentials, Auditory , Prefrontal Cortex/physiology , Adult , Electric Stimulation , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Neural Pathways , Young Adult
15.
J Med Eng Technol ; 36(8): 407-10, 2012 Nov.
Article in English | MEDLINE | ID: mdl-22953718

ABSTRACT

We have designed, built and tested an anthropomorphic-scale surrogate spinal canal, for use in preliminary evaluations of the performance characteristics of a novel intradural spinal cord stimulator. The surrogate employs a silicone mock spinal cord with semi-major and semi-minor diameters of 10 and 6 mm, respectively, commensurate with those of actual thoracic-level spinal cord. The axial restoring force provided by the 300 µm thick silicone denticulate ligament constructs on the mock cord is ~ 0.32 N mm(-1) over a 1.5 mm range of displacement, which is within a factor of 2 of that measured by others in human cadaver specimens. Examples of testing protocols of prototype intradural stimulators that employ this device are discussed.


Subject(s)
Biomedical Engineering/instrumentation , Implants, Experimental , Models, Biological , Spinal Canal/anatomy & histology , Spinal Cord/anatomy & histology , Spinal Cord/physiology , Biomechanical Phenomena , Electric Stimulation Therapy , Equipment Design , Humans
16.
Dalton Trans ; 41(39): 12048-53, 2012 Oct 21.
Article in English | MEDLINE | ID: mdl-22910978

ABSTRACT

In this paper we examine the effect of Ga doping on the structure and conductivity of the high Li ion content garnet-related system, La(3)Zr(2)Li(7)O(12). Without Ga doping, La(3)Zr(2)Li(7)O(12) is tetragonal and has low Li ion conductivity. The introduction of Ga leads to a change to a cubic unit cell, and a large enhancement in the conductivity. Prior structural studies of La(3)Zr(2)Li(7)O(12) have shown the presence of both tetrahedral and distorted octahedral sites for Li, and the low conductivity can be explained by the ordered nature of the Li distribution. The present structural study of La(3)Zr(2)Ga(0.5)Li(5.5)O(12) shows that Ga substitutes onto the tetrahedral site. Despite the presence of non-mobile Ga(3+) on the Li sites, the conductivity is enhanced as a result of the introduction of vacancies in the Li sites, and consequent disorder on the Li sublattice. Further work has suggested that over time in air, there is some H(+)/Li(+) exchange, and consequently some variation in the conductivity.

17.
J Med Eng Technol ; 36(3): 169-73, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22339111

ABSTRACT

We have designed, built and tested a novel device for placing intradural neurmodulator implants directly on the pial surface of the spinal cord. This applier tool is designed for ergonomic handling of delicate electro-mechanical devices such as the Iowa-Patch™ spinal cord stimulator implant, which is aimed at overcoming certain shortcomings in the performance of standard epidural stimulator devices. The applier is approximately 14 cm long, 6 mm in diameter, made of stainless steel components, and has simple and reliable mechanisms for the attachment and release of the implant from it. We describe the design of the device, details of its construction, and its performance during in vivo testing of somatosensory evoked potentials in an ovine model of intradural spinal cord stimulation.


Subject(s)
Dura Mater/surgery , Neural Prostheses , Neurosurgical Procedures/instrumentation , Spinal Cord/surgery , Animals , Equipment Design , Humans , Male , Models, Biological , Sheep
18.
J Med Eng Technol ; 36(1): 22-5, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22188575

ABSTRACT

We have designed, built and tested a novel spinal cord surrogate that mimics the low-amplitude cardiac-driven pulsations of the human spinal cord, for use in developing intradural implants to be used in a novel form of neuromodulation for the treatment of intractable pain and motor system dysfunction. The silicone surrogate has an oval cross section, 10 mm major axis × 6 mm minor axis, and incorporates a 3 mm diameter × 3 cm long angioplasty balloon that serves as the pulsation actuator. When pneumatically driven at 1 Hz and 1.5 atmospheres (≈ 1140 mm Hg), the surrogate's diametric pulsation is ≈ 100 µm, which corresponds well to in vivo observations. The applications for this surrogate are presented and discussed.


Subject(s)
Electric Stimulation Therapy/instrumentation , Spinal Cord/physiology , Electrodes, Implanted , Equipment Design , Pain, Intractable/therapy
19.
Chemosphere ; 84(1): 25-30, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21458842

ABSTRACT

The modified excised leaf disc method was used to measure the effects of six insecticides on eggs, larvae, adults, and female fecundity of Galendromus occidentalis (Nesbitt) in a 'worst case laboratory exposure'. This study identified insecticides that would be recommended for tier II field evaluations for an integrated pest management program. Commercially formulated insecticides were applied with a thin-layer chromatography sprayer adjusted to 10.34 kPa (1.5 psi), at the recommended label concentrations in Canada. LC(50) values were estimated from aliquots above and below that concentration. Spinetoram and spirotetramat were toxic at label concentrations. The label concentration for spinetoram was 34.3-fold the LC(50) estimate (0.006 gL(-1)) and for spirotetramat the label concentration was 7.7-fold the LC(50) estimate (0.03 gL(-1)). Clothianidin was considerably less toxic and the label concentration was 0.15-fold the LC(50) estimate (2.29 gL(-1)). Estimates of LC(50) for novaluron and chlorantraniliprole could not be established. Both materials showed slight toxicity to at least one growth stage of the predator. Novaluron, clothianidin and chlorantraniliprole should be evaluated in the field for compatibility in IPM programs. Flubendiamide was harmless to all growth stages and it is recommended for inclusion in IPM programs without additional tier II field evaluations. Field evaluations with spinetoram and spirotetramat should be pursued only if alternatives are unavailable.


Subject(s)
Acari/drug effects , Insecticides/toxicity , Acari/metabolism , Animals , Benzamides/toxicity , Female , Fertility/drug effects , Guanidines/toxicity , Laboratories , Larva/drug effects , Macrolides/toxicity , Male , Neonicotinoids , Phenylurea Compounds/toxicity , Risk Assessment , Sulfones/toxicity , Thiazoles/toxicity , ortho-Aminobenzoates/toxicity
20.
Exp Appl Acarol ; 47(1): 63-9, 2009 Jan.
Article in English | MEDLINE | ID: mdl-18792796

ABSTRACT

A laboratory evaluation of fenbuconazole, myclobutanil propiconazole, boscalid, fenhexamid and pyraclostrobin revealed these fungicides to be harmless to adult Galendromus occidentalis. None of these fungicides affected adversely fecundity and egg viability. Elemental sulphur also had no effect on adults and fecundity. However, 72.4% of the young larvae perished after hatching. The six novel fungicides are safer alternatives to sulphur in perennial crops in British Columbia.


Subject(s)
Fungicides, Industrial , Mites , Sulfur , Animals , Female , Oviposition/drug effects
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