Publications by authors named "Fiona James"

32 Publications

Seizure frequency discrepancy between subjective and objective ictal electroencephalography data in dogs.

J Vet Intern Med 2021 May 18. Epub 2021 May 18.

Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.

Background: Many studies of epilepsy in veterinary medicine use subjective data (eg, caregiver-derived histories) to determine seizure frequency. Conversely, in people, objective data from electroencephalography (EEG) are mainly used to diagnose epilepsy, measure seizure frequency and evaluate efficacy of antiseizure drugs. These EEG data minimize the possibility of the underreporting of seizures, a known phenomenon in human epileptology.

Objective: To evaluate the correlation between reported seizure frequency and EEG frequency of ictal paroxysmal discharges (PDs) and to determine whether seizure underreporting phenomenon exists in veterinary epileptology.

Animals: Thirty-three ambulatory video-EEG recordings in dogs showing ≥1 ictal PD, excluding dogs with status epilepticus.

Methods: Retrospective observational study. Ictal PDs were counted manually over the entire recording to obtain the frequency of EEG seizures. Caregiver-reported seizure frequency from the medical record was categorized into weekly, daily, hourly, and per minute seizure groupings. The Spearman rank test was used for correlation analysis.

Results: The coefficient value (r ) comparing reported seizure to EEG-confirmed ictal PD frequencies was 0.39 (95% confidence interval [CI] = 0.048-0.64, P = .03). Other r values comparing history against various seizure types were: 0.36 for motor seizures and 0.37 for nonmotor (absence) seizures.

Conclusions And Clinical Importance: A weak correlation was found between the frequency of reported seizures from caregivers (subjective data) and ictal PDs on EEG (objective data). Subjective data may not be reliable enough to determine true seizure frequency given the discrepancy with EEG-confirmed seizure frequency. Confirmation of the seizure underreporting phenomenon in dogs by prospective study should be carried out.
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http://dx.doi.org/10.1111/jvim.16158DOI Listing
May 2021

CD8 T cells specific for an immunodominant SARS-CoV-2 nucleocapsid epitope display high naive precursor frequency and TCR promiscuity.

Immunity 2021 05 15;54(5):1066-1082.e5. Epub 2021 Apr 15.

Department of Infectious Diseases, Austin Hospital, Heidelberg, VIC 3084, Australia; Department of Medicine and Radiology, The University of Melbourne, Parkville, VIC 3000, Australia; Data Analytics Research and Evaluation (DARE) Centre, Austin Health and The University of Melbourne, Heidelberg, VIC 3084, Australia.

To better understand primary and recall T cell responses during coronavirus disease 2019 (COVID-19), it is important to examine unmanipulated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells. By using peptide-human leukocyte antigen (HLA) tetramers for direct ex vivo analysis, we characterized CD8 T cells specific for SARS-CoV-2 epitopes in COVID-19 patients and unexposed individuals. Unlike CD8 T cells directed toward subdominant epitopes (B7/N, A2/S, and A24/S) CD8 T cells specific for the immunodominant B7/N epitope were detected at high frequencies in pre-pandemic samples and at increased frequencies during acute COVID-19 and convalescence. SARS-CoV-2-specific CD8 T cells in pre-pandemic samples from children, adults, and elderly individuals predominantly displayed a naive phenotype, indicating a lack of previous cross-reactive exposures. T cell receptor (TCR) analyses revealed diverse TCRαβ repertoires and promiscuous αβ-TCR pairing within B7/NCD8 T cells. Our study demonstrates high naive precursor frequency and TCRαβ diversity within immunodominant B7/N-specific CD8 T cells and provides insight into SARS-CoV-2-specific T cell origins and subsequent responses.
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http://dx.doi.org/10.1016/j.immuni.2021.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8049468PMC
May 2021

Multi-site assessment of rapid, point-of-care antigen testing for the diagnosis of SARS-CoV-2 infection in a low-prevalence setting: A validation and implementation study.

Lancet Reg Health West Pac 2021 Apr 2;9:100115. Epub 2021 Mar 2.

Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Australia.

Background: In Australia, COVID-19 diagnosis relies on RT-PCR testing which is relatively costly and time-consuming. To date, few studies have assessed the performance and implementation of rapid antigen-based SARS-CoV-2 testing in a setting with a low prevalence of COVID-19 infections, such as Australia.

Methods: This study recruited participants presenting for COVID-19 testing at three Melbourne metropolitan hospitals during a period of low COVID-19 prevalence. The Abbott PanBio COVID-19 Ag point-of-care test was performed alongside RT-PCR. In addition, participants with COVID-19 notified to the Victorian Government were invited to provide additional swabs to aid validation. Implementation challenges were also documented.

Findings: The specificity of the Abbott PanBio COVID-19 Ag test was 99.96% (95% CI 99.73 - 100%). Sensitivity amongst participants with RT-PCR-confirmed infection was dependent upon the duration of symptoms reported, ranging from 77.3% (duration 1 to 33 days) to 100% in those within seven days of symptom onset. A range of implementation challenges were identified which may inform future COVID-19 testing strategies in a low prevalence setting.

Interpretation: Given the high specificity, antigen-based tests may be most useful in rapidly triaging public health and hospital resources while expediting confirmatory RT-PCR testing. Considering the limitations in test sensitivity and the potential for rapid transmission in susceptible populations, particularly in hospital settings, careful consideration is required for implementation of antigen testing in a low prevalence setting.

Funding: This work was funded by the Victorian Department of Health and Human Services. The funder was not involved in data analysis or manuscript preparation.
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http://dx.doi.org/10.1016/j.lanwpc.2021.100115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8076656PMC
April 2021

The Role of Immunological and Clinical Biomarkers to Predict Clinical COVID-19 Severity and Response to Therapy-A Prospective Longitudinal Study.

Front Immunol 2021 17;12:646095. Epub 2021 Mar 17.

Centre for Antibiotic Allergy and Research, Department of Infectious Diseases, Austin Health, Heidelberg, VIC, Australia.

Background: The association of pro-inflammatory markers such as interleukin-6 (IL-6) and other biomarkers with severe coronavirus disease 2019 (COVID-19) is of increasing interest, however their kinetics, response to current COVID-related treatments, association with disease severity and comparison with other disease states associated with potential cytokine storm (CS) such as Staphylococcus aureus bacteraemia (SAB) are ill-defined.

Methods: A cohort of 55 hospitalized SARS-CoV-2 positive patients was prospectively recruited - blood sampling was performed at baseline, post-treatment and hospital discharge. Serum IL-6, C-reactive protein (CRP) and other laboratory investigations were compared between treatment groups and across timepoints. Acute serum IL-6 and CRP levels were then compared to those with suspected COVID-19 (SCOVID) and age and sex matched patients with SAB and patients hospitalized for any non-infectious condition (NIC).

Results: IL-6 was elevated at admission in the SARS-CoV-2 cohort but at lower levels compared to matched SAB patients. Median (IQR) IL-6 at admission was 73.89 pg/mL (30.9, 126.39) in SARS-CoV-2 compared to 92.76 pg/mL (21.75, 246.55) in SAB (p=0.017); 12.50 pg/mL (3.06, 35.77) in patients with NIC; and 95.51 pg/mL (52.17, 756.67) in SCOVID. Median IL-6 and CRP levels decreased between admission and discharge timepoints. This reduction was amplified in patients treated with remdesivir and/or dexamethasone. CRP and bedside vital signs were the strongest predictors of COVID-19 severity.

Conclusions: Knowledge of the kinetics of IL-6 did not offer enhanced predictive value for disease severity in COVID-19 over common investigations such as CRP and vital signs.
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http://dx.doi.org/10.3389/fimmu.2021.646095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8009986PMC
April 2021

Effect of prior general anesthesia or sedation and antiseizure drugs on the diagnostic utility of wireless video electroencephalography in dogs.

J Vet Intern Med 2020 Sep 13;34(5):1967-1974. Epub 2020 Jul 13.

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.

Background: Ambulatory wireless video electroencephalography (AEEG) is the method of choice to discriminate epileptic seizures from other nonepileptic episodes. However, the influence of prior general anesthesia (GA), sedation, or antiseizure drug (ASD) on the diagnostic ability of AEEG is unknown.

Hypothesis/objectives: The use of sedation/GA or ASD treatment before AEEG recording may affect the diagnostic ability of AEEG and the time to first abnormality on AEEG.

Animals: A total of 108 client-owned dogs undergoing ambulatory AEEG for paroxysmal episodes.

Methods: Retrospective cohort study. Proportions of diagnostic AEEG and time to first abnormality were compared between dogs that received sedation/GA or neither for instrumentation as well as dogs receiving at least 1 ASD and untreated dogs.

Results: Ambulatory EEG was diagnostic in 60.2% of all dogs including 49% of the sedation/GA dogs and 68% of dogs that received neither (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.02-5.00; P = .05). The AEEG was diagnostic in 51% of dogs receiving at least 1 ASD and 66% of untreated dogs (OR, 1.95; 95% CI, 0.9-4.3; P = .11). No difference was found in time to first abnormality between sedation/GA or neither or ASD-treated or untreated dogs (P = .1 and P = .3 respectively). Ninety-five percent of dogs had at least 1 abnormality within 277 minutes.

Conclusion And Clinical Importance: Sedation/GA and concurrent ASD administration were not identified as confounding factors for decreasing AEEG diagnostic capability nor did they delay the time to first abnormality. A 4-hour minimal recording period is recommended.
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http://dx.doi.org/10.1111/jvim.15856DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7517491PMC
September 2020

The Role of In Vivo and Ex Vivo Diagnostic Tools in Severe Delayed Immune-Mediated Adverse Antibiotic Drug Reactions.

J Allergy Clin Immunol Pract 2021 05 13;9(5):2010-2015.e4. Epub 2021 Jan 13.

Centre for Antibiotic Allergy and Research, Department of Infectious Diseases, Austin Health, Heidelberg, VIC, Australia; The National Centre for Infections in Cancer, Peter MacCallum Cancer Centre, Parkville, VIC, Australia; Department of Oncology, Peter MacCallum Cancer Centre, The University of Melbourne, Parkville, VIC, Australia; Department of Medicine (Austin Health), The University of Melbourne, Heidelberg, VIC, Australia.

Background: The use of in vivo and ex vivo diagnostic tools for delayed immune-mediated adverse drug reactions is currently ill defined.

Objective: To determine whether the combination of skin testing and/or IFN-γ enzyme-linked immunoSpot assay (ELISpot) can aid diagnosis of these allergy phenotypes.

Methods: Patients with antibiotic-associated severe delayed immune-mediated adverse drug reaction hypersensitivity, including Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis, generalized bullous fixed drug eruption, and severe maculopapular exanthema, were prospectively recruited. In vivo testing was completed to the implicated drug(s), and ex vivo testing was performed with the patient's PBMCs stimulated with the relevant antibiotic concentrations for IFN-γ release ELISpot measurement.

Results: Eighty-one patients met the inclusion criteria, with DRESS (42; 51.9%) accounting for most cases. Among the 63 (78%) who had an ELISpot assay performed, 34 (54%) were positive to at least 1 implicated antibiotic (median spot-forming units/million cells, 99.5; interquartile range, 68-187), with glycopeptide being a strong predictor of positivity (adjusted odds ratio, 6.11; 95% CI, 1.74-21.42). In combination (in vivo and ex vivo), 51 (63%) of those tested were positive to an implicated antibiotic. For DRESS and severe maculopapular exanthema associated with penicillins and cephalosporins, this combination confirmed the culprit agent in 11 of the 12 cases and in 6 of 7 for DRESS associated with glycopeptides.

Conclusions: This study demonstrates that using in vivo in combination with ex vivo testing can enhance the diagnostic approach in these severe phenotypes by assisting with the identification of possible culprit antibiotics.
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http://dx.doi.org/10.1016/j.jaip.2020.12.052DOI Listing
May 2021

COVID-MATCH65-A prospectively derived clinical decision rule for severe acute respiratory syndrome coronavirus 2.

PLoS One 2020 9;15(12):e0243414. Epub 2020 Dec 9.

Department of Infectious Diseases, Austin Health, Heidelberg, Australia.

Objectives: We report on the key clinical predictors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and present a clinical decision rule that can risk stratify patients for COVID-19.

Design, Participants And Setting: A prospective cohort of patients assessed for COVID-19 at a screening clinic in Melbourne, Australia. The primary outcome was a positive COVID-19 test from nasopharyngeal swab. A backwards stepwise logistic regression was used to derive a model of clinical variables predictive of a positive COVID-19 test. Internal validation of the final model was performed using bootstrapped samples and the model scoring derived from the coefficients, with modelling performed for increasing prevalence.

Results: Of 4226 patients with suspected COVID-19 who were assessed, 2976 patients underwent SARS-CoV-2 testing (n = 108 SARS-CoV-2 positive) and were used to determine factors associated with a positive COVID-19 test. The 7 features associated with a positive COVID-19 test on multivariable analysis were: COVID-19 patient exposure or international travel, Myalgia/malaise, Anosmia or ageusia, Temperature, Coryza/sore throat, Hypoxia-oxygen saturation < 97%, 65 years or older-summarized in the mnemonic COVID-MATCH65. Internal validation showed an AUC of 0.836. A cut-off of ≥ 1.5 points was associated with a 92.6% sensitivity and 99.5% negative predictive value (NPV) for COVID-19.

Conclusions: From the largest prospective outpatient cohort of suspected COVID-19 we define the clinical factors predictive of a positive SARS-CoV-2 test. The subsequent clinical decision rule, COVID-MATCH65, has a high sensitivity and NPV for SARS-CoV-2 and can be employed in the pandemic, adjusted for disease prevalence, to aid COVID-19 risk-assessment and vital testing resource allocation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0243414PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7725390PMC
December 2020

Diagnosis and long-term management of post-traumatic seizures in a white-crowned pionus ().

J Am Vet Med Assoc 2020 May;256(10):1145-1152

Case Description: A 13-year-old female white-crowned pionus () was examined because of seizures 22 months after it was treated for a traumatic brain injury (TBI) characterized by vision loss, hemiparesis, nystagmus, circling, and head tilt.

Clinical Findings: Bloodwork performed during the initial seizure workup revealed hypercalcemia and hypercholesterolemia, which were attributed to vitellogenesis given the bird's previous egg-laying history and recent onset of reproductive behavior. Magnetic resonance imaging of the brain revealed diffuse right pallium atrophy with multifocal hydrocephalus ex vacuo, which were believed to be the result of the previous TBI. Findings were most consistent with post-traumatic seizures (PTS).

Treatment And Outcome: Levetiracetam (100 mg/kg [45 mg/lb], PO, q 12 h) was initiated for PTS management. A 4.7-mg deslorelin implant was injected SC to suppress reproductive behavior. The bird was reexamined for presumed status epilepticus 5 times over 22 months. Seizure episodes coincided with onset of reproductive behavior. The levetiracetam dosage was increased (150 mg/kg [68 mg/lb], PO, q 8 h), and zonisamide (20 mg/kg [9.1 mg/lb], PO, q 12 h) was added to the treatment regimen. Additional deslorelin implants were administered every 2 to 6 months to suppress reproductive behavior. The owner was trained to administer midazolam intranasally or IM as needed at home. The treatment regimen helped control but did not eliminate seizure activity. The bird was euthanized 22 months after PTS diagnosis for reasons unrelated to the TBI or PTS.

Clinical Relevance: Long-term management of PTS in a pionus was achieved with levetiracetam and zonisamide administration.
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http://dx.doi.org/10.2460/javma.256.10.1145DOI Listing
May 2020

Immune Checkpoint Blockade - How Does It Work in Brain Metastases?

Front Mol Neurosci 2019 21;12:282. Epub 2019 Nov 21.

Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom.

Immune checkpoints restrain the immune system following its activation and their inhibition unleashes anti-tumor immune responses. Immune checkpoint inhibitors revolutionized the treatment of several cancer types, including melanoma, and immune checkpoint blockade with anti-PD-1 and anti-CTLA-4 antibodies is becoming a frontline therapy in metastatic melanoma. Notably, up to 60% of metastatic melanoma patients develop metastases in the brain. Brain metastases (BrM) are also very common in patients with lung and breast cancer, and occur in ∼20-40% of patients across different cancer types. Metastases in the brain are associated with poor prognosis due to the lack of efficient therapies. In the past, patients with BrM used to be excluded from immune-based clinical trials due to the assumption that such therapies may not work in the context of "immune-specialized" environment in the brain, or may cause harm. However, recent trials in patients with BrM demonstrated safety and intracranial activity of anti-PD-1 and anti-CTLA-4 therapy. We here discuss how immune checkpoint therapy works in BrM, with focus on T cells and the cross-talk between BrM, the immune system, and tumors growing outside the brain. We discuss major open questions in our understanding of what is required for an effective immune checkpoint inhibitor therapy in BrM.
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http://dx.doi.org/10.3389/fnmol.2019.00282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6881300PMC
November 2019

Evaluation of Brain Death in Laying Hens During On-Farm Killing by Cervical Dislocation Methods or Pentobarbital Sodium Injection.

Front Vet Sci 2019 3;6:297. Epub 2019 Sep 3.

Department of Pathobiology, University of Guelph, Guelph, ON, Canada.

This study investigated changes in the electroencephalograph (EEG) power spectrum as well as physiological and behavioral responses to on-farm killing via mechanical cervical dislocation (MCD), manual cervical dislocation (CD) or intravenous pentobarbital sodium administration in lightly anesthetized laying hens, to evaluate the welfare impact of each method. A mixed group of 44 white Leghorn and Smoky Joe laying hens (60 weeks-old) were anesthetized with isoflurane in oxygen and maintained at 1.5-2% isoflurane/O until the killing method was applied. Birds were randomly assigned to one of three experimental groups on each trial day. The EEG was recorded bilaterally in a four-electrode montage. After recording a 5-min baseline, the killing method was applied and EEGs and other behavioral and physiological responses, including convulsions, gasping, cessation of body movements and feather erection were recorded for 5 min. Changes in EEG frequency bands (alpha, beta, delta, theta), median frequency (F50), 95% spectral edge frequency (F95), and total power (Ptot) were used to assess the quality of the on-farm killing event. Within 15 s after administration of pentobarbital sodium, there were significant decreases in mean frequency bands, increases in mean F50 and F95, and decreases in Ptot, suggesting brain death. In addition, birds presented a shorter latency to cessation of movement after pentobarbital sodium injection compared to MCD and CD (22 vs. 115 s and 136 s, respectively). There were significant increases in F95 and decreases in Ptot at 120 s after application of CD; and a concomitant decrease in the frequency bands at 135 s and isoelectric EEG at 171 ± 15 s. Changes consistent with brain death after MCD included isoelectric EEG at 207 ± 23 s and a significant decreases in some frequency bands at 300 s post-application. No other significant spectrum frequency changes were observed in the MCD group, suggesting brain death likely occurred near the 5-min endpoint. There was no clear association between behavioral, physiological, and EEG responses within CD and MCD treatments. The data demonstrate that pentobarbital sodium induced a rapid death with minimal behavioral and physiological responses regardless of strain of hens. In comparison, use of CD and MCD resulted in a slow onset of brain death in hens.
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http://dx.doi.org/10.3389/fvets.2019.00297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6733910PMC
September 2019

Diagnostic imaging characteristics of canine infectious sacroiliitis.

Can Vet J 2019 06;60(6):630-636

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario.

Infectious sacroiliitis has not been described in dogs. This retrospective case series describes the presentation, diagnostic imaging characteristics, and outcomes of 2 canine patients with infectious sacroiliitis. Selection criteria included presentation with back pain from 2010 to 2017, diagnostic imaging of the sacroiliac joints, and short- and long-term response to antibiotic therapy. Medical records, and magnetic resonance imaging (MRI) were reviewed by a Board-certified veterinary radiologist, a neurologist, and a small animal intern. Two dogs met the inclusion criteria. Magnetic resonance imaging revealed unilaterally wide and irregular sacroiliac joint spaces, with juxta-articular soft tissue contrast enhancement and bone marrow edema. One patient had a communicating abscess of the psoas muscle, which cultured positive for Following treatment with pain relief medications and antibiotics, both patients made a complete clinical recovery, with no signs of lameness 2 to 4 weeks after cessation of treatment, and no lameness reported by the owner afterwards. Infectious sacroiliitis should be considered when dogs are presented with lumbosacral pain.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6515814PMC
June 2019

Electroencephalographic, physiologic and behavioural responses during cervical dislocation euthanasia in turkeys.

BMC Vet Res 2019 May 7;15(1):132. Epub 2019 May 7.

Depts of Pathobiology, University of Guelph, Guelph, ON, N1G 2W1, Canada.

Background: There is a critical need to develop appropriate on-farm euthanasia methods for poultry species. Euthanasia methods should affect the brain first causing insensibility, followed by cardiorespiratory arrest. Neck or cervical dislocation methods, either manual (CD) or mechanical (MCD), are reported to cause a prolonged time to loss of sensibility and death with inconsistent results upon application, especially MCD methods. However, there is limited information on cervical dislocation in turkeys. The overall objective of this study was to assess the welfare implications of CD and a newly developed MCD device for euthanasia of cull turkeys in comparison with intravenous (IV) pentobarbital sodium (1 mL/4.5 kg), the gold standard euthanasia method. Time to death using electroencephalographic (EEG) and behavioural responses were monitored in eight and eighteen week-old turkeys for five minutes after each euthanasia method application. Spectral analyses of EEG responses and onset of isoelectric EEGs were compared to baseline EEG recordings of birds under anesthesia and behavioural responses were studied among euthanasia treatments. A significant decrease in brain activity frequencies analysis and isoelectric EEG were recorded as time of brain death.

Results: All turkeys euthanized with IV pentobarbital sodium presented a rapid and irreversible decrease in the EEG activity at approximately 30s post-injection with minimal behavioural responses. CD and MCD methods caused EEG responses consistent with brain death at approximately 120 s and 300 s, respectively. Additionally, isoelectric EEGs resulted in all pentobarbital sodium and CD groups, but only in 54 and 88% of the eight and eighteen week-old turkeys in the MCD groups, respectively. There were few clear patterns of behavioural responses after CD and MCD application. However, cessation of body movement and time to isoelectric EEG after CD application were positively correlated.

Conclusions: Use of CD and MCD resulted in a prolonged time to death in both age groups of turkeys. MCD application presents a number of welfare risks based on electroencephalographic and behavioural findings. Intravenous pentobarbital sodium induced rapid brain death, but possesses several on-farm limitations. To develop improvements in cervical dislocation methods, further investigations into combined or alternative methods are required to reduce the prolonged time to insensibility and death.
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http://dx.doi.org/10.1186/s12917-019-1885-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6505191PMC
May 2019

The accuracy of computed tomography scans for rapid prototyping of canine skulls.

PLoS One 2019 25;14(3):e0214123. Epub 2019 Mar 25.

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.

This study's objective was to determine the accuracy of using current computed tomography (CT) scan and software techniques for rapid prototyping by quantifying the margin of error between CT models and laser scans of canine skull specimens. Twenty canine skulls of varying morphology were selected from an anatomy collection at a veterinary school. CT scans (bone and standard algorithms) were performed for each skull, and data segmented (testing two lower threshold settings of 226HU and -650HU) into 3-D CT models. Laser scans were then performed on each skull. The CT models were compared to the corresponding laser scan to determine the error generated from the different types of CT model parameters. This error was then compared between the different types of CT models to determine the most accurate parameters. The mean errors for the 226HU CT models, both bone and standard algorithms, were not significant from zero error (p = 0.1076 and p = 0.0580, respectively). The mean errors for both -650HU CT models were significant from zero error (p < 0.001). Significant differences were detected between CT models for 3 CT model comparisons: Bone (p < 0.0001); Standard (p < 0.0001); and -650HU (p < 0.0001). For 226HU CT models, a significant difference was not detected between CT models (p = 0.2268). Independent of the parameters tested, the 3-D models derived from CT imaging accurately represent the real skull dimensions, with CT models differing less than 0.42 mm from the real skull dimensions. The 226HU threshold was more accurate than the -650HU threshold. For the 226HU CT models, accuracy was not dependent on the CT algorithm. For the -650 CT models, bone was more accurate than standard algorithms. Knowing the inherent error of this procedure is important for use in 3-D printing for surgical planning and medical education.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0214123PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6433237PMC
December 2019

Manual polishing of 3D printed metals produced by laser powder bed fusion reduces biofilm formation.

PLoS One 2019 27;14(2):e0212995. Epub 2019 Feb 27.

Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.

Certain 3D printed metals and surface finishes may be better suited for canine patient specific orthopedic implants on the basis of minimizing potential bacterial biofilm growth. Thirty disks each of titanium alloy, stainless steel, and cobalt chromium alloy were 3D printed via laser powder bed fusion. Fifteen disks of each metal were subsequently polished. After incubation with a robust biofilm-forming methicillin-resistant Staphylococcus pseudintermedius isolate, disks were rinsed and sonicated to collect biofilm bacteria. Serial dilutions were plated on blood agar, and colony forming units were counted log (ln) transformed for analysis of variance. Interference microscopy quantified surface roughness for comparison to biofilm growth. Scanning electron microscopy on both pre- and post-sonicated disks confirmed biofilm presence and subsequent removal, and visualized surface features on cleaned disks. Significantly more bacteria grew on rough versus polished metal preparations (p < 0.0001). Titanium alloy had more bacterial biofilm growth compared to cobalt chromium alloy (p = 0.0001) and stainless steel (p < 0.0001). There were no significant growth differences between cobalt chromium alloy and stainless steel (p = 0.4737). Relationships between biofilm growth and surface roughness varied: positive with the rough preparations and negative with the smooth. Polished preparations had increased variance in surface roughness compared to rough preparations, and within disk variance predominated over between disk variance for all preparations with the exception of rough cobalt chromium alloy and rough stainless steel. Using scanning electron microscopy, bacterial biofilms tended to form in crevices. Overall, manual polishing of 3D printed surfaces significantly reduced biofilm growth, with preparation-specific relationships between surface roughness and biofilm growth. These results suggest that metallic implants produced by laser powder bed fusion should be polished. Further research will elucidate the optimal surface roughness per preparation to reduce potential biofilm formation and implant associated infection.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212995PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6392326PMC
November 2019

Magnetic resonance imaging muscle lesions in presumptive canine fibrocartilaginous embolic myelopathy.

Can Vet J 2018 12;59(12):1287-1292

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1.

This retrospective cohort study reports the observation of magnetic resonance imaging (MRI) epaxial muscle hyperintensity in dogs diagnosed with presumptive fibrocartilaginous embolic myelopathy (FCEM) ( = 61). It further reports the observation of vertebral column hyperesthesia lasting > 12 hours. The hypothesis tested was that the finding of MRI epaxial muscle hyperintensity correlated with dogs presenting with hyperesthesia. Client-owned dogs diagnosed with presumptive FCEM by specific MRI criteria were included. Statistical analysis was performed using Fisher's exact test. Twenty-three percent (14/61) of MRIs displayed abnormal muscle hyperintensity and 43% (26/61) exhibited vertebral column hyperesthesia. No relationship was found between muscle hyperintensity and pain persisting beyond 12 hours. The muscle hyperintensity remains of unknown significance. That 43% of presumptive FCEM cases have prolonged signs of pain is a higher prevalence than previously reported, and may affect clinical differential diagnoses. This is especially significant in cases in which MRI is not possible and a presumptive diagnosis must be based on the clinical signs.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237267PMC
December 2018

Intensive care decision-making: Identifying the challenges and generating solutions to improve inter-specialty referrals to critical care.

J Intensive Care Soc 2018 Nov 19;19(4):287-298. Epub 2018 Feb 19.

Critical Care Unit, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, UK.

Introduction: Decision-making regarding admission to UK intensive care units is challenging. Demand for beds exceeds capacity, yet the need to provide emergency cover creates pressure to build redundancy into the system. Guidelines to aid clinical decision-making are outdated, resulting in an over-reliance on professional judgement. Although clinicians are highly skilled, there is variability in intensive care unit decision-making, especially at the inter-specialty level wherein cognitive biases contribute to disagreement.

Method: This research is the first to explore intensive care unit referral and admission decision-making using the Critical Decision Method interviewing technique. We interviewed intensive care unit ( = 9) and non-intensive care unit ( = 6) consultants about a challenging referral they had dealt with in the past where there was disagreement about the patient's suitability for intensive care unit.

Results: We present: (i) a description of the referral pathway; (ii) challenges that appear to derail referrals (i.e. process issues, decision biases, inherent stressors, post-decision consequences) and (iii) potential solutions to improve this process.

Discussion: This research provides a foundation upon which interventions to improve inter-specialty decision-making can be based.
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http://dx.doi.org/10.1177/1751143718758933DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6259089PMC
November 2018

Decision-making in intensive care medicine - A review.

J Intensive Care Soc 2018 Aug 12;19(3):247-258. Epub 2017 Dec 12.

Critical Care Unit, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, UK.

Decision-making by intensivists around accepting patients to intensive care units is a complex area, with often high-stakes, difficult, emotive decisions being made with limited patient information, high uncertainty about outcomes and extreme pressure to make these decisions quickly. This is exacerbated by a lack of clear guidelines to help guide this difficult decision-making process, with the onus largely relying on clinical experience and judgement. In addition to uncertainty compounding decision-making at the individual clinical level, it is further complicated at the multi-speciality level for the senior doctors and surgeons to intensive care units. This is a systematic review of the existing literature about this decision-making process and the factors that help guide these decisions on both sides of the intensive care unit admission dilemma. We found many studies exist assessing the patient factors correlated with intensive care unit admission decisions. Analysing these together suggests that factors consistently found to be correlated with a decision to admit or refuse a patient from intensive care unit are bed availability, severity of illness, initial ward or team referred from, patient choice, do not resuscitate status, age and functional baseline. Less research has been done on the decision-making process itself and the factors that are important to the accepting intensivists; however, similar themes are seen. Even less research exists on referral decision and demonstrates that in addition to the factors correlated with intensive care unit admission decisions, other wider variables are considered by the referring non-intensivists. No studies are available that investigate the decision-making process in referring non-intensivists or the mismatch of processes and pressure between the two sides of the intensive care unit referral dilemma.
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http://dx.doi.org/10.1177/1751143717746566DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6110024PMC
August 2018

Computed Tomography and Biomechanical Comparison between Trans-Articular Screw Fixation and 2 Polymethylmethacrylate Cemented Constructs for Ventral Atlantoaxial Stabilization.

Vet Comp Orthop Traumatol 2018 Sep 20;31(5):344-355. Epub 2018 Aug 20.

School of Engineering, University of Guelph, Guelph, Ontario, Canada.

Objectives:  Canine ventral atlantoaxial stabilization methods have been constantly evolving over the past few decades. Yet, proper experimental data comparing the feasibility and biomechanical properties of currently available surgical options are lacking. The aims of this study were (1) to describe and compare the safety profiles and biomechanical properties of three ventral atlantoaxial stabilization methods; and (2) to test whether recently reported optimal implant definitions constitute reasonable guidelines.

Methods:  Three types of atlantoaxial stabilization including trans-articular screw fixation (TSF) and two cemented constructs (MI5 and MI6) were performed in 21 Beagle cadavers. Post-surgical computed tomography (CT) images of the constructs and biomechanical data were then generated and statistically analysed.

Results:  The CT data revealed that TSF achieved significantly better apposition than cemented constructs. Out of 91 screws positioned, 4.4% were graded as dangerous and 86.8% as optimal. Optimal positioning was most challenging to obtain for mono-cortical screws. Analysis of biomechanical data suggested that all three techniques could likely achieve similar rates of atlantoaxial fusion when submitted to physiological loads but also that cemented constructs were less prone to failure compared with TSF.

Clinical Significance:  This study provides evidence that all three techniques are technically feasible and biomechanically viable but also that the evaluated surgical guidelines could be improved.
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http://dx.doi.org/10.1055/s-0038-1661397DOI Listing
September 2018

Computed Tomographic Analysis of Ventral Atlantoaxial Optimal Safe Implantation Corridors in 27 Dogs.

Vet Comp Orthop Traumatol 2017 Nov 4;30(6):413-423. Epub 2017 Dec 4.

School of Engineering, University of Guelph, Guelph, Ontario, Canada.

 Ventral atlantoaxial stabilization techniques are challenging surgical procedures in dogs. Available surgical guidelines are based upon subjective anatomical landmarks, and limited radiographic and computed tomographic data. The aims of this study were (1) to provide detailed anatomical descriptions of atlantoaxial optimal safe implantation corridors to generate objective recommendations for optimal implant placements and (2) to compare anatomical data obtained in non-affected Toy breed dogs, affected Toy breed dogs suffering from atlantoaxial instability and non-affected Beagle dogs.  Anatomical data were collected from a prospectively recruited population of 27 dogs using a previously validated method of optimal safe implantation corridor analysis using computed tomographic images.  Optimal implant positions and three-dimensional numerical data were generated successfully in all cases. Anatomical landmarks could be used to generate objective definitions of optimal insertion points which were applicable across all three groups. Overall the geometrical distribution of all implant sites was similar in all three groups with a few exceptions.  This study provides extensive anatomical data available to facilitate surgical planning of implant placement for atlantoaxial stabilization. Our data suggest that non-affected Toy breed dogs and non-affected Beagle dogs constitute reasonable research models to study atlantoaxial stabilization constructs.
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http://dx.doi.org/10.3415/VCOT-17-03-0046DOI Listing
November 2017

Association between tumour infiltrating lymphocytes, histotype and clinical outcome in epithelial ovarian cancer.

BMC Cancer 2017 Sep 20;17(1):657. Epub 2017 Sep 20.

Department of Pathology, CRUK Cambridge Institute, University of Cambridge, Cambridge, UK.

Background: There is evidence that some ovarian tumours evoke an immune response, which can be assessed by tumour infiltrating lymphocytes (TILs). To facilitate adoption of TILs as a clinical biomarker, a standardised method for their H&E visual evaluation has been validated in breast cancer.

Methods: We sought to investigate the prognostic significance of TILs in a study of 953 invasive epithelial ovarian cancer tumour samples, both primary and metastatic, from 707 patients from the prospective population-based SEARCH study. TILs were analysed using a standardised method based on H&E staining producing a percentage score for stromal and intratumoral compartments. We used Cox regression to estimate hazard ratios of the association between TILs and survival.

Results: The extent of stromal and intra-tumoral TILs were correlated in the primary tumours (n = 679, Spearman's rank correlation = 0.60, P < 0.001) with a similar correlation in secondary tumours (n = 224, Spearman's rank correlation = 0.62, P < 0.001). There was a weak correlation between stromal TIL levels in primary and secondary tumour samples (Spearman's rank correlation = 0.29, P < 0.001) and intra-tumoral TIL levels in primary and secondary tumour samples (Spearman's rank correlation = 0.19, P = 0.0094). The extent of stromal TILs differed between histotypes (Pearson chi2 (12d.f.) 54.1, P < 0.0001) with higher levels of stromal infiltration in the high-grade serous and endometriod cases. A significant association was observed for higher intratumoral TIL levels and a favourable prognosis (HR 0.74 95% CI 0.55-1.00 p = 0.047).

Conclusion: This study is the largest collection of epithelial ovarian tumour samples evaluated for TILs. We have shown that stromal and intratumoral TIL levels are correlated and that their levels correlate with clinical variables such as tumour histological subtype. We have also shown that increased levels of both intratumoral and stromal TILs are associated with a better prognosis; however, this is only statistically significant for intratumoral TILs. This study suggests that a clinically useful immune prognostic indicator in epithelial ovarian cancer could be developed using this technique.
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http://dx.doi.org/10.1186/s12885-017-3585-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5607562PMC
September 2017

Anophthalmia in a Wild Eastern Gray Squirrel (Sciurus carolinensis).

J Wildl Dis 2017 10 28;53(4):942-945. Epub 2017 Jul 28.

3 Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan, S7N 5B4, Canada.

We describe bilateral true anophthalmia in a juvenile female eastern gray squirrel (Sciurus carolinensis) with histologic confirmation that orbital contents lacked ocular tissues. Additionally, the optic chiasm of the brain was absent and axon density in the optic tract adjacent to the lateral geniculate nucleus was reduced.
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http://dx.doi.org/10.7589/2017-02-048DOI Listing
October 2017

Generalized myoclonic epilepsy with photosensitivity in juvenile dogs caused by a defective DIRAS family GTPase 1.

Proc Natl Acad Sci U S A 2017 03 21;114(10):2669-2674. Epub 2017 Feb 21.

Research Programs Unit, Molecular Neurology, University of Helsinki, 00014 Helsinki, Finland;

The clinical and electroencephalographic features of a canine generalized myoclonic epilepsy with photosensitivity and onset in young Rhodesian Ridgeback dogs (6 wk to 18 mo) are described. A fully penetrant recessive 4-bp deletion was identified in the DIRAS family GTPase 1 () gene with an altered expression pattern of DIRAS1 protein in the affected brain. This neuronal gene with a proposed role in cholinergic transmission provides not only a candidate for human myoclonic epilepsy but also insights into the disease etiology, while establishing a spontaneous model for future intervention studies and functional characterization.
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http://dx.doi.org/10.1073/pnas.1614478114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5347561PMC
March 2017

Canine atlantoaxial optimal safe implantation corridors - description and validation of a novel 3D presurgical planning method using OsiriX™.

BMC Vet Res 2016 Sep 6;12(1):188. Epub 2016 Sep 6.

School of Engineering, University of Guelph, Guelph, ON, N1G 2W1, Canada.

Background: Canine ventral atlantoaxial (AA) stabilization is most commonly performed in very small dogs and is technically challenging due to extremely narrow bone corridors. Multiple implantation sites have been suggested but detailed anatomical studies investigating these sites are lacking and therefore current surgical guidelines are based upon approximate anatomical landmarks. In order to study AA optimal safe implantation corridors (OSICs), we developed a method based on computed tomography (CT) and semi-automated three-dimensional (3D) mathematical modelling using OsiriX™ and Microsoft®Excel software. The objectives of this study were 1- to provide a detailed description of the bone corridor analysis method and 2- to assess the reproducibility of the method. CT images of the craniocervical junction were prospectively obtained in 27 dogs and our method of OSIC analysis was applied in all dogs. For each dog, 13 optimal implant sites were simulated via geometrical simplification of the bone corridors. Each implant 3D position was then defined with respect to anatomical axes using 2 projected angles (ProjA). The safety margins around each implant were also estimated with angles (SafA) measured in 4 orthogonal directions. A sample of 12 simulated implants was randomly selected and each mathematically calculated angle was compared to direct measurements obtained within OsiriX™ from 2 observers repeated twice. The landmarks simulating anatomical axes were also positioned 4 times to determine their effect on ProjA reproducibility.

Results: OsiriX could be used successfully to simulate optimal implant positions in all cases. There was excellent agreement between the calculated and measured values for both ProjA (ρc = 0.9986) and SafA (ρc = 0.9996). Absolute differences between calculated and measured values were respectively [ProjA = 0.44 ± 0.53°; SafA = 0.27 ± 0.25°] and [ProjA = 0.26 ± 0.21°; SafA = 0.18 ± 0.18°] for each observer. The 95 % tolerance interval comparing ProjA obtained with 4 different sets of anatomical axis landmarks was [-1.62°, 1.61°] which was considered appropriate for clinical use.

Conclusions: A new method for determination of optimal implant placement is provided. Semi-automated calculation of optimal implant 3D positions could be further developed to facilitate preoperative planning and to generate large descriptive anatomical datasets.
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http://dx.doi.org/10.1186/s12917-016-0824-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5012052PMC
September 2016

The effect of topical lidocaine on muscle artefacts in awake canine electroencephalogram recordings.

Vet J 2016 Jul 31;213:6-8. Epub 2016 Mar 31.

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1.

Muscle artefacts in electroencephalogram recording data interfere with diagnostic accuracy. Lidocaine may reduce these artefacts. The objective of this study was to determine the effect of topical lidocaine on muscle artefacts in unanesthetized canine electroencephalogram (EEG) recording data. Topical 4% lidocaine was applied to each electrode site for six treated dogs prior to subdermal wire electrode placement and compared against historical untreated controls. Twenty-minute recordings began 30 min after lidocaine application. Three epochs (early, middle, and end) were sampled from each recording and scored for muscle artefact incidence and severity by two blinded reviewers. No significant treatment effects on incidence and severity were found. Application of topical lidocaine does not appear to reduce the occurrence of muscle artefacts in canine EEG recordings.
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http://dx.doi.org/10.1016/j.tvjl.2016.03.025DOI Listing
July 2016

Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors.

Nat Commun 2015 Oct 6;6:8518. Epub 2015 Oct 6.

Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute and Department of Veterinary Medicine, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.

Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination.
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http://dx.doi.org/10.1038/ncomms9518DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4600759PMC
October 2015

A CHRNE frameshift mutation causes congenital myasthenic syndrome in young Jack Russell Terriers.

Neuromuscul Disord 2015 Dec 8;25(12):921-7. Epub 2015 Sep 8.

Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA 92093-0709, USA. Electronic address:

Congenital myasthenic syndromes (CMSs) are a group of rare genetic disorders of the neuromuscular junction resulting in structural or functional causes of fatigable weakness that usually begins early in life. Mutations in pre-synaptic, synaptic and post-synaptic proteins have been demonstrated in human cases, with more than half involving aberrations in nicotinic acetylcholine receptor (AChR) subunits. CMS was first recognized in dogs in 1974 as an autosomal recessive trait in Jack Russell Terriers (JRTs). A deficiency of junctional AChRs was demonstrated. Here we characterize a CMS in 2 contemporary cases of JRT littermates with classic clinical and electromyographic findings, and immunochemical confirmation of an approximately 90% reduction in AChR protein content. Loci encoding the 5 AChR subunits were evaluated using microsatellite markers, and CHRNB1 and CHRNE were identified as candidate genes. Sequences of the splice sites and exons of both genes revealed a single base insertion in exon 7 of CHRNE that predicts a frameshift mutation and a premature stop codon. We further demonstrated this pathogenic mutation in CHRNE in archival tissues from unrelated JRTs studied 34 years ago.
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http://dx.doi.org/10.1016/j.nmd.2015.09.005DOI Listing
December 2015

Clinical and MRI findings in three dogs with polycystic meningiomas.

J Am Anim Hosp Assoc 2012 Sep-Oct;48(5):331-8. Epub 2012 Jul 27.

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.

One spayed female Labrador retriever and two castrated male golden retrievers were evaluated for chronic (i.e., ranging from 3 wk to 24 wk) neurologic signs localizable to the prosencephalon. Signs included seizures, circling, and behavior changes. MRI demonstrated extra-axial, contrast-enhancing, multiloculated, fluid-filled, cyst-like lesions with a mass effect, causing compression and displacement of brain parenchyma. Differential diagnoses included cystic neoplasm, abscess or other infectious cyst (e.g., alveolar hydatid cyst), or fluid-filled anomaly (e.g., arachnoid cyst). The cyst-like lesions were attached to the rostral falx cerebri in all cases. In addition, case 2 had a second polycystic mass at the caudal diencephalon. Surgical biopsy (case 3 with a single, rostral tumor via transfrontal craniectomy) and postmortem histology (in cases 1 and 2) confirmed polycystic meningiomas. Tumor types were transitional (cases 1 and 3) and fibrous (case 2), with positive immunohistochemical staining for vimentin. Case 3 was also positive for E-cadherin, s100, and CD34. In all cases, staining was predominantly negative for glial fibrillary acid protein and pancytokeratins, supporting a diagnosis of meningioma. This report describes the first cases of polycystic meningiomas in dogs. Polycystic meningiomas are a rare, but important, addition to the differential diagnoses for intracranial cyst-like lesions, significantly affecting planning for surgical resection and other therapeutic interventions.
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http://dx.doi.org/10.5326/JAAHA-MS-5774DOI Listing
November 2012

Autonomic dysfunction in a Jack Russell terrier.

Can Vet J 2011 Mar;52(3):297-9

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1.

A 4-year-old Jack Russell terrier was presented with an array of clinical signs suggestive of autonomic dysfunction. Many of the clinical signs were consistent with a diagnosis of dysautonomia; however, both chronicity and resolution of signs contradicted a diagnosis of this disease.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3039902PMC
March 2011

Investigation of the use of three electroencephalographic electrodes for long-term electroencephalographic recording in awake and sedated dogs.

Am J Vet Res 2011 Mar;72(3):384-90

Department of Clinical Studies, Ontario Veterinary College, University of Guelph, ON N1G 2W1, Canada.

Objective: To compare electroencephalography (EEG) artifact associated with use of the subdermal wire electrode (SWE), gold cup electrode (GCE), and subdermal needle electrode (SNE) over an 8-hour period in sedated and awake dogs.

Animals: 6 healthy dogs.

Procedures: 8 EEG channels were recorded during 20-minute video-EEG recording sessions (intermittently at 0.5, 2, 4, 6, and 8 hours) with and without chlorpromazine sedation. Nonphysiologic artifacts were identified. Duration of artifact was summed for each channel. Number of unaffected channels (NUC) was determined.

Results: NUC was significantly affected by electrode type and sedation over time; median for SWE (2.80 channels; 95% confidence interval [CI], 0.84 to 5.70 channels) was significantly different from medians for GCE (7.87 channels; 95% CI, 7.44 to 7.94 channels) and SNE (7.60 channels; 95% CI, 6.61 to 7.89 channels). After 4 hours, NUC decreased in awake dogs, regardless of electrode type. In awake dogs, duration of artifact differed significantly between SWE and GCE or SNE; medians at 8 hours were 61.55 seconds (95% CI, 21.81 to 173.65 seconds), 1.33 seconds (95% CI, 0.47 to 3.75 seconds), and 21.01 seconds (95% CI, 6.85 to 64.42 seconds), respectively.

Conclusions And Clinical Relevance: The SWE had a significant duration of artifact during recording periods > 2 hours, compared with results for the GCE and SNE, in awake dogs. The GCE, SNE, and sedation resulted in significantly more channels unaffected by artifact. For longer recordings, caution should be exercised in selecting EEG electrodes and sedation state, although differences among electrodes may not be clinically relevant.
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http://dx.doi.org/10.2460/ajvr.72.3.384DOI Listing
March 2011