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Webb AA, Ruhe AL, Neff MW. A missense mutation in MYO7A is associated with bilateral deafness and vestibular dysfunction in the Doberman pinscher breed. Can J Vet Res 2019; 83:142-148. [PMID: 31097876 PMCID: PMC6450158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 04/11/2018] [Indexed: 06/09/2023]
Abstract
Bilateral deafness with concurrent vestibular dysfunction was first reported in the Doberman pinscher in 1980. Here, we identify a coding mutation in the MYO7A gene that is perfectly associated with the disorder. The lack of visual deficits in affected dogs suggests that, like rodents but unlike humans, MYO7A is not required for retinal function. DNA testing of the mutation will enable dog breeders to manage the incidence of this genetic defect.
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Affiliation(s)
- Aubrey A Webb
- CullenWebb Animal Eye Specialists, Riverview, New-Brunswick E1B 4X2 (Webb); Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta T2N 1N4 (Webb); ProjectDog, Davis, California 95616, USA (Ruhe); Van Andel Research Institute, Grand Rapids, Michigan 49503, USA (Ruhe, Neff); Translational Genomics Research Institute, Phoenix, Arizona 85004, USA (Neff)
| | - Alison L Ruhe
- CullenWebb Animal Eye Specialists, Riverview, New-Brunswick E1B 4X2 (Webb); Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta T2N 1N4 (Webb); ProjectDog, Davis, California 95616, USA (Ruhe); Van Andel Research Institute, Grand Rapids, Michigan 49503, USA (Ruhe, Neff); Translational Genomics Research Institute, Phoenix, Arizona 85004, USA (Neff)
| | - Mark W Neff
- CullenWebb Animal Eye Specialists, Riverview, New-Brunswick E1B 4X2 (Webb); Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta T2N 1N4 (Webb); ProjectDog, Davis, California 95616, USA (Ruhe); Van Andel Research Institute, Grand Rapids, Michigan 49503, USA (Ruhe, Neff); Translational Genomics Research Institute, Phoenix, Arizona 85004, USA (Neff)
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Yokoyama JS, Lam ET, Ruhe AL, Erdman CA, Robertson KR, Webb AA, Williams DC, Chang ML, Hytönen MK, Lohi H, Hamilton SP, Neff MW. Variation in genes related to cochlear biology is strongly associated with adult-onset deafness in border collies. PLoS Genet 2012; 8:e1002898. [PMID: 23028339 PMCID: PMC3441646 DOI: 10.1371/journal.pgen.1002898] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 06/29/2012] [Indexed: 01/22/2023] Open
Abstract
Domestic dogs can suffer from hearing losses that can have profound impacts on working ability and quality of life. We have identified a type of adult-onset hearing loss in Border Collies that appears to have a genetic cause, with an earlier age of onset (3–5 years) than typically expected for aging dogs (8–10 years). Studying this complex trait within pure breeds of dog may greatly increase our ability to identify genomic regions associated with risk of hearing impairment in dogs and in humans. We performed a genome-wide association study (GWAS) to detect loci underlying adult-onset deafness in a sample of 20 affected and 28 control Border Collies. We identified a region on canine chromosome 6 that demonstrates extended support for association surrounding SNP Chr6.25819273 (p-value = 1.09×10−13). To further localize disease-associated variants, targeted next-generation sequencing (NGS) of one affected and two unaffected dogs was performed. Through additional validation based on targeted genotyping of additional cases (n = 23 total) and controls (n = 101 total) and an independent replication cohort of 16 cases and 265 controls, we identified variants in USP31 that were strongly associated with adult-onset deafness in Border Collies, suggesting the involvement of the NF-κB pathway. We found additional support for involvement of RBBP6, which is critical for cochlear development. These findings highlight the utility of GWAS–guided fine-mapping of genetic loci using targeted NGS to study hereditary disorders of the domestic dog that may be analogous to human disorders. The domestic dog offers a unique opportunity to study complex disorders similar to those seen in humans, but within the context of the much simpler genetic backgrounds of pure breeds, which represent closed populations. We performed a whole-genome search for genetic risk factors of adult-onset deafness in the Border Collie, a breed of herding dog that relies on acute hearing to perceive and respond to commands while working. Adult-onset deafness in Border Collies typically begins in early adulthood and is similar to age-related hearing loss in humans. This earlier onset has particular impact on the utility of working Border Collies and the livelihoods of their owners, and it appears to have a genetic cause. We identified three genetic variants that were strongly associated with adult-onset deafness in a sample of 405 Border Collies. These variants are located in two genes that have previously been linked to deafness, one involved in ear development and another that appears to mitigate tissue damage in the ear. These results provide new insight regarding genetic risk factors for age-related hearing loss in both dogs and humans.
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Affiliation(s)
- Jennifer S. Yokoyama
- Department of Psychiatry and Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Ernest T. Lam
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Alison L. Ruhe
- Neurogenomics Division, The Translational Genomics Research Institute, Phoenix, Arizona, United States of America
- Veterinary Genetics Laboratory, University of California Davis, Davis, California, United States of America
| | - Carolyn A. Erdman
- Department of Psychiatry and Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Kathryn R. Robertson
- Veterinary Genetics Laboratory, University of California Davis, Davis, California, United States of America
| | - Aubrey A. Webb
- CullenWebb Animal Neurology and Ophthalmology Centre, Riverview, New Brunswick, Canada
- Department of Clinical Neuroscience, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - D. Colette Williams
- School of Veterinary Medicine, University of California Davis, Davis, California, United States of America
| | - Melanie L. Chang
- Department of Anthropology, University of Oregon, Eugene, Oregon, United States of America
| | - Marjo K. Hytönen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Medicine, University of Helsinki and Folkhälsan Research Center, Helsinki, Finland
| | - Hannes Lohi
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Medicine, University of Helsinki and Folkhälsan Research Center, Helsinki, Finland
| | - Steven P. Hamilton
- Department of Psychiatry and Institute for Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Mark W. Neff
- Neurogenomics Division, The Translational Genomics Research Institute, Phoenix, Arizona, United States of America
- The Van Andel Research Institute, Grand Rapids, Michigan, United States of America
- * E-mail:
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Abstract
Traumatic neuroma in continuity (NIC) results in profound neurological deficits, and its management poses the most challenging problem to peripheral nerve surgeons today. The absence of a clinically relevant experimental model continues to handicap our ability to investigate ways of better diagnosis and treatment for these disabling injuries. Various injury techniques were tested on Lewis rat sciatic nerves. Optimal experimental injuries that consistently resulted in NIC combined both intense focal compression and traction forces. Nerves were harvested at 0, 5, 13, 21, and 65 days for histological examination. Skilled locomotion and ground reaction force (GRF) analysis were performed up to 9 weeks on the experimental (n=6) and crush-control injuries (n=5). Focal widening, disruption of endoneurium and perineurium with aberrant intra- and extrafascicular axonal regeneration and progressive fibrosis was consistently demonstrated in 14 of 14 nerves with refined experimental injuries. At 8 weeks, experimental animals displayed a significantly greater slip ratio in both skilled locomotor assessments, compared to nerve crush animals (p<0.01). GRFs of the crush- injured animals showed earlier improvement compared to the experimental animals, whose overall GRF patterns failed to recover as well as the crush group. We have demonstrated histological features and poor functional recovery consistent with NIC formation in a rat model. The injury mechanism employed combines traction and compression forces akin to the physical forces at play in clinical nerve injuries. This model may serve as a tool to help diagnose this injury earlier and to develop intervention strategies to improve patient outcomes.
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Kemp SWP, Webb AA, Dhaliwal S, Syed S, Walsh SK, Midha R. Dose and duration of nerve growth factor (NGF) administration determine the extent of behavioral recovery following peripheral nerve injury in the rat. Exp Neurol 2011; 229:460-70. [PMID: 21458449 DOI: 10.1016/j.expneurol.2011.03.017] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 03/14/2011] [Accepted: 03/21/2011] [Indexed: 11/19/2022]
Abstract
Nerve growth factor (NGF) has been previously shown to support neuron survival and direct neurite outgrowth in vitro, and to enhance axonal regeneration in vivo. However, a systematic analysis of NGF dose and dose duration on behavioral recovery following peripheral nerve injury in rodents has not been previously investigated. Here, we show that NGF promotes a bell shaped dose-response, with an optimal threshold effect occurring at 800 pg/μl. High dose NGF inhibited regeneration. However, this effect could be reversed through functional blockade of p75 receptors, thus implicating these receptors as mediators of the inhibitory response. Longer term evaluation showed that animals administered NGF at 80 ng/day for 3 weeks had greater sensorimotor recovery compared to all other treatment groups. These animals made significantly fewer errors during skilled locomotion, and displayed both increased vertical and fore-aft ground reaction forces during flat surface locomotion. Furthermore, terminal electrophysiological and myological assessments (EMG, wet gastrocnemius muscle weights) corroborated the behavioral data. Overall, these data support the hypothesis that both appropriate dose and duration of NGF are important determinants of behavioral recovery following nerve injury in the rat.
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Affiliation(s)
- Stephen W P Kemp
- Department of Clinical Neuroscience, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
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Webb AA, Kerr B, Neville T, Ngan S, Assem H. Kinematics and ground reaction force determination: a demonstration quantifying locomotor abilities of young adult, middle-aged, and geriatric rats. J Vis Exp 2011:2138. [PMID: 21403621 PMCID: PMC3059563 DOI: 10.3791/2138] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Behavior, in its broadest definition, can be defined as the motor manifestation of physiologic processes. As such, all behaviors manifest through the motor system. In the fields of neuroscience and orthopedics, locomotion is a commonly evaluated behavior for a variety of disease models. For example, locomotor recovery after traumatic injury to the nervous system is one of the most commonly evaluated behaviors 1-3. Though locomotion can be evaluated using a variety of endpoint measurements (e.g. time taken to complete a locomotor task, etc), semiquantitative kinematic measures (e.g. ordinal rating scales (e.g. Basso Beattie and Bresnahan locomotor (BBB) rating scale, etc)) and surrogate measures of behaviour (e.g. muscle force, nerve conduction velocity, etc), only kinetics (force measurements) and kinematics (measurements of body segments in space) provide a detailed description of the strategy by which an animal is able to locomote 1. Though not new, kinematic and kinetic measurements of locomoting rodents is now more readily accessible due to the availability of commercially available equipment designed for this purpose. Importantly, however, experimenters need to be very familiar with theory of biomechanical analyses and understand the benefits and limitations of these forms of analyses prior to embarking on what will become a relatively labor-intensive study. The present paper aims to describe a method for collecting kinematic and ground reaction force data using commercially available equipment. Details of equipment and apparatus set-up, pre-training of animals, inclusion and exclusion criteria of acceptable runs, and methods for collecting the data are described. We illustrate the utility of this behavioral analysis technique by describing the kinematics and kinetics of strain-matched young adult, middle-aged, and geriatric rats.
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Affiliation(s)
- Aubrey A Webb
- CullenWebb Animal Neurology & Ophthalmology Center, Riverview, NB
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Webb AA, Ngan S, Fowler D. Spinal cord injury II: Prognostic indicators, standards of care, and clinical trials. Can Vet J 2010; 51:598-604. [PMID: 20808569 PMCID: PMC2871353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This is the second of a 2-part review of spinal cord injury. The focus herein is to highlight recent findings regarding prognostic indicators used for spinal cord injury (SCI) in dogs, promote an awareness of the current recommendations of standard of care for traumatic spinal cord injury in veterinary medicine, and highlight the findings of clinical trials of therapies for spinal cord injury in dogs. This 2-part review provides information that will assist general and specialty veterinary practitioners in evidence-based veterinary medical practice in an area that has become particularly specialized.
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Affiliation(s)
- Aubrey A Webb
- Hotchkiss Brain Institute, Department of Comparative Biology and Experimental Medicine, University of Calgary, Alberta, Canada.
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Webb AA, Cullen CL. Coat color and coat color pattern-related neurologic and neuro-ophthalmic diseases. Can Vet J 2010; 51:653-657. [PMID: 20808581 PMCID: PMC2871368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- Aubrey A Webb
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Alberta, Canada
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Webb AA, Ngan S, Fowler JD. Spinal cord injury I: A synopsis of the basic science. Can Vet J 2010; 51:485-492. [PMID: 20676289 PMCID: PMC2857426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Substantial knowledge has been gained in the pathological findings following naturally occurring spinal cord injury (SCI) in dogs and cats. The molecular mechanisms involved in failure of neural regeneration within the central nervous system, potential therapeutics including cellular transplantation therapy, neural plasticity, and prognostic indicators of recovery from SCI have been studied. This 2-part review summarizes 1) basic science perspectives regarding treating and curing spinal cord injury, 2) recent studies that shed light on prognosis and recovery from SCI, 3) current thinking regarding standards of care for dogs with SCI, 4) experimental approaches in the laboratory setting, and 5) current clinical trials being conducted in veterinary medicine. Part I presents timely information on the pathophysiology of spinal cord injury, challenges associated with promoting regeneration of neurons of the central nervous system, and experimental approaches aimed at developing treatments for spinal cord injury.
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Affiliation(s)
- Aubrey A Webb
- Hotchkiss Brain Institute, Department of Comparative Biology and Experimental Medicine, University of Calgary, 3330 Hospital Drive, NW, Calgary, Alberta T2N 4N1.
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Kemp SWP, Alant J, Walsh SK, Webb AA, Midha R. Behavioural and anatomical analysis of selective tibial nerve branch transfer to the deep peroneal nerve in the rat. Eur J Neurosci 2010; 31:1074-90. [PMID: 20377620 DOI: 10.1111/j.1460-9568.2010.07130.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Stephen W P Kemp
- Department of Clinical Neuroscience, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada.
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Webb AA, McMillan C, Cullen CL, Boston SE, Turnbull J, Minassian BA. Lafora disease as a cause of visually exacerbated myoclonic attacks in a dog. Can Vet J 2009; 50:963-967. [PMID: 19949558 PMCID: PMC2726025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An 8-year-old, castrated male, miniature wire-haired dachshund was presented with a 4-month history of intermittent facial twitching (myoclonus). The myoclonic episodes progressed over a 16-month period. Generalized seizure activity was infrequent. Clinical examination revealed visually stimulated myoclonus. Response to therapy with antiepileptic drugs was equivocal. Genetic testing identified the dog as being affected by Lafora disease.
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Affiliation(s)
- Aubrey A Webb
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive, NW, Calgary, Alberta T2N 4N1.
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Cullen CL, McMillan C, Webb AA. Neurology: Impaired vision in a dog. Can Vet J 2009; 50:539-542. [PMID: 19436642 PMCID: PMC2671880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Cheryl L Cullen
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 1N4
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12
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Webb AA. Brainstem auditory evoked response (BAER) testing in animals. Can Vet J 2009; 50:313-318. [PMID: 19436486 PMCID: PMC2643461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Aubrey A Webb
- Hotchkiss Brain Institute, Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Webb AA, McMillan C, Szentimrey D. Unilateral vestibular disease. Can Vet J 2009; 50:202-204. [PMID: 19412404 PMCID: PMC2629430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Aubrey A Webb
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Western Veterinary Specialist Centre, Calgary, Alberta, Canada
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Abstract
In experimental spinal injury studies, damage to the dorsal half of the spinal cord is common but the behavioural effects of damage to specific pathways in the dorsal cord have been less well investigated. We performed bilateral transection of the dorsolateral spinal funiculus (DLF) on 12 Long-Evans rats at the third cervical spinal segment. We quantified overground locomotion by measuring ground reaction forces, step timing and step distances as animals moved unrestrained. We also assessed skilled locomotion by measuring footslip errors made while the animals crossed horizontal ladders, and examined paw usage in a cylinder exploration task and during a skilled reaching task. Ground reaction forces revealed that rats with bilateral DLF lesions moved with a symmetrical gait, characterized mainly by altered forces exerted by the hindlimbs, delayed onset of hindlimb stance, and understepping of the hindlimbs relative to the forelimbs. These alterations in overground locomotion were subtle but were nevertheless consistent between animals and persisted throughout the 6-week recovery period. During ladder crossing, rats with DLF lesions made more footslip errors with the hindlimbs after surgery than before. Spontaneous forelimb usage during exploration was not affected by DLF axotomy but lesioned animals were less successful during skilled reaching. This is the first study which describes preferentially altered hindlimb use during overground locomotion after cervical DLF transections. We discuss these findings in relation to previous work and to the possible contributions of different ascending and descending pathways in the DLF to locomotion and skilled movements in rats.
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Affiliation(s)
- Gillian D Muir
- Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, Canada S7N 5B4.
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Webb AA, Chan CB, Brown A, Saleh TM. Estrogen reduces the severity of autonomic dysfunction in spinal cord-injured male mice. Behav Brain Res 2006; 171:338-49. [PMID: 16712973 DOI: 10.1016/j.bbr.2006.04.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 04/06/2006] [Accepted: 04/11/2006] [Indexed: 11/21/2022]
Abstract
Autonomic dysreflexia is an autonomic behavioural condition that manifests after spinal cord injury (SCI) and is characterized by acute, episodic hypertension following afferent stimulation below the level of the injury. Common triggers of autonomic dysreflexia include colorectal distension (CRD), and various somatic stimuli. The development of autonomic dysreflexia is dependent, in part, upon the degree of intraspinal inflammation and the resultant spinal neuroplastic changes that occur following SCI. 17beta-estradiol (E) has neuroprotective, anti-inflammatory and smooth muscle relaxant properties, and is therefore a candidate drug for the treatment and/or prevention of autonomic dysreflexia. Autonomic dysreflexia was assessed in adult male mice treated with E. We investigated whether E could be acting centrally by altering: (1) the size of the small diameter primary afferent arbor, (2) the degree of microglia/macrophage infiltration at the site of the injury, or (3) the amount of fibrous scarring present at the injury site. To determine whether E could be working through uncoupling protein-2 (UCP-2), a protein involved with inflammation and regulated by estrogen in some tissues, autonomic dysreflexia was assessed in E-treated adult male mice lacking UCP-2 (UCP-2 KO). 17beta-estradiol was equipotent at reducing autonomic dysreflexia in both UCP-2 KO and WT mice following CRD but not tail pinch. We have shown that E reduces autonomic dysreflexic responses to visceral but not somatic stimulation in male mice independent of the size of the primary afferent arbour, the degree of chronic inflammation, and the presence of UCP-2.
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Affiliation(s)
- Aubrey A Webb
- Department of Biomedical Sciences, University of Prince Edward Island, Charlottetown, Canada.
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Webb AA, Cullen CL, Lamont LA. Brainstem auditory evoked responses and ophthalmic findings in llamas and alpacas in Eastern Canada. Can Vet J 2006; 47:74-7. [PMID: 16536233 PMCID: PMC1316125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Seventeen llamas and 23 alpacas of various coat and iris colors were evaluated for: (1) deafness by using brainstem auditory evoked response testing; and (2) for ocular abnormalities via complete ophthalmic examination. No animals were deaf. The most common ocular abnormalities noted were iris-to-iris persistent pupillary membranes and incipient cataracts.
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Affiliation(s)
- Aubrey A Webb
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island.
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Abstract
A 10-year-old, spayed female, Irish water spaniel was presented with a 2-week history of anisocoria characterized by mydriasis of the right eye compared to the left eye in ambient light. Ophthalmic and neurological examinations, combined with pharmacological testing, identified a disease process affecting the right parasympathetic nucleus of cranial nerve 3 (CN III) and/or the parasympathetic component of CN III. Magnetic resonance imaging (MRI) identified a mass involving the right midbrain and extending caudally to the rostral border of the medulla oblongata. The dog became comatose within 12 h following MRI and was euthanized. Histopathology identified the intracranial mass as a meningioma.
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Affiliation(s)
- Aubrey A Webb
- Department of Biomedical Sciences, Atlantic Veterinary College, Universit of Prince Edward Island, Charlottetown, PE, Canada
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Webb AA, Muir GD. Sensorimotor behaviour following incomplete cervical spinal cord injury in the rat. Behav Brain Res 2005; 165:147-59. [PMID: 16157393 DOI: 10.1016/j.bbr.2005.07.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 07/04/2005] [Accepted: 07/05/2005] [Indexed: 11/18/2022]
Abstract
Rats are one of the most commonly used species for spinal cord injury research. Since the advent of the Basso, Beattie, Bresnahan (BBB) locomotor rating scale, the majority of spinal cord injury research relies upon evaluating locomotor behaviour in thoracic spinal cord injury rat models. Slightly more than 50% of all traumatic spinal cord injuries in humans, however, occur at the level of the cervical spinal cord. Further, therapies aimed at thoracic spinal cord injuries may not be directly transferable to cervical spinal cord injuries. This could be due to (1) differences in distance between the cell bodies of injured axons and the injury site and (2) because some behaviours (e.g. stepping movements) used to evaluate the therapeutic potential of a given treatment are governed primarily by intraspinal neuronal circuitry while other behaviours (e.g. skilled reaching) require more sophisticated conscious integration of the sensorimotor system. Consequently, there is a need to develop and use experimental cervical spinal cord injury models and understand the behavioural characteristics of such models. The present review highlights the sensorimotor abilities of cervical spinal cord-injured rats, including both forelimb, hind limb, and whole body behaviours. We also provide insight into the neuroanatomic substrates important for performing a given behaviour, information which may prove essential in the development of site-directed therapeutic strategies.
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Affiliation(s)
- Aubrey A Webb
- Canadian Institutes of Health Research Post-doctoral Fellow, Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
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Abstract
OBJECTIVES To compare Schirmer tear test (STT) values, corneal sensitivity, tear film break up times (TFBUTs), and tear glucose concentrations in relation to conjunctival microflora, and conjunctival cytologic and histologic findings among diabetic cataractous, nondiabetic cataractous, and nondiabetic noncataractous dogs. Procedures Fifteen dogs in each category underwent neuro-ophthalmic examination; aerobic, anaerobic and fungal conjunctival cultures; assessment of corneal touch threshold (CTT), STT, tear glucose, TFBUT; and conjunctival cytology and histology (in certain cases only). Degree of cataract and uveitis were critically graded. Glycemic control was estimated using serum fructosamine and glycosylated hemoglobin. RESULTS STT values were significantly lower in diabetic cataractous than nondiabetic noncataractous dogs. CTT of diabetic cataractous dogs was significantly lower than that of nondiabetic noncataractous dogs. Mean TFBUTs were significantly less in diabetic cataractous dogs than nondiabetic cataractous and nondiabetic noncataractous dogs. Tear glucose concentrations were significantly higher in diabetic cataractous dogs than nondiabetic cataractous and nondiabetic noncataractous dogs. Conjunctival microbial isolates did not differ among groups. There were no significant differences in degree of cataract or uveitis between diabetic cataractous and nondiabetic cataractous groups. There was mild submucosal inflammatory infiltrate in conjunctival specimens from diabetic dogs. Conjunctival epithelial dysplasia and/or squamous metaplasia was/were detected in conjunctival biopsies of 5/7 diabetic dogs. Reductions in conjunctival goblet cell (GC) densities were noted in 4/7 diabetic dogs; there were no significant differences in mean GC densities among the three groups. CONCLUSIONS Diabetic cataractous dogs have significantly altered keratoconjunctival characteristics compared to nondiabetic cataractous and nondiabetic noncataractous dogs.
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Affiliation(s)
- Cheryl L Cullen
- Department of Companion Animals, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3.
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Webb AA, Muir GD. Course of motor recovery following ventrolateral spinal cord injury in the rat. Behav Brain Res 2004; 155:55-65. [PMID: 15325779 DOI: 10.1016/j.bbr.2004.04.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Revised: 04/02/2004] [Accepted: 04/02/2004] [Indexed: 11/18/2022]
Abstract
The purpose of this study was to determine the importance of the pathways running in the ventrolateral spinal funiculus for overground locomotion in adult, freely behaving rats. Left-sided ventrolateral cervical spinal cord injury was performed in adult female Long-Evans rats. The behavioural abilities of these animals were analyzed at 2 days, and weekly for up to 5.5 weeks following spinal cord injury. Behavioural testing consisted of Von Frey filament testing, ladder walking, a paw usage task, and the assessment of ground reaction forces during unrestrained trotting. Animals with injury to the left ventrolateral cervical spinal cord did not develop enhanced sensitivity to pedal mechanical stimulation. At 2 days following injury, animals had impaired skilled locomotion as indicated by increased number of footslips during ladder walking. At 2 days, these animals also used both limbs together more often for support while rearing, while using the forelimb ipsilateral to the injury less than did uninjured animals. Ground reaction force determination revealed that animals tend to bear less weight on the forelimb and hindlimb ipsilateral to the spinal cord injury 2 days after injury. All animals recovered normal or near normal sensorimotor abilities although subtle asymmetries in ground reaction forces were detectable at 5.5 weeks following spinal cord injury. These results suggest that axons in the ventrolateral spinal funiculi contribute to limb movements during exploration and locomotion but their roles can be served by other pathways after ventrolateral spinal injury.
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Affiliation(s)
- Aubrey A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Sask., Canada S7N 5B4.
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Abstract
There have been very few clinical trials evaluating therapies for naturally occurring spinal cord injury in dogs and cats. This review describes the methods suitable for evaluating the behavioural recovery of animals with spinal cord injuries, in either a clinical or a laboratory setting. A list of commonly used methods for evaluating behavioural recovery in animals is provided, both in the clinical and laboratory setting; the tests, their limitations and benefits and specific recommendations for their use are also discussed in more depth.
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Affiliation(s)
- A A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B4
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Brennan PA, Smith GI, Webb AA, Ilankovan V. Double mandibular osteotomy with coronoidectomy for tumours in the parapharyngeal space. Br J Oral Maxillofac Surg 2004; 42:79-80. [PMID: 14706313 DOI: 10.1016/s0266-4356(03)00206-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Webb AA, Gowribai K, Muir GD. Fischer (F-344) rats have different morphology, sensorimotor and locomotor abilities compared to Lewis, Long-Evans, Sprague-Dawley and Wistar rats. Behav Brain Res 2003; 144:143-56. [PMID: 12946605 DOI: 10.1016/s0166-4328(03)00076-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Locomotor and/or sensory behaviour is commonly evaluated in laboratory rats in the field of neuroscience. Many strains of rats, however, have been propagated through intensive breeding programs. With any breeding program, traits are selected purposefully or inadvertently. We set out to investigate whether differences in morphology, sensory or motor behaviours exist using five age-matched strains of laboratory rats. Personal observations of morphological differences between different strains of rats led us to hypothesize that Fischer rats were dissimilar to the other strains in each of the parameters investigated. Evaluation of morphology involved measuring long-bone lengths and body weights of each strain. Motor skills were evaluated by measuring paw preferences while rearing, abduction of the distal portion of hindlimbs during locomotion, footfalls through a horizontal ladder during locomotion, and ground reaction forces generated during trotting. Sensory ability was assessed by von Frey testing. Fischer rats had shorter long-bone lengths, weighed less, and had significantly abducted distal portion of their hindlimbs during locomotion compared to the other strains. Lewis and Sprague-Dawley rats were less sensitive to mechanical pedal stimulation compared to Fischer rats. While rearing, all strains of rats tended to use individual forelimbs 25% of the time for each right and left limbs, and both forelimbs together 50% of the time. There were no significant differences in the number of footfalls during the ladder task. Ground reaction force determination revealed that Fischer and Sprague-Dawley rats bore more weight on their hindlimbs compared to forelimbs during locomotion, Long-Evans and Lewis rats bore more weight on their forelimbs compared to their hindlimbs, while Wistar rats distributed weight evenly between forelimbs and hindlimbs during trotting. We conclude that morphologic, sensory and motor differences exist between the five strains of laboratory rats examined and several of these differences are most pronounced in the Fischer strain.
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Affiliation(s)
- Aubrey A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4.
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24
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Abstract
The purpose of this study was to determine the importance of the rubrospinal pathway and the ascending components of the dorsal column for overground locomotion in adult, unrestrained rats. The dorsal column (excluding the corticospinal tract), the rubrospinal tract or both were damaged unilaterally in rats at the level of the upper cervical spinal cord. Behavioural analysis consisted of skilled locomotion (an evaluation of footslips during ladder walking), a paw usage task and the assessment of ground reaction forces during unrestrained locomotion. All lesioned animals used the forepaw ipsilateral to the lesions less while rearing. Animals with dorsal column injuries used the forelimb contralateral to the spinal injury significantly more while rearing compared with uninjured animals. All lesioned animals produced more footfalls while crossing the ladder compared with uninjured animals. All injuries, regardless of the pathway affected, resulted in significant alterations in body weight support and reduced braking forces from the forelimb ipsilateral to the injury during overground locomotion. Animals typically bore less weight on the hindlimb ipsilateral to the lesion compared with the hindlimb contralateral to the spinal injury. Taken together with previously published work, our data indicate that the rubrospinal and dorsal column pathways are important for forelimb support while rearing and for skilled locomotion. Additionally, the ascending dorsal column pathways and the rubrospinal tract play a role during flat surface overground locomotion and combined damage to these pathways does not alter the acquired gait.
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Affiliation(s)
- Aubrey A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK, Canada
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25
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Abstract
Pathological neck and back pain occurs in many medical conditions of dogs and cats. Pain may arise from a variety of structures including the intervertebral discs, facet joint capsules, dorsal root ganglia, vertebral ligaments, the vertebral periosteum, and the meninges. The source of this pain is dependent upon the type of disease process and its location within or surrounding the spinal column. Diseases can directly or indirectly stimulate pain sensors (nociceptors). Inflammatory diseases may hypersensitize these receptors or nociceptive pathways with inflammatory mediating substances such as serotonin, histamine and potassium. Diseases resulting in mechanical compression of nociceptors or nociceptive pathways may also result in neck or back pain. A thorough understanding of spinal pain occurring in dogs and cats will lead to more accurate diagnoses and treatments and may provide information regarding prognoses for various diseases. Evidence pointing to sources of spinal pain taken from scientific and clinical studies of a variety of species including humans is provided. Suspected or known sources of neck and back pain occurring in several clinical conditions of dogs and cats are discussed.
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Affiliation(s)
- Aubrey A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, Sask., Canada S7N 5B4.
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Webb AA, Taylor SM, Muir GD. Steroid-Responsive Meningitis-Arteritis in Dogs with Noninfectious, Nonerosive, Idiopathic, Immune-Mediated Polyarthritis. J Vet Intern Med 2002. [DOI: 10.1111/j.1939-1676.2002.tb02368.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Webb AA, Taylor SM, Muir GD. Steroid-responsive meningitis-arteritis in dogs with noninfectious, nonerosive, idiopathic, immune-mediated polyarthritis. J Vet Intern Med 2002; 16:269-73. [PMID: 12041656 DOI: 10.1892/0891-6640(2002)016<0269:smidwn>2.3.co;2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Signs related to spinal pain are commonly reported in dogs with noninfectious, nonerosive, idiopathic immune-mediated polyarthritis (IMPA). This study examined the prevalence and etiology of spinal pain in these dogs through a retrospective review of 62 case records of dogs with IMPA. All dogs with IMPA and signs suggestive of spinal pain were described with regard to age, gender, breed, physical stature, location of vertebral pain, rectal temperature, and clinical laboratory findings. The prevalence of spinal pain in these dogs was 29% (18 of 62). Fourteen of the 18 dogs with spinal pain and IMPA were male. Cerebrospinal fluid (CSF) from 11 dogs with signs of spinal pain was analyzed. Five of these (46%) had concurrent steroid-responsive meningitis-arteritis (SRMA). We concluded that SRMA does occur concurrently in some dogs having IMPA. Meningeal involvement may explain the origin of spinal pain observed in some of these dogs.
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Affiliation(s)
- Aubrey A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
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28
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Abstract
The accurate measurement of behavioral compensation after CNS trauma, such as spinal cord injury, is important when assessing the functional effects of injury and treatment in animal models. We investigated the locomotor abilities of rats with unilateral thoracic or cervical spinal cord injuries using a locomotor rating (BBB) scale, reflex tests, and quantitative kinetic measurements. The BBB rating scale indicated that thoracic spinal hemisected (TH) rats had more severely affected hindlimbs compared to cervical spinal hemisected (CH) and sham-operated animals. Kinetic measurements revealed that CH and TH animals moved with different ground reaction force patterns, which nevertheless shared some similarities with each other and with the gait patterns of rats with different unilateral CNS lesions. Uninjured rats typically had an equal distribution of their body weight over the forelimbs and hind limbs, and used their forelimbs predominantly for braking while using their hind limbs mostly for propulsion. CH rats bore more weight on their hind limbs than their forelimbs, while TH animals bore more weight on their forelimbs than their hind limbs. Neither CH nor TH rats used the forelimb ipsilateral to the spinal hemisection for net braking or propulsion. The hindlimb contralateral to the hemisection was placed on the ground prematurely during the stride cycle for both CH and TH animals. The altered kinetics of the locomotor pattern in hemisected animals resulted in changes in the oscillations of total body potential and kinetic energies. These two forms of energy oscillate synchronously in intact locomoting rats, but were asynchronous during parts of the stride cycle in spinal hemisected animals. We conclude that rats develop a general compensatory response for unilateral CNS lesions, which may help stabilize the animal during locomotion.
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Affiliation(s)
- Aubrey A Webb
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada.
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Webb AA, Watts R, Read-Ward E, Hodgkins J, Markus AF. Audit of a multidisciplinary approach to the care of children with unilateral and bilateral cleft lip and palate. Br J Oral Maxillofac Surg 2001; 39:182-8. [PMID: 11384114 DOI: 10.1054/bjom.2000.0574] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cleft lip and palate affects the child in many ways, particularly appearance, dental arch relationships, growth of the face, and speech development. The key to successful care is management in a multidisciplinary team adhering to a well-designed protocol, and careful audit of results. We present the intermediate outcome audit of 15 patients with complete bilateral and unilateral cleft lip and palate whose condition was managed in a multidisciplinary team according to a strict protocol. We give the results observations of operations of a single surgeon's functional primary surgery over a 6-year period in terms of dental arch relationships, cephalometric analyses, aesthetic assessments, and speech analysis. The results show good early facial growth, with dental arch relationships appropriate for the age and group; we found only minor speech discrepancies, with no patients requiring pharyngoplasty. The results show the importance of multidisciplinary management, the value of keeping to sound surgical protocols, and functional techniques in cleft lip and palate surgery. Our study includes the neglected group of children who have bilateral cleft lip and palate, and it conforms to the style of pan-European projects.
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Affiliation(s)
- A A Webb
- Oral and Maxillofacial Surgery, The Dorset Cleft Centre, Poole Hospital NHS Trust, Poole, UK
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30
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Abstract
There is much interest in the transduction pathways by which abscisic acid (ABA) regulates stomatal movements (ABA-turgor signalling) and by which this phytohormone regulates the pattern of gene expression in plant cells (ABA-nuclear signalling). A number of second messengers have been identified in both the ABA-turgor and ABA-nuclear signalling pathways. A major challenge is to understand the architecture of ABA-signalling pathways and to determine how the ABA signal is coupled to the appropriate response. We have investigated whether separate Ca2+-dependent and -independent ABA-signalling pathways are present in guard cells. Our data suggest that increases in [Ca2+]i are a common component of the guard cell ABA-turgor and ABA-nuclear signalling pathways. The effects of Ca2+ antagonists on ABA-induced stomatal closure and the ABA-responsive CDeT6-19 gene promoter suggest that Ca2+ is involved in both ABA-turgor signalling and ABA-nuclear signalling in guard cells. However, the sensitivity of these pathways to alterations in the external calcium concentration differ, suggesting that the ABA-nuclear and ABA-turgor signalling pathways are not completely convergent. Our data suggest that whilst Ca2+-independent signalling elements are present in the guard cell, they do not form a completely separate Ca2+-independent ABA-signalling pathway.
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Affiliation(s)
- A A Webb
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster LA1 4YQ, UK.
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31
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Abstract
A retrospective audit was made of histological records and hospital case notes of patients who had cutaneous squamous cell carcinomas excised from the head and neck region at the Maxillofacial Units at St Richard's Hospital, Chichester and Southlands Hospital, Shoreham-By-Sea, UK. A total of 227 lesions were excised from 183 patients over a 5-year period between 1990 and 1995. The local recurrence rate was 4% (9/227) and 12 (7%) of the patients presented with or developed regional nodal metastases. Of the 183 patients, 177 (97%) were cured. These rates compare favourably with those of other published series of cutaneous squamous cell carcinoma managed by surgical techniques that did not follow the micrographical technique of Mohs. Certain characteristics may aid in the prediction of those cancers that may be more aggressive. It is important to evaluate each case in terms of histological grade and site and to design management plans to deal with each lesion in the most appropriate way.
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Affiliation(s)
- N J Baker
- Consultant Oral and Maxillofacial Surgeon, Maxillofacial Unit, Southampton General Hospital, Southampton, UK
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32
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Abstract
Intraspinal cysts of the L6-L7 and L7-S1 articular process joints in a six-year-old neutered female German Shepherd Dog were diagnosed using magnetic resonance (MR) imaging. Histopathology provided a diagnosis of ganglion cysts. Clinical, laboratory, radiographic and MR imaging findings are described. Briefly, radiographic findings revealed lumbarization of the first sacral vertebra, and fusion of the first caudal vertebra to the sacrum. In addition, spondylosis and articular process osteoarthrosis occurred at L6-L7 and L7-S1. MR imaging revealed multiple, well encapsulated structures ranging in size from 3-10 mm in diameter which were found to arise from the L6-L7 and L7-S1 articular process joints. These cysts had signal intensities that varied from hyperintense to the cerebrospinal fluid (CSF) on T1 weighted images to isointense to CSF on T2 weighted images. Decompressive surgery in conjunction with arthrodesis of these joints resulted in resolution of clinical signs. The dog remained pain-free 1 1/2 years following surgical therapy.
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Affiliation(s)
- A A Webb
- Department of Veterinary Physiological Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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33
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Abstract
Behavioural recovery is one of the primary goals of therapeutic intervention in animal models of disease. It is necessary, therefore, to have the means with which to quantify pertinent behavioural changes in experimental animals. Nevertheless, the number and diversity of behavioural measures which have been used to assess recovery after experimental interventions often makes it difficult to compare results between studies. The present review attempts to integrate and categorize the wide variety of behavioural assessments used to measure recovery in spinal-injured rats. These categories include endpoint measures, kinematic measures, kinetic measurements, and electrophysiological measurements. Within this categorization, we discuss the advantages and disadvantages of each type of measurement. Finally, we make some recommendations regarding the principles for a comprehensive behavioural analysis after experimental spinal cord injury in rats.
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Affiliation(s)
- G D Muir
- Department of Veterinary Physiological Sciences, University of Saskatchewan, Saskatoon, Canada S7N 5B4.
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Webb AA, Muir GD. The blood-brain barrier and its role in inflammation. J Vet Intern Med 2000; 14:399-411. [PMID: 10935890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
The unique microenvironment within the central nervous system (CNS) relies upon the integrity of the blood-brain barrier (BBB). This selectively permeable barrier comprises interendothelial tight junctions located at the capillaries and postcapillary venules. Cells and structures in the local environment are required to maintain normal BBB function. When inflammation is present, the BBB itself plays an integral role in the inflammatory response by either producing or expressing a variety of cytokines, adhesion molecules, metalloproteinases, serine proteases, products of arachidonic acid metabolism, and nitric oxide. Understanding the role of the BBB during inflammation is essential when creating and employing a therapeutic regime for animals with CNS disease. This review focusses on recent discoveries about the BBB and its role in inflammation, and applies this knowledge to our current understanding of inflammatory CNS disease in dogs and cats.
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Affiliation(s)
- A A Webb
- Department of Veterinary Physiological Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
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Gosti F, Beaudoin N, Serizet C, Webb AA, Vartanian N, Giraudat J. ABI1 protein phosphatase 2C is a negative regulator of abscisic acid signaling. Plant Cell 1999; 11:1897-1910. [PMID: 10521520 DOI: 10.2307/3871085] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The plant hormone abscisic acid (ABA) is a key regulator of seed maturation and germination and mediates adaptive responses to environmental stress. In Arabidopsis, the ABI1 gene encodes a member of the 2C class of protein serine/threonine phosphatases (PP2C), and the abi1-1 mutation markedly reduces ABA responsiveness in both seeds and vegetative tissues. However, this mutation is dominant and has been the only mutant allele available for the ABI1 gene. Hence, it remained unclear whether ABI1 contributes to ABA signaling, and in case ABI1 does regulate ABA responsiveness, whether it is a positive or negative regulator of ABA action. In this study, we isolated seven novel alleles of the ABI1 gene as intragenic revertants of the abi1-1 mutant. In contrast to the ABA-resistant abi1-1 mutant, these revertants were more sensitive than the wild type to the inhibition of seed germination and seedling root growth by applied ABA. They also displayed increases in seed dormancy and drought adaptive responses that are indicative of a higher responsiveness to endogenous ABA. The revertant alleles were recessive to the wild-type ABI1 allele in enhancing ABA sensitivity, indicating that this ABA-supersensitive phenotype results from a loss of function in ABI1. The seven suppressor mutations are missense mutations in conserved regions of the PP2C domain of ABI1, and each of the corresponding revertant alleles encodes an ABI1 protein that lacked any detectable PP2C activity in an in vitro enzymatic assay. These results indicate that a loss of ABI1 PP2C activity leads to an enhanced responsiveness to ABA. Thus, the wild-type ABI1 phosphatase is a negative regulator of ABA responses.
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Affiliation(s)
- F Gosti
- Institut des Sciences Végétales, Centre National de la Recherche Scientifique UPR 40, avenue de la Terrasse, 91190 Gif-sur-Yvette, France
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Gosti F, Beaudoin N, Serizet C, Webb AA, Vartanian N, Giraudat J. ABI1 protein phosphatase 2C is a negative regulator of abscisic acid signaling. Plant Cell 1999; 11:1897-910. [PMID: 10521520 PMCID: PMC144098 DOI: 10.1105/tpc.11.10.1897] [Citation(s) in RCA: 421] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The plant hormone abscisic acid (ABA) is a key regulator of seed maturation and germination and mediates adaptive responses to environmental stress. In Arabidopsis, the ABI1 gene encodes a member of the 2C class of protein serine/threonine phosphatases (PP2C), and the abi1-1 mutation markedly reduces ABA responsiveness in both seeds and vegetative tissues. However, this mutation is dominant and has been the only mutant allele available for the ABI1 gene. Hence, it remained unclear whether ABI1 contributes to ABA signaling, and in case ABI1 does regulate ABA responsiveness, whether it is a positive or negative regulator of ABA action. In this study, we isolated seven novel alleles of the ABI1 gene as intragenic revertants of the abi1-1 mutant. In contrast to the ABA-resistant abi1-1 mutant, these revertants were more sensitive than the wild type to the inhibition of seed germination and seedling root growth by applied ABA. They also displayed increases in seed dormancy and drought adaptive responses that are indicative of a higher responsiveness to endogenous ABA. The revertant alleles were recessive to the wild-type ABI1 allele in enhancing ABA sensitivity, indicating that this ABA-supersensitive phenotype results from a loss of function in ABI1. The seven suppressor mutations are missense mutations in conserved regions of the PP2C domain of ABI1, and each of the corresponding revertant alleles encodes an ABI1 protein that lacked any detectable PP2C activity in an in vitro enzymatic assay. These results indicate that a loss of ABI1 PP2C activity leads to an enhanced responsiveness to ABA. Thus, the wild-type ABI1 phosphatase is a negative regulator of ABA responses.
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Affiliation(s)
- F Gosti
- Institut des Sciences Végétales, Centre National de la Recherche Scientifique UPR 40, avenue de la Terrasse, 91190 Gif-sur-Yvette, France
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38
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Webb AA. Intradural spinal arachnoid cyst in a dog. Can Vet J 1999; 40:588-9. [PMID: 12001342 PMCID: PMC1539774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
An 8-month-old, spayed female dog was presented with signs localizing a neurologic lesion between the 3rd thoracic and 3rd lumbar vertebrae. An arachnoid cyst was diagnosed by myelography, and a dorsal laminectomy with durotomy was performed. The dog continues to do well 1-1/2 year after surgery.
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Affiliation(s)
- A A Webb
- Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4
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Abstract
INTRODUCTION When clinic appointments are missed, families deprive their child of health care opportunities and contribute to rising health care costs. The purpose of this study was to determine families' perceptions of barriers to attending clinic appointments. METHOD Two hundred participants with a history of missed appointments were randomly selected to participate in a telephone survey. Ninety-five of the families selected did not have telephones. Of the 105 families contacted by telephone, 101 consented to participate in a survey. For the group without phones (n = 95), demographic information was collected to use as comparison data with families that were reached. Patterns of missed appointments were also analyzed. RESULTS The majority of families were headed by young single mothers. The families identified transportation problems, wait times, and not knowing the reason for the appointment as barriers. DISCUSSION Clearly, many issues have an impact on decisions related to attending clinic appointments. In the interest of health, interventions to decrease barriers and increase attendance should be a priority for health care professionals. Further research of the effectiveness of these interventions will delineate the appropriate focus of health care professional's efforts.
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Affiliation(s)
- V Pesata
- Children's Hospital Medical Center of Akron, Ohio, USA
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40
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Webb AA, Cantwell SL, Duke T, Adkins E. Intravenous regional anesthesia (Bier block) in a dog. Can Vet J 1999; 40:419-21. [PMID: 10367159 PMCID: PMC1539732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Intravenous regional anesthesia was used in an adult dog as part of a balanced approach to general anesthesia for amputation of the 4th digit of its right hind limb. It allowed the concentration of isoflurane to be reduced to 0.5%.
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Affiliation(s)
- A A Webb
- Department of Veterinary Anesthesiology, Radiology and Surgery, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon
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41
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Abstract
Several factors influence the chronically ill child's susceptibility for skin breakdown. Nurses are an integral part of the care team that has the responsibility for identification of these factors, as well as pressure ulcer prevention and early intervention. An important aspect of this responsibility is identification of individuals at risk. This article provides a guide for assessment and early intervention for skin breakdown in chronically ill children. A care plan and consultation recommendations are included.
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Affiliation(s)
- G Pallija
- Children's Hospital Medical Center of Akron, OH, USA
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42
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Webb AA, Shipton EA. Re-evaluation of i.m. ephedrine as prophylaxis against hypotension associated with spinal anaesthesia for Caesarean section. Can J Anaesth 1998; 45:367-9. [PMID: 9597213 DOI: 10.1007/bf03012030] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
PURPOSE To assess the safety and efficacy of 37.5 mg ephedrine i.m. in preventing hypotension associated with spinal anaesthesia for Caesarean section. METHODS In a double-blind randomised controlled study, 40 patients (20 in each group) were given either 37.5 mg ephedrine or placebo i.m. The following parameters were recorded: (i) blood pressure; (ii) heart rate; (iii) ephedrine i.v. supplementation; (iv) umbilical venous blood gases and neonatal Apgar scores. RESULTS The incidence of hypertension in the study group was 30% compared with 20% for the control group (P:NS). There was no difference in mean highest blood pressure or mean highest heart rate between the groups. The incidence of hypotension was lower but not significantly lower in the study group (50%) than in the control group (80%) (P:NS). However, the incidence of delayed hypotension was only 10% in the study group patients compared with 50% in the control group patients (P < 0.05). CONCLUSION Giving 37.5 mg ephedrine i.m. prior to spinal anaesthesia was not associated with reactive hypertension or tachycardia. Intramuscular ephedrine provided more sustained cardiovascular support than intravenous ephedrine.
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Affiliation(s)
- A A Webb
- Department of Anaesthesiology, Chris Hani Baragwanath Hospital, Johannesburg, South Africa
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Somers DE, Webb AA, Pearson M, Kay SA. The short-period mutant, toc1-1, alters circadian clock regulation of multiple outputs throughout development in Arabidopsis thaliana. Development 1998; 125:485-94. [PMID: 9425143 DOI: 10.1242/dev.125.3.485] [Citation(s) in RCA: 224] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The coordination of developmental and physiological events with environmental signals is facilitated by the action of the circadian clock. Here we report a new set of circadian clock-controlled phenotypes for Arabidopsis thaliana. We use these markers together with the short-period mutant, toc1-1, and the clock-controlled cab2::luciferase reporter gene to assess the nature of the circadian clock throughout development and to suggest the position of TOC1 within the circadian clock system. In dark-grown seedlings, the toc1-1 lesion conferred a short period to the cycling of cab2::luciferase luminescence, as previously found in light-grown plants, indicating that the circadian clocks in these two divergent developmental states share at least one component. Stomatal conductance rhythms were similarly approximately 3 hours shorter than wild type in toc1-1, suggesting that a cell-autonomous clockwork may be active in guard cells in 5- to 6-week-old leaves. The effect of daylength on flowering time in the C24 ecotype was diminished by toc1-1, and was nearly eliminated in the Landsberg erecta background where the plants flowered equally early in both short and long days. Throughout a 500-fold range of red light intensities, both the wild type and the mutant showed an inverse log-linear relationship of fluence rate to period, with a 2–3 hour shorter period for the mutant at all intensities. These results indicate that TOC1 acts on or within the clock independently of light input. Temperature entrainment appears normal in toc1-1, and the period-shortening effects of the mutant remain unchanged over a 20 degrees C temperature range. Taken together our results are consistent with the likelihood that TOC1 codes for an oscillator component rather than for an element of an input signaling pathway. In addition, the pervasive effect of toc1-1 on a variety of clock-controlled processes throughout development suggests that a single circadian system is primarily responsible for controlling most, if not all, circadian rhythms in the plant.
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Affiliation(s)
- D E Somers
- NSF Center for Biological Timing, Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Webb AA, Taylor SM, McPhee L. Focal myasthenia gravis in a dog. Can Vet J 1997; 38:493-5. [PMID: 9262858 PMCID: PMC1576809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A 10-month-old American cocker spaniel was evaluated for megaesophagus, aspiration pneumonia, but no appendicular muscle weakness. During hospitalization, weakness of the facial muscles developed, this resolved with anticholinesterase administration. Serum antibodies against acetylcholine receptors were documented, confirming the diagnosis of focal myasthenia gravis. Diagnosis, management, and medical treatment are discussed.
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Affiliation(s)
- A A Webb
- Department of Veterinary Internal Medicine, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon
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Webb AA, Hetherington AM. Convergence of the abscisic acid, CO2, and extracellular calcium signal transduction pathways in stomatal guard cells. Plant Physiol 1997; 114:1557-60. [PMID: 9276963 PMCID: PMC158450 DOI: 10.1104/pp.114.4.1557] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We show that guard cells from Arabidopsis thaliana plants carrying the abscisic acid-insensitive mutations abi1 and abi2 fail to respond to CO2 and extracellular calcium. This demonstrates that the signal transduction pathways for all three stimuli converge on, or close to, the ABI1 and ABI2 gene products.
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Affiliation(s)
- A A Webb
- Division of Biological Sciences, University of Lancaster, United Kingdom
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Webb AA, Bower DA, Gill S. Satisfaction with nursing care: a comparison of patients with HIV/AIDS, non-HIV/AIDS infectious diseases, and medical diagnoses. J Assoc Nurses AIDS Care 1997; 8:39-46. [PMID: 9152890 DOI: 10.1016/s1055-3290(97)80017-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to describe patients' perceptions of nursing care and compare those perceptions based on patients' diagnoses (HIV/AIDS, non-HIV/AIDS infectious diseases, and medical diagnoses). One hundred forty-two patients on five units in a major medical center were surveyed using the Patient Satisfaction Instrument. In addition, 126 staff nurses completed the AIDS Vulnerability Survey. Results of data analysis indicated a statistically significant difference in patient satisfaction with nursing care among patients in the medical group compared to patients in the HIV/AIDS group, with the medical group being more satisfied with their nursing care. Further, there was a statistically significant difference across units between nurses' knowledge, attitude, and fear. In spite of their knowledge base related to HIV/AIDS, nurses felt vulnerable when providing care to this population, thus perpetuating fear and negative attitudes. Additional research into the dynamics of these relationships is imperative as we continue to see increases in the number of patients with HIV/AIDS.
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Affiliation(s)
- A A Webb
- Children's Hospital Medical Center of Akron, OH., USA
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Abstract
This study is a follow-up of 39 working class couples who were interviewed after suffering economic stress or unemployment and again six years later. Repeated measures related to economics, stress, family functioning, anxiety, and depression were collected and analyzed for couples and for husbands and wives separately. A model of long-term coping was suggested for future testing. Initially stressed families appeared to grow stronger. Mental health correlated negatively to family problems. Depressed wives seemed to maintain their depression over time if they perceived family life as stressful. Irrespective of marital problems, husbands were less likely to stay depressed.
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Taylor JE, Renwick KF, Webb AA, McAinsh MR, Furini A, Bartels D, Quatrano RS, Marcotte WR, Hetherington AM. ABA-regulated promoter activity in stomatal guard cells. Plant J 1995; 7:129-34. [PMID: 7894503 DOI: 10.1046/j.1365-313x.1995.07010129.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
CDeT6-19 is an ABA-regulated gene which has been isolated from Craterostigma plantagineum. The CDeT6-19 gene promoter has been fused to the beta-glucuronidase reporter gene (GUS) and used to stably transform Arabidopsis thaliana and Nicotiana tabacum. This construct has been shown to be expressed in stomatal guard cells and often in the adjacent epidermal cells of both species in response to both exogenous ABA and drought stress. These results indicate that the stomatal guard cell is competent to relay an ABA signal to the nucleus. In contrast GUS expression directed by the promoter from a predominantly seed-specific, ABA-regulated gene, Em, or the promoter from the ABA-regulated CDeT27-45 gene is not detectable in the epidermal or guard cells of tobacco or Arabidopsis in response to ABA. The fact that not all ABA-regulated gene promoters are active in stomatal guard cells suggests that effective transduction of the signal is dependent upon particular regions within the gene promoter or that guard cells lack all or part of the specific transduction apparatus required to couple the ABA signal to these promoters. This suggests that there are multiple ABA stimulus response coupling pathways. The identification of a regulatory sequence from an ABA-induced gene which is expressed in stomatal guard cells creates the possibility of examining the role of Ca2+ and other second messengers in ABA-induced gene expression.
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Affiliation(s)
- J E Taylor
- Division of Biological Sciences, Lancaster University, UK
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Taylor JE, McAinsh MR, Montgomery L, Renwick KF, Webb AA, Hetherington AM. The use of transgenesis to investigate signal-transduction pathways. Biochem Soc Trans 1994; 22:949-52. [PMID: 7698491 DOI: 10.1042/bst0220949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- J E Taylor
- Institute of Environmental and Biological Sciences, Lancaster University, U.K
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Abstract
The purpose of this quasiexperimental study was to examine the effectiveness of an experiential workshop on nursing students' anxiety and knowledge about AIDS. This study was based on Peplau's interpersonal theory in nursing practice. The sample included 67 senior nursing students and was designed as a three-group pre/post quasiexperiment. All groups received a pretest, posttest, and 6-week follow-up posttest. The experimental intervention was a 6-hour workshop that included anxiety awareness exercises in an experiential format and information about AIDS. Knowledge and anxiety scores were significantly higher for the group that attended the didactic portion of the workshop before the experiential portion. The control group showed no change in knowledge or anxiety. Results indicated that recognition of anxiety through experiential exercises contributed to learning about AIDS.
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Affiliation(s)
- D A Bower
- College of Nursing, University of Akron, OH 44325
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