PubMed Health⌕ Search

Biomedical subjects

K G Thompson

Publications and source records attributed to K G Thompson.

At least 19 recordsLinked to original sources
PubMed2005

Inherited chondrodysplasia in Texel sheep.

CASE HISTORY: A skeletal disease characterised by dwarfism, limb deformity and sometimes sudden death occurred over a period of 5 years in lambs born on a commercial sheep farm in Southland. The disease showed variable expression and occurred in crossbred sheep. A genetic aetiology was supported by the birth of affected lambs over two seasons in a flock of putative carrier and affected sheep transported to Massey University. CLINICAL FINDINGS: Affected lambs appeared normal at birth but showed evidence of dwarfism, wide-based stance and exercise intolerance as early as 1 week of age. Most died within the first 3 months of life, often after developing bilateral varus deformity of the forelimbs. Some severely-affected lambs died suddenly of respiratory embarrassment, probably due to tracheal collapse. Mildly-affected individuals had a short, blocky stature and some survived to breeding age. PATHOLOGICAL FINDINGS: Gross and microscopic lesions of variable severity were present in the tracheal, articular, epiphyseal and physeal cartilages. In severe cases, articular cartilage in major joints was eroded from weight-bearing surfaces. The trachea was flaccid, abnormally kinked, and had thickened cartilaginous rings and a narrow lumen. Affected sheep that survived to breeding age eventually developed severe degenerative joint disease. Histologically, chondrocytes were disorganised, surrounded by concentric rings of abnormal fibrillar material, and the matrix often contained focal to coalescing areas of chondrolysis. DIAGNOSIS: Inherited chondrodysplasia of Texel sheep. CLINICAL RELEVANCE AND CONCLUSIONS: This chondrodysplasia differs from those previously described in sheep and is considered to be a newly-recognised, recessively-inherited genetic disease of the Texel breed. A defect in the synthesis of glycosaminoglycans in cartilage matrix is suspected. This disease of sheep may provide a suitable model for studying various forms of therapy for human chondrodysplasias.

Animals↗
PubMed2005

Necrotising fasciitis associated with Escherichia coli in a dog.

CASE HISTORY: Lameness and limb pain associated with a laceration in the inner thigh of a Border Collie dog progressed over 4 days to extensive necrosis of the full-thickness of skin and subcutaneous (S/C) tissue. A successful outcome was achieved using surgical debridement and intensive supportive care, followed by limited local closure, axial pattern flap development, and free skin grafting. CLINICAL FINDINGS: Clinical findings included severe pain, depression, pyrexia and hypoalbuminaemia, and full-thickness loss of skin from the caudal thigh to the hock. Histopathologically, debrided tissue showed extensive necrosis of the dermis, adipose and muscle tissues, and the presence of numerous Gram-negative rods. Escherichia coli was cultured from deep tissue samples. DIAGNOSIS: Necrotising fasciitis (NF) associated with E. coli infection. CLINICAL RELEVANCE: NF associated with E. coli has not been previously reported in dogs. The importance of early diagnosis and surgical debridement is noted and the relevant medical literature is reviewed.

Animals↗
PubMed2005

Cerebral infarction and meningoencephalitis following hot-iron disbudding of goat kids.

CASE HISTORY: Twelve of 150 goat kids, 4-10 days old, died 3 days after disbudding with a hot iron. Another 18 kids had been ill the previous day but survived following antibiotic therapy. Five of the dead kids were necropsied. PATHOLOGICAL FINDINGS: There was necrosis and haemorrhage of the skin, subcutaneous tissues and frontal bone at disbudding sites in all five kids examined post mortem. Beneath disbudding sites in 4/5 kids there were bilateral, dark red, often cavitated areas of necrosis extending deep into the frontal cortex of the brain. Histologically, these areas consisted of coagulation necrosis, haemorrhage, vascular thrombosis and suppurative inflammation. Numerous bacteria, predominantly large Gram positive rods, were present in the necrotic brain tissue. In the remaining kid, bilateral areas of yellow discolouration and flattening of gyri in frontal lobes corresponded histologically to extensive polioencephalomalacia. A mixed growth of aerobes and anaerobes was cultured from the brain of one kid with suppurative lesions. CLINICAL RELEVANCE: Thermal disbudding of neonatal kids is widely practised in dairy goat herds and is considered the method of choice for disbudding in New Zealand. However, the skull of goat kids is much thinner than that of calves and the safety margin for thermal injury to the brain is markedly reduced. This report highlights the risks associated with the technique and its potential as a welfare issue.

Animal Husbandry↗
PubMed2005

Ectopic hepatocellular carcinoma in a dog.

CASE HISTORY: A 14-year-old neutered male Bearded Collie was presented with a history of recurrent, intermittent urinary incontinence of 7 years duration. CLINICAL FINDINGS: A large, firm, non-painful mass was found in the mid-abdominal region on palpation. Ultrasonography of the mass revealed a compartmentalised structure with mixed echogenicity, and which did not appear to be associated with any of the abdominal organs. Ultrasound-guided fine needle aspirates contained several clusters of epithelial cells with cytological features of hepatocytes. At exploratory laparotomy, the mass was found in the gastrosplenic ligament within the greater omentum. PATHOLOGICAL FINDINGS AND DIAGNOSIS: Histopathologically, the mass consisted of sheets of hepatocytes, but without the characteristic hepatic architecture. The cells showed moderate variation in nuclear size and were sometimes binucleate. A diagnosis of hepatocellular carcinoma (HCC) in the mesentery was made. CLINICAL RELEVANCE: The presence of ectopic hepatic tissue has been reported rarely in man and cats, but not in the dog. Neoplastic transformation of ectopic hepatic tissue is seen in man. This is the first report of the presentation, clinical findings and treatment of a dog with ectopic HCC.

Animals↗
PubMed2003

Chondrodysplasia of Texel sheep - a new disease of suspected genetic aetiology (abstract).

A chondrodysplasia characterised by dwarfism and varus deformity of the forelimbs has been recognised over four seasons in Texel and Texel-cross lambs on three related properties. Affected lambs appear normal at birth, but by 2 weeks of age have reduced growth rate, shortened neck and legs, varus forelimb deformities and a progressive reluctance to walk. Most die within the first 4 months of life. Some affected lambs have had normal co-twins. Post mortem examination of two severely affected 3-month-old lambs revealed extensive loss of articular cartilage and exposure of subchondral bone on the weight-bearing surfaces of the proximal humeri and femurs. Articular and physeal cartilages were thicker than normal, suggesting delayed or impaired endochondral ossification. Histopathologically, there was disorganisation of chondrocytes in articular and physeal cartilage of all bones examined. In addition, there were multiple foci of chondrolysis, which coalesced in some areas to form large clefts. The chondroid matrix surrounding chondrocytes had an abnormal fibrillar appearance. One lamb that exhibited early signs of the disease died of an unrelated cause at 3 weeks of age, and although there was no erosion of articular cartilage, characteristic microscopic lesions were present in articular and physeal cartilage. Although most of the affected lambs were born on a commercial property with a mix of different sheep breeds, all had Texel genes on both sire and dam sides of the pedigree. The farmer had been purchasing his Texel rams from the same flock for several seasons. Circumstantial evidence favours a genetic aetiology, characterised by either autosomal recessive inheritance or over dominance. Studies on the genetic and biochemical basis of the disease are continuing.

Journal Article↗
PubMed2002

The effect of even, positive and negative pacing on metabolic, kinematic and temporal variables during breaststroke swimming.

The aim of this investigation was to determine the effect of even, negative and positive pacing on metabolic, kinematic and temporal variables during breaststroke swimming. Nine male swimmers [mean (SD): age 21 (3) years, height 178 (5) cm, body mass 77.2 (6.7) kg, 200 m-time 158.6 (13.6) s] completed a 200-m breaststroke time trial and then 72 h later three paced (even, positive, negative) 175-m breaststroke swims in random order, 48 h apart. The swimmers paced accurately in all trials. The evenly paced trial produced lower post-exercise peak blood lactate and rating of perceived exertion values compared to the positively paced trial ( P<0.05). Peak oxygen uptake was not significantly different between trials ( P>0.05). Heart rate immediately following exercise was lower in the negatively paced trial ( P<0.05) than the other paced trials. Stroke rates were lower during the first half of the evenly and negatively paced trials compared to the positively paced trial ( P<0.01), but no differences were observed between the second half of the trials. Across all trials the stroke count increased as the trials progressed ( P<0.01). Turning times were observed to be shorter during the first half of the positively paced trial compared to the other paced trials ( P<0.01). Even paced swimming appears to be less physically stressful than positively paced swimming during high intensity exercise, as indicated by a lower post-exercise blood lactate concentration, perceived exertion and variability within turning times.

Adult↗
PubMed2002

Antigen-induced production of interferon-gamma in samples of peripheral lymph nodes from sheep experimentally inoculated with Mycobacterium avium subsp. paratuberculosis.

The production of interferon-gamma (IFN-gamma) in response to Johnin purified protein derivate was measured in samples of the prescapular lymph node (PLN) from 10 sheep, aged 2 years, and nine sheep, aged 1 year that had been inoculated orally with Mycobacterium avium subsp. paratuberculosis within their first month of life. Ten non-inoculated sheep, aged 1 year, constituted the negative control group. The results obtained in the PLN IFN-gamma assay were compared with those derived from serological tests: a complement fixation test (CFT), agar gel diffusion test (AGID) and enzyme-linked immunosorbent assay (ELISA), as well as an IFN-gamma test on samples of blood. Among the 19 inoculated sheep, 16 gave positive reactions in the PLN IFN-gamma assay on samples incubated overnight, and 18 tested positive when the assay was applied to PLN samples incubated for 48h. In comparison, three, four and seven inoculated sheep gave positive reactions in the ELISA, CFT and in the blood IFN-gamma assay on samples incubated overnight, respectively. The AGID and IFN-gamma assay on blood samples incubated for 48h detected eight inoculated animals. Twelve inoculated sheep, that tested positive in the PLN IFN-gamma assay were clinically normal, gave negative results in an IS900-based polymerase chain reaction (PCR) assay on samples of ileum and ileocaecal lymph node and had no histological evidence of paratuberculosis, but tested positive on more than two occasions in sequential serological testing before necropsy. None of the 10 non-inoculated sheep tested positive in the AGID, CFT, ELISA, blood IFN-gamma assay on samples incubated overnight and for 48h or the PLN IFN-gamma assay on samples incubated overnight, but one gave a positive result in the PLN IFN-gamma assay on samples stimulated for 48h. It is likely that the positive reactions obtained by the PLN IFN-gamma assay in the 12 inoculated sheep that tested negative in the PCR assay and histopathological examination represents immunological evidence of latent infection or previous exposure to M. paratuberculosis rather than active infection.

Animals↗
PubMed2001

Reliability of macaque frontal eye field neurons signaling saccade targets during visual search.

Although many studies have explored the neural correlates of visual attention and selection, few have examined the reliability with which neurons represent relevant information. We monitored activity in the frontal eye field (FEF) of monkeys trained to make a saccade to a target defined by the conjunction of color and shape or to a target defined by color differences. The difficulty of conjunction search was manipulated by varying the number of distractors, and the difficulty of feature search was manipulated by varying the similarity in color between target and distractors. The reliability of individual neurons in signaling the target location in correct trials was determined using a neuron-anti-neuron approach within a winner-take-all architecture. On average, approximately seven trials of the activity of single neurons were sufficient to match near-perfect behavioral performance in the easiest search, and approximately 14 trials were sufficient in the most difficult search. We also determined how many neurons recorded separately need to be evaluated within a trial to match behavioral performance. Results were quantitatively similar to those of the single neuron analysis. We also found that signal reliability in the FEF did not change with task demands, and overall, behavioral accuracy across the search tasks was approximated when only six trials or neurons were combined. Furthermore, whether combining trials or neurons, the increase in time of target discrimination corresponded to the increase in mean saccade latency across visual search difficulty levels. Finally, the variance of spike counts in the FEF increased as a function of the mean spike count, and the parameters of this relationship did not change with attentional selection.

Action Potentials↗
PubMed2001

Search efficiency but not response interference affects visual selection in frontal eye field.

Two manipulations of a visual search task were used to test the hypothesis that the discrimination of a target from distractors by visually responsive neurons in the frontal eye field (FEF) marks the outcome and conclusion of visual processing instead of saccade preparation. First, search efficiency was reduced by increasing the similarity of the distractors to the target. Second, response interference was introduced by infrequently changing the location of the target in the array. Both manipulations increased reaction time, but only the change in search efficiency affected the time needed to select the target by visually responsive neurons. This result indicates that visually responsive neurons in FEF form an explicit representation of the location of the target in the image.

Animals↗
PubMed2001

Lymphocytic neuritis of the ileum in sheep with naturally acquired and experimental paratuberculosis.

In a comparison of natural and experimentally induced ovine paratuberculosis, aggregations of mononuclear inflammatory cells were detected around nerves in the ileal submucosa in eight of 12 sheep with natural disease and in five of 14 animals with unequivocal experimental paratuberculosis. Such lesions were not seen in 10 other sheep that, despite attempted experimental infection, remained free from the disease, as judged clinically, histopathologically and by PCR assay. The lesions described resembled those observed in human leprosy.

Animals↗
PubMed2001

Dynamic dissociation of visual selection from saccade programming in frontal eye field.

Previous studies of visually responsive neurons in the frontal eye fields have identified a selection process preceding saccades during visual search. The goal of this experiment was to determine whether the selection process corresponds to the selection of a conspicuous stimulus or to preparation of the next saccade. This was accomplished with the use of a novel task, called search-step, in which the target of a singleton visual search array switches location with a distracter on random trials. The target step trials created a condition in which the same stimulus yielded saccades either toward or away from the target. Visually responsive neurons in frontal eye field selected the current location of the conspicuous target even when gaze shifted to the location of a distractor. This dissociation demonstrates that the selection process manifest in visual neurons in the frontal eye field may be an explicit interpretation of the image and not an obligatory saccade command.

Action Potentials↗
PubMed2000

Antecedents and correlates of visual detection and awareness in macaque prefrontal cortex.

We have investigated the neural basis of visual detection in monkeys trained to report the presence or absence of a visual stimulus that was rendered intermittently detectable by backward masking. Neurons were recorded in the frontal eye field (FEF), an area located in prefrontal cortex that is involved in converting the outcome of visual processing into a command to shift gaze. The behavioral and neuronal data were analyzed in terms of signal detection theory. We found that the initial visual responses in FEF provided signals that could form the basis for correct or erroneous detection of the target. A later phase of prolonged elevated activity occurred in many visual neurons and all movement neurons that was highly correlated with the monkey's report of target presence. When observed in movement cells that project to oculomotor structures, this period of activation is interpreted as a motor command leading to the behavioral response. When observed in visual cells that do not project to oculomotor structures, the later period of activation does not admit to the motor command interpretation. Because the visual neurons likely contribute to the feedback pathway to visual cortical areas, we hypothesize that the later selective activation in the prefrontal visual neurons interacts with ongoing activity in visual cortical areas contributing to the process by which a particular sensory representation receives enhanced activation and thereby engages attention and awareness.

Animals↗
PubMed2000

Splenic mast cell tumour and mastocytaemia in a cat: case study and literature review.

CASE: An 11-year-old female domestic shorthaired cat presenting with clinical signs of depression, anorexia, weight loss, fever, anaemia and a mid-abdominal mass was referred for abdominal ultrasound examination. CLINICAL FINDINGS: Ultrasonography of the abdomen identified a markedly enlarged spleen. Ultrasound-guided fine-needle aspiration biopsy of the spleen revealed a uniform population of mast cells, 11% of which were observed to have phagocytosed erythrocytes. It is speculated that this may have been a contributing factor in the development of anaemia in this case. Mast cells were detected in a peripheral-blood smear and a diagnosis of systemic mastocytosis (splenic mast cell tumour together with mastocytaemia) was made. This diagnosis was subsequently confirmed by histopathology of the spleen. CONCLUSION: Splenectomy and treatment with corticosteroids appears to have resulted in remission of clinical signs and anaemia. A reduction in the concentration of mast cells in the peripheral blood had not occurred 6 weeks postsplenectomy, but was evident by 10 months post-splenectomy.

Journal Article↗
PubMed2000

Unusual congenital deformities of the lower limb in two calves.

Congenital deformities of the lower limb were observed in 2 calves from different properties. One was a newborn Holstein-Friesian bull calf with polydactyly and polypodia of the right fore-limb. The other was an 8-month-old Friesian/Jersey crossbred heifer calf, which had a mirror image duplication of the plantar/palmar half of the distal portion of the digits. The abnormalities in the second calf have not previously been described in cattle. This paper presents details of the clinical, radiological and necropsy findings in these 2 calves.

Journal Article↗
PubMed2000

An analysis of selected kinematic variables in national and elite male and female 100-m and 200-m breaststroke swimmers.

The kinematic analysis of competition breaststroke swimming has tended to focus on the mean values of swimming speed, stroke rate and stroke length; values in individual lengths, as well as the start, turns and finish, have largely been ignored. This study includes all such variables and aims to improve the coach's holistic understanding of breaststroke racing by determining the relationships and differences between and within these selected kinematic variables. We also compare 100-m events with 200-m events to determine if there are characteristic differences between them. Competitive breaststroke swimming performances in 100-m events (males: n = 159, finishing time = 65.05 +/- 2.62 s; females: n = 158, finishing time = 74.04 +/- 3.66 s) and 200-m events (males: n = 159, finishing time = 141.47 +/- 6.15 s; females: n = 158, finishing time = 158.66 +/- 7.87 s) were collected and analysed from 12 world, international and national championships. The better 100-m and 200-m breaststroke swimmers were found to demonstrate greater competency in the kinematic variables measured, except stroke kinematics, which were unique to each individual. These findings suggest that coaches should place emphasis on all of the kinematic components in training and that they should attempt to identify the stroke rate to stroke length ratio most appropriate for the individual. Finally, characteristic differences do exist between the 100-m and 200-m events, which has implications for how swimmers might train for each event.

Biomechanical Phenomena↗
PubMed2000

Comparison of three serological tests and an interferon-gamma assay for the diagnosis of paratuberculosis in experimentally infected sheep.

OBJECTIVE: To compare the diagnostic performance of a complement fixation test, an agar gel immunodiffusion test, an enzyme-linked immunosorbent assay, and a whole-blood interferon-gamma assay for paratuberculosis in 14 sheep experimentally infected with Mycobacterium avium subsp paratuberculosis. EXPERIMENTAL DESIGN: Longitudinal study. RESULTS: The IFN-gamma assay detected more experimentally infected sheep, and earlier, than any of the serological tests. None of the antibody assays was able to detect all sheep with histologically confirmed paratuberculosis. CONCLUSIONS: The superior performance of the IFN-gamma assay in detecting infected sheep in this small experimental population warrants its further evaluation in a larger population of sheep naturally exposed to M a paratuberculosis.

Animals↗
PubMed2000

Vaccination against paratuberculosis of lambs already infected experimentally with Mycobacterium avium subspecies paratuberculosis.

OBJECTIVE: To assess the protective value of a live-attenuated vaccine in sheep already exposed to Mycobacterium avium subsp paratuberculosis and to investigate the progression of a systemic immune response in experimentally infected sheep. STUDY DESIGN: Twenty-eight lambs, aged 1 to 1.5 months, were dosed via stomach tube with approximately 4.4 x 10(8) M a paratuberculosis organisms. Two weeks later, 14 of these 28 animals received subcutaneous injections of 1 mL of a live-attenuated vaccine. Thirteen additional lambs were neither dosed nor vaccinated (negative controls). Antigen-induced production of IFN-gamma in blood, and antibody concentrations in serum were sequentially monitored in vaccinated, unvaccinated and control animals for 1 year. Each sheep was examined for infection by an IS900-based PCR test on samples of ileum and ileocaecal lymph node and histological examination at the time of necropsy. RESULTS: Seven of 14 unvaccinated and two of 14 vaccinated sheep developed clinical paratuberculosis that was later confirmed by histological examination and/or the IS900-based PCR test. The granulomatous inflammation in the jejunal and ileal mucosa was less severe in vaccinated than in unvaccinated sheep. Acid-fast organisms were detected only in the unvaccinated group. The PCR assay on ileal samples gave positive reactions in two vaccinated and eight unvaccinated sheep. Both the antibody response and IFN-gamma response were detected earlier and were more substantial in vaccinated than in unvaccinated sheep. Furthermore, in experimentally infected but unvaccinated sheep, the IFN-gamma concentrations were higher in those animals without acid-fast organisms than in those with them. CONCLUSIONS: Vaccination of lambs with live-attenuated vaccine 2 weeks after oral inoculation with M a paratuberculosis stimulated the host response against the organism and led to a reduced mycobacterial burden. The diminished IFN-gamma responses in experimentally infected sheep with acid-fast organisms suggest a positive relationship between the magnitude of the systemic cell-mediated immune response and an animal's ability to control infection.

Animals↗