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D J Wilson

Publications and source records attributed to D J Wilson.

At least 73 records · Page 4Linked to original sources
PubMed1998

Selecting linear-score distributions for modelling milk-culture results.

The data for this cross-sectional retrospective study are from surveys of 65 dairy-cattle herds in central New York, USA sampled between February, 1993 and March, 1995. The objective was to identify probability distributions of logarithmically transformed somatic-cell counts (linear score) for use in a simulation model of mastitis and milk quality. Probability density functions were estimated using maximum-likelihood estimators for the linear score of individual-cow composite-milk samples culture negative and culture positive for the pathogens Streptococcus agalactiae, Streptococcus non-agalactiae, Staphylococcus aureus, and coagulase-negative staphylococci for the complete dataset and by bulk-tank somatic-cell count group (< 500,000, > or = 500,000 SCC/ml). Based on the rankings of three goodness-of-fit tests (Anderson-Darling, Kolmogorov-Smirnov and chi 2), the Weibull distribution (among the three top-ranking distributions for 14 out of 15 cases) may be used to model the individual-cow linear-score response by culture-result-specific bulk-tank somatic-cell count group. A beta distribution was among the three top-ranking distributions for nine out of 15 culture-result-specific bulk-tank somatic-cell count groups and has a logical relationship to linear score because it is defined on a fixed interval. On the other hand, the normal distribution had a poorer fit than the Weibull and at least two other distributions for all culture negative and coagulase-negative staphylococci samples. We do not assume that the underlying biological processes are fully explained by either Weibull or beta distribution--but modelling the linear score for the above culture results with these distributions provided an adequate fit to the survey data, reduced the need for two-sided truncation that open intervals needed, and had errors that did not appear to be systematically positive or negative.

Animals↗
PubMed1998

Neuraxial opioids in labour.

Neuraxial opioids were first used for labour analgesia in 1980 following the description of spinal cord opioid receptors in 1979. Via these receptors in the dorsal horn, opioids modulate both the visceral and the somatic pain of labour. The onset and duration of action of the individual opioid are determined primarily by its relative lipid solubility. Neuraxial opioids have a local anaesthetic sparing effect, allowing the use of lower concentrations of both agents while maintaining analgesia. As a sole agent, intrathecal opioids can be used to provide analgesia during the first stage of labour, especially in the high-risk parturient. They also have a role in the management of perineal pain and the provision of rapid-onset analgesia. Unfortunately maternal and neonatal side-effects can occur, the most important being respiratory depression.

Female↗
PubMed1998

Increased platelet responsiveness following coronary stenting. Heparin as a possible aetiological factor in stent thrombosis.

AIMS: Platelet activation may be a determinant of thrombotic and restenotic complications following intracoronary stenting. In order to measure the effect of stenting on platelet activation antigen expression we used whole blood flow cytometry in 18 patients undergoing Palmaz-Schatz stenting (treated with full anticoagulation) and compared these with a group of 18 patients undergoing elective angioplasty. The effects of low molecular weight heparin and unfractionated heparin on platelet behaviour were also studied, both in vitro and in vivo to determine the contribution of prolonged heparin therapy to platelet activation following stenting. METHODS AND RESULTS: Fibrinogen binding to activated GPIIb-IIIa, and surface expression of P-selectin, GPIb and GPIIb-IIIa antigens were measured in unstimulated peripheral blood samples (rest) and on stimulation with adenosine diphosphate (0.1-10 micromol x 1(-1)) and thrombin (0.02-0.16 U x ml(-1)). No changes were seen in resting samples following angioplasty or stenting. Agonist responsiveness was unaltered after angioplasty, but in stented patients antigen expression in response to thrombin was significantly reduced (P< or =0.04), whilst the adenosine diphosphate response was significantly increased (P=0.01). Similar effects were observed in patients with unstable angina treated with either low molecular weight heparin or unfractionated heparin in vivo. In vitro, both unfractionated and low molecular weight heparin inhibited thrombin-induced platelet activation, but stimulation of adenosine diphosphate responses was more marked with unfractionated than low molecular weight heparin. CONCLUSIONS: There was a significant increase in platelet responsiveness to adenosine diphosphate following intracoronary stenting in patients treated with conventional anticoagulants. This was probably a consequence of treatment with heparin. Activation of platelets by heparin may explain the increased rate of stent thrombosis in patients treated with anticoagulant therapy. Low molecular weight heparins stimulate platelets less than unfractionated heparin.

Adenosine Diphosphate↗
PubMed1998

Histopathologic changes of the eyelid skin following trichloroacetic acid chemical peel.

The use of trichloroacetic acid (TCA) as a periorbital and eyelid peel for skin rejuvenation is gaining significant acceptance among oculoplastic surgeons, dermatologists, and other surgery groups. In spite of the current enthusiasm, there remain potentially serious complications resulting from any periorbital peel. Cases of cicatricial ectropion have been reported in phenol-peeled patients, and lower eyelid ectropion has reportedly occurred in patients undergoing deep eyelid peel in conjunction with a blepharoplasty (1,2). To avoid this complication, it is necessary to better understand the depth of the wound produced by different strengths and combinations of peeling agents applied to living eyelid tissue and, more important, to determine the concentrations of TCA that are likely to lead to cicatricial ectropion when applied in a consistent fashion. We chose upper-eyelid skin because it is easier to obtain for histopathologic study than lower-eyelid skin and, in our experience, is more sensitive to hypertrophic changes after chemical peeling or carbon dioxide laser resurfacing. We applied TCA to the preseptal skin of 10 patients 48 h before standard upper-eyelid blepharoplasty. The acid was applied to produce a "frost," using varying concentrations of acid, ranging from 20 to 50%. The treated skin removed at the time of blepharoplasty was reviewed in a masked fashion by a dermatopathologist to determine the depth of necrosis. We found that superficial peels with necrosis involving 30% of the epidermis were produced by the lowest-concentration combination of TCA applied (20% followed by 0%). As the strength increased, so did the depth of peel. The combination of 50% followed by a second application of 50% produced the deepest peel, with necrosis into the papillary dermis. This finding would indicate that the chance of developing cicatricial ectropion with any of the tested combinations of TCA should be very remote.

Administration, Topical↗
PubMed1998

Nodular sclerosing Hodgkin disease with primary manifestation in the orbit.

Hodgkin disease with primary manifestation in the orbit is extremely rare, and even when suspected can be very difficult to diagnose. Its clinical and histological presentation can be nearly impossible to differentiate from that of a benign inflammatory process, and it is necessary to utilize immunohistochemical techniques to confirm the diagnosis. This article focuses on a case of nodular sclerosing Hodgkin disease with initial manifestation in the orbit. A comparison of the clinical, histological, and immunohistochemical presentations associated with both Hodgkin disease and benign inflammation is discussed. A brief review of the immunohistochemistry specific for Hodgkin disease is also provided.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Identification of a common low density lipoprotein receptor mutation (C163Y) in the west of Scotland.

Familial hypercholesterolaemia (FH) is an autosomal codominant disorder characterised by high levels of LDL cholesterol and a high incidence of coronary artery disease. Our aims were to track the low density lipoprotein receptor (LDLR) gene in individual families with phenotypic FH and to identify and characterise any mutations of the LDLR gene that may be common in the west of Scotland FH population using single strand conformational polymorphism analysis (SSCP). Patient samples consisted of 80 heterozygous probands with FH, 200 subjects who were related to the probands, and a further 50 normal, unrelated control subjects. Tracking of the LDLR gene was accomplished by amplification of a 19 allele tetranucleotide microsatellite that is tightly linked to the LDLR gene locus. Primers specific for exon 4 of the LDLR gene were used to amplify genomic DNA and used for SSCP analysis. Any PCR products with different migration patterns as assessed by SSCP were then sequenced directly. In addition to identifying probands with a common mutation, family members were screened using a forced restriction site assay and analysed using microplate array diagonal gel electrophoresis (MADGE). Microsatellite D19S394 analysis was informative in 20 of 23 families studied. In these families there was no inconsistency with segregation of the FH phenotype with the LDLR locus. Of the FH probands, 15/80 had a mutant allele as assessed by SSCP using three pairs of primers covering the whole of exon 4 of the LDLR gene. Direct DNA sequencing showed that 7/15 of the probands had a C163Y mutation. Using a PCR induced restriction site assay for the enzyme RsaI and MADGE, it was determined that the C163Y mutation cosegregated with the FH phenotype in family members of the FH probands. This mutant allele was not present in any of the control subjects. Microsatellite analysis has proven useful in tracking the LDLR gene and could be used in conjunction with LDL cholesterol levels to diagnose FH, especially in children and young adults where phenotypic diagnosis can be difficult.

Adult↗
PubMed1998

Evaluation of mild lameness in horses trotting on a treadmill by clinicians and interns or residents and correlation of their assessments with kinematic gait analysis.

OBJECTIVE: To estimate sensitivity and accuracy of subjective evaluation of mild lameness in horses during treadmill locomotion and to correlate subjective evaluation with kinematic analysis. ANIMALS: 19 lame and 5 clinically normal horses. PROCEDURE: Lameness was evaluated by subjective score and kinematic analysis before and after palmar digital nerve block (PDNB). Evaluations were made by 6 clinicians and 7 interns or residents. Within- and between-observer agreement analyses (kappa values) were calculated and compared, using a Student's t-test. Pearson's product-moment correlation coefficients were calculated between clinician's change in score and the change in kinematic variables after PDNB. RESULTS: Within-observer agreement was within the range expected for conditions of moderate diagnostic difficulty. Within-observer agreement was higher for clinicians than for interns or residents. Between-observer agreement was acceptable for scores within 1 value of each other. Between-observer agreement of change in lameness score after PDNB was poor. When kinematic variables were ranked with each clinician's subjective change in score, only 2 were among the top 3 for the majority of clinicians. Asymmetry of vertical head movement between contralateral forelimb stance phases and the point of maximum hoof height during swing decreased as lameness subjectively improved. CONCLUSION: Mild lameness may be difficult to evaluate during treadmill locomotion. Although clinicians were more repeatable in their subjective evaluation of lameness than interns or residents, they were not more reliable at detecting the true state of lameness. CLINICAL RELEVANCE: Lack of agreement between clinician scoring of mild lameness emphasizes the need to use more objective measures for quantifying lameness.

Animals↗
PubMed1997

Association between management practices, dairy herd characteristics, and somatic cell count of bulk tank milk.

OBJECTIVE: To determine whether particular dairy management practices and herd characteristics were associated with somatic cell count (SCC) of bulk tank milk. DESIGN: Analysis of records. SAMPLE POPULATION: Milk samples collected from 59,435 cows housed in 843 dairy herds between March 1992 and June 1994. PROCEDURE: Results of bacterial culture of milk samples and data on farm housing, sanitation, milking system, and management were collected. Multiple regression analysis was used to determine sources of variation in bulk tank milk SCC among herds. RESULTS: Prevalence of Streptococcus agalactiae and Staphylococcus aureus mastitis was associated with bulk tank milk SCC. In herds free of S agalactiae mastitis, prevalence of S aureus and Corynebacterium bovis mastitis were important. For herds without S agalactiae mastitis, use of sawdust bedding was associated with a decrease in SCC and a dirty loose housing area was associated with an increase. Increased milk production, repeated mastitis control visits, and use of particular predip compounds were significantly associated with reduced SCC in all herds, regardless of whether any cows in the herd had S agalactiae mastitis. In herds with S agalactiae mastitis, use of iodine (certain concentrations), chlorhexidine, peroxide, or sodium chlorite-lactic acid as a predip was associated with a decrease in SCC. Only use of sodium chlorite-lactic acid predip was significantly associated with a decrease in SCC in herds without S agalactiae mastitis. CLINICAL IMPLICATIONS: Important factors associated with bulk tank milk SCC were prevalence of S agalactiae and S aureus mastitis, careful application of particular predip compounds, avoiding a dirty loose housing area, and use of a service to regularly monitor prevalence of mastitis in the herd.

Animal Husbandry↗
PubMed1997

Different effects of calcium antagonists, nitrates, and beta-blockers on platelet function. Possible importance for the treatment of unstable angina.

BACKGROUND: The three major classes of antianginal drug all inhibit platelet aggregation at high concentrations in vitro, but detecting clinically relevant effects has proved to be more difficult. We used whole-blood flow cytometry, a sensitive method that allows direct measurement of activation antigens on the surface of individual platelets in whole unfixed blood, to evaluate the effect of representative antianginal drugs on platelet function in vivo in healthy volunteers. METHODS AND RESULTS: The effects of glyceryl trinitrate (GTN), amlodipine, and atenolol were studied in nine normal volunteers. Fibrinogen binding to activated GP IIb/IIIa and expression of P-selectin, GP Ib, and GP IIb/IIIa on the platelet surface were measured. In addition, fibrinogen binding and P-selectin expression were measured in response to ex vivo stimulation with the agonists ADP and thrombin. The three drugs had very different effects on platelets. GTN inhibited platelet fibrinogen binding and expression of P-selectin at rest and in response to agonist stimulation, whereas amlodipine enhanced P-selectin expression and atenolol increased fibrinogen binding in response to agonists. Atenolol did not block the stimulatory effects of epinephrine on ADP-induced platelet activation. GTN neutralized the proactivatory effects of amlodipine, whereas the effects of atenolol and amlodipine were not additive. CONCLUSIONS: The three main classes of antianginal medication have different and possible clinically relevant effects on platelet behavior in vivo, nitrates causing inhibition of aggregation (fibrinogen binding) and degranulation (P-selectin expression), calcium antagonists enhancing degranulation, and beta-blockers enhancing aggregation.

Adrenergic beta-Antagonists↗
PubMed1997

Intravitreal methotrexate as an adjunctive treatment of intraocular lymphoma.

OBJECTIVE: To develop a protocol for the treatment of intraocular lymphoma by the intravitreal injection of methotrexate. METHODS: Patients whose results were negative for human immunodeficiency virus and who had pathologically confirmed intraocular lymphoma were eligible for participation in the study. A dose of 400 micrograms of methotrexate was given intravitreally twice weekly until the vitreous was clinically cleared of cells. Weekly injections were then given for 1 month, followed by monthly injections for 1 year. RESULTS: Seven eyes of 4 patients were treated. Three patients have completed the protocol. To date, only 1 eye has suffered a significant loss of vision. No serious ocular toxic reaction has been identified. CONCLUSIONS: Survival rates and time to relapse for patients with primary central nervous system lymphoma have improved. The role of ocular radiation therapy must be weighed against the potential drawbacks. Injecting chemotherapeutic agents into the vitreous is worthy of consideration. Four patients treated to date at our institution have had promising results. Intravitreal chemotherapy may result in improved treatment of intraocular lymphoma with reduced morbidity.

Aged↗
PubMed1997

Lumbar spinal moments in chronic back pain patients during supported lifting: a dynamic analysis.

OBJECTIVES: The main objective of this study was to test the hypothesis that peak L4/L5 moments (torque) placed on the lumbar spine by chronic back pain subjects are reduced using pain-reducing postural adaptations. A secondary objective was to determine the relation between lumbar moments while lifting and self-reported ratings of lower back pain. STUDY DESIGN: Cohort using seven men with a history of chronic lower back pain. An inverse dynamic model was used to calculate L4/L5 forces and moments while performing five trials each of two lifting styles. Subjective ratings of lumbar back pain were taken before and after the lifts. RESULTS: Significant (p < .001) differences were found between lifting postures on peak L4/L5 net reaction moments. Two distinct lifting profiles emerged characterized by the amount of lumbar spinal extensor musculature involved. Significant (p < .05) increases in pain were found after a bowed-back lifting style. CONCLUSIONS: Peak L4/L5 net reaction moments were less (spine extensor loading) for a lifting posture that produced lower levels of self-reported lower back pain. The dynamic model proved reliable and useful for future study of the pathomechanics of lower back pain.

Adaptation, Physiological↗
PubMed1997

The role of magnetic resonance imaging in the management of peripheral nerve tumours.

Fourteen cases of peripheral nerve tumour which had been examined by MRI were reviewed. T1-weighted images showed the tumours to be of intermediate signal and T2-weighted images showed a high signal with some heterogeneity. These appearances are not specific to peripheral nerve tumours, although the diagnosis may be suggested if the lesion arises from a major nerve trunk. The association with a nerve trunk may be defined by MRI, thus assisting with surgical planning. Neurilemmomas, neurofibromas and malignant nerve sheath tumours could not be differentiated with certainty using MR alone. The MR features of lipofibromatous hamartoma are reported.

Adult↗
PubMed1997

Muscle patterning, differentiation and vascularisation in the chick wing bud.

Adult muscle is highly vascularised, with blood vessels being essential for adequate oxygenation of the tissue and for supporting increased metabolic demands. Whether this is the case during muscle development has not been examined. Resin histology was used to map the muscle splitting process and conventional transmission electron microscopy to examine early muscle differentiation at the midlimb level or later at the mid radius/ulna level in the chick wing bud from stages 24 (4.5 d) to 36 (10 d) (Hamburger & Hamilton, 1951). Microinjection of India Ink into the extra-embryonic vasculature was used to visualise the patent muscle microcirculation. The results showed that the premuscle masses are present at stage 24 and initial splitting of the muscle masses commences at stage 28. The final muscle pattern is not established until stage 36. At stage 26 the cells within the premuscle masses exhibited a mesenchymal morphology, but at stage 28 overt muscle differentiation was evident with myofibrils present within myoblasts. Undifferentiated mononucleated cells were interspersed with the differentiating myoblasts. The ratio of mononucleated cells:myoblasts decreased and the myoblasts became plumper and increasingly packed with myofibrils with age. There was no evidence of secondary myotube formation at any of the stages examined. Vascular invasion of the limb occurred at stage 35 just prior to the establishment of the final muscle pattern. This was surprising as it was assumed that myogenic differentiation would be both oxygen and nutrient dependent. The results of this study provide descriptions of the splitting of the premuscle masses through to the establishment of the final muscle pattern at the midlimb or mid radius/ulna level of the chick wing bud together with the differentiation of the myogenic cells within the developing muscles. However, the relationship between muscle patterning at the tissue level and muscle differentiation at the cellular level with vascularisation remains unclear. It is hoped that the results of the study may provide the basis for future investigations into mechanisms involved in muscle patterning and the signalling mechanisms for vascular invasion.

Animals↗