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Biomedical subjects

M Wyatt

Publications and source records attributed to M Wyatt.

At least 19 recordsLinked to original sources
PubMed2006

Are initial demyelinating event recovery and time to second event under differential control?

BACKGROUND: Relapsing-remitting multiple sclerosis (RRMS) begins with an initial demyelinating event (IDE) that can be monosymptomatic, polysymptomatic, or polyregional. Failure to recover from the IDE is a known predictor of later development of disability. Factors that predict IDE recovery (outside optic neuritis) and time to second event are relatively unknown. The authors speculate that IDE recovery and time to second event are under separate biologic or genetic control, and as such, their clinical predictors are different. METHODS: Data on all UCSF MS clinic patients are entered prospectively into an ACCESS database. The authors identified all patients seen at the UCSF clinic within 1 year of their IDE. Expanded Disability Status Scale scores, functional system scores, and visual acuity were used to define IDE severity and recovery. RESULTS: The cohort included 186 patients (127 women, 59 men) with an average onset age of 34 +/- 10 years with 150 whites (non-Hispanic), 15 African Americans, 11 Hispanics, eight Asians, and two unknown/unreported. Worse onset severity predicted worse IDE recovery (23.1% of the patients with severe onset vs 32.9% with moderate severity vs 56.4% with mild onset recovered completely, p < 0.001). Polyregional onset predicted poor recovery compared to monoregional onset (46.2% vs 14.4%, p < 0.001). Nonwhite patients were 2.48 times more likely than whites to experience a second episode within 1 year from onset (95% CI: 1.45 to 4.23, p < 0.001). Similarly, age younger than 30 years predicted higher risk of a second exacerbation (hazard ratio 1.92, 95% CI: 1.17 to 3.15, p = 0.010). CONCLUSION: Initial demyelinating event recovery and time to second event may have distinct predictors. These findings suggest that recovery and time to second event might be under separate biologic control.

Adult↗
PubMed2005

Comparison of treatment planning dose calculations with measurements and Monte Carlo calculations in a RANDO phantom.

Solid tumours are often treated with external beams of photons generated by Bremsstrahlung radiation. These beams are shaped and filtered to optimise the dose to specific regions defined by the treatment plans, which may involve irradiations from multiple angles. It is important that doses to healthy tissue do not exceed tolerance doses and that the dose to the tumour is maximised. To accomplish these objectives, commercially available 3-D treatment planning software is used to calculate doses to healthy tissue and to the tumour. It is generally believed that these commercial software packages calculate doses through the patient to within a few per cent. In order to examine this claim, dose calculations obtained from ADAC software for external beam treatment to the pelvic region of a RANDO phantom are compared with 37 thermoluminescence dosemeters placed into several slices of a RANDO phantom. The phantom was irradiated to obtain a prescription dose of 180 cGy at the tumour location. Data from homogeneous regions agree within several per cent with results obtained from ADAC software, whereas this comparison is less favourable in regions of heterogeneity. Results from Monte Carlo calculations in a homogeneous phantom are comparable to results from ADAC treatment planning software.

Computer Simulation↗
PubMed2001

2001 Volvo Award Winner in Clinical Studies: Effects of a media campaign on back pain beliefs and its potential influence on management of low back pain in general practice.

STUDY DESIGN: Quasi-experimental, nonrandomized, nonequivalent, parallel group-controlled study involving before and after telephone surveys of the general population and postal surveys of general practitioners was conducted, with an adjacent state used as a control group. OBJECTIVES: To evaluate the effectiveness of a population-based intervention designed to alter beliefs about back pain, influence medical management, and reduce disability and workers' compensation-related costs. SUMMARY OF BACKGROUND DATA: A multimedia campaign begun during 1997 in Victoria, Australia, positively advised patients with back pain to stay active and exercise, not to rest for prolonged periods, and to remain at work. METHODS: The campaign's impact on population beliefs about back pain and fear-avoidance beliefs was measured in telephone surveys, and the effect of the campaign on the potential management of low back pain by general practitioners was assessed by eliciting their likely approach to two hypothetical scenarios in mailed surveys. Demographically identical population groups in Victoria and the control state, New South Wales, were surveyed at three times: before, during, and after intervention in Victoria. RESULTS: The studies were completed by 4730 individuals in the general population and 2556 general practitioners. There were large statistically significant improvements in back pain beliefs over time in Victoria (mean scores on the Back Beliefs Questionnaire, 26.5, 28.4, and 29.7), but not in New South Wales (26.3, 26.2, and 26.3, respectively). Among those who reported back pain during the previous year, fear-avoidance beliefs about physical activity improved significantly in Victoria (mean scores on the Fear-Avoidance Beliefs Questionnaire for physical activity, 14, 12.5, and 11.6), but not in New South Wales (13.3, 13.6, and 12.7, respectively). General practitioners in Victoria reported significant improvements over time in beliefs about back pain management, as compared with their interstate colleagues. There were statistically significant interactions between state and time for 7 of 10 responses on management of acute low back pain, and for 6 of 10 responses on management of subacute low back pain. CONCLUSION: A population-based strategy of providing positive messages about back pain improves the beliefs of the general population and general practitioners about back pain and appears to influence medical management.

Australia↗
PubMed2001

Population based intervention to change back pain beliefs and disability: three part evaluation.

OBJECTIVE: To evaluate the effectiveness of a population based, state-wide public health intervention designed to alter beliefs about back pain, influence medical management, and reduce disability and costs of compensation. DESIGN: Quasi-experimental, non-randomised, non-equivalent, before and after telephone surveys of the general population and postal surveys of general practitioners with an adjacent state as control group and descriptive analysis of claims database. SETTING: Two states in Australia. PARTICIPANTS: 4730 members of general population before and two and two and a half years after campaign started, in a ratio of 2:1:1; 2556 general practitioners before and two years after campaign onset. MAIN OUTCOME MEASURES: Back beliefs questionnaire, knowledge and attitude statements about back pain, incidence of workers' financial compensation claims for back problems, rate of days compensated, and medical payments for claims related to back pain and other claims. RESULTS: In the intervention state beliefs about back pain became more positive between successive surveys (mean improvement in questionnaire score 1.9 (95% confidence interval 1.3 to 2.5), P<0.001 and 3.2 (2.6 to 3.9), P<0.001, between baseline and the second and third survey, respectively). Beliefs about back pain also improved among doctors. There was a clear decline in number of claims for back pain, rates of days compensated, and medical payments for claims for back pain over the duration of the campaign. CONCLUSIONS: A population based strategy of provision of positive messages about back pain improves population and general practitioner beliefs about back pain and seems to influence medical management and reduce disability and workers' compensation costs related to back pain.

Adult↗
PubMed2001

Two sox9 genes on duplicated zebrafish chromosomes: expression of similar transcription activators in distinct sites.

Sox9 is a transcription factor required for cartilage formation and testis determination in mammals. We have cloned from zebrafish two sox9 genes, termed sox9a and sox9b. Gene phylogenies showed that both genes are orthologous to tetrapod SOX9 genes. Genetic mapping showed that these two loci reside on chromosome segments that were apparently duplicated in a large-scale genomic duplication event in ray fin fish phylogeny. Both Sox9a and Sox9b proteins bind to the HMG consensus DNA sequences in vitro. We tested different domains for transactivation potential and identified a potential activation domain located in the middle of both Sox9a and Sox9b. During embryogenesis, sox9a and sox9b expression patterns are distinct but overlap in some regions of the brain, head skeleton, and fins. Expression of sox9a/b correlates well with that of col2a1 in chondrogenic elements. In the adults, sox9a is expressed in many tissues including brain, muscle, fin, and testis, whereas sox9b expression is restricted to previtellogenic oocytes of the ovary. This expression pattern predicts that sox9a and sox9b may have unique functions in some specific tissues during development. The role of gene duplication for the evolution of developmental gene function is discussed.

Amino Acid Sequence↗
PubMed2000

Six cases of fibromatosis of the head and neck in children.

Six cases of aggressive fibromatosis occurring in the head and neck in children are described. Fibromatosis is a rare, benign but locally infiltrative condition. Primary excision is not always possible in the head and neck areas. It is not always appropriate to treat children using the same modalities as adults due to associated growth problems. The case histories illustrate the management difficulties that can be encountered when treating the paediatric population.

Child, Preschool↗
PubMed2000

Functional laryngeal dyskinesia: an important cause of stridor.

Functional laryngeal dyskinesia is a disorder that presents with stridor. Failure to recognize its features can result in inappropriate investigation and treatment for a condition that has a psychogenic origin. The key feature in diagnosis is paradoxical vocal fold adduction on inspiration, as seen on fibre-optic nasendoscopy. This phenomenon together with the associated stridor may disappear after distraction techniques or when the patient is asleep. We present five such cases which presented to hospitals in south west London over a 12 month period.

Adolescent↗
PubMed1999

Laryngeal paraganglioma in a five-year-old child--the youngest case ever recorded.

A paraganglioma is a neuroendocrine neoplasm that originates from the paraganglion cells of the parasympathetic system. The average age of presentation is in the fifth decade. We report a case of laryngeal paraganglioma in a five-year-old child, the youngest case ever recorded. The features of paraganglioma which differentiate it from other tumours are also discussed.

Age Factors↗
PubMed1999

Dercum's disease (adiposis dolorosa).

Dercum's disease (adiposis dolorosa) is a rare condition characterized by progressively painful fatty deposits, usually, in menopausal women with obesity, asthenia and mental phenomena. We report a case of a 48-year-old woman with recurrent neck swelling and pain in the neck and parotid region, and a review of management of this uncommon problem.

Adipose Tissue↗
PubMed1997

Prospective study of zero drift in fiberoptic pressure monitors used in clinical practice.

One hundred and one fiberoptic pressure transducers (59 subdural and 42 ventricular) were studied in 86 patients (some in whom more than one device had been inserted). Only four complications occurred: two transient cerebrospinal fluid leaks after removal and two clinically insignificant intracerebral hematomas. No intracranial infections could be attributed to the devices. Technical problems occurred 23 times, with 11 devices ceasing to function before removal, seven becoming displaced, and five microventricular catheters failing to enter the ventricles. Zero-drift readings were obtained for 83 devices at the time of removal (median 66 hours after insertion, range 2 hours-13 days). There was a clear negative bias in the readings (median -3), with a wide range of values (-12 to +14 mm Hg; interquartile range -6 to -1) that was apparent even in the first 3 days of use. There was no important relationship between zero drift and any recorded variable. It is concluded that zero drift of fiberoptic pressure transducers is a significant problem and that undue reliance should not be placed on intracranial pressure readings from these devices in isolation from other clinical and radiological information.

Equipment Failure↗
PubMed1996

Clinical use of prediction regions for motion analysis.

This study assesses the diagnostic capability of statistically defined prediction regions, developed by a 'bootstrap' method, for assessing the curves of angular rotation of joints in children as they walk. The prediction regions had been previously developed in the authors' laboratory from a study of 309 normal children. The goal of the present study was to determine whether these computer-generated prediction regions could be used as a screen in clinical gait analysis, to determine whether a movement falls outside the normal range of variability. Kinematic analysis of 38 consecutive children referred to the motion analysis laboratory for clinical gait assessment provided 912 curves of lower-extremity joint angle dynamics. An experienced observer first inspected the patients' curves with mean normal curves superimposed and designated the curves as normal or abnormal. The performance of the computer-generated prediction regions was judged by comparison with the experienced observer's designations. The prediction regions were found to have a high sensitivity (81%), indicating that they can be used as an initial screen to identify deficits in lower limb function.

Child↗
PubMed1993

Molecular surface comparison: application to drug design.

An interactive system for the display and manipulation of molecular surface properties is presented. The property at the molecular surface is mapped onto the sphere by gnomonic projection. This representation allows direct comparison of the surface properties of pairs of molecules. The system allows the user to explore the similarities between a pair of molecules in an interactive manner, and provides extensive visual (color-coded field and field difference maps) and numerical (rms difference value) aids to complement the user's chemical intuition. Examples of the use of the system to study beta-lactam compounds and phosphodiesterase inhibitors are presented.

Anti-Bacterial Agents↗
PubMed1993

Impedance analysis versus colour Duplex in femorodistal vein graft surveillance.

Fifty patients who have undergone femorodistal bypass surgery have been followed up using impedance analysis and colour Duplex, with biplanar intraarterial digital subtraction angiography being used as the arbiter to define "at risk" grafts. An impedance score of 0.49 (0.43-0.55) was found in the "at risk" grafts, all of which underwent an interventional procedure compared to 0.39 (0.36-0.42) (p = 0.003, Mann-Whitney U test) in those with no problem. In total, 166 examinations were performed. The sensitivity and specificity were all greater than 91% when compared to angiography. Impedance analysis is simple, non-invasive, easy to perform and it takes only 10 min to complete the examination. In view of the results obtained using impedance analysis in comparison with Duplex scanning, we suggest that non-invasive impedance is a suitable alternative to colour Duplex for graft surveillance (mean +95% confidence interval).

Adult↗