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Biomedical subjects

K J Stewart

Publications and source records attributed to K J Stewart.

At least 19 recordsLinked to original sources
PubMed2006

Complications of 278 consecutive abdominoplasties.

The case notes of 278 consecutive patients who underwent abdominoplasty, during a five-year period, in one institution under the care of four surgeons were reviewed. Patient details, early and late complications and revision procedures were noted. Seventy-five percent of patients had a 'full' abdominoplasty with undermining to costal cartilage and repositioning of the umbilicus and 23% had 'mini abdominoplasties', 2% were revision operations. Eighteen percent of patients suffered from early complications the most common of which were seroma (5%), haematoma (3%), infection (3%), skin or fat necrosis (2.5%) and delayed healing (2%). Twenty-five percent of patients had late complications which were often relatively minor. These included 'dog ears' (12%), localised fatty excess (10%) and unsatisfactory scars (8%). Twenty-four percent of patients underwent revision surgery. Most commonly further liposuction (12%), dog ear revision (10%) and scar revision (5%). Analysis failed to reveal significant risk factors. Despite an apparently high complication and revision rate the subjective impression is of a satisfied patient cohort.

Abdomen↗
PubMed2006

Comparison of cartilage scoring and cartilage sparing otoplasty--A study of 203 cases.

UNLABELLED: The Edinburgh experience of different methods of otoplasty techniques in 203 patients (406 ears) over a five-year period is reviewed. MATERIALS AND METHODS: The patients were divided into three groups - Group A (anterior cartilage scoring), Group B (cartilage sparing in the fashion of posterior suturing) and Group C (posterior suturing refined with posterior fascial flap). Demographic details, operation technique, operation time, grade of the surgeon, suture materials, early and late complications, recurrence and revision rates, patients' and physicians' comments at the follow-up clinic were retrieved from the case notes. The pre- and the post-operative photographs were assessed by a blinded lay observer and a physician and scored on a visual analogue scale. Median follow-up was 11 months. RESULTS: The recurrence rate was 11.0%, 8.0% and 4.8% in Groups A, B and C, respectively (p = 0.0214). Complications were more common in Group A (8.8%) and Group B (7.9%) compared to Group C (1.2%) (p = 0.0208). The cosmetic result was judged best in Group C. In our experience, cartilage-sparing otoplasty refined with the post-auricular fascial flap results in significantly reduced complication rate and improved aesthetic outcome.

Adolescent↗
PubMed2005

Exercise effects on cardiac size and left ventricular diastolic function: relationships to changes in fitness, fatness, blood pressure and insulin resistance.

OBJECTIVES: To determine exercise training effects on cardiac size and left ventricular (LV) diastolic function and relationships of exercise induced changes in physiological and body composition parameters with cardiac parameters. DESIGN: Prospective, randomised controlled trial. SUBJECTS: Men and women (63.6 (5.7) years, body mass index 29.5 (4.4) kg/m(2)) with untreated hypertension (systolic blood pressure (BP) 130-159 or diastolic BP 85-99 mm Hg). MAIN OUTCOME MEASURES: Cardiac size and LV diastolic function, peak oxygen uptake (Vo(2)), muscle strength, general and abdominal fatness, and insulin resistance. INTERVENTIONS: 6 months of exercise training versus usual care. RESULTS: When analysed by group at six months, cardiac size and LV diastolic function did not differ between exercisers (n = 51) and controls (n = 53), whereas exercisers had significantly higher peak Vo(2) (28 v 24 ml/kg/min) and strength (383 v 329 kg), and lower fatness (34% v 37%), diastolic BP (73 v 75 mm Hg) and insulin resistance (quantitative insulin sensitivity check index 0.35 v 0.34) versus controls (all p <or= 0.05). By regression analysis, among six month changes, increased peak Vo(2) and reduced abdominal fat were associated with increased cardiac size. Increased peak Vo(2) and reduced abdominal fat, BP and insulin resistance were associated with improved LV diastolic function. r Values ranged from 0.20 to 0.32 (p <or= 0.05). CONCLUSIONS: When examined by group assignment, exercise had no effect on cardiac size or LV diastolic function. When individual variations in six month changes were examined, participants attaining the greatest increases in fitness and reductions in abdominal fatness, insulin resistance and BP showed a modest trend towards physiological hypertrophy characterised by increased cardiac size and improved LV diastolic function. These results suggest that decreased abdominal fatness may have a role in improving cardiovascular health.

Aged↗
PubMed2004

Type 2 diabetes in Singapore: the role of exercise training for its prevention and management.

The prevalence of type 2 diabetes has been increasing in Singapore and is a major risk factor for cardiovascular disease. Exercise training is an important therapeutic modality for managing glycaemic control and improving cardiovascular health among persons with type 2 diabetes. It may also help to prevent or delay the onset of this harmful condition. This review examines the evidence and possible mechanisms by which exercise training produces these benefits, and gives a brief review of appropriate exercise activities.

Diabetes Mellitus, Type 2↗
PubMed2003

Exercise blood pressure response is related to left ventricular mass.

An exaggerated SBP response to exercise has been associated with increased left ventricular (LV) mass in some but not all studies. A total of 43 women and 34 men, aged 55-75 years, without evidence of cardiovascular disease, with a mean resting BP of 142+/-9/77+/-8 mmHg had their BP measured at rest and during maximal treadmill exercise. LV mass was measured using magnetic resonance imaging. LV mass was adjusted for lean body mass, which was assessed by dual energy X-ray absorptiometry. LV mass was within the normal range for the majority of the subjects. Among the resting and exercise BP indices, maximal SBP was the strongest correlate of LV mass (r=0.41, P<0.05). In multivariate analysis, maximal SBP was independently associated with LV mass after adjustment for lean body mass and gender, explaining 3% of the variance (P<0.05). Maximal exercise SBP is a modest but still independent predictor of LV mass in older persons with normal LV mass. These results raise the possibility that the SBP response to maximal exercise is an early marker of LV hypertrophy.

Aged↗
PubMed2003

Micromechanically based poroelastic modeling of fluid flow in Haversian bone.

To explore the hypothesis that load-induced fluid flow in bone is a mechano-transduction mechanism in bone adaptation, unit cell micro-mechanical techniques are used to relate the microstructure of Haversian cortical bone to its effective poroelastic properties. Computational poroelastic models are then applied to compute in vitro Haversian fluid flows in a prismatic specimen of cortical bone during harmonic bending excitations over the frequency range of 10(0) to 10(6) Hz. At each frequency considered, the steady state harmonic response of the poroelastic bone specimen is computed using complex frequency-domain finite element analysis. At the higher frequencies considered, the breakdown of Poisueille flow in Haversian canals is modeled by introduction of a complex fluid viscosity. Peak bone fluid pressures are found to increase linearly with loading frequency in proportion to peak bone stress up to frequencies of approximately 10 kHz. Haversian fluid shear stresses are found to increase linearly with excitation frequency and loading magnitude up until the breakdown of Poisueille flow. Tan delta values associated with the energy dissipated by load-induced fluid flow are also compared with values measured experimentally in a concurrent broadband spectral analysis of bone. The computational models indicate that fluid shear stresses and fluid pressures in the Haversian system could, under physiologically realistic loading, easily reach the level of a few Pascals, which have been shown in other works to elicit cell responses in vitro.

Adaptation, Physiological↗
PubMed2002

Posterior-variant alien hand syndrome: clinical features and response to rehabilitation.

PURPOSE: This case highlights the clinical features and course of recovery of a patient presenting to the rehabilitation service with posterior-variant alien hand syndrome (AHS) following thalamic stroke. METHODS: Single case report. RESULTS: Clinical signs and symptoms included mild hemiparesis, dyspraxia, dysmetria, primary sensory loss and hemispatial neglect. Autonomous movements and personification of the affected extremity which were ego-syntonic in nature were characteristic of posterior-variant AHS. The associated neurological impairments resolved early during the course of rehabilitation and the patient made excellent functional gains. CONCLUSION: This case highlights the distinguishing features differentiating posterior-variant AHS from more classical AHS and underscores the excellent prognosis of this variant.

Aged↗
PubMed2002

The effect of wall thickness on the response of a spherical ionization chamber.

Air-filled ionization chambers are used widely for radiation dosimetry. For some applications it is important to know the effect on the chamber response of photon attenuation and scattering in the chamber walls. Traditionally, the wall effect is determined by measuring the chamber response as a function of wall thickness and extrapolating linearly to zero thickness. We have constructed a spherical graphite chamber with variable wall thickness. The change in the chamber response with wall thickness has been measured in a 137Cs gamma-ray beam. Our data show that the change in response is not linear with wall thickness, in agreement with the theoretical prediction of Bielajew (1990 Med. Phys. 17 583-7). A linear versus non-linear extrapolation of the measured data to zero wall thickness leads to a difference of almost 1% in the estimate of the wall correction factor, Kw. The value of Kw obtained using the non-linear extrapolation is in good agreement with the result obtained using Monte Carlo techniques.

Algorithms↗
PubMed2002

Fitness, fatness and activity as predictors of bone mineral density in older persons.

OBJECTIVES: To determine relationships of bone mineral density (BMD) with fitness, physical activity, and body composition and fat distribution. DESIGN: Cross-sectional. SETTING: General Clinical Research Center, Johns Hopkins Bayview Medical Center, Baltimore, Maryland. SUBJECTS: Men (n = 38) and women (n = 46), aged 55-75 years with high normal blood pressure or mild hypertension but otherwise healthy. METHODS: Aerobic fitness (oxygen uptake) on a treadmill, muscle strength by one-repetition maximum, activity by questionnaire, abdominal obesity by magnetic resonance imaging; anthropometrics, and body composition by dual energy X-ray absorptiometry (DXA) which measured total fat and lean mass, and BMD for the total skeleton, lumbar spine (L1-L4) and total hip. RESULTS: Aerobic fitness did not correlate with BMD. Using multivariate analysis to ascertain independent contributions to the variance in BMD, in women, with adjustment for hormone replacement therapy (HRT), total skeleton BMD was independently related to muscle strength and abdominal total fat; total hip BMD to body weight; lumbar spine BMD to abdominal total fat. HRT also influenced BMD in the lumbar spine. In men, lumbar spine BMD was independently related to abdominal total fat physical activity and total hip BMD related to lower body strength. P < 0.05 for all of these correlations. CONCLUSIONS: Abdominal obesity and muscle strength emerge as predominant correlates of BMD in older persons with stronger relationships seen in women. Body weight and HRT also explained portions of the variance in BMD in women. Whether abdominal obesity is simply a marker for general obesity or has independent protective effects on bone is yet to be determined.

Abdomen↗
PubMed2002

Skin grafts for the salvage of degloved below-knee amputation stumps.

We present a series of six patients in whom a traumatic below-knee amputation was associated with significant degloving, such that there was inadequate local skin to achieve primary stump closure. In each case, skin grafts were used to cover the stump muscle flaps. The patients ranged in age from 21 years to 73 years; the mean hospital stay was 72 days and the mean follow-up was 48 months. Despite an average of five procedures to achieve stump healing and an average of 118 days to first limb fitting, all patients have achieved independent mobility with their prosthesis. All have had minor stump problems necessitating periods of time off their prosthesis. Three patients have required minor stump-revision surgery. The advantages of a below-knee amputation over an above-knee amputation compensate for these problems. The forgiving nature of modern prostheses has contributed to acceptable results in these patients, who had what may previously have been considered insufficiently durable stump cover.

Adult↗
PubMed2002

Altered speech following adenoidectomy: a 20 year experience.

Altered speech related to velopharyngeal insufficiency is a rare but well-recognised complication of adenoidectomy. Over a 20 year period, 42 patients were referred to the Edinburgh cleft team for investigation of altered speech persisting for more than 12 months after adenoidectomy. We studied the cases to ascertain the incidence, clinical features and causes of altered speech in these patients and to assess the efficacy of a selective treatment policy. All data were prospectively collected when the patients were assessed in a multidisciplinary clinic and investigated by videofluoroscopy. Nasopharyngoscopy was also possible in half of the patients. Overall, 27 patients were male and 15 were female, and their mean age was 6.5 years. The incidence was one in 1200 adenoidectomies. Diagnoses included five submucous cleft palates, six occult submucous cleft palates, 22 cases of velopharyngeal disproportion, seven developmental or neurological causes, one iatrogenic palatal injury and one case that defied diagnosis. In six patients treatment was not required, 13 responded to speech therapy and 23 required surgical intervention. The choice of operation was based on the findings at investigation. Ten patients were treated by a superiorly based pharyngeal flap, 10 underwent a sphincteric pharyngoplasty and three had an intravelar veloplasty. Speech outcome was assessed in 36 cases. Treatment resulted in significantly improved speech in all but one patient and normal speech in 16 patients. Persistently altered speech is a rare complication of adenoidectomy. Preoperative screening by clinical examination will prevent some but not all of such problems. When patients present they should undergo multidisciplinary assessment and multi-modality investigation. A good outcome can be anticipated in most patients.

Adenoidectomy↗
PubMed2002

Comparing calibration methods of electron beams using plane-parallel chambers with absorbed-dose to water based protocols.

Recent absorbed-dose-based protocols allow for two methods of calibrating electron beams using plane-parallel chambers, one using the N(Co)D,w for a plane-parallel chamber, and the other relying on cross-calibration of the plane-parallel chamber in a high-energy electron beam against a cylindrical chamber which has an N(Co)D,w factor. The second method is recommended as it avoids problems associated with the Pwall correction factors at 60Co for plane-parallel chambers which are used in the determination of the beam quality conversion factors. In this article we investigate the consistency of these two methods for the PTW Roos, Scanditronics NACP02, and PTW Markus chambers. We processed our data using both the AAPM TG-51 and the IAEA TRS-398 protocols. Wall correction factors in 60Co beams and absorbed-dose beam quality conversion factors for 20 MeV electrons were derived for these chambers by cross-calibration against a cylindrical ionization chamber. Systematic differences of up to 1.6% were found between our values of Pwall and those from the Monte Carlo calculations underlying AAPM TG-51, and up to 0.6% when comparing with the IAEA TRS-398 protocol. The differences in Pwall translate directly into differences in the beam quality conversion factors in the respective protocols. The relatively large spread in the experimental data of Pwall, and consequently the absorbed-dose beam quality conversion factor, confirms the importance of the cross-calibration technique when using plane-parallel chambers for calibrating clinical electron beams. We confirmed that for well-guarded plane-parallel chambers, the fluence perturbation correction factor at d(max) is not significantly different from the value at d(ref). For the PTW Markus chamber the variation in the latter factor is consistent with published fits relating it to average energy at depth.

Calibration↗
PubMed2000

Cowpox infection: not yet consigned to history.

Two patients presented with hard black eschars covering granulating ulcers. The ulcers healed within 6 weeks to leave small scars. The diagnosis of cowpox was confirmed by serology in both cases and in addition by polymerase chain reaction in the first. The source of infection was likely to be a rodent in the first case whilst the second was more typical in being transmitted by a cat.

Adult↗
PubMed2000

Phenytoin induced rhinophyma treated by excision and full thickness skin grafting.

A 49-year-old man suffering from post-traumatic epilepsy presented with a severe rhinophyma probably induced by phenytoin. Initial surgical shaving was soon followed by recurrence, formation of intraepidermal cysts and persistent infection. Ultimate treatment by full thickness excision and a full thickness skin graft resulted in a pleasing cosmetic result. Radical excision of the affected skin followed by full thickness skin graft nasal reconstruction should be considered for cases of recurrent severe rhinophyma with inclusion cysts to eradicate chronic infection and improve cosmesis.

Anticonvulsants↗