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Biomedical subjects

S Walker

Publications and source records attributed to S Walker.

At least 73 records · Page 4Linked to original sources
PubMed2000

Underreporting of energy intake in four populations of African origin.

OBJECTIVE: To investigate the frequency of dietary underreporting in four African populations in different geographic and cultural settings. SUBJECTS: Seven-hundred and forty three men and women from rural Cameroon, 1042 men and women from urban Cameroon, 857 men and women from Jamaica and 243 male and female African Caribbeans from the UK. Subjects who reported dieting or weight control were excluded. MEASUREMENTS: Habitual dietary intake was estimated with a quantitative food frequency questionnaire, developed specifically for each country. Underreporting was defined using three cut-off levels for energy intake/estimated basic metabolic rate (EI/BMRest), based on age, sex and weight, in each site. RESULTS: The EI/BMRest was highest in rural Cameroonian men at 3.07 (95% confidence interval: 2.97, 3.17) and women at 2.84 (2.74, 2.94), intermediate in urban Cameroon and Jamaica and lowest in the UK men and women at 1.44 (1.26, 1.62) and 1.41 (1.21, 1.61). This trend existed even after adjustment for age, BMI and education (P for trend<0.0001). The trend in the frequency of underreporting using the lowest cut-off level for EI/BMRest of 1.15 was 6% and 6% in rural Cameroon for women and men, respectively, 4% and 5% in urban Cameroon, 24% and 19% in Jamaica and 28% and 39% in the UK. With higher cut off levels this trend was similar. CONCLUSION: The results suggest that the frequency of dietary underreporting differs between societies and that Westernization may be one of the factors underlying this phenomenon.

Adult↗
PubMed2000

Feasibility of using dynamic contrast-enhanced magnetic resonance angiography as the sole imaging modality prior to endovascular repair of abdominal aortic aneurysms.

OBJECTIVES: to establish the feasibility of using magnetic resonance imaging (MRI) with dynamic contrast-enhanced (DCE) MRA as the sole imaging modality in the assessment of patients prior to endovascular repair of abdominal aortic aneurysms (AAAs). DESIGN: DCE MRA with MRI and helical computed tomography (CT) examinations were performed in patients being assessed for suitability for an endovascular approach to repair of their AAA. Management outcomes determined by the two techniques were compared. MATERIALS: sixteen patients with AAA. METHODS: all subjects underwent DCE MRA/MRI and helical CTA. Criteria for suitability for endovascular repair were established. The management outcomes determined by the MRI findings were compared with those obtained by CTA. RESULTS: high-quality MRA/MRI and CT images were obtained in 16 patients. Six patients were considered suitable for an endovascular approach, one was considered borderline and nine were judged unsuitable. In all cases, the overall management determined by the two methods concurred. CONCLUSIONS: comparison of the two imaging modalities resulted in agreement as to suitability for an endovascular approach. We therefore conclude that in our group the use of MRI and DCE-MRA proved effective as a sole imaging modality for the assessment of these patients.

Aged↗
PubMed2000

Does the mechanism of action of biatrial pacing for atrial fibrillation involve changes in cardiac haemodynamics? Assessment by Doppler echocardiography and natriuretic peptide measurements.

AIMS: The antifibrillatory mechanism of biatrial (BI) pacing has not been fully elucidated. We investigated the role of a haemodynamic mechanism in eight patients implanted with a BI pacemaker (Chorus RM) by comparing changes in mitral Doppler flow and atrial and B-type natriuretic peptide levels (ANP, BNP) with BI pacing compared with sinus rhythm and right atrial (RA) pacing. METHODS AND RESULTS: Measurements were taken after 60 min in the supine position in each of two pairs of randomized pacing modes: (a) AAI40 beats x min(-1), (allows sinus rhythm mean rate 56 beats x min(-1), SR) vs AAI 40 beats x min(-1) with synchronized left atrial pacing (SRSync); (b) overdrive AAI RA pacing (89 beats x min(-1) (n = 6) or 70 beats x min(-1) (n = 2)) vs overdrive AAI BI pacing. Within each pair there was significant earlier activation of the left atrial Doppler signal in relation to the surface ECG P wave with BI pacing (SR 163 +/- 10 ms vs SRSync 144 +/- 21 ms (P = 0.02), and RA 232 +/- 14 ms vs BI 196 +/- 16 ms (P = 0.001)), and significant shortening of the P-R interval (SR 163 +/- 29 ms vs SRSync 148 +/- 20 (P = 0.007) and RA 261 +/- 27 ms vs BI 232 +/- 23 (P = 0.001)). The net observed effect was of no change in the atrioventricular timing sequence (delay of peak E or A to QRS/ mitral valve closure) and no change in other Doppler echo parameters. Levels of the cardiac peptides ANP and BNP were raised compared with healthy controls, but did not significantly change during the study. CONCLUSION: Acute BI pacing shortens the P-R interval and causes earlier left atrial contraction in relation to the surface electrocardiogram P wave. It does not alter the atrioventricular timing cycle, any other Doppler measurements or change cardiac peptide levels. This suggests that BI pacing does not cause haemodynamic changes that could account for any antifibrillatory properties.

Aged↗
PubMed2000

A comparison between passive and active fixation leads in the coronary sinus for biatrial pacing: initial experience.

AIMS: It has been reported that biatrial pacing can prevent the recurrence of atrial fibrillation. This technique requires a stable coronary sinus (CS) lead position for left atrial pacing. We report our experience of CS pacing with a specifically designed lead [Medtronic 2188 (n= 19)] and active fixation leads [Pacesetter Tendril (n=3), Medtronic Capsurefix (n=6)] in 21 patients with paroxysmal atrial fibrillation and a normal mean left atrial size of 39 mm (range 33-54 mm). METHODS AND RESULTS: Using the Medtronic 2188 lead, successful initial CS canulation and lead positioning was achieved in all 19 patients. One patient developed subclavian vein thrombosis 3 months after initial implant. Eight patients (42%) experienced subsequent lead displacement (12 displacements in total). Of these, seven had their lead replaced with active fixation leads. In addition, two patients underwent active fixation lead implantation at first implant. CS canulation and lead positioning was successful in all nine patients. No patient suffered displacement of an active fixation lead. There were no complications in this group. Twelve of the 19 (66%) Medtronic 2188 leads were functioning at long-term follow-up (11 +/- 4 months) with a biatrial pacing threshold of 2.4 +/- 1 V. Eight of the nine (89%) active fixation leads were functioning at long-term follow-up (6 +/- 3 months) with a biatrial pacing threshold of 2.9 +/- 1.1 V. Using a combined approach 95% of patients had a functioning CS lead at long-term follow-up. CONCLUSION: Active fixation leads can safely be used for left atrial pacing via the CS with good long-term pacing thresholds and stability.

Aged↗
PubMed2000

Initial United Kingdom experience with the use of permanent, biventricular pacemakers: implantation procedure and technical considerations.

AIMS: To describe the institution of a biventricular pacing programme with particular reference to the implantation procedure and new technological considerations. METHODS AND RESULTS: Analysis of outcomes of a consecutive series of 54 patients undergoing attempted biventricular pacemaker implantation between February 1998 and April 1999. Successful implantation was achieved in 49 of the 54 patients (91%). Five patients required lead repositioning after initial successful implantation. Left ventricular lead pacing thresholds were found to be satisfactory and stable in the long term, with pacing thresholds of 1.3 V, 1.9 V and 1.6 V at implantation, 1 and 3 months, respectively. Left-sided lead function was not dependent on lead position within the tributaries of the coronary sinus. The implantation procedure was found to be safe, although one patient died during long-term follow-up. CONCLUSION: With appropriate previous experience in complex and coronary sinus pacing and with access to up-to-date pacemaker and lead technology, a biventricular pacemaker implantation service can be instituted with good medium-term results.

Adult↗
PubMed2000

Emergency medicine and "acute" general practice: comparing apples with oranges.

Emergency Departments (EDs) operate at the interface between the inpatient and ambulatory sectors of health care. Because of shared funding between the Commonwealth and States for ambulatory care, there has been intense focus on the ED patient population, and the potential to shift the locus of care for non-inpatients. One of the frequently cited models for the provision of after-hours GP services is the Balmain General Practice Casualty (GPC). This paper analyses the GPC model, looking in detail at casemix, clinical quality, waiting times and cost-effectiveness. It is argued that the services provided and the casemix of the patient population of GPC and EDs are distinctly different. Cost-effectiveness for GPC has not been objectively established. Health service planning should recognise the distinct but complementary roles of general practice and emergency medicine. Evaluation of alternative models of service provision should critically examine the available evidence, and comparisons should be based on a precise analysis of equivalent services.

Cost-Benefit Analysis↗
PubMed2000

Information technology adoption in health care: when organisations and technology collide.

The implementation of advanced information systems is enabling great social and organisational changes. However, health care has been one of the slowest sectors to adopt and implement information technology (IT). This paper investigates why this is so, reviewing innovation diffusion theory and its application to both health organisations and information technology. Innovation diffusion theory identifies variables that influence the 'innovativeness' of organisations and the rate at which a technology diffuses. When analysed, these variables show why IT implementation has progressed at a slower rate in health compared with other industry sectors. The complexity of health organisations and their fragmented internal structure constrain their ability to adopt organisation wide IT. This is further impacted upon by the relative immaturity of strategic health IT which is complicated and unable to show quantifiable benefits. Both organisational and technological factors lead to the slow adoption of strategic IT. On the other hand, localised IT solutions and those providing measurable cost reductions have diffused well.

Diffusion of Innovation↗
PubMed2000

Reproductive decision making in mothers with HIV-1.

Eighty percent of women with human immunodeficiency virus (HIV) are of childbearing age and the incidence of HIV in women is rapidly increasing. Despite the risk of perinatal transmission and The Centers for Disease Control's (CDC) recommendation that HIV-positive women delay pregnancy, HIV-infected women continue to become pregnant and have children. To gain insight into reproductive decision-making of women with HIV, 25 mothers who participated in a natural history study of perinatal HIV transmission were interviewed using open-ended questions based on Fishbein's Theory of Reasoned Action. Three major themes emerged from the content analysis of transcripts from interviews with HIV infected women: (1) motherhood viewed as a joy and a means of meeting their own needs, (2) concerns about their children's well-being, and (3) the minor role of HIV infection in their lives. Women reported negative reactions to providers who focused exclusively on their HIV status, and not on the need to view the women's lives as a whole.

Adult↗
PubMed2000

Incidence and outcome of pauci-immune rapidly progressive glomerulonephritis in Wessex, UK: a 10-year retrospective study.

BACKGROUND: The Wessex Renal Unit serves a large stable population (2.5 million). Pauci-immune rapidly progressive glomerulonephritis (RPGN) is a frequent cause of acute renal failure requiring admission to our unit ( approximately 8%). At a population level, little is known of the epidemiology and outcome of RPGN. METHODS: Between 1 April 1986 and 31 March 1996, 141 cases of biopsy proven pauci-immune RPGN were seen in the Wessex region. The records of 128 patients were reviewed. Median (range) follow-up was 1.8 (0.9-9.64) years from diagnosis. RESULTS: The incidence of 4 per million was stable throughout the period. No clustering was seen. The diagnosis was made (median, 25th, 75th centile) 78.5 (45, 166) days after symptom onset. Co-morbidity (mostly hypertension) was seen in 47% of patients. Other organs affected were lungs 63%, nose/sinuses 50%, joints 42%, muscle 33%, skin 22% and nervous system 14%. Anti-neutrophil cytoplasmic antibody (ANCA) was positive in 73%; cytoplasmic ANCA 34%, peri-nuclear ANCA 26% and undifferentiated 14%. Twenty-seven per cent tested ANCA negative. The differences between the groups were small; time to diagnosis was shorter in the ANCA negative (-ve) group (P=0.02) and there were more airway symptoms in the ANCA positive (+ve) group (P:<0.05). All biopsies demonstrated a necrotizing process; crescents were seen in 96% involving (mean+/-SD) 54+/-26% of the glomeruli. Creatinine concentration (mean+/-SD) at diagnosis was 806+/-540 micromol/l. Treatment followed established immunosuppressive regimens. Initial dialysis was required by 59%, 36% needing long-term dialysis. At 1 year 68% were alive. The need for dialysis (P=0.0004) and age (P=0. 004) were poor prognostic markers. Ten per cent were transplanted, graft survival was 90% at 1 year, no recurrence was seen. CONCLUSIONS: This study, looking at a large cohort, has established the incidence and outcome of ANCA +ve and ANCA -ve RPGN in a defined stable population. It stresses the similarities between ANCA +ve and ANCA -ve cases and supports the notion that pauci-immune RPGN is part of a continuum of vasculitic illness. In this series transplantation is a safe option.

Age Distribution↗
PubMed2000

An observer-blinded comparison of supervised and unsupervised aerobic exercise regimens in fibromyalgia.

OBJECTIVE: To compare a supervised 12-week aerobic exercise class with unsupervised home aerobic exercises in the treatment of patients with fibromyalgia. METHODS: This was a 48-week randomized single (observer) blind study in a teaching hospital rheumatology and physiotherapy department. The subjects were 74 patients who fulfilled the American College of Rheumatology criteria for fibromyalgia. Results and conclusions. A 12-week exercise class programme with home exercises demonstrated no benefit over a single physiotherapy session with home exercises in the treatment of pain in patients with fibromyalgia. Neither group (nor the groups combined) showed an improvement in pain compared with baseline. There was some significant benefit in psychological well-being in the exercise class group and perhaps a slowing of functional deterioration in this group.

Exercise↗
PubMed2000

The efficacy of intrathecal morphine and clonidine in the treatment of pain after spinal cord injury.

We performed a double-blinded, randomized, controlled trial in 15 patients to determine the efficacy of intrathecal morphine or clonidine, alone or combined, in the treatment of neuropathic pain after spinal cord injury. The combination of morphine and clonidine produced significantly more pain relief than placebo 4 h after administration; either morphine or clonidine alone did not produce as much pain relief. In addition, lumbar and cervical cerebrospinal fluid (CSF) concentrations, sampled at these levels at different times after administration were examined for a relationship between pain relief and CSF drug concentration. Lumbar CSF drug concentrations were initially several orders of magnitude larger than those in cervical CSF. After 1-2 h, the concentrations of morphine in cervical CSF markedly exceeded those of clonidine. The concentration of morphine in the cervical CSF and the degree of pain relief correlated significantly. We conclude that intrathecal administration of a mixture of clonidine and morphine is more effective than either drug administered alone and is related to the CSF-borne drug concentration above the level of spinal cord injury. If there is pathology that may restrict CSF flow, consideration should be given to intrathecal administration above the level of spinal cord damage to provide an adequate drug concentration in this region.

Adult↗
PubMed2000

Outcome and follow-up study of an adolescent psychiatric day treatment school program.

OBJECTIVES: To evaluate outcome and follow-up of 55 subjects who attended a classroom-based, adolescent psychiatric day treatment unit school program (ADTU) situated in a community high school by examining pre-post changes in emotional, behavioral, family, and academic functioning and to identify preadmission and family variables associated with outcome. METHOD: Student-patients were assessed on clinical/academic variables at admission, discharge, and follow-up, using standardized assessment measures. Patient satisfaction was also evaluated. RESULTS: Significant improvements in emotional-behavioral and academic functioning were found at discharge and follow-up. Hierarchical regression analysis revealed that parent and clinician ratings at admission, total number of separations from family greater than 3 months, parental history of mental illness, and patient history of treatment for emotional problems were significantly associated with outcome. Satisfaction questionnaires revealed a high degree of satisfaction with the program. CONCLUSIONS: The ADTU is a successful treatment program for adolescents with chronic, severe emotional and behavioral disorders, despite limitations of the study.

Adolescent↗
PubMed2000

The 1.9 A crystal structure of Escherichia coli MurG, a membrane-associated glycosyltransferase involved in peptidoglycan biosynthesis.

The 1.9 A X-ray structure of a membrane-associated glycosyltransferase involved in peptidoglycan biosynthesis is reported. This enzyme, MurG, contains two alpha/beta open sheet domains separated by a deep cleft. Structural analysis suggests that the C-terminal domain contains the UDP-GlcNAc binding site while the N-terminal domain contains the acceptor binding site and likely membrane association site. Combined with sequence data from other MurG homologs, this structure provides insight into the residues that are important in substrate binding and catalysis. We have also noted that a conserved region found in many UDP-sugar transferases maps to a beta/alpha/beta/alpha supersecondary structural motif in the donor binding region of MurG, an observation that may be helpful in glycosyltransferase structure prediction. The identification of a conserved structural motif involved in donor binding in different UDP-sugar transferases also suggests that it may be possible to identify--and perhaps alter--the residues that help determine donor specificity.

Amino Acid Sequence↗
PubMed2000

Dissection of the coronary sinus secondary to pacemaker lead manipulation.

We report a 64-year-old man with atrial fibrillation and impaired left ventricular function in whom pacemaker lead manipulation during biatrial pacemaker lead removal and biventricular pacemaker lead insertion caused coronary sinus dissection. After further manipulation of the biventricular pacing lead, the true lumen of the coronary sinus could be entered and satisfactory left ventricular pacing undertaken. The dissection was managed conservatively without long-term sequelae.

Aortic Dissection↗
PubMed2000

Initial results with left ventricular pacemaker lead implantation using a preformed "peel-away" guiding sheath and "side-wire" left ventricular pacing lead.

We report our preliminary experience with the use of preformed "peel-away" guiding sheaths and "side-wire" pacing leads for permanent biventricular pacemaker insertion in 13 patients with heart failure. Three of these patients were undergoing an upgrade of a preexistent VVIR pacing system after prior His ablation for medically refractory atrial fibrillation. Six of the patients had undergone attempted biventricular pacemaker insertion, but required left ventricular lead repositioning after total implantation failure or late displacement of the lead. The remaining patients were undergoing new system implantation. Target vessel cannulation was achieved in all patients. However, in one patient, diaphragmatic pacing throughout the target vessel length prevented successful implantation. All other implants were ultimately successful (92% success rate). We conclude that device implantation using a preformed sheath and side-wire pacing lead is feasible and may offer significant benefits over implantation with currently available technology.

Adult↗
PubMed2000

Preliminary results with the simultaneous use of implantable cardioverter defibrillators and permanent biventricular pacemakers: implications for device interaction and development.

We report our preliminary experience with the combined use of implantable cardioverter defibrillators (ICD) and biventricular pacemakers in six patients with heart failure and malignant ventricular arrhythmia. Two patients underwent ICD implantation for malignant ventricular arrhythmia after previous biventricular pacemaker implantation. One patient underwent biventricular pacemaker insertion for NYHA Class III heart failure after previous ICD implantation. Two patients underwent single device implantation. In the sixth patient, a combined implantation failed due to an inability to obtain a satisfactory left ventricular pacemaker lead position. The potential for device interaction was explored during implantation. In two patients a potentially serious interaction was discovered. Subsequent alterations in device configuration and programming prevented these interactions with long-term use. No complication of combined device use has been demonstrated during a mean follow-up of 2 months (range 1-4 months). Satisfactory ICD and pacemaker function has also been demonstrated. We conclude that combined device implantation may be feasible with currently available pacing technology and that further prospective studies are required in this area.

Adult↗
PubMed2000

Localisation of a gene for prepubertal periodontitis to chromosome 11q14 and identification of a cathepsin C gene mutation.

Prepubertal periodontitis (PPP) is a rare and rapidly progressive disease of young children that results in destruction of the periodontal support of the primary dentition. The condition may occur as part of a recognised syndrome or may occur as an isolated finding. Both autosomal dominant and recessive forms of Mendelian transmission have been reported for PPP. We report a consanguineous Jordanian family with four members affected by PPP in two nuclear sibships. The parents of the affected subjects are first cousins. We have localised a gene of major effect for PPP in this kindred (Zmax=3.55 for D11S901 at theta=0.00) to a 14 cM genetic interval on chromosome 11q14 flanked by D11S916 and D11S1367. This PPP candidate interval overlaps the region of chromosome 11q14 that contains the cathepsin C gene responsible for Papillon-Lefèvre and Haim-Munk syndromes. Sequence analysis of the cathepsin C gene from PPP affected subjects from this Jordanian family indicated that all were homozygous for a missense mutation (1040A-->G) that changes a tyrosine to a cysteine. All four parents were heterozygous carriers of this Tyr347Cys cathepsin C mutation. None of the family members who were heterozygous carriers for this mutation showed any clinical findings of PPP. None of the 50 controls tested were found to have this Tyr347Cys mutation. This is the first reported gene mutation for non-syndromic periodontitis and shows that non-syndromic PPP is an allelic variant of the type IV palmoplantar ectodermal dysplasias.

Aggressive Periodontitis↗