Biomedical subjects
R J Hall
Publications and source records attributed to R J Hall.
Teaching cardiology auscultation. A wireless FM broadcast system.
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The effect of nisin concentration and nutrient depletion on nisin production of Lactococcus lactis.
The kinetics of nisin production was studied in batch cultures using a construct of Lactococcus lactis subsp. lactis C2SmPrt-, containing a transposon (TnNip) that encodes nisin production. The introduction of TnNip into C2SmPrt- significantly lowered the specific growth rate and the maximum A620 reached was reduced from 15.2 to 11.0. The effect of nisin concentration and nutrient depletion on nisin production of the construct, C2SmPrt-(TnNip), was examined. Nisin production was found to be inhibited by high concentrations of nisin, when grown in excess nutrient, even though growth of the culture continued because nutrient limitation was not operating. However, in low nutrient concentrations nisin production was limited by nutrient depletion. The specific growth rate of C2SmPrt-(TnNip) was altered, by using different nutrient concentrations and different sugars, in order to examine the relationship between nisin production and growth. Nisin production was shown to be growth-associated for most of growth, but near the end of growth, when the specific growth rate was 0.05 h-1 or less, the production ceased.
Characterization of a class II pilin expression locus from Neisseria meningitidis: evidence for increased diversity among pilin genes in pathogenic Neisseria species.
Strains of Neisseria meningitidis elaborate one of two classes of pili. Meningococcal class I pili have many features in common with pili produced by N. gonorrhoeae, including the ability to bind monoclonal antibody SM1 and a common gene and protein structure consisting of conserved, semivariable, and hypervariable regions. Class II pili are SM1 nonreactive and display smaller subunit molecular weights than do gonococcal or meningococcal class I pili. In this study, we have determined the N-terminal amino acid sequence for class II pilin and isolated the expression locus encoding class II pilin from N. meningitidis FAM18. Meningococcal class II pilin displays features typical of type IV pili and shares extensive amino acid identity with the N-terminal conserved regions of other neisserial pilin proteins. However, the deduced class II pilin sequence displays several unique features compared with previously reported meningococcal class I and gonococcal pilin sequences. Class II pilin lacks several conserved peptide regions found within the semivariable and hypervariable regions of other neisserial pilins and displays a large deletion in a hypervariable region of the protein believed to be exposed on the pilus face in gonococcal pili. DNA sequence comparisons within all three regions of the coding sequence also suggest that the meningococcal class II pilin gene is the most dissimilar of the three types of neisserial pilE loci. Additionally, the class II locus fails to display flanking-sequence homology to class I and gonococcal genes and lacks a downstream Sma/Cla repeat sequence, a feature present in all other neisserial pilin genes examined to date. These data indicate meningococcal class II pili represent a structurally distinct class of pili and suggest that relationships among pilin genes in pathogenic Neisseria do not necessarily follow species boundaries.
An unusual midfoot dislocation: a case report.
An unusual case of dislocation of the midfoot through the calcaneocuboid and naviculocuneiform joints is presented. The prognosis is excellent for most midfoot dislocations, as long as they are recognized and treated early.
Risk factor analysis among Egyptian patients who underwent coronary artery bypass surgery.
We conducted a retrospective review of Egyptian patients who underwent coronary artery bypass graft surgery at our institution between 1980 and 1995. We examined the prevalence of coronary artery disease risk factors and evaluated the early postoperative results. We then compared these results with the corresponding data in a subset of American patients who underwent coronary artery bypass grafting at our institution in 1993. There were 290 Egyptian patients: 275 men and 15 women. The mean age was 54.5 years (range, 30 to 70 years). Angina was present in 258 (89%) of the Egyptian patients; of these, 186 (72.1%) were in Canadian Cardiovascular Society class 3 or 4. Risk factor analysis revealed a high prevalence of hyperlipidemia (69.7%), cigarette-smoking (66.6%), family history of coronary artery disease (53.1%), hypertension (46.9%), obesity (46.2%), and diabetes mellitus (32.4%). Comparisons between the 2 groups showed that the risk factors, except for hypertension, were significantly higher in the Egyptian patients, despite the older age of the Americans (mean, 65.5 years; range, 22 to 88 years). The prevalence of triple-vessel disease was 86.6% in the Egyptian patients and 51.0% in the American patients (p < 0.001). The operative morbidity rates in the Egyptian patients were low: these included arrhythmias (13.8%), bleeding (13.4%), infection (7.6%), low cardiac output (3.4%), myocardial infarction (3.4%), and cerebrovascular accident (1.4%). The hospital mortality rate was 1.4% for the Egyptians and 1.7% for the Americans (NS). These results show that, despite the high prevalence of risk factors among Egyptian patients with coronary artery disease, coronary artery bypass grafting can be performed with low operative morbidity and mortality rates.
Coronary artery ectasia in Egyptian patients with coronary artery disease.
We conducted a retrospective study of 45 Egyptian patients with coronary artery ectasia who underwent coronary bypass grafting at our institution between 1980 and 1995. We examined the anatomic distribution and type of coronary ectasia and its association with coronary risk factors in these patients, and evaluated the severity of their coronary artery disease. We compared these findings with those from a group of 230 Egyptian patients who did not have coronary ectasia. These patients also underwent coronary artery bypass grafting between 1980 and 1995 at our institution. Obesity was present in 60% of the patients who had coronary artery ectasia, compared with 42% of patients who did not have ectasia (P < 0.01). Coronary artery ectasia was not related to any coronary risk factors other than obesity. However, patients who had ectasia did have a higher rate of triple-vessel coronary artery disease than did patients without ectasia (82% vs 67%, P < 0.05). Of the coronary vessels affected by ectasia, 43% were left anterior descending arteries. Diffuse disease was noted in 84% of all ectatic segments. We conclude that in this patient population, 2 conditions had a positive correlation with coronary ectasia: obesity and the severity of coronary artery disease.
Closed removal of a segmental intramedullary rod: a technical report.
This report describes a technique for removal of a segmental broken intramedullary femoral rod. Using a closed, stacked wire technique, removal of the broken hardware can be accomplished in a relatively easy and expeditious manner.
Guidelines for clinical use of cardiac radionuclide imaging. A report of the American Heart Association/American College of Cardiology Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures, Committee on Radionuclide Imaging, developed in collaboration with the American Society of Nuclear Cardiology.
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Can an echocardiographic score predict who will benefit clinically from balloon dilation of the mitral valve?
Deciding whether a patient with sub-optimal mitral valve anatomy will benefit from percutaneous mitral valvotomy remains a demanding clinical problem. We assessed the ability of an established echo score applied to transoesophageal images to predict absolute increases in mitral valve area and improvement in exercise capacity. Twenty five consecutive patients undergoing routine percutaneous mitral valvotomy were studied. Changes in exercise tolerance were measured by serial cardiorespiratory treadmill exercise testing. Before the procedure, exercise duration was directly related to mitral valve area (rs = 0.44, P < 0.05). Following percutaneous mitral valvotomy there was an increase in valve area (0.9 +/- 0.2 to 1.4 +/- 0.3 cm2, P < 0.0001) and repeat exercise testing demonstrated increases in exercise duration (470 +/- 220 to 610 +/- 240 s, P < 0.001) and peak VO2 (12.6 +/- 4.2 to 15.1 +/- 4.5 ml/kg/min, P < 0.01). There was an inverse correlation between the echo score and the increase in valve area (rs = -0.52, P < 0.05) but no relationship between the echo score and the increase in exercise duration or peak minute oxygen consumption (VO2). These data demonstrate that a score applied to transoesophageal images echocardiographic images can predict changes in mitral valve area but that the score fails to predict functional improvement for an individual patient. This suggests, therefore, that patients without contraindications to valvotomy whose valves have a high echo score should still be considered for valvotomy as they may benefit considerably from the procedure.
Guidelines for clinical use of cardiac radionuclide imaging. Report of the American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Committee on Radionuclide Imaging), developed in collaboration with the American Society of Nuclear Cardiology.
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Comparison of Nottingham Health Profile (NHP) scores with exercise duration and measures of ischaemia during treadmill exercise testing in patients with coronary artery disease.
A cross-sectional study of patients with stable coronary artery disease was performed to compare perceived health status with the results of a treadmill exercise test. One hundred and twenty one patients, mean age 55.07 years, 106 male, who had all suffered a myocardial infarction under the age of 56 years, up to 9 years earlier were studied. Perceived health status was assessed using the Nottingham Health Profile, part 1 of which assesses six dimensions of normal living, and part 2 seven areas of daily life. Nottingham Health Profile scores were higher (worse perceived health status) in patients with poor treadmill exercise capacity within all dimensions of part 1 (energy, pain, physical mobility P < 0.001, emotional reactions, sleep P < 0.01, social isolation P < 0.05) and most of those within part 2 (care of home, taking holidays P < 0.001, hobbies P < 0.01, relationships at home, sex life P < 0.05). The perceived health status of patients without a history of angina is significantly better than those with angina (pain, physical mobility P < 0.001, energy, emotional reactions, social isolation P < 0.01, sleep P < 0.05, within part 1, taking holidays P < 0.01, care of the home, social life, sex life, hobbies P < 0.05, within part 2). Thus, patients with a poor perceived health status, also have poorer results using more conventional clinical measures of coronary artery disease. The Nottingham Health Profile may be a useful adjunct in patient assessment.
Training in cardiology: the future.
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Exercise ventilation after balloon dilatation of the mitral valve.
BACKGROUND: Exertional dyspnoea is a limiting symptom in many patients with mitral stenosis but its causes remain incompletely understood. Ventilation during exercise is abnormal in chronic heart failure of all causes and there is increased ventilatory cost of carbon dioxide production. PATIENTS: 23 patients with rheumatic mitral stenosis undergoing percutaneous balloon dilatation of the mitral valve were studied to investigate exercise ventilation. METHODS: Treadmill exercise tests with respiratory gas analysis were performed before and 1 day, 7 days, and 10 weeks after balloon dilatation of the mitral valve. The relation between ventilation (VE) and production (VCO2) was analysed by linear regression. RESULTS: The VE/VCO2 slope was linear in all patients and before balloon dilatation of the mitral valve it correlated inversely with peak minute oxygen consumption (VO2) (rs = -0.47, P < 0.05), exercise duration (rs = -0.66, P < 0.01), and mitral valve area (rs = -0.5, P < 0.05). The VE/VCO2 slope declined acutely after balloon dilatation of the mitral valve (n = 10) (mean (SD) 41 (4) v 36 (2.9), P < 0.05) and did not change again thereafter. At 10 weeks (n = 23) exercise duration (460 (230) v 630 (240) s, P < 0.01) and peak VO2 (12.7 (4.3) v 14.9 (4.8) ml/kg/min, P < 0.05) increased significantly. CONCLUSIONS: Patients with rheumatic mitral stenosis have a similar increase in the VE/VCO2 slope to that of patients with heart failure from other causes. Successful balloon dilatation of the mitral valve is associated with an acute reduction in the exercise VE/VCO2 slope.
Prospective study of patients aged 55 years or less with acute myocardial infarction between 1981 and 1985: outcome 7 years and beyond.
OBJECTIVE: To determine the long-term prognosis of patients after a myocardial infarction (MI) at a young age. DESIGN: Prospective cohort study of patients aged 55 years or less suffering a myocardial infarction. SETTING: A single coronary care unit admitting patients from the community. PATIENTS: 255 consecutive patients (210 men) aged 55 years or less admitted between 1981 and 1985 after acute MI. Twenty four patients died in hospital or within 3 months of infarction and 11 were lost to further follow up after discharge. Of the remaining patients, 150 (mean (SD) age 48 (5.7) years) able to exercise 3 weeks after infarction and who agreed to undergo coronary angiography were recruited to a study group and seen 18 months, and 3, 5, and 7 years after MI. In addition, a cross sectional analysis of survival was made to a median of 120 months. Seventy 3 month survivors (mean (SD) age 48 (5.8) years) were not recruited to the study group but were traced for late survival through their general practitioners and family health service associations to a median of 130 months. MAIN OUTCOME MEASURES: Survival in young patients after MI and the survival of 3 month survivors stratified by their ability to exercise and agreement to undergo angiography. The rate of coronary artery surgery (CAGB) and reinfarction during the first 7 years after index MI in patients recruited to the study group. RESULTS: Sixteen patients (6%) died in hospital and eight (3%) within 3 months of the index infarction. The 7 and 11 year survival rates in the whole cohort of 255 patients were 80% and 66% respectively using life table methods. Survival 7 years after MI, in patients recruited to the study group was better than in those not recruited (93% v 79%, P = 0.001), but thereafter mortality in the study group accelerated and there was no significant difference in survival 11 years after infarction (76% v 67%, P = 0.05). There was a trend towards higher mortality in patients with multivessel disease and severely impaired left ventricular function. During the first 7 years after MI, 38 of 150 patients in the study group underwent CABG and 19 suffered reinfarction, which was fatal in three. CONCLUSION: The medium-term prognosis of young survivors of MI is good, particularly in patients recruited to the study group. After 7 years there is an increase in mortality and the long-term prognosis is less favourable. This should be taken into account when planning future management and follow up of young patients after MI.
Severe coronary vasospasm associated with hyperthyroidism causing myocardial infarction.
A 48 year old woman presented with angina after an anterior myocardial infarction and was found to be hyperthyroid. Coronary angiography showed a stenosis of the left coronary os and a long, severe stenosis of the left anterior descending artery which was partially relieved by glyceryl trinitrate. Three months later, after radioactive iodine treatment had rendered her euthyroid, repeat coronary angiography showed entirely normal coronary arteries. This unusual case establishes an association between hyperthyroidism and coronary vasospasm resulting in myocardial infarction.
Assessment of intracardiac masses by transesophageal echocardiography.
Transesophageal echocardiography and 2-dimensional transthoracic echocardiography have proved to be extremely valuable in the diagnosis of cardiac masses. In this report, we review the echocardiographic findings, clinical history, and histopathologic findings in 21 patients with intracardiac masses who underwent transthoracic echocardiography, transesophageal echocardiography, or both, at our institution. Of these patients, 14 had benign masses and 7 had malignant tumors. The potential role of transesophageal echocardiography in the diagnosis and treatment of patients with intracardiac masses is discussed. We believe that transesophageal echocardiography offers the cardiologist and cardiovascular surgeon the capability of more accurate preoperative and intraoperative assessment of cardiac masses.
Stress fracture of the acromion: an unusual mechanism and review of the literature.
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