Biomedical subjects
Publications and source records attributed to R M Oliver.
The assessment of patients with chest pain is challenging for any emergency physician because of the spectrum of illness covered by this symptom. Patients may have a serious life-threatening condition or a trivial self-limiting illness. This article presents an approach to the assessment and early management of patients presenting with acute non-traumatic chest pain in the emergency department.
OBJECTIVE: Abnormal right ventricular function in patients with pulmonary heart disease (PHD) may contribute to their reduced exercise capacity. We have evaluated the effect of subacute dosing with xamoterol, a beta-1 adrenoreceptor partial agonist with inotropic properties, on right ventricular function in patients with PHD. PATIENTS: Twelve patients with advanced chronic obstructive pulmonary disease and clinical evidence of PHD received xamoterol 200 mg twice daily or placebo for 7 days in a randomised double-blind crossover study. Right heart krypton-81m radionuclide ventriculography was used to derive right ventricular ejection fraction (RVEF) both at rest and during submaximal exercise, and indices of right ventricular systolic and diastolic function at rest. RESULTS: During treatment with placebo, mean RVEF was 0.53 at rest and was unchanged during exercise. After xamoterol, mean RVEF was 0.55 at rest and increased to 0.59 during exercise. Xamoterol increased right ventricular peak ejection rate from 3.04 to 3.45 EDV.s-1 and mean early diastolic filling rate from 1.00 to 1.20 EDV.s-1. CONCLUSION: Subacute treatment with xamoterol in patients with PHD improves right ventricular systolic and diastolic function at rest and results in a favourable augmentation in right ventricular function during submaximal exercise.
OBJECTIVE: To identify features associated with success or failure of aspiration of pericardial effusion. METHOD: A retrospective analysis of 36 drainage procedures in 30 patients with pericardial effusion was performed using patient records and echocardiograms. RESULTS: Unsuccessful aspiration was associated with pericardial loculation but not with the seniority of the operator or the size and position of the effusion. Pericardiocentesis relieved symptoms of breathlessness in 21 of 26 patients who had a pericardial effusion suspected of causing dyspnoea. These 21 patients had few clinical or echocardiographic signs of classic tamponade. CONCLUSION: The paucity of abnormal physical or echocardiographic signs of tamponade in breathless patients with pericardial effusion does not exclude symptomatic benefit being derived from pericardiocentesis. Pericardial aspiration is safe in appropriate hands, although aspiration of loculated effusions may not be as successful as aspiration of non-loculated effusions.
Krypton-81m equilibrium ventriculography was used to study right ventricular function in 23 healthy male volunteers. Technetium-99m lung perfusion scintigraphy was employed to subtract radionuclide activity within lung during image analysis thereby enhancing image quality. The imaging technique was used to generate a time-activity curve for the right ventricle allowing the definition of indices of normal systolic and diastolic function for the right ventricle. At rest, indices of systolic ejection and diastolic filling were comparable to those previously reported for the left ventricle. Using the imaging technique, movement artifact during exercise reduces image quality and limits accurate measurement of these indices to resting studies.
OBJECTIVES: To measure the association between spermicide use and HIV infection, adjusting for condom use, and to measure the association between condom use and HIV infection, adjusting for spermicide use. DESIGN: Prospective study of women using nonoxynol-9 (N-9) spermicides and latex condoms, with up to 12 monthly clinic visits for interviews, examinations and tests, and re-supply. METHODS: A total of 273 HIV-negative women with multiple sexual partners were enrolled, given latex condoms and N-9 vaginal spermicidal suppositories, and advised to use both every time they had sexual intercourse. Participants recorded data on sexual activity on pictorial coital logs. New HIV infections were detected and confirmed by quarterly enzyme-linked immunosorbent assays and Western blots, respectively. RESULTS: Nineteen HIV infections occurred during mean follow-up of 8.1 months (an incidence rate of 10.4 infections per 100 women-years). The adjusted HIV rate ratio (RR) was 0.1 [95% confidence interval (CI), 0.1-0.6] for more consistent compared with less consistent spermicide users; and 1.1 (95% CI, 0.4-2.9) for more consistent compared with less consistent condom users. Among the subgroup of experienced condom users, the RR for more versus less consistent condom use was 0.3. CONCLUSIONS: This is the first epidemiological evidence that N-9 spermicides can reduce the incidence of HIV infection. A more definitive randomized clinical trial is urgently needed.
81Krm equilibrium ventriculography was used to study right ventricular function in 37 healthy male volunteers. 'Anatomical' lung subtraction using 99Tcm lung perfusion scintigraphy was compared with conventional background correction in the calculation of resting right ventricular ejection fraction (RVEF). Resting RVEF was significantly greater following 'anatomical' lung subtraction than that using background correction (0.59 +/- 0.06 versus 0.55 +/- 0.05). The exercise response of the normal right ventricle was defined in 23 subjects during exercise. Right ventricular ejection fraction showed a progressive increase during graded submaximal exercise (0.55 +/- 0.05 at rest, 0.60 +/- 0.05 at 50 W and 0.66 +/- 0.05 at 100 W). Right heart 81Krm equilibrium ventriculography is well suited to the evaluation of right ventricular function at rest and during exercise. The absolute value of RVEF will however be dependent upon the method of image analysis.
Right ventricular function was assessed in 24 patients with COPD, at rest and during submaximal exercise, using both technetium-99m (99mTc) blood-pool and krypton-81m (81mKr) equilibrium ventriculography. Technetium-99m right ventricular ejection fraction (RVEF) at rest was lower than 81mKr RVEF (0.39 +/- 0.12 and 0.54 +/- 0.08, respectively; p < 0.001). During submaximal exercise, there was no increase in RVEF using either imaging technique. This observation contrasted with an increase in RVEF in a group of age-comparable normal subjects during modest submaximal exercise. An inability to obtain spatial separation of right heart structures using 99mTc imaging leads to a value for RVEF that is consistently lower than that measured using 81mKr ventriculography. Resting RVEF is well preserved at rest in most patients with COPD. In contrast to normal subjects, many show an inability to augment right ventricular function during exercise that may contribute to the reduced exercise capacity observed in these patients.
Calculation of S factors for 81Krm for a full range of target organs from each source organ relevant in 81Krm peripheral venous infusion imaging has been performed. Typical equilibrium activities in the source organs have been measured using quantitative planar gamma camera imaging for a generator with a mean activity at imaging time of 468 MBq eluted at 10 ml min-1. Based on the above measurements and assuming a 10 min infusion period, the mean effective dose equivalent for 81Krm infusion imaging in the assessment of right heart function in adults was found to be 0.365 mSv.
Congenital left ventricular diverticula are a rare cause of sudden cardiac death. We describe the first reported case of ventricular fibrillation in association with congenital diverticula of the heart. The diagnosis of left ventricular diverticula was made by cardiac catheterization and confirmed by magnetic resonance imaging. Treatment was initiated with anti-arrhythmic and anticoagulant drugs to prevent life-threatening arrhythmias and emboli.
Explore the source record for details and available documents.
The structure of ornithine decarboxylase (Mr approximately 1.04 x 10(6] from Lactobacillus 30a was investigated by electron microscopy and x-ray crystallography. Electron micrographs showed the structure to be well preserved in methylamine tungstate stain. The molecules interacted little with the Butvar support film, yielding three unique projections: a hexagonal ring (front view) and two rod-shaped projections (edge views). Stereo pairs revealed a novel feature of the Butvar film in that some molecules were suspended in the stain in random orientations. Consequently, the relatedness of the hexagonal ring and the rod-shaped particles could be demonstrated since some particle shapes interconverted when the stage was tilted +/- 45 degrees. The two edge views were related by a 30 degrees rotation about the sixfold axis. Image averaging of the three primary views suggested a dodecamer (point group symmetry 622) composed of two hexameric rings, apparently in an eclipsed configuration. To investigate the structural organization of the complex, the dissociation of the enzyme was studied by electron microscopy. The dissociation process involved the initial breakage of the ring followed by separation of dimers from the ring (one subunit from each of the two hexamers). Thus, the dodecamer forms as a hexamer of dimers rather than a dimer of hexamers. These structural studies were confirmed and extended by x-ray crystallographic analysis. A 4.0-A resolution electron density map revealed two hexameric rings, consisting of six closely associated dimers, tilted approximately 10 degrees with respect to the molecular twofold axis. Electron density projections of the three primary views of the molecule derived from the x-ray data corresponded closely to those obtained from image averaging of the electron microscopy data, thereby establishing in a novel way the reliability of the electron microscopy studies. Methylamine tungstate stain and Butvar support film therefore offer unique advantages for investigating protein structures by electron microscopy.
Simultaneous measurements of the clearance rates of technetium 99m diethylenetriaminepentaacetic acid (99mTc-DTPA) and chronium 51 ethylenediaminetetraacetic acid (51Cr-EDTA) were performed in 30 patients with a range of renal function (glomerular filtration rates between 9 and 120 ml/min). Using multiple blood samples, the two clearance values correlated well (r = 0.991, standard error 3.9 ml/min), but DTPA clearance was systematically higher by 7.6%. For each radiopharmaceutical, an equation was derived to correct clearance values obtained using only plasma samples taken at 2 and 4 h for the systematic error inherent in this technique compared with analysis of the complete plasma concentration-time curve. The root mean square error remaining after application of these equations was 1.9 ml/min for both the EDTA and DTPA data. The corresponding errors obtained using the equation derived by Brochner-Mortensen for EDTA plasma clearance were 2.2 ml/min and 1.9 ml/min, respectively, these values were not significantly different from those obtained using the equations derived in this study.
Right ventricular ejection fraction and right ventricular volumes were derived in 12 healthy male subjects using krypton-81m equilibrium radionuclide ventriculography whilst subjects breathed 30% (high inspired oxygen) and then 8-12% oxygen in nitrogen mixture (hypoxia). 'Physiological' tricuspid valve regurgitation was identified in 7 of the subjects by Doppler echocardiography, and right ventricular peak systolic pressure was estimated during high inspired oxygen and during hypoxia. Mean right ventricular peak systolic pressure was 24.1 +/- 3.3 mmHg during high inspired oxygen and increased to 41.3 +/- 8.4 mmHg during hypoxia (P less than 0.01). Mean right ventricular ejection fraction was 0.612 +/- 0.075 during high inspired oxygen and was unchanged at 0.590 +/- 0.073 during hypoxia. There was no significant change in right ventricular end-diastolic volume or stroke volume in response to hypoxia. The systolic performance of the normal right ventricle is well-maintained during an acute rise in afterload induced by hypoxia.
Pituitary apoplexy describes the clinical syndrome characterised by headache, visual impairment and ophthalmoplegia caused by sudden enlargement of a pituitary adenoma. This is usually due to extensive tumour infarction or haemorrhage. Pituitary apoplexy is rare, mimics spontaneous intracranial bleeding, and thus may be easily mistaken for acute subarachnoid haemorrhage. Urgent surgical intervention and hormone replacement therapy are required.
Right heart 81mKr equilibrium radionuclide ventriculography was used to derive right ventricular ejection fraction (RVEF) in 12 healthy male volunteers. Anatomical lung subtraction using 99mTc-MAA perfusion scintigraphy was compared with conventional background correction and the effect of imaging projection on the techniques of image analysis evaluated. Both intra and inter observer variability were reduced by anatomical lung subtraction when compared to conventional background correction. In the right anterior oblique (RAO) projection, background corrected RVEF was lower than lung subtracted RVEF - 0.544 +/- 0.05 and 0.612 +/- 0.08 (mean +/- SD) (P less than 0.02). Lung subtracted RVEF in the anterior projection was lower than that with background correction (P less than 0.05) and lower than lung subtracted RVEF in the RAO projection (P less than 0.001). We conclude that optimal separation of right heart structures is achieved in the RAO projection and that reproducibility of the analytical technique is improved by anatomical lung subtraction.
1. The pharmacokinetics of doxazosin, following a single oral dose (1 mg) and chronic oral dosing (doubling doses up to a maximum of 16 mg day-1), were studied in 18 patients with mild to moderate hypertension and stable renal function varying from normal to severely impaired. In addition, the effect of chronic administration of doxazosin on renal haemodynamics was evaluated. 2. Significant accumulation of doxazosin occurred with chronic dosing, but comparison of dose-adjusted AUC after single and chronic dosing suggested that there was no change in clearance or bioavailability during chronic administration. 3. There was no significant relationship between plasma elimination half-life or the AUC for doxazosin and the degree of renal impairment. 4. Symptomatic postural hypotension occurred in six patients following the initial dose of 1 mg doxazosin. Systolic and diastolic blood pressure measured 24 h after the previous dose were significantly reduced during chronic administration of doxazosin by a mean of 12/6 mm Hg supine and 10/7 mm Hg on standing. 5. During chronic administration of doxazosin, there was a significant reduction of 13% in glomerular filtration rate compared with pre-treatment, but no change in effective renal plasma flow.
Splenic abscess formation is a serious condition which usually requires prompt surgical intervention. We report on a patient with Salmonella virchow septicaemia, complicated by peritonitis and multiple splenic and renal abscesses. This is an uncommon manifestation of non-typhoid salmonella infection, which was managed conservatively with oral ciprofloxacin, leading to satisfactory resolution and cure.
The pharmacokinetics of doxazosin given once daily are similar in patients both with normal and with impaired renal function and consequently doxazosin can be used effectively in both at similar doses. Renal blood flow is well preserved during long-term treatment but effects on glomerular filtration rates are less consistent and small reductions may occur. It is uncertain whether these reflect a reduction in perfusion pressure, progression of the underlying renal disease or a combination of the two. Postural hypotension may occur in some patients after an initial dose of 1 mg.