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Biomedical subjects

M O'Sullivan

Publications and source records attributed to M O'Sullivan.

At least 19 recordsLinked to original sources
PubMed1996

Survey of immunity to measles in schoolchildren in Cork.

Surveillance of measles in the Republic of Ireland has relied until now on notifications of clinically diagnosed infections and a manual system for monitoring coverage. In the light of a measles epidemic predicted in the United Kingdom in 1995, it was considered timely to review the epidemiology of measles and obtain baseline seroepidemiological data on measles immunity in Cork City in the Republic of Ireland. The age specific prevalence of measles IgG in saliva from 2000 schoolchildren aged 5 to 15 years was determined. The study also compared susceptibility rates in children with and without a history of measles vaccination or infection. Histories provided by parents were found to be unreliable in informing vaccination practice, as 79 of the 102 seronegative children would have been classified as immune. The proportion of children immune to measles, as gauged by seropositivity, was 91.9% in children aged 5 to 10 years and 95.8% in 11 to 15 year olds. The implications of the study results are discussed in relation to future prevention and control strategies.

Adolescent↗
PubMed1996

Molecular cloning, functional expression, and selective regulation of ovine prostaglandin H synthase-2.

Structural characterization for ovine prostaglandin H synthase-1 (PGHS-1) is extensive, but the corresponding structure for the homologous ovine PGHS-2 isoform is undefined. Accordingly, we isolated a full-length (3.4 kb) ovine PGHS-2 cDNA from a primary-culture cell model (ovine tracheal epithelial cells) originally described as containing both PGHS isoforms. Analysis of ovine PGHS-2 cDNA sequence indicated conservation of critical amino acid residues, but differences in other hydrophilic regions allowed for the development of an anti-peptide antibody highly selective for PGHS-2. Enzymatic activities of the recombinant ovine PGHS isozymes indicated significant differences in response to aspirin-acetylation consistent with the characteristics of endogenous cellular PGHS activities under basal and serum-induced conditions. The results fully account for previous evidence of two distinct PGHS activities in cultured airway epithelial cells and provide for additional definition of PGHS structure-function relationships.

Amino Acid Sequence↗
PubMed1996

Bifonazole, but not the structurally-related clotrimazole, induces both peroxisome proliferation and members of the cytochrome P4504A sub-family in rat liver.

Male Wistar rats were treated with a low (150 mumol/kg) and a high (750 mumol/kg) dose of either clotrimazole of bifonazole. Bifonazole, but not clotrimazole, exhibited the characteristics of a peroxisome proliferator including hepatomegaly (increase in liver:body weight ratio), up to a 4-fold induction of lauric acid omega-hydroxylase activity and an 8-fold induction of palmitoyl-CoA oxidation by rat liver peroxisomes. This induction of enzyme activities was paralleled by increased protein levels as determined by immunochemical analysis for both liver microsomal cytochrome P4504A1 and the peroxisomal trifunctional protein of the beta-oxidation spiral. In contrast, clotrimazole did not increase protein levels of either cytochrome P4504A or the trifunctional protein. Western blot analyses demonstrated that bifonazole also induced P4502B1/2B2, P4503A and P4501A1, but not P4502E1. Clotrimazole induced a similar spectrum of P450s as determined by Western blotting with the exception that this azole was a marginal P4501A1 inducer under the conditions studied. Taken collectively, our data provides evidence that bifonazole is one of the increasingly recognised, non-carboxylate containing xenobiotics that induce both peroxisome proliferation and the cytochrome P4504A sub-family in rat liver.

Administration, Oral↗
PubMed1996

The effect of posture change on the position of the skin marks for the transverse horizontal axis.

Marks are placed on facial skin in clinical dentistry to indicate the position of more deeply placed landmarks or reference points. In this study the movement of the transverse horizontal axis skin points overlying the craniomandibular articulation were observed and quantified. The time taken for the skin displacement to occur when the posture changed between upright and supine was also studied. The extent of displacement of the skin point was approximately 3 mm in the sagittal plane and 2 mm in the frontal plane when the posture was changed from upright to supine and vice versa. The displacement was complete after 30 seconds in 95% of subjects. The direction of the displacement was primarily cephalad but with a dorsal component of more than 10 degrees in 87% of subjects. The extent of the movement in the sagittal and frontal planes was correlated. There was no gender difference for the skin displacement. Awareness by clinicians of the extent and direction of such facial skin movements can help to prevent errors.

Adult↗
PubMed1996

Coronary flow reserve: noninvasive measurement in humans with breath-hold velocity-encoded cine MR imaging.

PURPOSE: To measure coronary vasodilator reserve with breath-hold velocity-encoded cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eight healthy adult volunteers underwent 1.5-T MR imaging. Velocity-encoded cine images were acquired at seven to 13 temporal phases in 25 seconds, with k-space segmentation and view-sharing reconstruction (+/- 1 m/sec velocity-encoding value) (repetition time msec/echo time msec = 16/9). Flow velocity in the left anterior descending (LAD) artery was measured twice before and twice after administration of dipyridamole (0.56 mg per kilogram of body weight). RESULTS: Peak diastolic coronary flow velocity in the LAD artery was 14.8 cm/sec +/- 1.9 (mean +/- standard deviation) in the baseline state. It increased significantly (P< .01) to 46.3 cm/sec +/- 10.2 after dipyridamole administration, with an average coronary reserve of 3.14 +/- 0.59. Interstudy and interobserver reproducibilities for measurement of peak diastolic velocity were, respectively, 9.5% +/- 1.6 and 7.0% +/- .2.5 in the baseline state and 6.8% +/- 2.2 and 3.4% +/- 1.5 after dipyridamole administration. CONCLUSION: Breath-hold velocity-encoded cine MR imaging provided reproducible assessment of coronary flow reserve in humans.

Adult↗
PubMed1995

Evaluation of mitral stenosis with velocity-encoded cine-magnetic resonance imaging.

Velocity-encoded cine-magnetic resonance imaging (VEC-MRI) is a new method for quantitation of blood flow with the potential to measure high-velocity jets across stenotic valves. The objective of this study was to evaluate the ability of VEC-MRI to measure transmitral velocity in patients with mitral stenosis. Sixteen patients with known mitral stenosis were studied. A 1.5 Tesla superconducting magnet was used to obtain velocity-encoded images in the left ventricular short-axis plane. Images were obtained throughout the cardiac cycle at 3 consecutive slices beginning proximal to the mitral coaptation point. To determine the optimal slice thickness for MRI imaging, both 10 mm and 5 mm thicknesses were used. Echocardiography including continuous-wave Doppler was performed on every patient within 2 hours of MRI imaging. Peak velocity was determined for both VEC-MRI and Doppler-echo images. Two observers independently measured the VEC-MRI mitral inflow velocities. Of the 16 patients, imaged data were incomplete in only 1 study, and all images were adequate for analysis. Strong correlations were found for measurements of mitral valve gradient for both 10 mm (peak r = 0.89, mean r = 0.84) and 5 mm (peak r = 0.82, mean r = 0.95) slice thicknesses. Measurements of peak velocity with VEC-MRI (10 mm) agreed well with Doppler: mean 1.46 m/s, mean of differences (Doppler MRI) 0.38 m/s, standard deviation of differences 0.2 m/s. These findings suggest that VEC-MRI can noninvasively determine the severity of mitral stenosis.

Adult↗
PubMed1995

Quantitative comparison of asbestos and talc bodies in an individual with mixed exposure.

Tissue from an individual with a history of exposure to asbestos and other dust was referred for particulate analysis. The digested material was reviewed by light microscopy to establish the numbers of ferruginous bodies per gram of tissue. Typical asbestos bodies were found at levels consistent with occupational exposure. A second type of elongated ferruginous body was formed on a thicker transparent core which suggested the minerals were sheet silicates. The number of ferruginous bodies with nonasbestos cores was over four times the number of asbestos cored ferruginous bodies. Electron microscopy was used to confirm the core composition of both populations and also to establish the levels of uncoated fibers. The nonasbestos ferruginous bodies were predominantly formed on talc.

Adenocarcinoma↗
PubMed1995

Comparative induction of cytochrome P4504A in rat hepatocyte culture by the peroxisome proliferators, bifonazole and clofibrate.

1. The influence of imidazole and triazole antifungal drugs on cytochrome P450 levels in male Wistar primary rat hepatocyte culture for 70 h has been investigated and compared with clofibrate. 2. Bifonazole, clotrimazole, geniconazole clofibrate induced total P450 in hepatocytes, whereas itraconazole, miconazole and UK-47,265 did not. 3. When the CYP4A subfamily was examined, only bifonazole and clofibrate induced CYP4A as assessed by both Western blot analysis and the 11- and 12-hydroxylation of lauric acid. 4. By analysis of concentration-response curves in hepatocyte culture, bifonazole was 160 and 40 times more potent than clofibrate for induction of the 11- and 12-hydroxylation of lauric acid respectively. 5. Taken collectively, our data have identified bifonazole as a relatively potent, non-carboxylate inducer of CYP4A and the mechanism of induction and specificity of this azole is discussed.

Animals↗
PubMed1995

Psychosocial issues in breast cancer. Helping patients get the support they need.

Patients are becoming increasingly involved in making informed choices regarding their care. However, in the case of breast cancer, more than medical treatment of a body part is at stake. The breast is an important cultural symbol of femininity and an intimate part of the patient's self-esteem. The disease and its treatment may cause ongoing sadness, fear, anxiety, and anger. Primary care physicians, because of their close relationship with patients, are often in a position to notice when natural and reasonable emotional reactions go too far or last too long. Sensitive support and education of patients who are trying to choose a treatment method may minimize anxiety. Formal programs, such as the American Cancer Society's Reach to Recovery and Look Good... Feel Better, can be very supportive. For interested patients, support groups provide a chance to freely express their thoughts and feelings. However, not all women wish to participate in programs and groups. In some cases, careful listening on the part of the primary care physician is the most powerful intervention.

Adaptation, Psychological↗
PubMed1995

Myocardial infarction in a rural hospital.

Little is known of the outcome of myocardial infarction in patients managed in regional hospitals, where investigational and therapeutic modalities may have limited availability. Policies in place in the Intensive Care Unit of Wimmera Base Hospital for the management of myocardial infarction are designed to ensure that current 'best practice' is followed where possible. In order to audit our practices, and to ensure that these practices lead to patient outcomes similar to those published in cardiological literature, we performed a case note audit of patients admitted with myocardial infarction. We were keen to assess the risk factors of our patients, as it has been our impression that most patients with myocardial infarction have risk factors for ischaemic heart disease. Over a three year period (1991 to 1994) 88 persons with diagnosis of myocardial infarction were discharged from the intensive care unit. The in-hospital and 30 day mortality rates were 7.95%.

Aged↗
PubMed1994

Quantification of mitral regurgitation by velocity-encoded cine nuclear magnetic resonance imaging.

OBJECTIVES: The feasibility of velocity-encoded cine nuclear magnetic resonance (NMR) imaging to measure regurgitant volume and regurgitant fraction in patients with mitral regurgitation was evaluated. BACKGROUND: Velocity-encoded cine NMR imaging has been reported to provide accurate measurement of the volume of blood flow in the ascending aorta and through the mitral annulus. Therefore, we hypothesized that the difference between mitral inflow and aortic systolic flow provides the regurgitant volume in the setting of mitral regurgitation. METHODS: Using velocity-encoded cine NMR imaging at a magnet field strength of 1.5 T and color Doppler echocardiography, 19 patients with isolated mitral regurgitation and 10 normal subjects were studied. Velocity-encoded cine NMR images were acquired in the short-axis plane of the ascending aorta and from the short-axis plane of the left ventricle at the level of the mitral annulus. Two independent observers measured the ascending aortic flow volume and left ventricular inflow volume to calculate the regurgitant volume as the difference between left ventricular inflow volume and aortic flow volume, and the regurgitant fraction was calculated. Using accepted criteria of color flow Doppler imaging and spectral analysis, the severity of mitral regurgitation was qualitatively graded as mild, moderate or severe and compared with regurgitant volume and regurgitant fraction, as determined by velocity-encoded cine NMR imaging. RESULTS: In normal subjects the regurgitant volume was -6 +/- 345 ml/min (mean +/- SD). In patients with mild, moderate and severe mitral regurgitation, the regurgitant volume was 156 +/- 203, 1,384 +/- 437 and 4,763 +/- 2,449 ml/min, respectively. In normal subjects the regurgitant fraction was 0.7 +/- 6.1%. In patients with mild, moderate and severe mitral regurgitation, the regurgitant fraction was 3.1 +/- 3.4%, 24.5 +/- 8.9% and 48.6 +/- 7.6%, respectively. The regurgitant fraction correlated well with the echocardiographic severity of mitral regurgitation (r = 0.87). Interobserver reproducibilities for regurgitant volume and regurgitant fraction were excellent (r = 0.99, SEE = 238 ml; r = 0.98, SEE = 4.1%, respectively). CONCLUSIONS: These findings suggest that velocity-encoded NMR imaging can be used to estimate regurgitant volume and regurgitant fraction in patients with mitral regurgitation and can discriminate patients with moderate or severe mitral regurgitation from normal subjects and patients with mild regurgitation. It may be useful for monitoring the effect of therapy intended to reduce the severity of mitral regurgitation.

Adult↗
PubMed1994

Evaluation of the optimal hand-scrub duration prior to total hip arthroplasty.

Orthopaedic surgeons in many major arthroplasty centres advocate the use of a prolonged surgical hand-scrub prior to total joint replacement. In this study we evaluated the antimicrobial efficacy of a 5 compared with a 10 min scrub before both long (> 90 min) and short (< 90 min) operations for total hip arthroplasty. Surgical hand disinfection was performed on one occasion for 5 min and on a second for 10 min by 41 surgeons and theatre nurses using 4% chlorhexidine gluconate as a detergent formulation ('Hibiscrub', ICI Pharmaceuticals). None of the subjects had previously scrubbed on the day of each test. Bacterial colony counts on the fingers were measured using the method described by Rotter (vide infra) before scrubbing, immediately after scrubbing, and at the end of each operation. Our results showed that for arthroplasty procedures lasting less than 90 min (35 operations) a 5 min hand-scrub was equally as effective as one of 10 min. However, following longer procedures (36 operations) colony counts were significantly higher on subjects who had scrubbed for 10 min than on those who only scrubbed for 5 (P < 0.05, Mann-Whitney U-Test). This study suggests that the practice of a prolonged scrub before total joint replacement does not have a scientific basis and that such a policy should be discontinued where it is still practised.

Aerosols↗
PubMed1994

Effect of magnetic susceptibility contrast medium on myocardial signal intensity with fast gradient-recalled echo and spin-echo MR imaging: initial experience in humans.

PURPOSE: To show the effect of dysprosium diethylenetriaminepentaacetic acid bis-methylamine injection on the images of normal human myocardium. MATERIALS AND METHODS: T2-sensitive fast gradient-recalled echo (GRE) (repetition time [TR], 10.8 msec; echo time [TE], 4.2 msec) and spin-echo (SE) (TR, three RR intervals; TE, 60 msec) magnetic resonance (MR) imaging with driven equilibrium-preparation pulse was used to produce T2 contrast material enhancement. The contrast agent was injected into 12 healthy subjects at doses of 0.05, 0.1, 0.2, 0.4, and 0.6 mmol/kg. RESULTS: Driven equilibrium-prepared GRE images showed a transient decrease of myocardial signal intensity at doses of 0.2-0.6 mmol/kg. Postcontrast T2-weighted SE images showed a myocardial signal attenuation (30%-45% decrease) at a dose of 0.4 mmol/kg or higher. CONCLUSION: Dynamic MR imaging with a magnetic susceptibility contrast medium can be used to monitor the first pass of contrast media through human myocardium with a conventional MR imager and a fast GRE sequence.

Adult↗
PubMed1994

Quantification of collateral blood flow in coarctation of the aorta by velocity encoded cine magnetic resonance imaging.

BACKGROUND: Knowledge about the volume of collateral flow provides insight into the severity of coarctation of the aorta and may be critical in planning the operative approach. There is currently no method for the quantification of collateral flow in coarctation of the aorta. In this study, we applied velocity encoded cine magnetic resonance imaging (VENC-MR) to establish the flow pattern and volume of collateral flow in the descending thoracic aorta in normal subjects and patients with coarctation, introducing a new possibility to quantify the severity of the coarctation by determining the amount of collateral flow. METHODS AND RESULTS: VENC-MR was used to measure flow in the proximal and distal descending thoracic aorta in 10 normal subjects. In 23 patients with coarctation, flow was measured near the coarctation site and above the diaphragm. Patients were divided into a group with moderate to severe coarctation and a group with mild coarctation on the basis of clinical gradient between upper and lower extremities and the estimation of the gradient across the coarctation by Doppler echocardiography. The gradient across the coarctation and the degree of anatomic narrowing were also assessed by MR imaging. In normal volunteers, VENC-MR showed a 7 +/- 6% decrease in total flow, from proximal to distal aorta. The interobserver reproducibility was 3.9% to 4.9% (mean, 4.4%). In patients with moderate to severe coarctation, VENC-MR demonstrated an 83 +/- 50% increase in total flow from proximal to distal aorta, yielding a significant change compared with normal subjects (P < .01). Patients with mild coarctation showed a normal flow pattern and no significant change in total flow. There was a significant relation between the amount of flow increase in the distal aorta and the reduction in luminal diameter at the coarctation site (r = .94) as well as the clinical gradient (r = .84). CONCLUSIONS: This study shows the normal flow pattern in the descending thoracic aorta and its reversal in coarctation due to collateral flow. Thus, VENC-MR can measure collateral flow in coarctation and serves as a unique method for providing this important measurement of the severity of coarctation of the aorta.

Aorta, Thoracic↗
PubMed1994

Breath-hold MR cine angiography of coronary arteries in healthy volunteers: value of multiangle oblique imaging planes.

OBJECTIVE: Breath-hold MR cine angiography was used to depict the coronary arteries in healthy volunteers. Multiangle oblique imaging planes were evaluated for feasibility in showing continuous segments of the proximal and middle portions of the left anterior descending and right coronary arteries. SUBJECTS AND METHODS: Eighteen healthy subjects were examined with a 1.5-T MR imager. Fat-suppressed fast gradient-echo images (TR = 9.8 msec, TE = 3.5 msec) were acquired with a 13-cm receive surface coil. A segmented k-space data acquisition was used to obtain images of the coronary arteries at several phases of the cardiac cycle within a single breath-hold. Multiangle double oblique images that were tangential and sequential to the epicardial surface of the left ventricle were used to show the left anterior descending artery, and oblique coronal images were used to show the right coronary artery. Images of consecutive slice locations were shown in a cine format, and the length of each major coronary artery that was continuously visualized was measured. RESULTS: The left main coronary artery, proximal left anterior descending artery, and right coronary artery were demonstrated in all subjects. The mid and distal portions of the left anterior descending artery and diagonal branches were visualized best on multiangle oblique imaging planes. Continuous segments (> 6 cm) of the left anterior descending artery and right coronary artery were imaged in 14 subjects (78%) and 12 subjects (67%), respectively. Cine display was useful for showing the continuity of the coronary arterial segments and also for distinguishing arteries from veins. CONCLUSION: Double oblique imaging planes were useful in showing long segments of left anterior descending and right coronary arteries on coronary MR angiograms. Further work is necessary to improve detection of the left circumflex artery.

Adult↗
PubMed1994

An experimental study to evaluate the accuracy of diencephalic and pallidal target localization using the Brown-Roberts-Wells stereotactic system and unreformatted axial GE8800 CT scanning.

An experimental study was undertaken to evaluate the accuracy with which the intercommissural line (IL) length and anterior-posterior commissural (AC-PC) plane could be selected using unreformatted axial CT8800 imaging. Using these reference points, the Schaltenbrandt and Bailey stereotactic atlas and the Brown-Roberts-Wells (BRW) stereotactic system 1.82 mm ball bearings were deposited at selected diencephalic and pallidal targets in cadaver brains. There were errors in both IL length (median 1.5 mm) and AC-PC plane (median forward angulation of 9 degrees) estimation. Ball bearing deposition into large nuclei such as the pulvinar and globus pallidus and those in proximity to the mid IL such as the nuclei ventro oralis anterior (Voa), ventro oralis posterior (Vop) and ventro intermedius (Vim) was generally good; however, localization of the relatively small intralaminar nucleus was poor. This study suggests that when the AC and PC are not well imaged on sagittal reformations of axial diencephalic CT scans estimation of the AC-PC plane and IL from axial CT scans may be accurate enough for anatomical localization of certain functional stereotactic targets. The implications of this experimental study to operative functional stereotaxy are discussed.

Biopsy↗
PubMed1994

Teaching image-guided stereotactic methodology and functional neuroanatomy of the thalamus and pallidum: a simple ex vivo technique.

A simple and cheap model that enables on site, ex vivo, but very practical, learning of frame-based image-guided stereotactic technique and methodology, and the functional anatomy of the pallidum and thalamus is described. Using a cadaver skull, a specially prepared, formalin-fixed cadaver brain, and a modified stereotactic probe application of a stereotactic frame to the cranium, fiducial point acquisition, target point acquisition, computation of both arc and probe depth settings, and verification of target point accuracy can all be practiced. If diencephalic targets are selected for targeting with ball bearings then section of the cadaver brains, and study of a human thalamic stereotactic atlas provides an excellent and clinically relevant method of learning functionally important thalamic and pallidal anatomy. The method and techniques are described for CT imaging using the Brown-Roberts-Wells frame, but they are equally applicable to other frame types.

Brain Mapping↗