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Biomedical subjects

H McCann

Publications and source records attributed to H McCann.

12 recordsLinked to original sources
PubMed2003

Isolated chylopericardium.

A 25-year-old male was discovered to have an asymptomatic pericardial effusion during routine pre-employment medical evaluation. During pericardiocentesis 1200 ml of milky-white fluid was obtained; subsequent biochemical evaluation confirmed the chylous nature of this fluid. Following thorough evaluation a diagnosis of isolated chylopericardium was made. Following several recurrences he underwent thoracotomy with ligation of the thoracic duct and creation of a pericardial window. There are relatively few published reports of true isolated chylopericardium and the aetiology and pathogenesis remain unknown. A primary abnormality of the thoracic lymphatic valve system is postulated. The most effective treatment is surgical with ligation of the thoracic duct above the diaphragm and creation of a pericardial window

Adult↗
PubMed2001

Corticobasal syndrome with tau pathology.

Six cases with a clinical corticobasal syndrome (progressive asymmetric apraxia and parkinsonism unresponsive to levodopa) and tau pathology were selected from 97 brain donors with parkinsonism. Postmortem volumetric measures of regional brain atrophy (compared with age/sex-matched controls) were correlated with clinical features and the degree of underlying cortical and subcortical histopathology. At death, no significant asymmetry of pathology was detected. All cases had prominent bilateral atrophy of the precentral gyrus (reduced by 22-54%) with other cortical regions variably affected. Subcortical atrophy was less severe and variable. Two cases demonstrated widespread atrophy of basal ganglia structures (44-60% atrophy of the internal globus pallidus) and substantial subcortical pathology consistent with a diagnosis of progressive supranuclear palsy (PSP). The remaining four cases had typical pathology of corticobasal degeneration. In all cases, neuronal loss and gliosis corresponded with subcortical atrophy, while the density of cortical swollen neurons correlated with cortical volume loss. Atrophy of the internal globus pallidus was associated with postural instability, while widespread basal ganglia histopathology was found in cases with gaze palsy. This study confirms the involvement of the precentral gyrus in the corticobasal syndrome and highlights the variable underlying pathology in these patients.

Aged↗
PubMed2001

Neurofilament-immunoreactive neurons are not selectively vulnerable in Alzheimer's disease.

Abnormal neurofilament protein distribution and phosphorylation contributes to the cytoskeletal pathology of Alzheimer's disease. Anatomical studies suggest that cortical neurons immunoreactive for nonphosphorylated 200-kDa neurofilament are most vulnerable. We repeated these studies in formalin-fixed temporal lobe tissue from five Alzheimer's disease cases with tissue volume loss compared to five controls without tissue loss. Immunohistochemistry for nonphosphorylated and phosphorylated forms of the neurofilament protein was counterstained for Nissl substance and immuno-positive and -negative pyramidal neurons quantified using areal fraction counts. Compared with controls, cases with Alzheimer's disease had similar numbers of neurons expressing the nonphosphorylated neurofilament protein, suggesting these neurons are largely spared by the disease process. In Alzheimer's disease there was a significant increase in neurons containing phosphorylated neurofilament and tau proteins and a decrease in neurons devoid of neurofilament protein. Our results challenge the theory that neurons containing 200 kDa neurofilament are selectively vulnerable in Alzheimer's disease.

Aged↗
PubMed2000

Cortical inflammation in Alzheimer disease but not dementia with Lewy bodies.

BACKGROUND: There have been no previous studies on the role of inflammation in the brain for the second most common dementing disorder, dementia with Lewy bodies. OBJECTIVE: To investigate the degree of cortical inflammation in dementia with Lewy bodies (DLB) compared with Alzheimer disease (AD) and control brains. DESIGN AND MAIN OUTCOME MEASURES: Post-mortem tissue collection from a brain donor program using standardized diagnostic criteria. Brains collected from January 1, 1993, through December 31, 1996, were screened and selected only for the presence or absence of tau neuritic plaques. Results of immunohistochemistry for HLA-DR were quantified using area fraction counts. Counts were performed by investigators who were unaware of the diagnosis. Results were compared across groups using analysis of variance and posthoc testing. SETTING: A medical research institute in Sydney, Australia. PATIENTS: Eight brains with DLB and without the tau neuritic plaques typical of AD, 10 brains with AD and no Lewy bodies, and 11 nondemented controls without significant neuropathological features were selected from a consecutive sample. RESULTS: Compared with AD, DLB demonstrated significantly less inflammation in the form of HLA-DR-reactive microglia in all cortical regions (P<.001, posthoc). The level of inflammation in DLB was comparable to that seen in controls (P=.54, post hoc). CONCLUSIONS: Inflammation appears related to the tau neuritic plaques of AD. Despite similar clinical presentations, therapeutic anti-inflammatory strategies are not likely to be effective for pure DLB. Arch Neurol. 2000.

Aged↗
PubMed2000

Effect of anti-inflammatory medications on neuropathological findings in Alzheimer disease.

BACKGROUND: There has been no analysis of brain tissue from longitudinally observed, cognitively tested patients to validate whether anti-inflammatory medications protect against the pathological changes of Alzheimer disease. OBJECTIVE: To investigate the role of anti-inflammatory medications in alleviating the pathological features of Alzheimer disease. DESIGN AND MAIN OUTCOME MEASURES: A 5-year postmortem tissue collection was performed after a case-control study of Alzheimer disease (approximately 90 [30%] of patients died during follow-up, of whom consent for autopsy was obtained in 44 [50%]). Cases were selected on the basis of (1) adequate clinical histories of nonsteroidal anti-inflammatory drug usage, (2) no neuropathological findings other than Alzheimer disease, and (3) no generalized sepsis at death. Variables analyzed included neuropsychological test scores and amount of tissue inflammation and Alzheimer-type pathological changes. Two-way analysis of variance was used to determine whether drug usage significantly affected these variables. SETTING: The Centre for Education and Research on Ageing and the Prince of Wales Medical Research Institute, Sydney, Australia. PATIENTS: Twelve patients with Alzheimer disease (5 taking anti-inflammatory drugs) and 10 nondemented controls (3 taking anti-inflammatory drugs) were selected (50% of available sample). RESULTS: Of the patients with Alzheimer disease, anti-inflammatory drug users performed better on neuropsychological test scores than did nonusers. However, there were no significant differences in the amount of inflammatory glia, plaques, or tangles in either diagnostic group. CONCLUSION: Long-term anti-inflammatory medications in patients with Alzheimer disease enhanced cognitive performance but did not alleviate the progression of the pathological changes. Arch Neurol. 2000.

Aged↗
PubMed2000

3D simulation of EIT for monitoring impedance variations within the human head.

A preliminary analysis is presented concerning the use of EIT for detecting impedance inhomogeneities within the human brain. The work to date is centred around the monitoring of two distinct impedance variations: those associated with the application of a carotid clamp during surgery and changes caused by the redistribution of blood flow during auditory stimuli. Using the commercially available Ansoft Maxwell package, a 3D finite element model of the human head has been developed to solve the forward problem. The model is hemispherical in shape and comprises regions of brain, cerebrospinal fluid, skull and skin and includes 16 scalp electrodes each of area 1 cm2. Results from simulations using the model suggest that an EIT system, incorporating diametric current excitation, would require a voltage measurement sensitivity of 100-120 dB in order to detect the impedance variations in the above cases.

Acoustic Stimulation↗
PubMed1998

Dobutamine stress echocardiography: false positive scans in proteinuric patients with type 1 diabetes mellitus at high risk of ischaemic heart disease.

Patients with Type 1 diabetes mellitus have an increased risk of ischaemic heart disease (IHD). When diabetes is complicated by nephropathy this risk is further increased and asymptomatic IHD is common. New techniques for non-invasive cardiac evaluation are now available and one of these, Dobutamine Stress Echocardiography (DSE), was studied in subjects with Type 1 DM and nephropathy who had no evidence of IHD. DSE was performed on 18 subjects (13 male, 5 female; mean age 37.8 +/- 3.4 years), diabetes duration 23.7 +/- 1.2 years and nephropathy diagnosed for 10.9 +/- 1.3 years. There were 7 (38%) positive scans-suggesting asymptomatic IHD; 16.7% of subjects studied had a significant arrhythmia. Coronary angiography was performed in 6 of the 7 subjects with positive DSEs and was positive in only 2. These results suggest that DSE has a high rate of false positive results in Type 1 DM patients suffering from nephropathy and may limit its usefulness in these subjects.

Adult↗
PubMed1998

Correlation of myocardial histologic changes in hibernating myocardium with dobutamine stress echocardiographic findings.

OBJECTIVE: The objective of this study was to correlate histologic changes in hibernating myocardium with dobutamine stress echocardiography (DSE). METHODS: Patients (n = 8) with anterior regional wall motion abnormalities in the seven echocardiographic segments representing the territory supplied by a significantly stenosed left anterior descending coronary artery had preoperative DSE performed (yielding 56 segments for analysis). Two transmural biopsy specimens were taken from the anterior wall of the left ventricle during coronary artery bypass grafting. RESULTS: Morphometric histologic analysis of biopsy specimens showed significantly less fibrosis in segments demonstrating inotropic reserve (p < 0.05) and significantly less fibrosis in segments demonstrating improvement in wall motion on echocardiography 3 months after revascularization (p < 0.05). DSE had a sensitivity of 100% and a specificity of 62% for detection of hibernating myocardial segments. Percent fibrosis was inversely correlated with percent nucleated cells (r = 0.66, p < 0.01) and directly correlated with cytoplasmic clearance (r = 0.76, p < 0.01). CONCLUSION: Inotropic response during DSE correlates with histologic evidence of hibernating myocardium.

Cardiotonic Agents↗
PubMed1997

Coronary Stenting in Clinical Practice: Patient Profile, Immediate Outcome, Clinical and Angiographic Follow-up in 243 Consecutive Patients.

The purpose of this study is to assess immediate outcome and long term results in unselected consecutive patients (pts) representing a spectrum of clinical and angiographic subgroups and stent designs. RESULTS: From first implantation in November 1989 through to October 1995, 243 pts underwent coronary stent insertion (307 stents, males n=188, females n=55, mean age 57.8 years. Palmaz-Schatz stents were implanted in 210 pts, Wiktor in 30 pts, both in 3. Bailout stenting was performed in 11 patients. Overall procedural success was 97%. Complete revascularization was achieved in 155 (64%) patients. Stenting of an infarct-related artery within 6 hours of an acute myocardial infarction was performed in 6 patients, and for unstable angina in 107. Pre-procedure 223 (92%) pts had class III/IV angina. Stenting of 11 vein grafts and 5 left main arteries was performed. Subacute stent thrombosis occurred in 13 (5%) pts while 6 (2.5%) pts died in hospital, and 8 (3%) had a Q-wave myocardial infarction. At a mean (SD) 7.3 (12.9) months follow-up 233 (96%) pts were alive, 213 (91%) had no or mild angina. Angiographic follow-up in 201 (83%) pts at 19 (30) weeks showed a 13% in stent restenosis rate. CONCLUSIONS: In an unselected, consecutive series of patients undergoing coronary stenting, mortality was low, procedural success was high and late clinical and angiographic results were satisfactory. Subacute stent thrombosis, though uncommon remains a challenge.

Journal Article↗
PubMed1994

Post-myocardial infarction ventricular septal defect: an angiographic study.

Clinical and angiographic findings are reported in a consecutive series of nineteen patients with post infarction ventricular septal defect (PIVSD). In all patients PIVSD complicated a first myocardial infarct and none had a history of angina pectoris prior to presentation. In over 50% of the patients PIVSD occurred within three days of infarction. The mean patient age was 65 years. Single vessel disease was noted in 63% of the patients. The mean left ventricular ejection fraction was 27%. Contrast left ventriculography localised the defect in all patients. Although a comprehensive cardiac ultrasound examination will generally confirm the diagnosis of PIVSD, preoperative coronary angiography is essential for the selection of those patients most likely to benefit from concomitant coronary artery bypass grafting at the time of surgical repair of the interventricular septum.

Aged↗