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M Magee

Publications and source records attributed to M Magee.

At least 37 records · Page 2Linked to original sources
PubMed1998

Enhanced accuracy and reproducibility in reporting of lung scintigrams by a segmental reference chart.

UNLABELLED: The diagnostic probability of pulmonary embolic disease is based on the recognition of unmatched segmental perfusion defects. Although interobserver and intraobserver reproducibility have been studied, accuracy has been an elusive goal due to the lack of a gold standard. We investigated the accuracy and reproducibility of reporting in a virtual scintigraphic model of the lungs, with and without the use of a lung segmental reference chart. METHODS: A Monte Carlo package was used to model lung scintigraphy from a digital phantom of the human lungs. An ideal lung segmental reference chart was created from the phantom. Five experienced nuclear medicine physicians reported a set of all possible defects involving 100% of a segment, without and with the chart. A further set of defects involving 45%-55% of a segment in the lower lobes was investigated using the chart. RESULTS: There was a significant improvement in accuracy (from 48% to 72%) and intraobserver agreement (from 61% to 77%) with the chart. The accuracy of reporting defects in the upper and middle lobes was consistently better than that in the lower lobes. There was no significant difference between the accuracy of reporting large defects and that of reporting moderate defects in the lower lobes. CONCLUSION: The lung segmental reference chart significantly improves both the accuracy and reproducibility of reporting lung scintigrams; however, although reporting in the lung bases is improved, absolute accuracy is substantially less than that in the upper and middle lobes. This emphasizes the need for caution because the lung bases are the most common site of embolic disease.

Computer Simulation↗
PubMed1997

Structural organization and developmental expression of the protein isoaspartyl methyltransferase gene from Drosophila melanogaster.

A protein carboxyl methyltransferase activity (PCMT) with a specificity for age-damaged protein D-aspartyl and L-isoaspartyl residues (E.C. 2.1.1.77) has been identified and cloned in Drosophila. The Drosophila gene was localized by chromosome in-situ hybridization to region 83AB of the third chromosome. The methyltransferase coding sequence is distributed among four exons within a 1.4-kb segment of the genome; it predicts a polypeptide of 226 amino acids that is 55% identical to the mouse enzyme. When expressed in bacteria, the Drosophila protein exhibits PCMT activity. A single 1.4-kb Pcmt transcript is detected in RNA preparations from embryos, larvae, pupae and adults. The abundance of the transcript, which is lowest in larvae and highest in adults, parallels the specific activity of the enzyme measured in extracts from the same developmental stages. It has been proposed that the PCMT initiates the repair of structurally damaged cellular proteins. The constitutive expression of PCMT and the relatively high level of expression in postmitotic adult cells suggest that PCMT activity is required through development, but acquires additional significance in aging tissues.

Animals↗
PubMed1997

Induction, mobilization of peripheral blood stem cells (PBSC), high-dose chemotherapy and PBSC infusion in patients with untreated stage IV breast cancer: outcomes by intent to treat analyses.

We investigated the outcomes of patients with breast cancer undergoing induction chemotherapy, mobilization of peripheral blood stem cells (PBSC) and high-dose chemotherapy (HDC) with PBSC infusion. One hundred and fourteen patients with untreated stage IV breast cancer, with a median age of 46 years (range 24-62), were entered on a phase II trial consisting of; (1) doxorubicin, 5-flurouracil, methotrexate (AFM) x 4 courses at 2 week intervals; (2) cyclophosphamide (4 g/m2), etoposide (600 mg/m2), cisplatin (105 mg/m2) (CEP), filgrastim (6 micrograms/kg/day) and PBSC collection; (3) cyclophosphamide (6 g/m2), thiotepa (500 mg/m2), carboplatin (800 mg/m2), (CTCb) followed by PBSC infusion. All patients received AFM, 107 (94%) received CEP, 93 (82%) received CTCb and PBSC as per protocol and 99 (87%) ultimately received HDC and PBSC. There was one infectious death after AFM and all other deaths were associated with progressive disease. Fifty-two patients (46%) are alive, 21 (18%) without progression, at a median 31 months (range 22-47). The probabilities of survival and progression-free survival at 3.5 years were 0.40 and 0.17, respectively. All 62 patients with visceral disease and/or a prior history of doxorubicin adjuvant therapy have relapsed or progressed. We conclude that the sequential administration of AFM, CEP and CTCb followed by PBSC resulted in long-term PFS only in patients who were NED, had bone-only disease or had lymph node or soft tissue disease with or without bone disease. Other strategies, aimed at improving responses to initial therapy, improving HDC regimens and/or developing immunomodulatory therapies, will be necessary to improve PFS for patients who fail doxorubicin adjuvant or who have visceral disease.

Adult↗
PubMed1997

Physical properties and use of pertechnegas as a ventilation agent.

UNLABELLED: Pertechnegas, a variant of technegas, produces similar ventilation images with a much increased clearance rate. This work aims to determine the properties of pertechnegas and its use as a ventilatory agent. METHODS: Fourteen men and 11 women were scanned for PE, after pertechnegas ventilation. Six were reimaged with technegas within 1 wk. Studies were reported according to PIOPED criteria. Pertechnegas samples were analyzed by transmission electron microscopy (TEM), cascade impaction (CI), aerosol mobility analysis (AMA), Fourier transform mass spectrometry (FTMS), x-ray photoelectron spectroscopy (XPS), paper strip (PC) and gas chromatography (GC). RESULTS: Post-test probabilities were normal in 5, low in 8, high in 5 and indeterminate in 7. There were 15 Grade 1, 6 Grade 2 and 4 Grade 3 studies. All Grade 3 patients had FEV1 < 1.5 liters, 3 with rates < 1.0 liter. Patients with high probability had proven deep venous thrombosis in three by venography and in one by doppler. TEM identified 0.3 micron salt particles. CI demonstrated a 7-min time to half clearance from the chamber for particles in the < 0.1 micron range. AMA indicated all particles were < 0.032 micron when salt was excluded. Pertechnegas behaves in PC as pertechnetate, GC demonstrated CO levels below 516 ppm. CO2 concentrations were 0.146 +/- 0.0009%. FTMS found molecular pertechnetate species including 99TcO3(OH)+, Na99TcO3(OH)3+ and Na99TcO3(OH)3+. XPS confirmed that these Tc species exist in oxidation state +7. CONCLUSION: Comparison with technegas images in the follow-up group proved equivalent in the first five views, but indistinct lung boundaries and a high background activity characterized the final anterior images. The active component of pertechnegas is molecular pertechnetate.

Adult↗
PubMed1997

Optimization of the scintigraphic segmental anatomy of the lungs.

UNLABELLED: Accurate and reproducible reporting of lung scintigraphy is predicated on a sound knowledge of the segmental anatomy of the lungs. A limited amount of hard data exists about the true segmental anatomy of the lungs. A virtual model of human lungs was created using a CT-based dataset and a Monte Carlo simulation technique to examine the optimal projections for the visualization of each segment in the lungs. METHODS: Segmental anatomy of the lungs was modeled using CT, cadaveric lungs and standard anatomical texts. The emission, scatter and attenuation of photons was modeled within these virtual lungs and the surrounding tissues. Single segmental lesions were created in eight projections and submitted for blinded reporting to four experienced nuclear medicine physicians to obtain the best views for each segment. RESULTS: The anterior and posterior oblique projections yielded the best views for 10 of 18 segments, with the laterals contributing four views, the anterior contributing two views and the posterior contributing one view. The majority of basal segments (six of nine) were best seen in the anterior and posterior oblique projections. CONCLUSION: This model overcomes the major problems associated with experimentation in the normal human and has the potential to provide answers to the major problems of scatter, attenuation and "shine-through" in lung scintigraphy.

Cadaver↗
PubMed1996

The use of the iSTAT portable analyzer in patients undergoing cardiopulmonary bypass.

OBJECTIVE: To evaluate the utility of the iSTAT blood analyzer, a bedside device for hematocrit, sodium, potassium, and glucose measurement during cardiopulmonary bypass (CPB). METHODS: Forty patients scheduled for elective CPB were evaluated prospectively. In addition to using the iSTAT analyzer, blood samples were analyzed at four time points: following induction of anesthetic, 10 min. after initiation of CPB, 60 min. after initiation of CPB, and following heparin neutralization by protamine. Blood glucose concentration was measured by the hospital laboratory using a Kodak Analyzer and by a glucose meter, electrolytes were evaluated by the Kodak Analyzer and BGE (a device which is commonly used for "satellite laboratory" determinations of electrolyte and blood gas results), and hematocrit samples were measured by the hospital laboratory using an NE 8,000 and a centrifuge. The means and standard deviations of the differences between the methods were calculated. RESULTS: The hematocrit values determined by the iSTAT machine, when adjusted for the level of total protein (according to manufacturer's directions), differed from the laboratory values by 0.53 +/- 1.46 percentage points. An alternative to measuring total protein and making the adjustment is simply adding 1% to the hematocrit in the pre-CPB period and 3% on-CPB or post-CPB, which we found to yield values that differed from the laboratory by 0.52 +/- 1.42 percentage points. For all four tests (hematocrit, sodium, potassium, and glucose) the iSTAT had a similar relationship to the laboratory values as did the other commonly used means (centrifuge, BGE, and glucose meter) of clinical evaluation. CONCLUSION: In summary, we found that in patients undergoing CPB, the iSTAT values agreed sufficiently well with standard laboratory values and that the iSTAT instrument can be relied upon for bedside measurements.

Blood Chemical Analysis↗
PubMed1996

Thoracoscopic laser bullectomy: a prospective study with three-month results.

One hundred forty-one patients were prospectively enrolled in a study of contact-tip laser bullectomy at four institutions. Ninety-one have had both preoperative and postoperative testing at 3 months. Nonsmoking patients with disabling dyspnea at less than 50 yards and with a forced expiratory volume in 1 second of 35% or less were enrolled. Testing included formal pulmonary function tests, arterial blood gasses, computed tomographic scans, ventilation/perfusion scans, echocardiograms, electrocardiograms, 6-minute walk testing, transdiaphragmatic pressures, and quality of life and dyspnea index questionnaires. A modest 16% improvement was noted in forced expiratory volume in 1 second (0.69 to 0.80 L), and there was a 29% improvement in 6-minute walk distances (655.2 to 846.3 feet). Oxygen use was completely discontinued in 16%. Risk factors for mortality included age, 6-minute walk distances, low diffusing capacity for carbon monoxide, high carbon dioxide tension, and high base excess. Minor improvement was judged from the dyspnea index and the Medical Outcome Study Short Form-36. Preoperative predictors of good outcome included heterogeneous disease, lack of carbon dioxide retention, and no emaciation (weight < 40 kg). Comparison of our results with those in the literature suggests that the improvement seen with the contact neodymium:yttrium-aluminum-garnet laser is not as good as that provided by the stapled techniques for volume reduction.

Acid-Base Imbalance↗
PubMed1993

Differential autoantibody responses to thyroid peroxidase in patients with Graves' disease and Hashimoto's thyroiditis.

In order to examine the specificity of the autoantibody response to thyroid peroxidase (TPO, previously identified as thyroid microsomal antigen) in autoimmune thyroid disease, we examined reactivity of sera from 45 Hashimoto's and 48 Graves' patients to native thyroid microsomes, denatured and reduced human TPO and several recombinant fragments of human TPO corresponding to amino acids 457-933 of the native protein. Both Graves' and Hashimoto's sera bound native, denatured and reduced TPO at significantly greater rate than normal controls, and no differences were noted between the two disorders in binding to these forms of the autoantigen. Binding was also noted to two recombinant fragments of TPO, corresponding to amino acids 513-633 and 633-933 in TPO. The frequency of autoantibodies to the TPO AA(633-933) region was not significantly different in Hashimoto's vs. Graves' disease patients (58% vs. 65% respectively), and appeared to relate to evidence of glandular inflammation in the Graves' patients (presence of anti-thyroglobulin antibodies and elevated anti-microsomal antibody levels). In contrast, antibodies to the TPO AA(513-633) fragment were significantly more common and of higher titer in Hashimoto's vs. Graves' disease patients, and did not correlate with any measure of glandular inflammation. These results identify two specific regions of TPO autoantibody binding and indicate that there are differences in the autoantibody response to TPO in Hashimoto's and Graves' diseases.

Adolescent↗
PubMed1993

An interactive image processing system for the quantification of cardiac function in the embryonic chick.

This paper describes an interactive computer-based method for quantifying embryonic chick heart blood pool volumes that have been recorded as digitized image sequences. The primary motivation for the development of such a system is to be able to extract measurement data that is useful for evaluating potential drug-induced effects on intracardiac blood flow while minimizing variabilities in the measurements that typically occur when human evaluators extract the measurements visually from photographs. The processing that is used to achieve this goal can be divided into four basic steps: enhancing the contrast of the digitized embryonic chick heart image, extracting the shape of the blood pool in the embryonic chick heart ventricle from the enhanced image, quantifying the axial dimensions of the blood pool and calculating the required cardiac blood flow data. The technical details and the basic theory motivating each processing step are provided as well as an analysis of the results obtained by applying the method to actual image data.

Animals↗
PubMed1993

Thoracoscopic stapled resection for spontaneous pneumothorax.

Video-assisted thoracoscopy has recently evolved as an alternative to thoracotomy for several thoracic disorders. Spontaneous pneumothorax may be ideally suited for thoracoscopic management. Stapling of apical blebs and pleurodesis or pleurectomy can now be performed thoracoscopically in a fashion identical to the standard operation done through a lateral or axillary thoracotomy. We compared our results with thoracoscopic management of spontaneous pneumothorax in 26 patients (group I) with a group of 20 patients previously subjected to axillary thoracotomy (group II). Indications for operation, sex distribution, and average age (group I, 32.3 years; group II, 33.7 years) were comparable. Hospital stay was less in group I (2.88 +/- 0.99 days versus 4.47 +/- 1.07 days; p = 0.07), as was the use of parenteral narcotics after 48 hours (2/26 = 7.7% versus 14/20 = 70%; p = 0.01). There have been no recurrences to date (mean follow-up, 8 months) in the thoracoscopic group. Video-assisted thoracoscopic management of spontaneous pneumothorax allows performance of the standard surgical procedure while avoiding the thoracotomy incision. Video-assisted thoracoscopic management is safe and offers the potential benefits of shorter hospital stays and less pain.

Adult↗
PubMed1992

The HOME inventory: a new scale for families of pre- and early adolescent children with disabilities.

A preliminary form of a new version of the Home Observation for Measurement of the Environment (HOME) is presented. It is designed for use with families of children aged 10-15. The 80-item preliminary version of the Preadolescent HOME (PA-HOME) was field tested on 117 children with varying disabilities. The 80 items were selected from a pool of over 250 items by means of several field tests and accompanying item analyses. Both factor analyses and item analyses were used to help pare down items and produce a scale with acceptable psychometric properties. The psychometric properties of the PA-HOME are quite similar to those reported for the other three versions of the HOME Inventory. It appears to be a reasonably reliable scale with moderate correlations with other measures of the family environment, such as SES, social support, and marital stability. It has low to moderate correlations with measures of child competence in this sample of children with disabilities. The correlations are of the same general magnitude of correlations between the Infant-Toddler, Early Childhood, and Middle Childhood versions of HOME in samples of younger children with disabilities.

Adaptation, Psychological↗
PubMed1990

Late (one month) reversible ischaemia after primary coronary occlusion treated with recombinant tissue plasminogen activator (rTPA).

The incidence of reversible ischaemia was assessed four weeks after primary coronary occlusion in 36 patients who had not required earlier revascularisation after randomisation to receive rTPA (n = 19) or placebo (n = 17). Coronary arteriography was performed at three weeks and thallium scintigraphy with dynamic stress testing at four weeks. Patients were followed for one year without planned intervention in the absence of symptoms. Managing physicians remained blinded to thrombolytic therapy. Patency rate of the infarct related artery at three weeks was greater after rTPA (rTPA 16, placebo 9; p = 0.04). Reversible perfusion defects within infarct related artery territory occurred with similar frequency in both treatment groups (rTPA 7, placebo 8). Multivessel disease was frequent (rTPA 11, placebo 12) but associated with a low incidence of reversible perfusion defects outside infarct related artery territory (rTPA 3, placebo 2). Thallium scintigraphy identified six of seven patients requiring subsequent revascularisation (sensitivity 86%, specificity 59%, negative predictive value 94%). Dynamic stress testing was positive for reversible ischaemia in 28% (rTPA 6, placebo 4) and identified two patients requiring revascularisation (sensitivity 29%, specificity 72%, negative predictive value 81%). The greater patency rate achieved with rTPA at three weeks after primary coronary occlusion was not associated with a significantly greater incidence of reversible perfusion defects at four weeks in patients who had not required prior revascularisation. The absence of reversible perfusion defects at four weeks was associated with a low incidence of revascularisation procedures during one year follow-up.

Aged↗