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Biomedical subjects

Michael A McDonald

Publications and source records attributed to Michael A McDonald.

5 recordsLinked to original sources
PubMed2005

Angiotensin receptor blockers and risk of myocardial infarction: systematic review.

OBJECTIVE: To evaluate the effect of angiotensin receptor blockers on the risk of myocardial infarction in patients at risk for cardiovascular events. DESIGN: Systematic review of controlled trials of angiotensin receptor blockers. DATA SOURCES: Medline, Embase, Cochrane central register of controlled trials, hand search, and contact with investigators. SELECTION OF STUDIES: Predefined criteria were used to select controlled clinical trials comparing use of angiotensin receptor blockers with angiotensin converting enzyme (ACE) inhibitors or placebo in patients at risk for cardiovascular events. Data were extracted for patients' characteristics, interventions, quality of trials, and rates of myocardial infarction. RESULTS: 19 studies with 31,569 patients were included in the analysis. Two studies investigated the use of angiotensin receptor blockers in hypertensive patients, four studies in patients with diabetes and nephropathy, 10 studies in patients with heart failure, and three in patients with recent myocardial infarction or ischaemic syndrome. 11 studies of 21,062 patients allowed for comparison between angiotensin receptor blockers and placebo; nine studies of 10,625 patients allowed for comparison between angiotensin receptor blockers and ACE inhibitors. Use of angiotensin receptor blockers was not associated with increased risk of myocardial infarction compared with placebo (odds ratio 0.94, 95% confidence interval 0.75 to 1.16) nor with increased risk of myocardial infarction compared with ACE inhibitors (1.01, 0.87 to 1.16). CONCLUSIONS: Treatment with angiotensin receptor blockers was not associated with a significantly increased risk of myocardial infarction. The 95% confidence intervals do, however, not exclude an increase of up to 16% in the risk of myocardial infarction or a reduction in risk of up to 25%. Until further information specifically dealing with this issue is available from large prospective trials, our findings may alleviate recent concerns over the safety of this class of medications.

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PubMed2003

Small particulate gadolinium oxide and gadolinium oxide albumin microspheres as multimodal contrast and therapeutic agents.

RATIONALE AND OBJECTIVE: To prepare and characterize new particulate contrast media, small particulate gadolinium oxide (SPGO) and gadolinium oxide albumin microspheres (GOAM), as prototype multimodal imaging and therapeutic agents. METHODS: SPGO was purchased from Alfa Aesar Inc. (Ward Hill, MA). GOAM were synthesized via ultrasonic irradiation using SPGO and 5% bovine serum albumin in aqueous solution. SPGO and GOAM were characterized by size, concentration, structure, and gadolinium content. Their relaxivity at high magnetic field strength and x-ray attenuating abilities were evaluated in 0.4% agar gel at room temperature. RESULTS: SPGO were confirmed to be 20-40 nm in diameter. GOAM have an average size of 2 to 5 microm and show a relatively homogeneous distribution of SPGO within the albumin microspheres. T1 and T2 relaxivity of GOAM was 6.7 seconds(-1) mmol/L(-1) and 38.5 seconds(-1) mmol/L(-1), respectively, while that of SPGO was 0.2 seconds(-1) mmol/L(-1) and 6.8 seconds(-1) mmol/L(-1), respectively. At 0, 0.004, 0.16, 4.0, and 16.0 mmol/L SPGO, x-ray attenuation values were measured at 2.11, 3.48, 7.06, 39.83, and 187.33 Hounsfield units, respectively. CONCLUSIONS: Use of SPGO and SPGO encapsulated in non-heat-hardened albumin microspheres (GOAM) represents a new approach. SPGO and GOAM have suitable physicochemical properties to warrant further biophysical and animal studies and reevaluation of toxicity limitations.

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PubMedDate not supplied

Gadolinium-rhodamine nanoparticles for cell labeling and tracking via magnetic resonance and optical imaging.

A novel dual-labeled nanoparticle for use in labeling and tracking cells in vivo is described. We report the construction and characterization of these gadolinium-rhodamine nanoparticles. These particles are constructed from lipid monomers with diacetylene bonds that are sonicated and photolyzed to form polymerized nanoparticles. Cells are efficiently labeled with these nanoparticles. We have inoculated labeled tumor cells subcutaneouosly into the flanks of C3H mice and have been able to image these labeled tumor cells via MRI and optical imaging. Furthermore, the labeled tumor cells can be visualized via fluorescent microscopy after tissue biopsy. Our results suggest that these nanoparticles could be used to track cells in vivo. This basic platform can be modified with different fluorophores and targeting agents for studying metastisic cell, stem cell, and immune cell trafficking among other applications.

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