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Biomedical subjects

W Durán

Publications and source records attributed to W Durán.

3 recordsLinked to original sources

Endovascular management of arterial intimal defects: an experimental comparison by arteriography, angioscopy, and intravascular ultrasonography.

To determine the feasibility of the endovascular management of intimal defects while comparing the accuracy of arteriography with angioscopy and intravascular ultrasonography, we developed an in vivo model of arterial intimal flaps. In 10 superficial femoral arteries of five anesthetized mongrel dogs, intimal flaps were constructed and then imaged by arteriography, angioscopy, and intravascular ultrasound. A flexible microbiopsy forceps was used to remove each intimal flap under angioscopic guidance. Arteriographic lumen diameters were measured and cross-sectional areas calculated. Corresponding measurements by angioscopy and intravascular ultrasound with reduction in luminal area at the flap were obtained by use of computerized planimetry. Uniplanar arteriography identified 60% (6/10) of the intimal flaps, whereas angioscopy and intravascular ultrasound demonstrated 100%. Lumen diameter (in millimeters) measured by arteriography (3.4 +/- 0.6) correlated significantly with measurements by angioscopy (3.5 +/- 0.5, r = 0.77) and intravascular ultrasound (3.5 +/- 0.6, r = 0.96). Similarly, lumen area (square millimeters) by arteriography (9.2 +/- 2.9) correlated with measurements by angioscopy (8.9 +/- 2.2, r = 0.82) and intravascular ultrasound (8.6 +/- 2.7, r = 0.91). Reduction in lumen area by the flap by angioscopy (37 +/- 7%) and intravascular ultrasound (33 +/- 8%) also correlated significantly (r = 0.72). The intimal flaps were removed successfully in all 10 arteries as confirmed by arteriography, angioscopy, and intravascular ultrasound. We conclude that the endovascular management of intimal defects is possible. Additionally, angioscopy and intravascular ultrasound accurately evaluate lumen diameter and area while providing direct assessment of intimal defects.

Animals

Visualization of the coronary microcirculation using digital image processing.

A system was constructed to allow direct visualization of the coronary microcirculation of a beating rat heart under a microscope. An electrocardiogram (EKG) triggered strobe is used on the video recording and display system to "stop" the action of the beating heart so the surface microvessels can be directly observed. Experimental results are recorded on videotape and played back for frame-by-frame analysis of the data using digital image extraction, image enhancement and edge detection. The digital image processing techniques are designed for multi-purpose applications using recorded video images.

Animals

Fine structure of the electrotonic synapse of the lateral giant axons in a crayfish (Procambarus clarkii).

The electrotonic synapse of lateral giant axons of the crayfish was studied by conventional thin sectioning. The most prominent membrane specialization observed in this synaptic region is the communicating junction. It is characterized by a close apposition of the two axonal membranes which are separated by a 4--5 nm wide gap. Other characteristics of the junction are an array of particles spaced about 20--22 nm apart and a row of vesicles symmetrically arranged at the cytoplasmic leaflets of each membrane. The communicating junction does not cover the entire surface of the electrotonic synapse. Indeed, we have found other specializations such as: finger-like Schwann cell processes extending between synaptic membranes, saccular invaginations of one synaptic membrane into its axon, and coated vesicles continuous with one of the membranes. In addition, large vesicular pieces of the communicating junctions, with their accompanying vesicles, appeared to extend deeply inside the axoplasm. The morphological appearance of the communicating junction is found to be different from the one reported for mammalian maculae communicans such as liver or heart muscle. This is surprising because, regardless of their morphological differences, both junctions seem to transmit electrotonically.

Animals