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Biomedical subjects

J Gallet

Publications and source records attributed to J Gallet.

6 recordsLinked to original sources
PubMed1998

An investigation of possible effects of high-frequency ultrasound on cellular integrity of cultured fibroblasts.

Several investigators have demonstrated the feasibility of imaging at the cellular level using acoustical microscopy. It has also been proposed that acoustical microscopy technology might be adopted for in vivo applications. Before such applications are implemented, it is important to demonstrate that any major deleterious effects are highly unlikely. To this end, we have repeatedly scanned NIH/3T3 mouse fibroblasts in culture using an Olympus UH3 acoustical microscope operating at 600 MHz. No adverse effects were observed even after exposures for 1 h. Spatial peak temporal averaged intensities were estimated to be below 300 mW/cm2.

3T3 Cells↗
PubMed1997

Characterization of collagen by high-frequency ultrasound: evidence for different acoustic properties based on collagen fiber morphologic characteristics.

Fibrous tissue on conventional ultrasound images appears as an echo-bright area. We have observed that on high-frequency ultrasonography images of thin sections of myocardium, fibrous tissue may appear as either a dark or light area. This study was designed to test the hypothesis that echo characteristics of fibrous tissue on high-frequency ultrasonography are determined by collagen fiber morphologic characteristics. We examined 16 tissue specimens from human beings and rats containing different forms of fibrosis. The specimens were sectioned at 5 microns, placed on a glass slide, and imaged with a 600 MHz transducer. On ultrasound images, collagen appeared either as a dark amorphous area or a light area that had a fibrillar pattern. The same specimens were then stained with picrosirius red and examined with polarized light. When viewed with polarized light microscopy, thick collagen fibers appear red or orange and thin fibers appear green or yellow. Polarized light microscopy revealed that dark areas on ultrasound images corresponded to thick collagen fibers that were predominantly longitudinally sectioned. In contrast, light areas corresponded to regions of thin, loosely packed fibers, or to thick collagen fibers that were obliquely sectioned. Collagen has different appearances on high-frequency ultrasound images depending on collagen fiber morphologic characteristics. If such variation in echo intensity also occurs with lower frequency transducers used in clinical echocardiography, the differentiation between normal myocardium and immature scar may be difficult.

Acoustics↗
PubMed1992

Visualization of myocardial cellular architecture using acoustic microscopy.

The resolution of an ultrasound transducer depends on its frequency. The resolution improves when higher frequency transducers are used. A 1000 MHz transducer has a resolution of approximately 1 micron. Acoustic microscopy utilizes very high-frequency ultrasound (600 to 1000 MHz) to visualize structures on a microscopic level. Unstained, deparaffinized, 5 microns sections of myocardial biopsy specimens from 10 patients were placed on a slide and imaged using an Olympus UH3 scanning acoustic microscope. To compare with light microscopy, the section used for acoustic microscopy was subsequently stained with hematoxylin and eosin and a serial section from the paraffin block was stained with PTAH stain. Myocytes, myofibrils, and interstitial tissue were accurately imaged. Pathologic phenomena such as cell fallout, interstitial fibrosis, and lymphocytic infiltration were identified by acoustic microscopy. Intramural vessels, nuclei of endothelial cells, and the media were clearly identified by this technique. There was close correlation between findings by acoustic microscopy and light microscopy. Acoustic microscopy permitted the visualization of cardiac cellular detail with a resolution similar to that of light microscopy. Unlike light microscopy, acoustic microscopy requires no staining of the specimen.

Biopsy↗