Biomedical subjects

F S Foster

Publications and source records attributed to F S Foster.

94 records · Page 6Linked to original sources

PubMedDate not supplied

Ultrasonic detection and developmental changes in calcification of the placenta during normal pregnancy in mice.

High resolution ultrasound imaging of the mouse placenta during development revealed highly echogenic foci localized near the materno-placental interface in early gestation and, near term, in the placental labyrinth (the exchange region of the placenta). Echogenic foci and calcium deposits identified in histological sections using Alizarin red staining showed similar localization and changes with gestation. Calcium deposits caused the echogenic foci because incubating uteri in a decalcifying solution eliminated both the deposits and echogenic foci. Transmission electron microscopy, X-ray microanalysis, and electron diffraction were used to show that deposits were calcium hydroxyapatite crystals. Calcium deposits were extensive and densely packed at days 7.5-9.5 of gestation at the border between the maternal decidua and the fetal trophoblast giant cells of ectoplacental cone. After the formation of the chorio-allantoic placenta (approximately day 10.5), calcification deposits appeared larger and more rarefied but were still localized at the border between the maternal decidua and the fetal trophoblast giant cells of the placenta. Calcification deposits were not observed in the labyrinthine region of the mouse placenta until > or = day 15.5 (day 18.5 is full term). We conclude that deposits of calcium hydroxyapatite crystals in the mouse placenta are detectable by high resolution ultrasound imaging. These deposits provide an ultrasound detectable marker of the maternal-placental interface that is particularly prominent during the establishment of the chorio-allantoic placenta between days 7.5 and 9.5 of gestation.

Animals↗

PubMedDate not supplied

Ultrasound backscatter microscopy images the internal structure of living tumour spheroids.

Ultrasound microscopes have the potential for imaging structure at depth in thick specimens, yet this is not possible in biological specimens using conventional ultrasound transmission or reflection methods. But, subsurfacing imaging is possible with ultrasound if a backscatter (pulse-echo) technique, similar to that used in medical imaging, is used. The central problem of extending backscatter imaging to ultrasound microscopy has been the development of high frequency (greater than 100 MHz) transducers with sufficient bandwidth and sensitivity to detect the low levels of backscatter from biological materials. We recently reported the development of such a transducer which we have now incorporated into a new ultrasound backscatter microscope capable of providing tomographic images at depths of up to 4 mm in biological specimens. Here we present the first ultrasound backscatter micrographs of living biological specimens. The benefits of this technique are demonstrated by its application to imaging the internal structures of living tumour spheroids showing striking contrast between the necrotic core and the viable rim of the spheroid.

Cell Aggregation↗

PubMedDate not supplied

Arterial imaging: comparison of high-resolution US and MR imaging with histologic correlation.

The potential roles of intravascular ultrasound (US) and magnetic resonance (MR) imaging in evaluating the artery wall and atherosclerotic plaque were compared. Excised human femoral and carotid arteries were imaged with a 42-MHz intravascular US system and a 1.5-T MR imager equipped with enhanced gradients. In-plane resolution was 40-280 microns for US and 156 microns for MR imaging. Stained histologic tissue sections were obtained for correlation with the imaging findings. Intravascular US and MR imaging both had sufficient resolution and contrast to demonstrate arterial layers and allow distinction of atheroma. Correspondence between structures identified with the two modalities was excellent and in agreement with histologically defined arterial structures. Findings on state-of-the-art intravascular US and MR images correlate well with histologic findings in normal and diseased arteries. Intravascular US has the advantages of speed and resolution, whereas MR imaging demonstrates superior contrast in the depiction of atheroma.

Aged↗

PubMedDate not supplied

An ultrasound biomicroscopic dark-room provocative test.

Ultrasound biomicroscopy can image the relationship of angle structures under any lighting conditions. Eight patients with narrow angles were examined in the light and in the dark. All of the eyes showed iris thickening and shortening, increased anterior convexity of the iris, and varying degrees of angle narrowing in the dark. In one eye, the angle was completely closed. Iridotomy in this patient flattened the iris profile and opened the angle. The degree of angle opening observed after the iridotomy did not change depending on the lighting conditions. Ultrasound biomicroscopy allows imaging of dynamic changes in anterior ocular structures as they occur and provides information regarding angle occludability in the dark.

Aged↗