Lipoma arborescens: high-resolution ultrasonographic findings.

Three patients with lipoma arborescens of the knee joint were evaluated with high resolution ultrasonography. All patients demonstrated a hyperechoic, frondlike mass in the suprapatellar bursa with a large associated effusion. All had popliteal cyst formation without involvement by the mass. Dynamic compression and manipulation of the suprapatellar effusion demonstrated pliable and flexible nature of mass with bending and waving of the frondlike mass in real time. Comparison with MR imaging demonstrated similar extent, location, and morphology of the mass. The characteristic features of this lesion as well as its distribution in the knee joint can be demonstrated readily by sonography.

The use of human repetitive DNA to target selectable markers into only the human chromosome of a human-hamster hybrid cell line (AL)

We used the plasmid BLUR-8 that contains an 800-base pair (bp) sequence of human repetitive Alu DNA in a cotransfection protocol to target the plasmids pSV2neo or EBO-pcD-leu-2 (hygro) into a single site of the sole human chromosome, number 11, of a Chinese hamster-human hybrid cell line (AL). The neo and hygro plasmids confer resistance to the antibiotics G418 and hygromycin, respectively. Of the 33 cotransfected clones with single-site insertions, 1/13 without BLUR-8 and 6/20 with BLUR-8 were only in human chromosome 11. A frequency of insertion of 1/13 is not different than expected by chance (rho = 0.3512). On the other hand, the probability that 6/20 insertions, as seen with BLUR-8, occurred by chance is low (rho = 0.0003). We suggest that the human DNA sequences contained in BLUR-8 targeted insertions into only the human chromosome.

Absence of mutagenic effects of continuous and pulsed ultrasound in cultured (AL) human-hamster hybrid cells.

Mutagenic effects of continuous and pulsed ultrasound were looked for using an in vitro assay system, the AL hybrid, that is up to 100 times more sensitive for mutagens such as x-rays and neutrons than the assays used previously to evaluate ultrasound. Cells in suspension in rotated plastic test tubes were insonated with continuous wave ultrasound at 1 MHz, ISPTP = 0.62-40 W/cm2 for 0-40 min. Cells attached in the central region of culture flasks received pulsed exposures at fc = 2.5 MHz, PRF = 1 kHz, 2 and 8 cycles per pulse, with p- = 1.2 MPa (ISPTA = 31-180 mW/cm2) for 0-30 min. Although these exposures were cytotoxic (the plating efficiency was decreased to approximately 65% by the highest doses), induction of mutation, if any occurred, was less than would be expected in this test system from 10-30 cGy of x-ray.