PubMed Health⌕ Search

Biomedical subjects

F Dunn

Publications and source records attributed to F Dunn.

94 records · Page 6Linked to original sources
PubMedDate not supplied

Ultrasonically induced temperature elevation in mouse ovary.

Temperature increases, resulting from exposure to 1 MHz ultrasound, were measured in in situ and in exteriorized mouse ovaries. It is concluded that temperature increases from exposure to 10 W/cm2 and less are probably not significant for producing ovarian tissue damage, but that 25 W/cm2 exposures, and greater, are of such magnitude that damaging thermal levels ensue. The significance of blood flow in removing ultrasonically generated heat has been observed quantitatively.

Animals↗
PubMedDate not supplied

Determination of the nonlinearity parameter B/A of biological media.

The nonlinearity parameter B/A has been determined for various biological solutions and soft tissues using the thermodynamic and finite amplitude methods. Agreement between the two methods is better than 10% for the tissues and 1% for the solutions. Fat has a B/A value around 11, the highest among soft tissues studied. Other soft tissues including liver, muscle, brain, and heart muscle have B/A values close to 7. Based on the observed linear relation between the B/A value and solute concentration in protein solutions, and also the lack of dependence of the B/A value on solute molecular weight in dextran solutions, it is postulated that the nonlinearity in these solutions is due to solute-solvent interactions. The general trend of increasing B/A value with specimen structural hierarchy suggests that the nonlinearity of biological materials is related to this feature. These observations suggest the use of the nonlinearity parameter B/A in tissue characterization, particularly since structural alteration often attends the pathological state.

Adipose Tissue↗
PubMedDate not supplied

Ultrasound biologic effects: a suggestion of strain specificity.

Pregnant hybrid LAF1/J mice were exposed to continuous-wave ultrasonic energy at a frequency of 1 MHz at a spatial peak intensity of either 2.5 W/cm2 or O W/cm2 (sham) for 20 seconds on the eighth day of gestation. Fetal weight (day 18 of gestation) and postpartum pup weight (21, 29 and 42 days post conception) were determined. No significant differences in weight were observed. This result differs from findings in others studies using outbred mouse strains. It is suggested that hybrid mice exposed to ultrasonic energy in utero may be more resistant to alterations in fetal and pup weight progression as compared with outbred strains.

Animals↗