Functional assessment of pulmonary capillary surface area in the 2-mo-old lamb.

We recently reported that measurements of the maximal velocity of pulmonary endothelial angiotensin-converting enzyme (Vmax) in vivo provide information regarding microvascular surface area in the developing lamb. To obviate any subtle influences of development on Vmax aside from simple increases in surface area, we correlated Vmax with postmortem stereological assessments of alveolar surface area in the relatively mature lung of the 2-mo-old lamb (n = 14). We attempted to increase the range of surface area beyond its normal variability by injecting nine of the lambs with bleomycin, an antineoplastic agent with significant pulmonary toxicity in other species. Vmax, measured shortly after birth and then weekly, increased monotonically in all lambs. Despite their wide dispersion, Vmax and the stereological determinations correlated strongly at 2 mo of age, confirming that Vmax is a robust indicator of the surface area of the air-blood barrier. There was no significant difference in either measurement between the control lambs and those treated with bleomycin, suggesting that the newborn lamb is resistant to the effect of this agent.     

Comparison of aromatase activity in human prostatic, testicular and placental tissues.

The aromatase enzyme was quantified by the release of tritiated water from [1 beta-3H] androstenedione. Tritiated water was released by the crude homogenates in 4 of 18 samples of benign prostatic hyperplasia tissue and one of 5 samples of prostate carcinoma tissue. However, this apparent aromatase activity was not inhibited by 4-hydroxyandrostenedione (0.5 and 5.0 microM), and none of the particulate fractions (100,000 g pellet) prepared from each of the prostatic tissues exhibited aromatase activity. Particulate fractions from rat ovary (n = 3) and human testes (n = 6) displayed significant aromatase activity (mean values of 9.9 and 0.033 nmol estrone formed/g protein/h, respectively). The testicular aromatase was inhibited by aminoglutethimide, 4-hydroxyandrostenedione and CGS 16949A with IC50 values of 6.4, 0.17 and 0.0017 microM, respectively. These are of a similar order to values obtained with the aromatase enzyme from human placental microsomes (14, 0.43 and 0.0075 microM, respectively).     

Submerged reefs and terraces on the shelf edge of the Great Barrier Reef,Australia

The morphology and distribution of seabed features on the shelf edge and upper slope adjacent to the Great Barrier Reef, Australia, has been examined using shallow seismic profiling, side-scan sonar and precision echo sounding data, supplemented by submersible investigations. The data reveal a submerged barrier reef system at different locations between 15° 45 S and 21° 00 S. At two locations, an extensive offshore platform rising above the 50 m isobath and extending for over 20 km parallel to the shelf edge is backed by a relict lagoon at an average depth of 75 m. In addition, outer shelf and upper slope terraces are found at many depths; however, only some occur consistently throughout the region while most others occur only locally. Frequency distributions indicate the greatest occurrence of features at depths of 44–46, 60–66, 72–78, 80–84, 102–106 and 146–148 m. Caution should be exercised when interpreting these features with respect to specific lower sea level stands.