First experiences in using a new ultrasound mode and ultrasound contrast agent in the diagnosis of blunt renal trauma: a feasibility study in an animal model

RATIONALE AND OBJECTIVES

To evaluate the diagnostic value of the new ultrasound mode "wide-band harmonic" (WBH) using an ultrasound contrast agent in blunt renal trauma in an animal model.

METHODS

A defined blunt renal trauma was induced in 10 rabbits according to published standards. Ultrasound (B-mode, color and power Doppler, WBH) was performed before and after trauma, with and without using a contrast agent (Levovist). Ultrasound features were compared with histologic findings.

RESULTS

In 2 of the 10 rabbits, three focal renal intraparenchymal lesions with diameters ranging from 1.0 to 1.8 mm were found that could be identified only using WBH with contrast. Six of the 10 rabbits developed a subcapsular hematoma with a thickness of up to 1.5 mm, which was identified by conventional B-mode as well as WBH. Histologic workup confirmed these findings of intraparenchymal hematomas and did not reveal further lesions.

CONCLUSIONS

Only 20% of the experimental subjects developed parenchymal lesions with diameters of 1.0 mm or larger. All these lesions were identified only using WBH. These results indicate the potential to use WBH plus contrast for the diagnosis of blunt renal trauma.

A high-affinity human antibody that targets tumoral blood vessels

Angiogenesis is a characteristic feature of many aggressive tumors and of other relevant disorders. Molecules capable of specifically binding to new-forming blood vessels, but not to mature vessels, could be used as selective vehicles and would, therefore, open diagnostic and therapeutic opportunities. We have studied the distribution of the ED-B oncofetal domain of fibronectin, a marker of angiogenesis, in four different tumor animal models: the F9 murine teratocarcinoma, SKMEL-28 human melanoma, N592 human small cell lung carcinoma, and C51 human colon carcinoma. In all of these experimental models we observed accumulation of the fibronectin isoform containing the ED-B domain around neovascular structures when the tumors were in the exponentially growing phase, but not in the slow-growing phase. Then we performed biodistribution studies in mice bearing a subcutaneously implanted F9 murine teratocarcinoma, using a high-affinity human antibody fragment (L19) directed against the ED-B domain of fibronectin. Radiolabeled L19, but not an irrelevant anti-lysozyme antibody fragment (D1.3), efficiently localizes in the tumoral vessels. The maximal dose of L19 accumulated in the tumor was observed 3 hours after injection (8.2% injected dose per gram). By virtue of the rapid clearance of the antibody fragment from the circulation, tumor-to-blood ratios of 1.9, 3.7, and 11.8 were obtained at 3, 5, and 24 hours, respectively. The tumor-targeting performance of L19 was not dose-dependent in the 0.7 to 10 microg range of injected antibody. The integral of the radioactivity localized in tumoral vessels over 24 hours was greater than 70-fold higher than the integral of the radioactivity in blood over the same time period, normalized per gram of tissue or fluid. These findings quantitatively show that new-forming blood vessels can selectively be targeted in vivo using specific antibodies, and suggest that L19 may be of clinical utility for the immunoscintigraphic detection of angiogenesis in patients.

Correlation of surfactant phosphatidylcholine synthesis and 11 beta-hydroxysteroid dehydrogenase in the fetal lung

Glucocorticosteroids (GCS) are prerequisite for the induction of surfactant synthesis in the fetal lung. The 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) regulates the intracellular concentration of biologically active GCS. In this study we demonstrate the correlation of 11 beta-HSD activity and the GCS-induced surfactant phosphatidylcholine synthesis in organoid cultures of fetal rat lung. In the first series of experiments, [3H]corticosterone (CORT) or [3H]11-dehydrocorticosterone (11-DHC) were added to lung organoid cultures to test 11 beta-HSD activity. We found a low oxidative and a high reductive conversion indicating that in intact cells the equilibrium tends to biologically active GCS. However, in homogenized organoid cultures oxidative outweighed reductive activity. Secondly, the phosphatidylcholine synthesis of organoid cultures was enhanced by preincubation with GCS. CORT, as well as the hormonally inactive 11-DHC, increased the incorporation of [14C]choline into phosphatidylcholine. The effect of the latter was completely inhibited by glycyrrhetinic acid (inhibitor of 11 beta-HSD) indicating that it is caused by a previous conversion of 11-DHC into CORT via 11 beta-HSD. Thirdly, preincubation with GCS also altered 11 beta-HSD activity: dexamethasone or CORT both decreased the oxidative and increased the reductive activity in intact cells, indicating that glucocorticoids increase the rate of their own activation by positive feedback.