Materials used in urological devices.

The most commonly used materials in the manufacture of urological devices are discussed with respect to their application to urinary catheters, penile implants, testicular implants, artificial urinary sphincters, and urological stents. The manufacturing, physical properties, and general chemical and biological behavior of there materials are reviewed. Attention is paid to future research trends and the general condition of the field of urological device materials.

Myocardial uptake of thallium 201 and technetium 99m-labeled sestamibi after ischemia and reperfusion: comparison by quantitative dual-tracer autoradiography in rabbits.

BACKGROUND: Myocardial scintigraphy with 99mTc-labeled sestamibi (99mTc-sestamibi) or 201Tl is used to assess regional perfusion in acute coronary syndromes associated with metabolic or functional abnormalities, such as acute coronary thrombosis with reperfusion and ischemia at rest. However, the initial uptake of these agents may be affected by a recent ischemic insult because the myocardial retention of these tracers depends on cellular metabolism. METHODS AND RESULTS: Accordingly, 99mTc-sestamibi and 201Tl were injected simultaneously in rabbits after transient brief (10 to 15 minutes, group I) or prolonged (45 to 60 minutes, group II) coronary occlusion. Accumulated subendocardial and subepicardial 99mTc-sestamibi and corresponding 201Tl activity were determined from autoradiographs of 30 microns short-axis slices comounted with serial tissue standards. Circumferential 99mTc-sestamibi and 201Tl activity profiles closely overlapped in both groups. The initial global and segmental myocardial activity per unit blood flow within the ischemic zone did not differ from unity for either tracer regardless of the duration of the ischemic insult. The initial myocardial uptake of both 99mTc-sestamibi and 201Tl after an acute ischemic insult reflected predominantly coronary blood flow, independent of myocardial viability. CONCLUSIONS: Thus this study supports the use of both 99mTc-sestamibi and 201Tl as perfusion probes in acute coronary syndromes characterized by acute occlusion and reperfusion.

Effect of triphenyl tetrazolium chloride staining on the distribution of radiolabeled pharmaceuticals.

Myocardial tissue is routinely exposed to the vital stain triphenyl tetrazolium chloride (TTC) to delineate infarction in conjunction with myocardial isotope research. However, it is unknown whether TTC has a direct effect on tracer deposition. We evaluated this possibility in rabbit hearts injected with either teboroxime, sestamibi or 201Tl. The hearts were excised and treated as follows: (1) TTC or normal saline was perfused through the heart and the residual activity monitored; (2) hearts were sliced into 0.5-cm thick sections, counted and incubated in either TTC or normal saline for 10 min then recounted; and (3) the circumflex artery was ligated postmortem and TTC perfused. Autoradiographic images were produced from 30-microns slices to depict any disparity in activity concentration from the selective perfusion of TTC. Both perfusion and incubation by TTC resulted in a significant activity loss of both 201Tl and sestamibi, but not teboroxime, compared to normal saline. An independent octanol extraction experiment measured the change in the partition coefficient of labeled teboroxime and sestamibi induced by the addition of TTC. TTC was shown to liberate the radiolabel from sestamibi, but not from teboroxime. We conclude that histochemical staining techniques involving TTC can alter the distribution of radiolabeled pharmaceuticals. As a result, experiments using TTC with 201Tl and sestamibi should be interpreted cautiously.