In situ saphenous vein bypass grafts: angiographic evaluation and interventional repair of complications

In situ saphenous vein grafts are being used with increasing frequency for bypass procedures involving the femoral and popliteal arteries. Complications of these procedures include anastomotic stenoses and persistent arteriovenous fistulae that may result in failure of the graft. Balloon angioplasty and embolotherapy with detachable balloons were employed successfully in three or four recent cases of patients with complications from in situ grafts. Tailored angiography is essential for evaluating in situ grafts, and interventional techniques are extremely useful for managing complications.     

Spontaneous firing level distinguishes the effects of NMDA and non-NMDA receptor antagonists on the ganglion cells in the cat retina.

Different responses of retinal ganglion cells to iontophoretically applied NMDA receptor antagonists and non-NMDA receptor antagonists were studied in anaesthetized cats. Cells with normal range of spontaneous firing and those with abnormally high spontaneous firing levels showed a different response to these drugs. Both visually driven and spontaneous firing of cells with 'normal' spontaneous firing level were blocked by non-NMDA receptor antagonists, but not by NMDA receptor antagonists which often raised spontaneous firing. In contrast, the responses of cells with abnormally high spontaneous firing level were blocked effectively by NMDA antagonists including MK-801, an NMDA channel blocker, as well as by non-NMDA receptor antagonists. The results suggest that under normal physiological conditions, NMDA receptors which are not involved in synaptic transmission may play a role in reducing the resting discharge level of the retinal ganglion cells. NMDA receptors, however, appear to open ion channels in response to glutamate input when ganglion cells become abnormally depolarized.     

Hepatic ketogenesis and peripheral ketone body utilization in the ruminant

Hepatic and alimentary ketogenesis occur at similar rates in fed, nonpregnant, nonlactating goats, sheep and dairy cows. Alimentary ketogenesis begins to diminish within 24 h after fasting but compensatory increases in hepatic ketogenesis maintain total splanchnic release and, therefore, no change in circulating concentrations of ketone bodies is observed. By the third day of fast the gut is utilizing acetoacetate and beta-hydroxybutyrate and alimentary ketogenesis has ceased. Hepatic ketogenesis of both ketone bodies accelerates rapidly due to portal-drained visceral and hindquarter lipolysis and subsequent hepatic fatty acid uptake and total circulating concentrations are doubled. During pregnancy and lactation in sheep and cows alimentary ketogenesis is maintained as long as digestible organic matter intake is constant. Hepatic and total splanchnic release of beta-hydroxybutyrate increases in late gestation and early lactation. Again, this is due to increased portal-drained visceral and hindquarter free fatty acid release and hepatic free fatty acid uptake. Hindquarter uptake of both ketones during late gestation is similar to the ratio observed in nonpregnant fed sheep but the percentage of utilization decreases, perhaps reflecting partitioning to uteroplacental tissues. Hindquarter uptake of both ketone bodies in sheep increases in early lactation due to increased circulating concentrations because extraction ratios are similar to those of fed animals. Ketosis during pregnancy in sheep and lactation in cows may be prevented by beta-hydroxybutyrate stimulation of pancreatic insulin production. However, an insulin-independent intrahepatic mechanism apparently occurs in sheep.(ABSTRACT TRUNCATED AT 250 WORDS)