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.     

Ionic modulation of the effects of heparin and 6-aminohexanoic acid on plasminogen activation by streptokinase: the role of ionic strength, divalent cations and chloride.

Studies were conducted on the effect of heparin or 6-aminohexanoic acid (6-AH) on the activation of glutamic plasminogen (Glu-Plg) by streptokinase in the presence of different concentrations of buffer, NaCl and divalent cations. Heparin and 6-AH inhibited streptokinase-mediated activation of Glu-Plg using 10 mM Tris-HCl buffer pH 7.4. This inhibition was partially reversed by the addition of 0.2-1.0 mM of Mg ions. Increasing the ionic strength of Tris-HCl buffer from 10 to 50 mM or addition of 50-150 mM of NaCl to 50 mM Tris-HCl pH 7.4 inhibited the activation of Glu-Plg by streptokinase while decreasing the % inhibition by heparin over the control samples. Double reciprocal plot of the activation of Glu-Plg by streptokinase using 50 mM Tris-HCl pH 7.4 containing 100 mM NaCl showed that the addition of heparin lowered Vmax by 50% without affecting Km. To determine whether the inhibitory effect of heparin was specifically directed towards Glu-Plg or streptokinase, the ratios of the initial rate of plasmin generation in the presence of heparin over the controls were plotted against the inverse of the volume fraction of Glu-Plg or streptokinase after serial dilutions. The results indicated that the dilutions of streptokinase but not of Glu-Plg influenced the ratios, suggesting an interaction of heparin with streptokinase. Addition of 6-AH reversed the inhibitory effect of NaCl on the activation of Glu-Plg by streptokinase and the results of the near UV CD spectra of Glu-Plg showed that addition of 6-AH enhanced the spectra in this region with an increase in the ellipticity which was not affected by addition of NaCl.     

The effects of antioxidant supplementation during Percoll preparation on human sperm DNA integrity

The integrity of sperm DNA is crucial for the maintenance of genetic health. A major source of damage is reactive oxygen species (ROS) generation; therefore, antioxidants may afford protection to sperm DNA. The objectives of the study were, first, to measure the effects of antioxidant supplementation in vitro on endogenous DNA damage in spermatozoa using the single cell gel electrophoresis (comet) assay and, second, to assess the effect of antioxidant supplementation given prior to X-ray irradiation on induced DNA damage. Spermatozoa from 150 patients were prepared by Percoll centrifugation in the presence of ascorbic acid (300, 600 microM), alpha tocopherol (30, 60 microM), urate (200, 400 microM), or acetyl cysteine (5, 10 microM). DNA damage was induced by 30 Gy X-irradiation. DNA strand breakage was measured using the comet assay. Sperm DNA was protected from DNA damage by ascorbic acid (600 microM), alpha tocopherol (30 and 60 microM) and urate (400 microM). These antioxidants provided protection from subsequent DNA damage by X-ray irradiation. In contrast, acetyl cysteine or ascorbate and alpha tocopherol together induced further DNA damage. Supplementation in vitro with the antioxidants ascorbate, urate and alpha tocopherol separately has beneficial effects for sperm DNA integrity.