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.     

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.      

Enlarged motor units resulting from partial denervation of cat hindlimb muscles

1. It was the aim of this study to determine the extent to which a mammalian motoneuron can sprout in a partially denervated muscle, which motor unit types are involved in sprouting, and whether polyneuronal innervation exists between sprouted units. 2. The fast-twitch flexor digitorum longus (FDL) and slow-twitch soleus were partially denervated by unilateral section of the L7 ventral root in 12-wk-old kittens. After approximately 100 days single motor units were isolated, and their isometric contractile characteristics were determined. FDL units were also tested for their resistance to fatigue and categorized as fast-twitch, fatiguing fibers (FF), fast-twitch, fatigue-resistant fibers (FR), and slow-twitch, fatigue-resistant fibers (S). The presence of polyneuronal innervation was investigated between pairs of like and unlike units. 3. The extent of the original denervation was variable and was estimated from the distribution of motor axons innervating the muscle via the L7 and S1 (soleus) or L6 and L7 (FDL) ventral roots on the contralateral side. In soleus, denervations ranged from 75 to 98%; in FDL, 60 to 97% (denervations less than 60% were not investigated). In general, motor-unit force increased in proportion to the extent of the denervation. 4. Within soleus, unit force increased to over 2 N, which was about 16 times greater than the average for a normal muscle (133 mN). However, most units increased in force to between five and 12 times normal. 5. Within FDL, the force development of type S units was unaffected by partial denervation. Type FF units increased by up to 11 times (4.3 N) compared with normal FF units (395 mN) with most increasing between two and four times. FR units exhibited the greatest relative increase in force [up to 19 times (4.3 N) compared with normal (225 mN)]. Most units were two to seven times the normal. 6. A few FDL units were glycogen depleted, the muscles frozen, and cross sections prepared for histochemical analysis. This indicated that the largest units contained approximately 5,000 fibers, and there was little fiber hypertrophy. In the extensively denervated soleus muscle, large numbers of small, presumably denervated fibers were observed. The innervation ratio of several large units was determined indirectly using mean fiber area. This gave estimates of 3,000-4,000 fibers for the largest units. Again, fiber hypertrophy contributed little to the increase in unit force. It was concluded that the increased force of units in both muscles was largely attributable to terminal and axonal sprouting of the intact motor axons. 7. No evidence for polyneuronal innervation was found in either FDL or soleus muscle.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-term persistence of enlarged motor units in partially denervated hindlimb muscles of cats

1. It was the aim of this study to determine the effect that regenerating motor axons would have on enlarged or sprouted motor units that had been established for a relatively long time. 2. The fast-twitch flexor digitorum longus (FDL) and slow-twitch soleus were partially denervated by unilateral section of the L7 ventral root in 12-wk-old kittens. After 200+ days single motor units were isolated, and their isometric contractile properties were determined. FDL units were also tested for their resistance to fatigue and categorized as fast-twitch-fatigable (FF), fast-twitch-fatigue-resistant (FR), and slow-twitch-fatigue-resistant (S). 3. It had been established previously that regenerating motor axons via L7 returned to the experimental muscles by approximately 100 days. Therefore from 100 to 200 days it was assumed that the sprouted units would be in competition with the regenerating axons. The extent of the original denervations was variable and was estimated from the contralateral side. In soleus most denervations ranged from 83 to 99%; in FDL, from 37 to 81%. 4. In both soleus and FDL there was no evidence that the motor units had sprouted to any less extent than found previously. Within some soleus muscles the largest motor units were developing substantially more force than was expected. However, determination of mean fiber cross-sectional area from muscles frozen, sectioned, and prepared for histochemical analysis showed that this was attributable to increased mean cross-sectional area of the type I fibers.(ABSTRACT TRUNCATED AT 250 WORDS)