Effects of subacute boric acid administration on rat kidney tissue.

BACKGROUND/AIMS: Boron is used in manufacturing processes and numerous consumer products. Clarification of boron toxicity is important because of industrial and consumer exposure to boron and boron-containing compounds. The aim of this study was to observe effects of subacute boric acid administration on rat kidney tissue. MATERIALS AND METHODS: A total of 96 male albino Sprague-Dawley rats were used in this study. Seventy-two rats were selected for the experimental group and 24 rats constituted the control group. Experimental group rats were divided into three groups for exposure to three different doses of orally administered boric acid (100-275-400 mg/kg/day). Kidney tissues were removed at the 10th, 30th, and 45th day after sacrificing the rats. Kidney weights, kidney boron concentration and histopathological changes were determined. RESULTS: In the experimental group, a significant accumulation of boron in kidney tissue was seen, but there was a significant drop in boron concentration on the 45th day compared with the 30th day. Histopathological degenerative changes were observed especially in the proximal tubule cells that were dose- and time-dependent. CONCLUSION: Subacute boric acid exposure caused dose-dependent histopathological changes in kidney tissue.

Superficial or deep implantation of motor nerve after denervation: an experimental study--superficial or deep implantation of motor nerve.

Neurorraphy, conventional nerve grafting technique, and artificial nerve conduits are not enough for repair in severe injuries of peripheral nerves, especially when there is separation of motor nerve from muscle tissue. In these nerve injuries, reinnervation is indicated for neurotization. The distal end of a peripheral nerve is divided into fascicles and implanted into the aneural zone of target muscle tissue. It is not known how deeply fascicles should be implanted into muscle tissue. A comparative study of superficial and deep implantation of separated motor nerve into muscle tissue is presented in the gastrocnemius muscle of rabbits. In this experimental study, 30 white New Zealand rabbits were used and divided into 3 groups of 10 rabbits each. In the first group (controls, group I), only surgical exposure of the gastrocnemius muscle and motor nerve (tibial nerve) was done without any injury to nerves. In the superficial implantation group (group II), tibial nerves were separated and divided into their own fascicles. These fascicles were implanted superficially into the lateral head of gastrocnemius muscle-aneural zone. In the deep implantation group (group III), the tibial nerves were separated and divided into their own fascicles. These fascicles were implanted around the center of the muscle mass, into the lateral head of the gastrocnemius muscle-aneural zone. Six months later, histopathological changes and functional recovery of the gastrocnemius muscle were investigated. Both experimental groups had less muscular weight than in the control group. It was found that functional recovery was achieved in both experimental groups, and was better in the superficial implantation group than the deep implantation group. EMG recordings revealed that polyphasic and late potentials were frequently seen in both experimental groups. Degeneration and regeneration of myofibrils were observed in both experimental groups. New motor end-plates were formed in a scattered manner in both experimental groups. However, they were more dense in the superficial implantation group than the deep implantation group. It was concluded that superficial implantation has a more powerful contractile capacity than that of deep implantation. We believe that this might arise from the high activity of glycolytic enzymes in peripheral muscle fibers of gastrocnemius muscle, decrease in insufficient intramuscular guidance apparatus, and intramuscular microneuroma formation at the insufficient neuromuscular junction since the motor nerve had less route to muscle fibers.