The effect of the dosing schedule on aminoglycoside ototoxicity was investigated in the guinea pig. The animals were given amikacin or isepamicin either by once-daily intramuscular injection of 200 mg/kg or by twice-daily injections of 100 mg/kg for 28 days. The once-daily treatment induced a lesser degree of ototoxicity than the twice-daily injections, which may indicate that the once-daily treatment therapy has a potential value in the clinical use of aminoglycoside antibiotics. Isepamicin sulfate is a new aminoglycoside antibiotic currently undergoing clinical investigation. This study revealed that isepamicin also has ototoxic properties as has been observed in all other aminoglycosides. The degree of ototoxicity, however, was markedly less than that of amikacin.

A cochlear fistula found in a naturally healed mastoid cavity is reported. The patient is a 53-year-old Japanese woman who was complaining of unsteadiness. She hada long history of otorrhoea in childhood. Her tympanic and mastoid cavities were widely open and were covered by thin epithelium. The posterior wall of the ear canal was missing. She had no hearing in the ear but responded to electrical promontory testing. Exploratory surgery was indicated at which fistulae of the basal turn of the cochlea and the horizontal semicircular canal were found. These fistulae were sealed by pieces of bone andmuscle.

This work presents our improvement of the failure localization techniques of logic circuits using voltage contrast (VC) in yield enhancement. VC analysis is known as a useful technique for finding defects by comparing scanning electron microscope (SEM) images of a faulty device with those of a good device. However, the observation region in VC analysis should be narrowed down in advance and then failure analysis (FA) engineers need to find small differences in the SEM images in order to make it effective. We improved the software tools of the scan-based diagnosis and VC analysis support to overcome these difficulties. A hybrid technique using the fail data in both the bypass and compression modes in chain fault diagnosis reduces the diagnosis time while suppressing the amount of data explosion concerning the faulty chains. In VC analysis, accurate VC images were emulated from the design layout by taking into account the states of the transistors in the FA phase such as the "on/off" states, gate leakage, and short to ground of the power lines. FA engineers can localize the fault sites with an anomalous contrast by cross-matching between a SEM image of a faulty device and the emulated VC image without using a SEM image of a good device. These techniques accelerate the failure localization in yield enhancement and we demonstrate some examples in this paper.

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