PD is a common, late-onset neurodegenerative disorder that results in part from the gradual loss of dopaminergic neurons in the substantia nigra pars compacta. The neurotoxin MPTP can induce PD-like clinical symptomatology and neuropathological destruction and, thus, has been used as a PD model. The human neuroblastoma cell line SH-SY5Y possesses many of the qualities of human neurons and, as such, has served as a model for them. Apoptosis is the mode of cell death induced in SH-SY5Y cells by MPTP, and this was confirmed with nick end labeling and bisbenzimide staining. Transmission electron microscopic analysis of the ultrastructural changes occurring in neurotoxin exposed SH-SY5Ys revealed many morphological characteristics consistent with apoptosis. These changes included plasmalemmal blebbing, altered cytosolic density, nuclear condensation and fragmentation, pronounced vacuole formation, ribosomal dispersion, and the disappearance of the golgi complex, microtubules, and smooth endoplasmic reticulum. Limited amounts of rough endoplasmic reticulum and mitochondria exhibited normal morphology throughout the apoptotic changes but then were disrupted during secondary necrotic changes. The in vitro induction of apoptosis by a parkinsonism neurotoxin might be reflective of the mechanisms of in vivo nigral degeneration occurring during PD.

\s=b\The possible synergism between noise and aspirin for causing cochlear damage was examined histologically. Six chicks fed aspirin for five days and five chicks fed a normal diet only were paired and placed in sound chambers. They were exposed to a 1500-Hz tone at 115 dB sound pressure level for eight hours. The mean serum salicylate level just before noise exposure was 24 mg/dL (1.74 mmol/L). Ten days later they were killed, and the temporal bones were processed. Hair cell counts were made at 100-\g=m\m intervals throughout the length of the basilar papilla (cochlea). The noise produced a discrete cochlear lesion centered about 30% of the distance from the base to apex. The addition of aspirin did not significantly alter the extent or location of this lesion. One aspirin-fed chick had a unilateral middle ear effusion, and a striking shift in the center of damage toward the apex was noted in this cochlea.

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In a previous publication 1 it has been suggested that the circula tion of the labyrinthine fluids is probably a dynamic process. This paper reports experiments with dyes as the second of a series of various methods of investigation to determine the origin and absorption of the labyrinthine fluids in living animals. Fluorescein (molecular weight 332.296) and trypan blue (molecular weight 960.808) were selected. This approach was tried because it is simple and the advan tages and disadvantages of these dyes are well known. It was realized that the use of dyes alone could never provide all the information re quired.It was hoped, however, that this method might supply sufficient data to provide a foundation for research of a more complex nature.Guild 2 used Prussian blue to investigate the circulation of endo lymph and Altmann and Waltner 3 examined both endolymph and