The quantity of rhodopsin in human eyes

The content of rhodopsin in the eyes of 15 donors (30 eyes) was determined. Both retinal and pigment epithelial fractions were collected from each globe, extracted using 1% CTAB, and the rhodopsin difference spectrum of each fraction was obtained separately. The total amount of rhodopsin, obtained by summing the amounts recovered from the retinal and PE fractions, ranged from 2.00 to 11.94 (median: 6.40) nmoles/eye. Previously reported mean values of about 3.5 to 4.0 nmoles per retina have been obtained using a variety of methods. The present higher values, perhaps largely dependent on procedural details described herein, appear plausible given the known concentrations of rhodopsin in rod outer segments, rod outer segment volumes, and number of rods in the human retina.     

Carney's triad

A 26 year old female presented with partial expression of Carney's triad. This is the first Australian report of the condition. The role of surgery and the need for vigilance to detect the occurrence of the complete triad are stressed.     

CARNEY'S TRIAD

A 26 year old female presented with partial expression of Carney's triad. This is the first Australian report of the condition. The role of surgery and the need for vigilance to detect the occurrence of the complete triad are stressed.     

Strontium and quantal release of transmitter at the neuromuscular junction

1. Previous work has shown that in calcium-free solutions nerve impulses invade the motor nerve terminals at the neuromuscular junction, but fail to release transmitter. In these conditions, strontium ions applied iontophoretically to a minute part of a junction, or to the whole muscle by bath application, restore to the nerve impulse its ability to release transmitter.2. As with calcium, the transmitter released in the presence of strontium is in the form of packages (quanta) whose release can be predicted from Poisson's Theorem.3. The mean number of quanta released by a nerve impulse increases with the concentration of strontium. Strontium is much less effective than calcium in equimolar concentrations.4. Transmitter quanta released in the presence of strontium evoke larger unit potentials than quanta released in the presence of calcium. The larger size of the Sr-unit potentials is caused by a prolongation of transmitter action, presumably due to a post-synaptic effect of strontium.5. Neuromuscular transmission was blocked in some fibres when the concentration of strontium was raised beyond 10 mM. This junctional block was presumably due to a failure in the propagation of nerve impulses.6. The post-stimulation increase in the frequency of miniature end-plate potentials, which is normally seen in calcium solutions, is also observed when calcium is substituted by strontium. The post-stimulation effect increases with the concentration of strontium.7. It is concluded that strontium can substitute for calcium in the process of quantal release of transmitter. The physico-chemical mechanism of this substitution remains unknown.     

Sex-dependent effects of amygdaloid lesions on the social play of prepubertal rats

Male and female prepubertal rats, like many primate species, differ in the frequency with which they engage in social play (play-fighting); males engage in more social play than females. This sex difference in the rat has been found to be under the control of gonadal hormones acting during the neonatal period. In the present study we examined the effects of lesions of the amygdala, a prominent neuroendocrine control area, on the play-fighting of male and female prepubertal rats. Bilateral, electrolytic lesions and sham control treatments were made at 21 or 22 days of age and the animals were then observed daily in intact groups between 26 and 40 days of age. Amygdaloid lesions suppressed social play in male rats to levels that were indistinguishable from those of control females. In contrast to males, amygdaloid lesions had no effect on the social play of females. Sex differences in the anatomy and physiology of the amygdala are discussed as a possible explanation of its apparent differential influence on the social play of male and female prepubertal rats.