The Effects of Imidates on the Encephalitogenicity of Myelin Basic Protein

Because the encephalitogenic tryptophan region within the porcine basic protein contains a lysine essential for disease induction, modification of the residue with imidates should further elucidate its contribution to basic protein encephalitogenicity. The modification of the encephalitogenic basic protein from myelin does not eliminate encephalitogenicity irrespective of the size of the imidate employed. This result suggests that the positive group in the tryptophan region functions only to help maintain a necessary overall conformation of the region.     

Adaptation of the vestibulo-ocular reflex in amblyopia

Adaptation of the vestibulo-ocular reflex (VOR) is demonstrated by changes in gain in response to discrepancies between visual and vestibular stimulation. The authors have investigated the effect of monocular asymmetries of OKN in amblyopia upon adapting the gain of the VOR. Adaptation was investigated by modifying the horizontal balance of the VOR. While monocularly fixating a head referenced spot for 2 min, subjects were sinusoidally oscillated on a chair inside an optokinetic drum that rotated in one direction (left or right) at the peak velocity of sinusoidal chair rotation. The VOR was then measured during continued sinusoidal body oscillation in darkness for 1 min. Imbalance of the horizontal VOR gain equalled the ratio of slow phase velocities in the rightward and leftward directions. After rotating the drum in the nasalward direction, an increase was observed in slow phase gain of the VOR in the nasalward direction for either eye of our amblyopes that was significantly greater than similar changes in gain for the normals. Increased VOR gains for the amblyopic group following temporalward stimulation were significantly less than the nasal aftereffect. Gain changes of the VOR in normals had similar magnitudes following nasal or temporal stimulation. These results suggest that disturbances of OKN in amblyopia are common to the pathways that modify the slow phase gain of the VOR.     

Asymmetries of optokinetic nystagmus in amblyopia: the effect of selected retinal stimulation

Open loop optokinetic eye movements were measured in response to monocular nasalward and temporalward visual field movement presented at four selected retinal sites in 6 strabismic amblyopes and 4 normal observers. Stimulus sites included the central retina (10 X 10 deg), a large field (40 X 32 deg), a large peripheral field with the center (10 X 10 deg) blocked out and a hemiretinal field (15 X 32 deg) excluding the fovea. We found directional preferences of OKN in amblyopia to nasalward stimulus movement for the foveal and concentric peripheral stimuli. The results of peripheral hemiretinal optokinetic stimulation of amblyopic subjects revealed a deficient OKN slow phase response from the temporal hemiretina, particularly for temporalward stimulus movement. There was no marked asymmetry of OKN in the normal group for the concentric stimuli. A normal preference was found for nasalward and temporalward stimulus field movement imaged on the nasal and temporal hemiretinae respectively. These results are interpreted in terms of a model of cortical and subcortical pathways for OKN derived from comparative studies of cat and monkey.     

Urinary melatonin excretion throughout the ovarian cycle in menstrually related migraine

Nocturnal urinary melatonin excretion was significantly decreased throughout an ovarian cycle in 12 migraine without aura patients compared to 8 healthy controls. Normal increases in urinary melatonin excretion during the luteal phase was less pronounced in the migraine patients. Melatonin excretion was further decreased during headache. The data indicate impaired pineal function in migraine.     

High dose inhibition of the tryptophan peptide induced encephalitogenicity.

In a previous publication (Immunol. Comm. 3:219, 1974) a hypothesis was proposed that the high dose inhibition of encephalitogenicity in giunea pigs seen with the tryptophan peptide, phe ser trp gly ala glu gly gln arg, and not observed with the whole myelin basic protein which contains this sequence, was the result of competitive inhibition by non-encephalitogenic fragments of the tryptophan peptide produced in vivo possibly by exopeptidases. I present data which disagrees with this hypothesis.