Metabolic, pediatric, and systemic ophthalmology最新文献

Two different hypotheses in modern physics according to which protons might disappear are discussed: Gravitational collapse of matter into black holes, and proton decay according to Unified Gauge Theories. The latter might soon be observed in experiments in which sensitive detectors are placed in a mass of 1000 tons of matter (10(33) protons) in a deep tunnel or mine. One hundred observed decays per year would correspond to an "expected lifetime" of 10(31) years for an individual proton, as predicted by these theories.

Electroretinographic studies have been helpful in differentiating human forms of retinitis pigmentosa inherited by different patterns. The prognosis appears to be correlated with the mode of inheritance. The recessively inherited form along with the x-linked and dominantly inherited with reduced penetrance type of inheritance are associated with more severe forms of the disease than is the dominantly inherited with complete penetrance. The underlying biochemical defects have not been identified. Human pathological specimens early in the disease have been almost nonexistent. Animal models have been identified but correlation with human disease has been markedly limited [1]. Electrophysiology and recent technology offer some prospect for differentiating responsible abnormalities and offer a noninvasive evaluation of the disease process and treatment. Three cases of dominantly inherited retinitis pigmentosa with complete penetrance are presented. These show a decreasing B-wave amplitude on successive photopic evaluations using fast random stimuli.

In bovine ocular tissues, cornea and retina-including choroid provide the intracellular proline synthetic pathway from ornithine, but not from glutamate. In C3H retinal degeneration mice, P5C reductase activity in the retina and choroid was decreased to about one-third that of CRJ control mice in the specific activity after the tenth day. The activity of an incorporation of 14C-ornithine into proline in the retina and choroid was also decreased to the same extent after the weaning period, in the retinal degeneration mice. Postnatal changes of P5C reductase and ornithine oxoacid aminotransferase activities in the livers of C3H mice showed a pattern that reflected a delayed weaning. Thus, possibly due to the blood-retinal barrier, "an abiotrophy of some membrane formation" resulting from a proline deficiency at the locus may be attributable as an important factor for the development of retinal degeneration.

Environmental influences on the developing primary visual cortex of kittens were studied by exposing dark reared kittens to prism-induced interocular rotational disparities of 32 degrees, the visual input rotated equally and oppositely in the two eyes. The present report describes preliminary results obtained from two kittens that received this altered visual exposure during 1-6 hours each day from 4 until 12 weeks of age. Subsequent single-unit recordings from the striate cortex revealed three major changes in functional cortical visual physiology. First, there was a disruption in binocularity, with many more cells being monocularly driven in the rotated conditions compared to control conditions. Second, there was an increased variance in the distribution of cells' interocular differences in preferred stimulus orientation (interocular orientation disparity, or IOD) as compared to control conditions. Third, changes were noted in orientation tuning and in the distribution of orientation preferences: cells most selective for orientation tended to be in the extreme ocular dominance groups, and monocular cells were often the most highly selective; also, both binocular and monocular cells showed a tendency for preferred orientations for both eyes to fall near the horizontal or vertical (+/- 22.5 degrees). Thus, a large optically-induced orientation disparity between the two eyes' visual fields during the critical period can modify the characteristics of striate cortical neurons, particularly binocularity and IOD. In addition, these results indicate that an inherent cortical mechanism may ensure the encoding of horizontal and vertical orientation specificities for a subclass of primary visual cortical neurons.

We have studied the effect of surgically induced monocular rotation of the eye on cells in visual area 17 of normal kittens (N = 420 cells) and of kittens monocularly deprived (N = 296 cells) at early (1-1.5 months) or late (3 months) ages. The receptive fields of cortical neurons in monocularly deprived kittens of the early operated group were abnormal in shape, a condition which is reflected by the high proportions of cells missing orientation (46.9%) and direction (47.7%) specificity when driven through the rotated eye. In addition, many cells (46%) were visually inactive in these kittens. The proportions of the above cell groups were less pronounced in the operated kittens with binocular vision and in all late operated kittens, indicating a specific effect of the rotation itself. In the early operated kittens with binocular vision, the rotation resulted in 35.9% binocular cells in the hemisphere contralateral and 40.0% in the hemisphere ipsilateral to the rotated eye. The results for the monocularly deprived early operated kittens were 42.8% and 21.5% respectively. Thus, the rotation was effective in limiting the influence of the deprivation to only the contralateral hemisphere. The distribution of the cells in accordance with their receptive field orientations following correction for the surgical rotation shows a considerable disturbance to orientation specificity, as reflected by the wide range of angular disparities found for the binocular cells. While for three kittens (28 cells) a tendency toward the zero line was found, for four kittens (28 cells) we could not prove, it indicating that a compensation for the interocular difference surgically induced is not seen.