[Vitrectomy combined with scleral buckling for the treatment of complicated retinal detachment]

PURPOSE

To raise operative successful rate of complicated retinal detachment, we used the methods of vitrectomy combined with scleral buckling for the treatment of complicated retinal detachment.

METHODS

The operative methods included: scleral buckling, vitrectomy, membrane peeling, intraocular and extraocular drainage, gas and silicone oil tamponade.

RESULT

Being followed up for 1-16 months, 22 eyes got anatomic reattachment in 29 eyes, the operative successful rate was 75.8%; 15 eyes were injected with silicone oil intraocular tamponade, with 12 eyes getting reattachment. The successful rate was 80%.

CONCLUSION

Since the vitreous surgery is used, it is possible for the treatment of complicated retinal detachment, the operative successful rate can be raised. The technique of membrane peeling and intraocular tamponade was very important. Silicone oil has been accepted by more and more ophthalologists in the world, which acts as an effective material of intraocular tamponade.

Widespread expression of Huntington's disease gene (IT15) protein product

Huntington's Disease (HD) is caused by expansion of a CAG repeat within a putative open reading frame of a recently identified gene, IT15. We have examined the expression of the gene's protein product using antibodies developed against the N-terminus and an internal epitope. Both antisera recognize a 350 kDa protein, the predicted size, indicating that the CAG repeat is translated into polyglutamine. The HD protein product is widely expressed, most highly in neurons in the brain. There is no enrichment in the striatum, the site of greatest pathology in HD. Within neurons, the protein is diminished in nuclei and mitochondria and is present in the soluble cytoplasmic compartment, as well as loosely associated with membranes or cytoskeleton, in cell bodies, dendrites, and axons. It is concentrated in nerve terminals, including terminals within the caudate and putamen. Thus, the normal HD gene product may be involved in common intracellular functions, and possibly in regulation of nerve terminal function. The product of the expanded allele is expressed, consistent with a gain of function mechanism for HD at the protein level.

Brain L-glutamate decarboxylase. Inhibition by phosphorylation and activation by dephosphorylation

Previously we showed that the activity of the gamma-aminobutyric acid-synthesizing enzyme L-glutamate decarboxylase (GAD) in crude brain extract is inhibited by ATP and protein phosphatase inhibitors. We suggested that GAD activity is regulated by protein phosphorylation. In this paper we further present evidence to support our hypothesis that protein kinase A and calcineurin may be involved in regulation of GAD activity through phosphorylation and dephosphorylation fo GAD, respectively. In addition, the effect of neuronal stimulation on GAD activity in cultured neurons is also included. A model to link neuronal excitation and activation of GAD by Ca(2+)-dependent phosphatase is proposed.

Traumatic brain injury reduces hippocampal high-affinity [3H]choline uptake but not extracellular choline levels in rats

Hippocampal cholinergic hypofunction may contribute to memory deficits following experimental traumatic brain injury. These studies examined two important factors in acetylcholine synthesis: choline availability and neuronal uptake. No reductions in basal extracellular choline levels, using microdialysis, were observed 2 weeks after cortical impact injury. However, studies of high affinity [3H]choline uptake in the hippocampus, measured in a synaptosomal preparation, found a reduction in the maximum velocity of choline uptake (Vmax), while no differences in affinity constants (Km) were found. The results suggest that post-traumatic cholinergic deficits are not attributable to decreased availability of choline, but may be associated with either a decreased ability of cholinergic neurons to take up choline and/or a loss of cholinergic neurons.

Role of Protein Phosphorylation in Regulation of Brain L-Glutamate Decarboxylase Activity

In the brain, the gamma-aminobutyric acid (GABA) level is primarily controlled by the activity of its synthesizing enzyme, L-glutamate decarboxylase (GAD). At present, mechanisms responsible for regulation of GAD activity remain largely unknown. Here we report that GAD activity is inhibited by conditions favoring protein phosphorylation, and this inhibition can be reversed by phosphatase treatment. Furthermore, this inhibition appears to result from the suppression of a Ca(2+)-dependent phosphatase. Phosphorylation of GAD is demonstrated by direct incorporation of (32)P into the GAD protein. These results suggest that GAD activity in the brain is inhibited by phosphorylation and activated by dephosphorylation. A model for regulation of GABA synthesis related to neuronal excitation is discussed. Copyright 1994 S. Karger AG, Basel