Efficacy of portable X-ray in identifying retained suture needles in ophthalmologic cases.

AIMS: To evaluate the role and efficacy of portable X-ray in reliably identifying retained suture needles in ophthalmologic surgical cases. METHODS: Ophthalmologic 10-0 nylon suture needles were placed into 10 of 20 porcine eyes positioned within the orbit of a human skull. Portable, plain film radiographs were taken of all eyes with a C-arm fluoroscopy machine. The films were reviewed by six ophthalmologists and six radiologists who were blinded to the presence or absence of needles, as well as the number of needles used in the protocol. The sensitivity and specificity of identifying retained suture needles by plain film radiographs were then analysed based on the results of the physicians' interpretations of the films. RESULTS: The overall sensitivity and specificity for physicians reviewing radiographs with suspected intraoperative suture needles were 54 and 77%, respectively. When looking separately at radiologists reviewing the films, the sensitivity was 57% and the specificity was 87%. Ophthalmologists reviewing the films identified retained needles less reliably with a sensitivity of 51% and a specificity of 67%. CONCLUSIONS: Significant controversy exists regarding the reliability and utility of plain film radiography in identifying intraocular foreign bodies. This study demonstrates that the use of plain film radiographs to rule-out the presence of an intraocular surgical needle is neither a sensitive nor specific imaging modality.

Subcellular and subsynaptic localization of presynaptic and postsynaptic kainate receptor subunits in the monkey striatum.

The localization and functions of kainate receptors (KARs) in the CNS are still poorly known. In the striatum, GluR6/7 and KA2 immunoreactivity is expressed presynaptically in a subpopulation of glutamatergic terminals and postsynaptically in dendrites and spines. The goal of this study was to further characterize the subcellular and subsynaptic localization of kainate receptor subunits in the monkey striatum. Immunoperoxidase data reveal that the relative abundance of GluR6/7- and KA2-immunoreactive terminals is homogeneous throughout the striatum irrespective of the differential degree of striatal degeneration in Huntington's disease. Pre-embedding and post-embedding immunogold data indicate that >70% of the presynaptic or postsynaptic GluR6/7 and KA2 labeling is expressed intracellularly. In material stained with the post-embedding immunogold method, approximately one-third of plasma membrane-bound gold particles labeling in axon terminals and spines is associated with asymmetric synapses, thereby representing synaptic kainate receptor subunits. On the other hand, >60% of the plasma-membrane bound labeling is extrasynaptic. Both GluR6/7 and KA2 labeling in glutamatergic terminals often occurs in clusters of gold particles along the membrane of large vesicular organelles located at various distances from the presynaptic grid. Anterograde labeling from the primary motor cortex or the centromedian thalamic nucleus indicate that both corticostriatal and thalamostriatal terminals express presynaptic GluR6/7 and KA2 immunoreactivity in the postcommissural putamen. In conclusion, these data demonstrate that kainate receptors in the striatum display a pattern of subcellular distribution different from other ionotropic glutamate receptor subtypes, but consistent with their metabotropic-like functions recently shown in the hippocampus.

Ionotropic and metabotropic GABA and glutamate receptors in primate basal ganglia.

The functions of glutamate and GABA in the CNS are mediated by ionotropic and metabotropic, G protein-coupled, receptors. Both receptor families are widely expressed in basal ganglia structures in primates and nonprimates. The recent development of highly specific antibodies and/or cDNA probes allowed the better characterization of the cellular localization of various GABA and glutamate receptor subtypes in the primate basal ganglia. Furthermore, the use of high resolution immunogold techniques at the electron microscopic level led to major breakthroughs in our understanding of the subsynaptic and subcellular localization of these receptors in primates. In this review, we will provide a detailed account of the current knowledge of the localization of these receptors in the basal ganglia of humans and monkeys.

Anatomy of the dopamine system in the basal ganglia.

The dopaminergic nigropallidal and nigrosubthalamic projections control the activity of the globus pallidus and subthalamic nucleus neurons in both normal and pathological conditions. Intrastriatal dopaminergic neurons increase substantially in animal models of Parkinson's disease. They contain GABA, display the ultrastructural features of interneurons and form axo-axonic synapses with putative cortical-like glutamatergic boutons. The local dendritic release of dopamine by neurons in the substantia nigra pars compacta and ventral tegmental also influences basal ganglia functions. Thus, the long-term belief that the effects of dopamine in the basal ganglia were solely mediated through the nigrostriatal system must be changed to take into account extrastriatal dopaminergic projections and intrastriatal dopaminergic neurons.