RESUMEN
Glutamate is used as an excitatory neurotransmitter by the koniocellular (K), magnocellular (M), and parvocellular (P) pathways to transfer signals from the primate lateral geniculate nucleus (LGN) to primary visual cortex (V1). Glutamate acts through both fast ionotropic receptors, which appear to carry the main sensory message, and slower, modulatory metabotropic receptors (mGluRs). In this study, we asked whether mGluR5 relates in distinct ways to the K, M, and P LGN axons in V1. To answer this question, we used light microscopic immunocytochemistry and preembedding electron microscopic immunogold labeling to determine the localization of mGluR5 within the layers of V1 in relation to the K, M, and P pathways in macaque and squirrel monkeys. These pathways were labeled separately via wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injections targeting the LGN layers. mGluR5 is of interest because it: 1) has been shown to be expressed in the thalamic input layers; 2) appears to be responsible for some types of oscillatory firing, which could be important in the binding of visual features; and 3) has been associated with a number of sensory-motor gating-related pathologies, including schizophrenia and autism. Our results demonstrated the presence of mGluR5 in the neuropil of all V1 layers. This protein was lowest in IVCα (M input) and the infragranular layers. In layer IVC, mGluR5 also was found postsynaptic to about 30% of labeled axons, but the distribution was uneven, such that postsynaptic mGluR5 label tended to occur opposite smaller (presumed P), and not larger (presumed M) axon terminals. Only in the K pathway in layer IIIB, however, was mGluR5 always found in the axon terminals themselves. The presence of mGluR5 in K axons and not in M and P axons, and the presence of mGluR5 postsynaptic mainly to smaller P and not larger M axons suggest that the response to the release of glutamate is modulated in distinct ways within and between the parallel visual pathways of primates.
RESUMEN
Processing hazardous solid wastes in a DC arc melter offers several advantages over other competitive methods, including the ability to vary the mixture chemistry independently of the energy input. This decoupling allows the melter to be operated in conditions that enhance material recovery while continuing to provide robust waste destruction. This paper describes the use of a previously developed model to investigate the effect of chlorinated additives on metal volatilization in batch melters. Chlorinated species are shown to vary in their effectiveness as an additive; the potential to simultaneously treat solid wastes and chlorinated organics is also confirmed. At low additive levels the amount of chlorine, regardless of molecular form, determines the volatilization level, with a linear relationship between chlorine feed amount and volatilization. At high additive levels, CCl4 becomes increasingly more effective as an additive, causing greater volatilization by a preferred set of species, while NaCl volatilizes almost completely without reacting, rendering it an ineffective additive.
RESUMEN
Ashley Wenger is a graduate student in the Mechanical Engineering and Mechanics (MEM) Department at Drexel University. Dr. Bakhtier Farouk is a professor in the MEM Department at Drexel University, 32nd and Chestnut Streets, Philadelphia, PA 19104. Dr. J. Kenneth Wittle is the vice president of Electro-Pyrolysis, Inc., Suite 1118, 996 Old Eagle School Road, Wayne, PA 19087. Please address all correspondence to Dr. Bakhtier Farouk.