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S L Shannon

Publications and source records attributed to S L Shannon.

5 recordsLinked to original sources
PubMed1988

Functional zones in the auditory cortex of the echolocating bat, Myotis lucifugus.

Neurophysiological mapping experiments in the auditory cortex of the frequency-modulated bat, Myotis lucifugus, reveal 3 functional subregions: a tonotopic zone located dorsally, a delay-sensitive zone more ventrally, and an intermediate zone of major overlap. The unique finding of an overlapping cortical region representing both spectral and time-delay information of echoes is intriguing in view of a recent behavioral study suggesting the convergence of such echo cues in auditory perception. (Simmons et al., Soc. Neurosci. Abstr., 13 [1987] 870).

Acoustic Stimulation↗
PubMed1973

Peroxidase arthritis. 3. Sequential changes in cellular composition of the developing inflammatory infiltrate.

Repeated daily injections of horseradish peroxidase into rabbit knee joints lead to a characteristic sequence of cellular events. Early transient infiltration with polymorphonuclear leukocytes was followed by a progressive increase in the number of macrophages. This appeared to represent, at least in part, a consequence of increased emigration of monocytes. Subsequently, increasing numbers of lymphocytes appeared. Many of the lymphocytes had frequent cytoplasmic polyribosomes. By the eighth or ninth day, immunoblasts, plasmablasts and immature plasma cells were observed; cytochemical evidence of local specific antibody synthesis first was demonstrated in such cells at this stage. These results demonstrate the sequential cellular events in an immunologic inflammatory response to local antigen. Questions remain concerning the stimulus for early monocyte emigration and macrophage accumulation, and the site of initial sensitization of lymphocytes; these problems are discussed.

Animals↗
PubMed1972

Peroxidase arthritis. I. An immunologically mediated inflammatory response with ultrastructural cytochemical localization of antigen and specific antibody.

Synovitis was produced in rabbits by daily intra-articular injections of the heterologous antigen horseradish peroxidase. The resulting "peroxidase arthritis" resembled rheumatoid arthritis histologically. Many of the subsynovial plasma cells, plasmablasts and immunoblasts contained specific antibody to horseradish peroxidase; the remainder appeared to contain immunoglobulins of other specificities. Peroxidase arthritis has unique advantages for the study of the cellular and subcellular events in the pathogenesis of the local immune inflammatory response to heterologous antigen. Antigen and specific antibody can be localized precisely by ultrastructural cytochemical technics. The reaction can be terminated at any stage, permitting observation of the early events in its pathogenesis.

Albumins↗
PubMed1972

Peroxidase arthritis. II. Lymphoid cell-endothelial interactions during a developing immunologic inflammatory response.

The interaction of lymphoid cells with vascular endothelium was studied during the development of immunologic synovitis in response to repeated intraarticular injections of a heterologous protein antigen. Lymphoid cells emigrated in venules and small veins, both by penetrating the endothelial cytoplasm and by traversing intercellular junctions. Frequent endothelial mitoses were coincident with lymphoid cell emigration. Endothelial cells in the involved vessels increased in number and bulged prominently into the vascular lumen. Endothelial nuclei contained dispersed chromatin and prominent nucleoli; the cytoplasm contained many vacuoles and abundant polyribosomes and rough-surfaced endoplasmic reticulum. Intercellular junctions were numerous and complex. These phenomena were prominent in rabbits studied after 12 to 16 daily injections; they then receded, despite continued antigenic stimulation. In animals studied after 35 or 37 daily injections, the venules appeared relatively normal, and lymphoid cell emigration was observed infrequently. Growth of new vessels was prominent at this stage. The present data do not establish whether the endothelial changes were the cause or the result of lymphoid cell emigration, although the latter seems more likely. Further studies are needed to elucidate the exact nature of these interactions.

Animals↗