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Biomedical subjects

A R Eden

Publications and source records attributed to A R Eden.

30 records · Page 2Linked to original sources
PubMed1983

A study of some of the ascending and descending vestibular pathways in the pigeon (Columba livia) using anterograde transneuronal autoradiography.

A mixture of tritiated proline and fucose was injected into the endolymph of one of the membranous labyrinths of each of 5 white king pigeons (Columba livia). The membranous labyrinth was resealed and the animals were allowed to survive for 15 days. Brains and upper parts of the spinal cords were sectioned and processed by standard autoradiographic procedures. Clear labeling was noted in structures usually associated with both the ascending auditory pathways and the ascending and descending vestibular pathways. Vestibular structures ipsilateral to the injected labyrinth which contained heavy labeling were Scarpa's ganglion and all 6 vestibular nuclei. No labeling was noted in the contralateral Scarpa's ganglion and sparce, if any, labeling was noted in the contralateral vestibular nuclei. Contralateral structures associated with ascending vestibulo-ocular pathways which contained heavy labeling were the medial longitudinal fasciculus, abducens nucleus, trochlear nucleus, and two parts of the oculomotor nucleus--the dorsolateral part and the ventromedial part. Less heavily labeled ipsilateral vestibulo-ocular-related structures included the medial longitudinal fasciculus, abducens nucleus and the ventrolateral edge of the trochlear nucleus. The dorsomedial part of the oculomotor nucleus was heavily labeled on the side ipsilateral to the injected labyrinth. Slight, if any, labeling was noted in either the ipsilateral or contralateral brachium conjunctivum or regions corresponding to the mammalian ascending tract of Deiters. The medullary core of most folia but primarily the medullary core and granular areas of folia IX and X of the cerebellum were labeled.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1982

Identification of multiple groups of efferent vestibular neurons in the adult pigeon using horseradish peroxidase and DAPI.

This study was designed to investigate the efferent innervation of the pigeon labyrinth. Horseradish peroxidase (HRP) was injected and confined within the endolymphatic space of one labyrinth in 9 adult pigeons. The brain was perfused by transcardiac carotid catheterization and the HRP reacted by the tetramethylbenzidine (TMB) blue reaction process. Five different groups of HRP-labeled vestibular efferent neurons were identified. Three groups were located within the confines of the ipsilateral vestibular nuclear complex (in the lateral, tangential and descending nucleus) and two additional groups, each bilateral, were located in the reticular formation. In 9 additional pigeons, 4,6-diamidino-2-phenylindole (DAPI) was also injected and confined within the endolymphatic space of one labyrinth. DAPI-labeled cells were noted in 3 of the 5 locations (tangential nucleus, and both reticular groups) which in the other animals contained HRP-labeled cells. These findings raise the possibility of different physiological roles for the efferent vestibular groups in the ipsilateral vestibular nuclear complex and bilateral reticular formation.

Animals↗
PubMed1982

Medullary proprioceptive neurons from extraocular muscles in the pigeon identified with horseradish peroxidase.

Three to five microliters of 50% HRP in saline was injected along a central axis into one of the 6 extraocular muscles in each of 18 adult pigeons. The brain was fixed and serially sectioned 16-20 h postinjection and the HRP reacted with tetramethylbenzidine (TMB). HRP-labeled proprioceptive neurons were located in the ipsilateral nucleus descendens nervi trigemini (TTD) for all muscle injections. The labeled neurons were further subdivided into two groups based on size and shape. In each experiment the number of labeled proprioceptive cells relative to the number of labeled motoneurons ranged between 4.9 and 15.5%. There were no labeled cells in the trigeminal mesencephalic nucleus or contralateral TTD. The study suggests that at least partial afferent (proprioceptive) innervation of the extraocular muscles in the pigeon derived from neurons in the ipsilateral TTD.

Animals↗
PubMed1982

Organization of ascending auditory pathways in the pigeon (Columba livia) as determined by autoradiographic methods.

A mixture of tritiated proline and fucose was injected into the labyrinthine endolymphatic space of 5 white king pigeons (Columba livia). Using standard autoradiographic techniques, we observed transsynaptic labeling in ascending auditory pathways to the level of the mesencephalon. Auditory system structures, ipsilateral to the injection site, which labeled heavily were the cochlear nerve, the magnocellular and angular nuclei, and the superior olive. Those ipsilateral structures which were slightly labeled were the lateral lemniscus and the dorsal part of the lateral mesencephalic nucleus. Contralateral structures which labeled were the superior olive, lateral lemniscus, and dorsal part of the lateral mesencephalic nucleus. The results of this study suggest that ascending auditory pathways (to the level of the mesencephalon) in the pigeon are more similar to those described for mammals in general than previously thought.

Abducens Nerve↗
PubMed1981

Vestibular efferent neurons and catecholamine cell groups in the reticular formation of the pigeon.

This study was designed to investigate the relationship between vestibular efferent neurons and catecholamine cell groups within the reticular formation of the pigeon. Horseradish peroxidase (HRP) was injected into the endolymphatic space of one labyrinth. The brain was perfused with glyoxylic acid and serial sections were examined with a fluorescence microscope. After documentation of the location of fluorescent cells the sections were reacted for HRP with tetramethylbenzidine. Fluorescent cells were noted intermingled among the HRP-labeled vestibular efferent neurons in the nucleus reticularis pontis caudalis. No neurons were both fluorescent and HRP-positive. Fluorescent cells were also noted bilaterally in locus ceruleus, raphe nucleus, and in close proximity to the abducent, facial, hypoglossal and ambiguus nuclei.

Animals↗
PubMed1978

Sudden bilateral hearing loss and meningitis in adults.

Sudden profound bilateral sensorineural hearing loss is a serious complication of bacterial meningitis. With high dosage Dexamethasone it is possible to halt, and, in some instances, to reverse the progression of the hearing loss. The efficacy of treatment depends upon early diagnosis. Hearing may worsen upon steroid cessation and low dosage oral steroid may be required for several months. The eventual hearing loss may be considerably worse than anticipated. Two cases illustrating differing aspects of the disease are described.

Adult↗
PubMedDate not supplied

Evaluation of three cyanoacrylate glues for ossicular reconstruction.

We evaluated and compared the separate effects of ethyl, isobutyl, and fluoroalkyl cyanoacrylate on the promontory mucosa and surgically disarticulated incudostapedial joint in the adult cat middle ear. The animals were sacrificed at 10-, 30-, and 60-day intervals after glue application. All three cyanoacrylates elicited a chronic inflammatory response when placed directly on the promontory mucosa. The use of ethyl and isobutyl cyanoacrylate resulted in persisting discontinuity of the incudostapedial joint with erosion of the incus. Fluoroalkyl cyanoacrylate maintained incudostapedial continuity without ossicular erosion. Ethyl and isobutyl cyanoacrylate are probably not appropriate for middle ear surgery. The less toxic fluoroalkyl cyanoacrylate may be useful as an ossicular adhesive in selected cases. Our findings are further contrasted with those obtained in similar studies with methyl and butyl cyanoacrylate. The effects of each of the five cyanoacrylates are reviewed in the continuing search for a safe and effective ossicular adhesive.

Animals↗