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Biomedical subjects

J A Donaldson

Publications and source records attributed to J A Donaldson.

At least 19 recordsLinked to original sources
PubMed1988

Surgical management of otitis media (recurrent and nonsuppurative).

In 1977 Paradise outlined the role of tympanostomy tubes in nonsuppurative otitis media. Over the intervening 10 years the role has changed little. Exceptions would be the demonstrated advantage of tube placement over myringotomy alone in those patients with effusion for longer than 2 or 3 months, or over prophylactic sulfonamide or placebo in recurrent otitis media.

Anesthesia↗
PubMed1982

Entrainment of circadian rhythms: retinofugal pathways and unilateral suprachiasmatic nucleus lesions.

The role of retinohypothalamic input to the suprachiasmatic nuclei (SCN) as well as SCN afferents from the ventrolateral geniculate nuclei (LGNV) in the entrainment of circadian drinking rhythms was investigated in the rat. Bilateral lesions of the LGNV and the primary optic tracts had no affect on the entrainment of drinking rhythms to a light-dark cycle, the response to a 12 hr phase shift of the light-dark cycle, or on the period of the free-running circadian rhythm in constant light or constant darkness. Unilateral blinding in rats with or without LGNV lesions retarded the rate of phase shifting by 2 days and decreased the period of the free-running rhythm in constant light. For rats with unilateral SCN lesions, or such lesions combined with either ipsi- or contra-lateral blinding, the rate of re-entrainment was intermediate between intact and unilaterally blinded rats indicating that unilateral SCN lesions partially reversed the effects of unilateral blinding. Unilateral SCN lesions had no effect on the period of the free-running rhythm in constant light or darkness. These results are consistent with the interpretation that the asymmetrical innervation of the two SCN by the RHT in unilaterally blinded rats delays re-entrainment by changing the phase response curve of the circadian system. This change may be mediated by neural connections between the two SCN.

Animals↗
PubMed1981

Middle ear fluid.

Most middle ear effusions are preceded by an episode of acute otitis media. Craniofacial abnormalities predispose to such problems, and eustachian tube dysfunction is thought to be an important factor as well. Mechanical obstruction of the tube by inflammation or functional obstruction due to increased compliance leads to a failure to clear secretions produced by the middle ear. Removal of the obstruction is essential. If medical management does not clear the fluid, myringotomy with ventilating tubes may be required.

Humans↗
PubMed1980

Hyperactive vestibular response of peripheral origin.

Hyperactive vestibular response in a patient was documented with electronystagmography (ENG). The patient's symptoms were relieved for a year following placement of a shunt from the saccus endolymphaticus to the subarachnoid space. Recurring symptoms were relieved for three years by cryosurgery to the hyperactive labyrinth. Activity of the involved labyrinth was shown on electronystagmography to be hyperactive when the patient was symptomatic and normal or hypoactive when the patient was asymptomatic.

Caloric Tests↗
PubMed1979

Vestibular effects of electrical stimulation of the cochlea. Monitored in the awake primate.

The effect of electrical stimulation of the cochlea on vestibular response was monitored in six rhesus monkeys. Eye movements and single-unit activity from the vestibular portion of the eighth nerve, vestibular nuclei, reticular formation, and abducens nucleus were observed while electrical stimulation was delivered through an implanted cochlear prosthesis. In one animal of this series, neural activity from the inferior colliculus and cochlear nuclear complex was also recorded. Electrical stimulation elicited eye-movement responses in only one animal. In the animals from which single-unit activity was recorded, no positive vestibular effects were noted. In one animal of this study, responses were elicited from auditory structures by relatively low intensities of electrical stimulation.

Acoustic Stimulation↗
PubMed1979

Heparin therapy for sudden sensorineural hearing loss.

Twenty-three patients with sudden unilateral sensorineural hearing loss were treated with a course of intravenous heparin sodium within one week of the onset of the hearing loss. Complete or good recovery developed in a total of 69.6% of these patients, but this is very similar to previously reported criteria of 66% spontaneous recovery. There was one complication in the series, ie. priapism.

Female↗
PubMed1975

Normal anatomy of the inner ear.

The three parts of the inner ear have been reviewed: the membranous (endolymph containing) labyrinth surrounded by the osseous (perilymph containing) labyrinth, and the otic capsule of bone that encases the osseous labyrinth. This is a brief survey of the normal anatomy, but one must always remember that the hallmark of the temporal bone is variation.

Ear, Inner↗