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Biomedical subjects

J D Harris

Publications and source records attributed to J D Harris.

106 records · Page 6Linked to original sources
PubMed1967

An ion displacement membrame model.

The usual assumption in treating the diffusion of ions in an electric field has been that the movement of each ion is independent of the movement of the others. The resulting equation for diffusion by a succession of spontaneous jumps has been well stated by Parlin and Eyring. This paper will consider one simple case in which a different assumption is reasonable. Diffusion of monovalent positive ions is considered as a series of jumps from one fixed negative site to another. The sites are assumed to be full (electrical neutrality). Interaction occurs by the displacement of one ion by another. An ion leaves a site if and only if another ion, not necessarily of the same species, attempts to occupy the same site. Flux ratios and net fluxes are given as functions of the electrical potential, concentration ratios, and number of sites encountered in crossing the membrane. Quantitative comparisons with observations of Hodgkin and Keynes are presented.

Ions↗
PubMedDate not supplied

Human cytomegalovirus nucleic acids in tissues from congenitally infected infants.

In situ nucleic acid hybridization methods were used to study autopsy tissues from 2 infants with clinical or pathologic evidence of congenital cytomegalovirus infections: a premature infant with multiple congenital malformations and inclusion bodies in several organs and an infant with culture-proved symptomatic congenital cytomegalovirus infection. Cytomegalovirus nucleic acids were detected in lung, kidney, adrenal, thyroid, skin, pancreas, and anterior pituitary tissues. In the second infant, hybridization studies of neural tissues failed to reveal cytomegalovirus nucleic acids despite neuropathologic abnormalities consisting of extensive necrotizing ependymitis and periventricular cavitation.

Cytomegalovirus↗
PubMedDate not supplied

Eardrum displacement following stapedius muscle contraction.

Simultaneous monitoring in human subjects on the same ear of eardrum displacement by tympanomanometry, and impedance with the electroacoustic bridge, provided information concerning contraction of the stapedius muscle and its effect on eardrum displacement. Extensive control procedures were employed to elicit only the stapedius reflex; lower intensity auditory stimulation, electrocutaneous stimulation of the homolateral external ear canal, and anesthetization of nerves leading to the tensor tympani. Following these procedures the following results were obtained: (1) Extremely small biphasic and monophasic eardrum movements were seen in the stapedius--only ear to auditory and electrocutaneous stimulation; the form of the response was much less predictable to auditory stimulation. (2) At high sound intensities relatively large inward and biphasic movements of the eardrum occurred in the normal ear, unquestionably due to contraction of the tensor tympani. These results were further validated in a group of stapedectomized ears, without the stapedius but with normal tensor tympani. (3) Biphasic responses did not occur in the tensor tympani--only ear, only monophasic inward responses. (4) Upon air-jet stimulation to the orbit of the eye, these subjects had an accentuated tensor response in that large inward movements of the eardrum occurred as compared with those in normal ears, suggesting that there is an alteration of the tensor response by the presence of the stapedius muscle. Estimates of the actual eardrum displacement were calculated based on a model of the external ear canal and eardrum.

Acoustic Stimulation↗
PubMedDate not supplied

Editorial. Definition of audiology.

It is noted that the generic term audiology as the science of hearing, and the concept of the multidisciplinary audiology center, is some years older than the emergent independent profession of clinical audiology. The broader term is still useful as a device to lend much needed cohesion to a variety of approaches to the study of hearing, as a term to elicit public support for hearing research in general, and as a device to attract young persons to aspects, not necessarily clinical, of the biology of the auditory process. A trend is deplored to dissuade or even force all persons involved in serious study of hearing to refrain from designating themselves as audiologists; it is hoped that the words audiology and audiologist will continue to be very broadly defined, and it is thought that to restrict them would do ASHA-certified audiologists in the long run more harm than good. It is suggested that these virtues of the generic word audiology could be amicably retained, while offering a fully professional identity to practitioners of audiology in the clinic, by rewording the current "CCC-A" to read "Certificate of Competence in Clinical Audiology" and its holders be known, as in fact they commonly are, as "Clinical Audiologists;" this by analogy with the current widespread practice in psychology.

Audiology↗