Biomedical subjects

L J Hood

Publications and source records attributed to L J Hood.

8 recordsLinked to original sources

PubMed1991

Derived guinea pig compound VIIIth nerve action potentials to continuous pure tones.

A technique is described which verifies neural activity to a very faint continuous sine wave through subtraction of two different far-field whole nerve action potentials from one another. A brief transient is presented to an animal in order to elicit a supra-threshold action potential. The technique is then repeated, but on the second trial a near-threshold sine wave is mixed with the transient and another action potential is collected. The resultant evoked is then subtracted from the evoked potential generated by the transient alone and a small but persistent difference potential is acquired that presumably represents the unit activity occupied by the continuous sine wave. Four experiments are presented to show the validity of this technique, along with a surprising stability of the derived-response latency despite a 30 dB range of the probes. The technique may have promise in predicting behavioral responses to sinusoids acquired from individual animals.

Acoustic Stimulation↗

PubMed1991

Objective auditory threshold estimation using sine-wave derived responses.

A derived response method of acquiring frequency specific auditory evoked potentials that utilizes a pure tone in combination with a toneburst is applied to the measurement of hearing sensitivity in guinea pigs, chinchillas and pocket gophers. Two experiments which demonstrate that thresholds acquired via tone-derived responses are 10 to 15 dB more sensitive than thresholds to solitary tonebursts are described. The derived potentials approximate behaviorally acquired thresholds at frequencies of 0.5 kHz and above. This technique may provide a more rapid means of assessing hearing sensitivity in laboratory animals than by behavioral means.

Acoustic Stimulation↗

PubMed1991

Measurement of sound.

The measurement of sound involves the analysis of frequency, intensity, and temporal dimensions of acoustic signals. Each dimension of sound can be related directly to clinically observed phenomena. Frequency information, measured in Hz, can be extracted from pure-tone and complex stimuli. Intensity represents the physical energy of a signal and is described by using the decibel scale--a logarithmic scale of ratios. Temporal characteristics of sound include duration, phase, and repetition rate. In the analysis of human hearing sensitivity, the middle ear system and its impedance characteristics also must be considered. In this article, we have reviewed some major principles of sound and have presented a series of practical clinical applications. Such principles as these help to predict and explain frequency of laryngeal tones, middle ear mechanics, ear canal resonance, real-ear measurements of hearing aids, the Articulation Index, hearing loss, understanding of speech in quiet and in noise, and the relation between hearing and speech.

Acoustic Stimulation↗

PubMed1990

Auditory evoked potentials differ at 50 milliseconds in right- and left-handed listeners.

Left-handed individuals show a 4 ms later Wave Pb in the 45-60 ms latency range of the auditory middle latency response (MLR) than right-handed individuals. Examination of auditory evoked potentials in fifteen right-handed and fifteen left-handed normal hearing adults showed that this difference was not evident in time periods earlier or later than 45-60 ms. The isolation of this latency difference to a specific time period suggests that the source or sources of Wave Pb may be an independent physiological index which correlates with hand preference.

Acoustic Stimulation↗

PubMed1990

Myasthenia gravis: regimens and regimen-associated problems in adults.

Two hundred eighteen persons with myasthenia gravis (MG) responded to a mailed survey regarding experiences with their disease. The most commonly used regimen reported to control MG was taking medication on a regular schedule. One hundred ninety-four respondents reported using pyridostigmine bromide with 104 reporting experiencing diarrhea from their medication. Respondents reported situations that aggravated and alleviated adverse effects associated with their medication. Sixty-two respondents reported taking prednisone regularly for their MG. Forty-five of these respondents reported a weight gain. Seventy-seven respondents reported having had a thymectomy. The total remission rate was 11.6% for those who had undergone thymectomy and was 10.2% for those who had not undergone thymectomy. Thirty-one respondents reported having had plasmapheresis with only 3 respondents using plasmapheresis on a regular basis. Results generated by this study can provide useful information to assist nurses in the development of educational materials for persons with MG, their significant others and health care professionals.

Activities of Daily Living↗

PubMed1990

Update on frequency specificity of AEP measurements.

Auditory evoked potentials acquired with frequency-specific stimuli are useful in estimating hearing sensitivity in difficult-to-test patients. Stimulus characteristics, test methods, strengths, and limitations of the auditory brainstem response, SN10 response, middle latency response, and 40-Hz response are reviewed. Clinical strategies using frequency-specific stimuli are suggested for the evaluation of children and adults.

Acoustic Stimulation↗

PubMed1978

Breast feeding and some reasons for electing to wean the infant: a report from the Dunedin Multidisciplinary Child Development Study.

Data are presented on the prevalence of breast feeding among 1037 Dunedin mothers who gave birth to infants between April 1972 and March 1973 and their reasons for weaning. Although breast feeding was becoming more common at that time, more than two-thirds of the mothers weaned their babies as a result of the difficulties they encountered. One of the most significant factors in lactation failure is the mismanagement of breast feeding by health professionals.

Attitude to Health↗

PubMedDate not supplied

Reversible conductive hearing loss in mice.

Fibrin tissue adhesive was injected into the right ears of four 7-week-old CBA/J mice. Auditory brain stem responses (ABRs) were used to monitor changes in auditory sensitivity over the next 26 days, after which the middle ears and cochleas were examined histologically. Mean maximum ABR threshold shifts were as great as 36 dB, and were larger for higher frequencies than for lower. Maximum shifts occurred between 1 and 8 days; by 26 days, thresholds had returned to intensity levels observed before injection.

Animals↗