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Biomedical subjects

L D Lowry

Publications and source records attributed to L D Lowry.

At least 73 records · Page 4Linked to original sources
PubMed1983

Some parameters affecting Békésy audiometric thresholds.

Bekesy automatic audiometric findings may be affected by various factors such as contralateral masking, starting frequency, starting level, exposure to stimulating sound and different stages of some disease entity. These findings are seen mostly on steady-tone tracings as revealed by peak-to-peak amplitude reductions and threshold drifts. This paper is concerned with automatic audiometry parameters which have been little known or ignored by many investigators. Detailed audiometric case histories from 6 patients with a variety of unilateral sensorineural hearing impairments showed, e.g., that contralateral masking in the normal ear can produce striking effects on tracings to steady-state tones in the affected ear. Various starting frequencies produced marked effects on separation between pulsed-and steady-tone tracings if hearing was tested starting at suprathreshold levels. A patient diagnosed as having an early endolymphatic hydrops retested within 1 hr following an episodic attack displayed varieties of findings. The automatic audiometric method demonstrates the interrelation of level and adaptation.

Adult↗
PubMed1982

Horizontal nystagmus in methylmercury poisoned squirrel monkeys.

Chronic states of methylmercurialism were induced in squirrel monkey subjects. Principal neurological signs included ataxia, abnormal gait, incoordination and amaurosis. Although slight to moderate vacuolization occurred in supporting cell layers of the cristae and maculae, receptor cell function was essentially normal. Except for a lowered cold threshold, bithermal caloric-induced nystagmus was not significantly different from control values. Pre and postrotatory (Barany chair) tests revealed a reduction only in frequency related variables. The development of spontaneous and positional nystagmus (sometimes with eyes open) coupled with the behavioral signs and the evidence of normal receptor response suggested cerebellar dysfunction. Severe pathologic changes were present in the cerebral cortex, but no lesions were found in the cerebellar cortex. Substantial neuronal degeneration and gliosis, however, were observed in several subcortical nuclei, including cerebellar and vestibular nuclei.

Acoustic Maculae↗
PubMed1982

Loudness recruitment in abrupt drop sensorineural hearing impairment.

Monaural bifrequency loudness balance tests were performed on 11 adults with abrupt drop sensorineural hearing impairment. To study frequencies on the slope, 2-octave Bekesy threshold measurements were made beginning at a frequency exhibiting normal hearing nearest to initiation of the slope (F1). Loudness was matched (Test 1) between F1 and F2 (a frequency nearest to termination of the slope), (Test 2) between F1 and F1 + F2/2 (a frequency halfway between F1 and F2), and (Test 3) between F1 and 2F1 (a frequency an octave above F1). Our data indicated that a combination of asymptotic and straight-line recruitment was demonstrated in Test 1, pure asymptotic recruitment in Test 2, and straight-line recruitment in Test 3. It was speculated that diffuse hair cell lesions such as in frequency areas in the vicinity of 2F1 in abrupt drop sensorineural hearing impairment or endolymphatic hydrops may show straight-line recruitment, and discrete outer hair cell lesions such as frequency regions around F1 + F2/2 may demonstrate pure asymptotic recruitment. Our results were discussed in relation to histopathological findings of human and animal subjects with abrupt drop hearing loss reported by other investigators. Data appeared to show a relationship between the types of loudness recruitment and the hair cell damage.

Adult↗
PubMed1981

Nonfunctional paraganglioma of the larynx: clinical and pathological considerations.

Paraganglioma of the larynx is a rare neoplasm. A review of the 16 previously reported cases in English medical literature is presented along with the details of an additional case. The tumor was analyzed by light and electron microscopy. The anatomy and embryology of the laryngeal paraganglia and controversies in nomenclature are discussed. Hoarseness, pain, dysphagia, and neck mass are the cardinal symptoms of this neoplasm; other clinical characteristics are reviewed. Partial laryngectomy and excision via lateral pharyngotomy and extralaryngeal approaches are the most commonly employed methods of treatment. More aggressive therapy including radical neck dissection, total laryngectomy, and radiation therapy have been used for malignancies.

Aged↗
PubMed1981

Endocrine, cardiovascular, and psychological correlated of olfactory sensitivity changes during the human menstrual cycle.

Signal detection measures olfactory sensitivity (d') and measures of blood pressure, heart rate, body temperature, nasal airflow, and respiration rate were repeatedly established within approximately 2.5-hr test sessions held every other day across 17 menstrual cycles of women not taking oral contraceptives, 6 menstrual cycles of women taking oral contraceptives, and 6 equivalent time periods of three men. In addition, radioimmunoassay-determined serum levels of luteinizing hormone, follicle stimulating hormone, estrone, estradiol, progesterone, and testosterone, as well as responses to the Moos Menstrual Distress Questionnaire (MDQ), were established daily or bidaily throughout the study periods. Peaks in olfactory sensitivity were noted during the second half of menses, midcycle, and midluteally in women taking and in women not taking oral contraceptives. The lack of correlation between the fluctuations in d' and the circulating hormone levels in the group using oral contraceptives suggests factors other than gonadal hormones were responsible for these changes. Significant fluctuations were also noted across the cycle phases of the normally cycling women for all the hormones examined, as well as for body temperature, nasal airflow, and the MDZ Water Retention and Pain Scales. In the oral contraceptive group, very small but statistically significant changes were observed across the cycle in body temperature and in circulating levels of luteinizing hormone and estrone. Interrelations between a number of the variables were noted both within and across the test periods in all three subject groups. The results are discussed in relation to fluctuations reported in a number of sensory systems during the menstrual cycle.

Adolescent↗
PubMed1980

The maturation of frequency selectivity in C57BL/6J mice studied with auditory evoked response tuning curves.

The present study was designed to examine the ontogeny of frequency selectivity in the neonatal auditory system. Mice were tested between 12 and 65 days of age. At each age two measures of auditory sensitivity were made from cochlear nucleus evoked responses. Tone-burst evoked-response thresholds in the quiet were determined for frequencies between 1.0 and 39.0 kHz. A two-tone simultaneous masking procedure was then used to obtain evoked response tuning curves. The frequency selectivity of the tuning curves was quantified by calculating a Q ratio. The results show that tuning is poor in neonates but rapidly improves to adult-like levels within 5-16 days after the inception of auditory function. The data also indicate that the development of frequency selectivity varies directly with the maturation of threshold sensitivity.

Aging↗
PubMed1980

Randomized preoperative and postoperative radiation therapy for patients with carcinoma of the head and neck: preliminary report.

Two hundred and ninety-eight patients with squamous cell carcinoma of the oral cavity, oropharynx, supraglottic larynx, hypopharynx or maxillary sinus have been randomized for preoperative radiation therapy and surgery vs. surgery and postoperative radiation therapy plus, in the case of patients with lesions of the oral cavity and oropharynx, radical radiation therapy. Data have been analyzed on 243 patients in this interim report. The differences between the three groups with respect to local control and survival are not statistically significant at this time. Additional accrual and continued follow-up are necessary to make definite treatment comparisons.

Carcinoma, Squamous Cell↗
PubMed1979

Effect of kanamycin sulfate on the endocochlear dc potential of guinea pigs.

The magnitudes of the endocochlear dc potential (EP) during adequate ventilation and during five minutes of anoxia were recorded in control guinea pigs and guinea pigs administered various dosages of kanamycin sulfate. The magnitudes of the EP after five minutes of anoxia were -44.6 +/- 5.9 mV in the controls and +26.6 +/- 9.9 mV in the guinea pigs that received kanamycin for seven or ten days. This change occurred after five or six days of administration of kanamycin. However, there was no significant change in the magnitude ot the EP with adequate ventilation with kanamycin intoxication. There is a significant correlation between the magnitude of the negative EP and the maximum output of the cochlear microphonics (r = -.770, P less than .001). These results suggest that the EP may not be the mathematical summation of the positive electrogenic potential and the negative diffusion potential. The mechanism for generating the negative EP during anoxia may have some relationship to hair cell integrity.

Animals↗
PubMed1979

Does malignant hibernoma exist?

The authors present a case of a highly atypical, possibly malignant, hibernoma. It presented as a deep-seated tumor in the retropharynx of a 57-year-old male. A review of possible similar cases is presented. The patient is without recurrence 4 years after complete excision and radiation therapy. The tumor must be differentiated from liposarcoma. The clinical potential must await the accumulation and observation of additional cases.

Diagnosis, Differential↗
PubMed1978

Bilateral choristomas of the external auditory canals.

To our knowledge, we report the first case of external auditory canal choristomas in the American literature. The pathologic condition of each side was serous salivary tissue, and at surgery, there was no connection with the parotid gland.

Child↗