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L J Matthews

Publications and source records attributed to L J Matthews.

13 recordsLinked to original sources
PubMed1999

Gender-specific effects of drugs on hearing levels of older persons.

As part of a study of human presbyacusis, a questionnaire on medicinal drug usage was given to 357 subjects (184 females, 173 males). Previous results from 211 subjects showed gender effects, that is, for males, none of the drugs had any measurable effects on hearing, whereas women taking calcium channel blockers (CCBs) had hearing levels 12 dB better than women not taking them; women taking beta adrenergic medication had hearing levels 20 dB poorer, and women taking antihistamine/cold preparations had hearing levels 9 dB poorer. Results from the original 211 subjects were confirmed when the sample size was increased from 211 to 357 subjects only for the beta adrenergic medications. Results for antihistamine/cold preparation medications showed small effects only for female subjects. Data from 13 additional female subjects who used CCBs showed hearing levels 10-14 dB poorer than predicted from the original data. Male data were consistent in both samples. The inconsistency for females could reflect sampling error. A more likely possibility is that since the original 10 subjects using CCBs had a mean age of 72 yr and the second sample of 13 had a mean age of 79.5 yr, poorer hearing levels might be anticipated because of the difference in chronological age and possibly duration of drug usage.

Adrenergic beta-Agonists↗
PubMed1998

Cross-linked filamentous phage as an affinity matrix.

Filamentous phage can be cross-linked to make a hydrophilic aggregate that is pelleted by low-speed centrifugation. The aggregate is stable at near-neutral pHs, and withstands exposure to the acid buffers (pH down to 2.2) that are often used as eluents in immunoaffinity purification. If a peptide epitope is genetically fused to a coat protein on the virion surface, the aggregate serves as an effective affinity matrix for absorbing and affinity-purifying antibodies that bind the peptide. When the peptide epitope is first obtained in this form by selection from large phage display libraries, this ability to fashion an affinity matrix directly from the selected phage represents a significant streamlining of research and development.

Amino Acid Sequence↗
PubMed1998

Gender-specific effects of medicinal drugs on hearing levels of older persons.

As part of a large-scale study of presbyacusis, responses to a medicinal drug questionnaire from 85 female and 126 male human subjects were analyzed. Medicinal drugs were divided into 35 categories based on their pharmacologic effects. Subjects' ages ranged from 60 to 82 years. At least 10% of subjects reported taking drugs in 14 of 35 categories. Results were significantly different between female and male subjects. In men, none of the 14 categories showed a statistically significant relation to the pure-tone average (PTA) of 500, 1000, 2000, and 4000 Hz. In women, 3 of the 14 categories showed a statistically significant relation to the PTA. First, the average PTA of female subjects taking beta-adrenergic medication was 20 dB higher (poorer) than those not taking beta-adrenergic medication. Second, women taking antihistamine/cold preparations had an average PTA 9 dB higher (poorer) than those not taking antihistamine/cold preparations. Third, the average PTA of women taking calcium-channel blockers (CCBs) was 12 dB lower (better) than those not taking CCBs. In men, however, these drugs produced effects on the PTA of less than 3 dB. Differences between women and men were not explainable by differences in age or hearing level.

Adrenergic beta-Agonists↗
PubMed1998

Analysis of blood chemistry and hearing levels in a sample of older persons.

OBJECTIVE: As part of an ongoing study of presbyacusis, the relationship between blood chemistry levels and hearing levels was investigated. Previous reports often used small sets of blood chemistry measures, and results were inconclusive. This experiment examined hearing levels and 27 measures of blood chemistry using various univariate and multivariate statistical procedures. DESIGN: Blood from 89 female and 128 male human subjects was collected. Subjects' ages ranged from 60 to 82 yr, and hearing levels ranged from normal to moderate/severe. Subjects with a history of middle ear disease were excluded. Electrolyte panel (Na, K, Cl, CO2, Ca, urea nitrogen, glucose, creatinine, and Mg), hematology panel (WBC, RBC, Hgb, hematocrit, platelet, etc.), serum lipids (total cholesterol, low-density lipoprotein [LDL], and high-density lipoprotein [HDL]), immunoglobulins (IgG, IgA, IgM, and IgE), and thyroxine were analyzed using univariate and multivariate statistical procedures. RESULTS: Blood chemistry levels of most subjects were within normal ranges as defined by our laboratory. Correlation between blood chemistry measures and pure-tone averages (PTAs) ranged from minimal to low. Results of factor analysis, discriminant analysis, and canonical analysis showed that combining blood chemistry measures from the same panel still could not predict PTA effectively. One exception to this was a gender-specific effect of cholesterol. Hearing levels of women with high LDL/HDL ratios were 5 dB better than those of women with low LDL/HDL ratios. The comparable difference in men was only 1 dB. CONCLUSION: Results suggest that blood chemistry measures that are primarily within the normal range have very little value in predicting pure-tone thresholds in older subjects.

Age Factors↗
PubMed1997

Extended high-frequency thresholds in older adults.

Most measures of auditory sensitivity at extended high frequencies (frequencies greater than 8 kHz) have been obtained from listeners with normal hearing less than 40 years of age. The purpose of this study was (a) to measure thresholds at frequencies above 8 kHz in older listeners who, as a group, have elevated thresholds at lower frequencies, and (b) to assess test-retest reliability, age and gender effects, and the influence of thresholds below 8 kHz. Extended high-frequency (EHF) thresholds were measured for 162 older listeners (60-79 years) using a commercially available high-frequency audiometer, with a frequency range of 8 to 18 kHz and an intensity range of 0 to 110 dB SPL. Thresholds were measured once at the beginning of a 1- to 2-hour test session and then remeasured at the end of the test session. EHF thresholds of older listeners with normal hearing at conventional audiometric frequencies were substantially higher than the thresholds reported for younger listeners, with normal hearing by Dreschler and van der Hulst (1987). EHF thresholds of older listeners with hearing loss at conventional audiometric frequencies were further elevated as compared to older listeners with normal hearing. Differences in EHF thresholds between females and males were either not present or were reduced when gender differences in conventional audiometric thresholds were taken into account. No significant differences were seen in thresholds at 8 kHz and higher between the 60- to 69-and 70- to 79-year-old age groups. Results also indicated that thresholds above 8 kHz can be measured in older listeners within a clinically acceptable +/- 10 dB test-retest range.

Age Factors↗
PubMed1997

Age-related and gender-related changes in monaural speech recognition.

Previous studies of older listeners suggest age-related declines in speech recognition. However, the interpretation of these results is not straightforward because auditory thresholds, which account for the largest proportion of the variance in speech-recognition scores, also vary considerably with age. Here, effects of age, gender, and auditory thresholds on several measures of speech recognition were assessed for a large sample of individuals enrolled in a longitudinal study of age-related hearing loss. Participants ranged in age from 55-84 years. They were evaluated with a battery of conventional audiometric measures and speech-recognition materials, including NU-6 monosyllabic words, Synthetic Sentence Identification sentences, and high-context and low-context sentences from the Speech Perception in Noise test. Two analyses were conducted to assure that changes in speech-recognition scores with age were examined independently of age-related changes in auditory thresholds. In the first analysis, no significant differences in speech recognition were observed for individuals in three age groups (55-64, 65-74, 75-84 years) who were selected so that average puretone thresholds for the groups were within 5 dB. In the second analysis, using partial correlations to adjust both score and age for their association with average thresholds, significant declines with age were observed for males in maximum word recognition, maximum synthetic sentence identification, and keyword recognition in high-context sentences. For females, no significant changes in speech recognition with age were observed for any test.

Age Factors↗
PubMed1995

Confidence limits for maximum word-recognition scores.

Clinical judgments are often made regarding whether maximum word-recognition scores (PBmax) are appropriate in relation to degree of sensorineural hearing loss. In order to determine if word recognition is significantly poorer than expected, it is necessary to consider the lower boundary of PBmax associated with a particular degree of hearing loss for speech materials commonly used to measure word recognition. The purpose of this experiment was to define a confidence limit for PBmax from Northwestern University Test #6 (NU-6) word-recognition scores obtained from a large group of young and aged subjects with confirmed cochlear hearing loss. Word-recognition scores at several speech levels were obtained from 407 ears with a wide range of pure-tone averages. Because the characteristics of the distribution of maximum scores are not known, a procedure was developed using computer simulations to approximate the distribution of word-recognition scores corresponding to PBmax and determine the 95% confidence limit (CL). Results of the simulation were confirmed by comparing means and standard deviations of PBmax derived from experimental and simulation data. Percentages of young and aged subjects with scores outside the 95% CL are equal to their proportions in the entire subject sample. If PBmax determined from a score-level psychometric function is poorer than the 95% CL, PBmax may be considered "disproportionately" poor in relation to the degree of hearing loss. One score measured at a single arbitrary suprathreshold level that is poorer than the 95% CL suggests that the score may underestimate PBmax and that word recognition should be measured at additional levels to obtain a more reasonable estimate of the listener's maximum word-recognition score.

Adult↗
PubMed1992

SPIN test performance of elderly hearing-impaired listeners.

Normative information is available on the expected performance of hearing-impaired individuals on the revised version of the Speech Perception in Noise (SPIN) test. This normative sample includes individuals with sensorineural hearing loss drawn from an age range of 19 to 69 years, with 79 percent of the sample being less than 65 years of age. In the present study, SPIN scores were obtained from both ears of 98 elderly, hearing-impaired listeners (age range: 60 to 78 years). When the percent-correct scores on the High-Predictability (PH) items and on the Low-Predictability (PL) items are viewed as two separate measures, mean performance of the current "elderly-only" sample is similar to the performance of the original normative sample. However, for a certain percentage (18%) of the aged ears, the contextual cues provided in the PH sentences were not used as effectively as expected based on the normative guidelines.

Acoustic Stimulation↗
PubMed1991

Actual and predicted word-recognition performance of elderly hearing-impaired listeners.

Word-recognition scores in quiet and in noise were obtained from both ears of 101 elderly listeners demonstrating sensorineural hearing loss. These performance scores were compared to word-recognition scores predicted using Articulation Index analysis procedures. Negative difference scores (actual performance less predicted performance) would reflect aspects of the hearing impairment and/or the aging process that extend beyond the simple speech audibility constraints imposed by the hearing loss and masking noise. The distributions for both the left and right ears of difference scores in quiet revealed the majority of scores to be grouped near 0. In contrast, both distributions of difference scores in noise were normally distributed around means of approximately -25. These results suggest that the typical elderly hearing-impaired listener should be expected to demonstrate word-recognition performance in quiet similar to that of a normally hearing listener, given the same level of audibility of the speech material. On the other hand, in noise, this typical listener may be expected to demonstrate some word-recognition performance decrement, even after accounting for the audibility constraints of the hearing loss and noise.

Aged↗
PubMed1990

Audiometric and subjective assessment of hearing handicap.

This study compares self-perceived assessment of hearing handicap with audiometrically derived measures of hearing handicap in a sample of elderly persons. Subjects were evaluated by traditional audiometric tests, the Speech Perception in Noise test, and the Hearing Handicap Inventory for the Elderly, a self-assessment questionnaire. Hearing handicap was also calculated by the audiometrically derived American Academy of Otolaryngology (1979) method. Our results are consistent with other studies that indicate a low correspondence between audiometric measures of hearing handicap and self-assessment of hearing handicap. Furthermore, if the Hearing Handicap Inventory for the Elderly is considered the true measure of hearing handicap, our data indicate that the American Academy of Otolaryngology method tends to overestimate handicap among persons with no self-perceived hearing handicap and underestimates handicap among persons with significant self-perceived hearing handicap.

Aged↗