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Biomedical subjects

D Byrne

Publications and source records attributed to D Byrne.

At least 91 records · Page 5Linked to original sources
PubMed1988

Evaluation of the National Acoustic Laboratories' new hearing aid selection procedure.

This study evaluated the National Acoustic Laboratories' (NAL) new formula for prescribing the gain and frequency response of a hearing aid. The frequency response prescribed for 44 clients (67 fitted ears) was compared with a series of variations having increased or decreased low-frequency and/or high-frequency emphasis. The evaluations consisted of paired-comparison judgments of the intelligibility of speech in quiet and the pleasantness of speech in noise. There were only 4 ears (6%) where a comparison response was more intelligible than the NAL response, but there were 16 ears (24%) where one of the comparison responses was more pleasant. On the average, hearing aid gain that was used by each subject agreed closely with prescribed gain. These trends were not affected by audiogram configuration, experience in aid usage, or type of aid limiting. The formula was found to be highly effective, but there were some cases where a change in aid prescription was indicated. A simple evaluation procedure using paired-comparison judgments is proposed for detecting such cases.

Aged↗
PubMed1988

Manipulation of ascitic fluid pressure in cirrhotics to optimize hemodynamic and renal function.

Intra-abdominal pressure (IAP), measured via a transurethral catheter, hemodynamic, and renal functions were evaluated in 25 cirrhotic patients admitted to ICU with variceal bleeding, tense ascites, and peripheral edema. In patients with an IAP greater than 25 cm H2O, a paracentesis was performed to decrease the IAP by 10 cm H2O. After paracentesis, a decrease in the IAP from 33.47 to 19.06 cm H2O (p less than 0.001) resulted in a decrease in total peripheral resistance (TPR) (p less than 0.01) and a significant increase in cardiac index (CI) (p less than 0.001), stroke index (p less than 0.001), left ventricular stroke work (LVSW) (p less than 0.01), and right ventricular stroke work (p less than 0.01). The therapeutic effects of paracentesis on renal function were: a decrease in BUN and serum creatinine (p less than 0.001) and an increase in the creatinine clearance (Ccr) (p less than 0.001), urine volume (p less than 0.001), osmolar clearance (Cosm) (p less than 0.001), and urine creatinine (p less than 0.001) values. The IAP correlated directly with the TPR (r = +0.35, p less than 0.01) and inversely with the CI (r = -0.39, p less than 0.001) and LVSW (r = -0.37, p less than 0.001) in the 126 studies of IAP performed with the 25 patients. IAP also correlated directly with BUN (r = 0.40, p less than 0.001), serum creatinine (r = 0.28, p less than 0.01), and free water clearance (CH2O) (r = 0.3, p less than 0.001); IAP correlated negatively with Ccr (r = -0.54, p less than 0.001) and Cosm (r = -0.43, p less than 0.001). In critically ill cirrhotic patients, IAP, when measured noninvasively via a bladder catheter, is an accurate and useful method to follow manipulation of ascitic fluid pressure quantitatively in order to optimize hemodynamic and renal function.

Abdomen↗
PubMed1987

Sexual attitudes and contraception among females across five college samples.

The relationships among sexual attitudes, sexual and contraceptive behavior, and responses to statements about sexual topics are explored using data obtained in the Sexual Opinion Survey concerning 772 women attending four midwestern U.S. universities in the period 1977-1979. "Associations generally occurred between the expression of more positive sexual attitudes and the reporting of behaviors and attitudes supportive of effective contraceptive activity."

Adolescent↗
PubMed1986

Treatment of colorectal hepatic metastases by intrahepatic chemotherapy alone or as an adjuvant to complete or partial removal of metastatic disease.

Because of the wide variation in reported benefits from the use of intrahepatic chemotherapy for colorectal hepatic metastases, the authors performed their own phase II studies comparing the use of intrahepatic chemotherapy alone and intrahepatic chemotherapy as an adjuvant to complete or partial removal of metastatic colorectal cancer to the liver. Techniques for partial removal included unilateral and bilateral wedge resection, peripheral presinusoidal embolization of the liver, and portal vein branch ligation. Patients were staged using the per cent hepatic replacement method of Pettavel and Taylor, and patients with bilateral metastases were included in the study. Twenty-seven patients, mean age 60.3 years, were examined. There were 19 males, mean age 60.4 years, and eight females, mean age 60 years. The patients were divided into four groups. Group A had an implantable pump only; Group B had an implantable pump and resection; Group C had an implantable pump and arterial embolization and portal vein branch ligation; and Group D had an implantable pump, partial resection, arterial embolization, and portal vein branch ligation. Kaplan-Meyer survival curves were calculated for all of these groups. A separate analysis was carried out for each of the stages, and a comparison was made. The study indicated that the overall median survival time was 18 months and that the more radical the treatment in addition to chemotherapy, the better the results. Such results were not totally dependent on the staging of the tumor volume but were dependent on the degree of extirpation of the tumor. In Group C, consisting primarily of Stage IIa, IIIa, and IV patients (i.e., unresectable patients), a doubling of expected median survival to 12 months could be achieved, compared to those in Group A, which achieved a median survival of only 6 months.

Adult↗
PubMed1986

Predictability of the required frequency response characteristic of a hearing aid from the pure-tone audiogram.

This paper examines the predictability of the optimal frequency response characteristic of a hearing aid from the shape of the pure-tone audiogram. The main data were derived from two studies, using 14 and 16 sensorineurally hearing-impaired ears, representing a wide variety of audiometric configurations. Optimal (required) frequency response slopes were estimated from most comfortable loudness levels for speech bands after finding that such responses were superior to ones derived from other procedures. The low (0.4 or 0.5 to 1.25 kHz), high (1.25 to 3 kHz), and total (0.4 or 0.5 or 3 kHz) slopes of the optimal responses were analyzed relative to the corresponding audiogram slopes. A moderately strong relationship was found between audiogram slopes and required response slopes (correlations averaged almost 0.6) and different studies agreed substantially regarding the formula describing that relationship. We conclude that it is justifiable to select the frequency response of a hearing aid from the pure-tone audiogram and that an appropriate formula would be more effective than providing a standard frequency response for all clients.

Adult↗
PubMed1986

The National Acoustic Laboratories' (NAL) new procedure for selecting the gain and frequency response of a hearing aid.

A new procedure is presented for selecting the gain and frequency response of a hearing aid from pure-tone thresholds. This was developed from research which showed that a previous procedure did not meet its aim of amplifying all frequency bands of speech to equal loudness but that frequency responses which did so were considerably more effective. Measurements of 30 sensorineurally hearing-impaired ears (27 subjects), together with data from other studies, were analyzed to determine the best formula for predicting the optimal frequency response, for each individual, from the audiogram. The analysis indicated that a flat audiogram would require a rising frequency response characteristic of about 8 dB/octave up to 1.25 kHz and thereafter a falling characteristic of about 2 dB/octave. Variations in audiogram slope required about one-third as much variation in response slope. Three frequency average (3FA) gain was calculated to equal the 3FA gain of the previous procedure. Forty-four subjects (67 aided ears) fitted by the new procedure were evaluated by paired comparison judgments of the intelligibility and pleasantness of speech. The prescribed frequency response was seldom inferior to, and usually better than, any of several variations having more, or less, low and/or high-frequency amplification. On the average, used gain was approximately equal to prescribed gain. It is concluded that the new formula should prescribe a near optimal frequency response with few exceptions.

Audiometry, Pure-Tone↗
PubMed1986

Effects of bandwidth and stimulus type on most comfortable loudness levels of hearing-impaired listeners.

Measurements were made of the effects of stimulus bandwidth and type (speech bands versus pure tones) on interfrequency differences at the most comfortable loudness level (MCL). The MCLs were measured for speech bands of three bandwidths (1/3 octave, 1 octave, and 1 2/3 octaves) at three frequencies (0.4 kHz, 1.25 kHz, and 3.15 kHz) for 11 sensorineurally hearing-impaired subjects (14 test ears). The MCLs were also measured with pulsed pure tones. It was found that bandwidth and stimulus type both had significant effects on interfrequency differences in MCLs. Also, the mean speech band MCLs were significantly higher than the mean pure-tone MCLs. A subsidiary experiment suggested that, when bands of speech from different frequency regions are all presented at MCL, they will be approximately, but not precisely, equal in loudness. The findings have implications for hearing aid selection procedures because most aim to amplify all frequency bands of speech to MCL, or equal loudness at a comfortable level. The use of different types or bandwidths of test stimuli would result in substantially different frequency response prescriptions in some cases.

Adult↗
PubMed1986

Effects of frequency response characteristics on speech discrimination and perceived intelligibility and pleasantness of speech for hearing-impaired listeners.

Frequency response characteristics were selected for 14 hearing-impaired ears, according to six procedures. Three procedures were based on MCL measurements with speech bands of three bandwidths (1/3 octave, 1 octave, and 1 2/3 octaves). The other procedures were based on hearing thresholds, pure-tone MCLs, and pure-tone LDLs. The procedures were evaluated by speech discrimination testing, using nonsense syllables in noise, and by paired comparison judgments of the intelligibility and pleasantness of running speech. Speech discrimination testing showed significant differences between pairs of responses for only seven test ears. Nasals and glides were most affected by frequency response variations. Both intelligibility and pleasantness judgments showed significant differences for all test ears. Intelligibility in noise was less affected by frequency response differences than was intelligibility in quiet or pleasantness in quiet or in noise. For some ears, the ranking of responses depended on whether intelligibility or pleasantness was being judged and on whether the speech was in quiet or in noise. Overall, the three speech band MCL procedures were far superior to the others. Thus the studies strongly support the frequency response selection rationale of amplifying all frequency bands of speech to MCL. They also highlight some of the complications involved in achieving this aim.

Adult↗
PubMed1985

Respiratory conditions: effect of housing and other factors.

The public health movement has been concerned with the relation between housing and health for well over a century. Nevertheless the Black Report still identified housing as one of the major causes of ill-health and suggested, on one indicator at least, that council housing is the least healthy form of tenure. An exploratory study concerning housing and health in a north eastern local authority area is described. It was found that smoking, work experience, and age were the most important determinants of self assessed respiratory conditions. When the background factors were held constant people in areas of 'bad' housing were found to report more respiratory symptoms than those in 'good' housing areas. Respiratory conditions were affected by the age of housing, and flats were found to be worse than houses. High rise flats were worse than low or medium rise flats.

Adult↗
PubMed1985

The concept of stress.

Any notion or concept of stress should fulfil the following requirements. First, the definition should be readily communicable both to professionals and the community at large. Second, the concept should be readily converted into constructs which are suitable for research. In this latter regard it is easier to present and discuss a stress model. This model differentiates a number of factors which, although interdependent, are conceptually distinct. By adequately discriminating between these factors, operational criteria may be defined and a systematic assessment of the effects of stress will be facilitated. A model is thus presented which describes the stress process.

Humans↗
PubMed1985

Urinary bladder glycoproteins of the rabbit: extraction, biochemical and immunological studies.

The mucin layer of the bladder covering the transitional epithelium is thought to be an anti-adherence substance for bacteria. We have previously demonstrated that removal of this layer results in increased bacterial colonization. In this present communication we report our attempts to isolate and characterize the components of the mucin layer. Bladders were removed from female NZW rabbits and the mucosal layer was extracted with 0.1 M NaCl. Fractional centrifugation and column chromatography on AcA 34 and AcA 22 resulted in the separation of a partially purified glycoprotein, containing 30% carbohydrate, migrating as a single peak (4.5S) in the analytical ultracentrifuge. It was immunogenic in mice and the antisera were used to develop both a radioimmunoassay and an enzyme linked immunosorbent assay (ELISA). The antigenic activity of the glycoprotein was destroyed by protease or extremes of pH, but not by several glycosidases. In addition the murine antisera could not be inhibited by a panel of naturally occurring glycoproteins or glycosaminoglycans.

Animals↗
PubMed1984

The effects of multichannel compression/expansion amplification on the intelligibility of nonsense syllables in noise.

The effects of six-channel compression and expansion amplification on the intelligibility of nonsense syllables embedded in speech spectrum noise were examined for four hearing-impaired subjects. For one condition (linear) the stimulus was given six-channel amplification with frequency shaping to suit the subject's hearing loss. The other condition (nonlinear) was the same except that low level inputs, to any given channel, received expansion amplification and high level inputs received compression. For each condition, each subject received the nonsense syllables at three different input levels, representing low, average, and high intensity speech. The results of this study, like those of most other studies of multichannel compression, are mainly negative. Nonlinear processing (mainly expansion) of low intensity speech resulted in a significant degradation of speech intelligibility for two subjects and in no improvement for the others. One subject showed a significant improvement in intelligibility for the nonlinearly processed average intensity speech and another subject showed significant improvement for the high intensity input (mainly compression). Clearly, nonlinear processing is beneficial for some subjects, under some listening conditions, but further research is needed to identify the relevent characteristics of such subjects. An acoustic analysis of selected items revealed that the failure of expansion to improve intelligibility was primarily due to the very low intensity consonants /e/ and /k/, in final position, being presented at an even lower intensity in the expansion condition than in the linear condition. Expansion may be worth further investigation with different parameters. Several other problems caused by the multichannel processing were also revealed. These included alteration of spectral shapes and band interaction effects. Ways of overcoming these problems, and of capitalizing on the likely advantages of multichannel amplification, are currently being investigated.

Hearing Aids↗
PubMed1984

The relationships among sexual beliefs, attitudes, experience, and homophobia.

Male and female subjects were given a series of questionnaires to assess their attitudes, behaviors, and experiences in relation to homosexuality. The findings indicated the presence of two systems, one dealing with affective orientation and the other with general beliefs (learned problem or physiological problem) about the origins of homosexuality. It was found that the greatest dislike toward homosexuals existed in those subjects who responded with negative affect and believed that homosexuality was a learned problem. Avoidance of social situations where homosexuals are present was evidenced in subjects who responded with negative affect and believed homosexuality was due to genetic factors.

Adolescent↗
PubMed1981

The reliability of reports of early separations.

A random sample of adult community residents (n 244) was asked about separations in their childhood. Eight months later, the group was asked the same questions again. Only the death of a parent and the break-up of the parental marriage were reported with high reliability. These events made up one third of all reported separations.

Adolescent↗
PubMed1980

Preferred listening levels for bands of speech in relation to hearing aid selection.

The Most Comfortable Loudness Level (MCL) was measured for 24 normal-hearing subjects, using narrow bands of speech having centre frequencies of 0.25, 0.5, 1.2 and 4kHz. MCL's were equivalent for octave band and one-third octave band stimuli. The sensation levels (SL) for various frequencies closely matched the SL of the 60 phon equal loudness contour for pure tones. It was concluded, for levels around MCL, sounds which are equally comfortable are equally loud and that equal loudness contours for pure tones are also applicable to narrow bands of speech. Some implications for hearing aid selection are discussed. However, this investigation was primarily a preliminary to other studies more directly related to hearing aid selection issues.

Adolescent↗