Biomedical subjects
Publications and source records attributed to T S Bell.
Hepatitis C virus (HCV) infection may be associated with neurocognitive deficits. The Hemophilia Growth and Development Study enrolled HIV-infected and HIV-uninfected patients and a group of nonhemophiliac siblings. After controlling for multiple factors, HCV monoinfection was not associated with deficits in adaptive behavior, intelligence, or attention/concentration.
OBJECTIVE: To increase the uptake of breast screening in three inner city GP practices with a high proportion of ethnic minority patients. SETTING: The study was carried out in May and June 1997 in the South East Wales division of Breast Test Wales (BTW). Three inner city general practices in Cardiff, with a low uptake in the previous round of breast screening and a high proportion of ethnic minority women on their lists, were targeted to receive interventions to increase uptake. This preliminary study was not randomized but sought to offer insights into the interventions which may be worth pursuing and the groups that are harder to reach. DESIGN INTERVENTIONS: identification of ethnic language groups; GP endorsement letter; translated literature including: multilingual leaflet, GP letter, screening invitation; transport to the screening centre; language support. RESULTS: Of 369 women invited, 187 attended for screening. This gives an uptake of 50.7% compared with an uptake of 35.2% in the previous screening round, a statistically significant increase of 15.5%. (95% CI +8.2% to +22.5%). CONCLUSION: Findings show that translated literature, GP endorsement letter and language support by linkworkers were beneficial. The provision of free transport was ineffective and under-utilized. Uptake was highest amongst Urdu and Gujarati speaking groups and lowest for Bengali and Somali speakers which are hardest to reach. There is scope for improving the attendance rate amongst ethnic minority groups but this can costly.
Patients attending an outpatient clinic with the complaint of dizziness were given a set of five items to rank the magnitude of the frequency and severity of their dizziness and the impact of dizziness on their quality of life. They were given instruments to evaluate their degree of anxiety and depression. The impact of frequency and severity on the patients' daily activities, on the quality of life, and on the fear of becoming dizzy was self-rated by the patient. The score on quality of life was compared with that provided by the physician in a blind questionnaire. The items that were developed addressed the physical, functional, and emotional impact of dizziness and can be considered promising for the evaluation of the patients' degree of overall impairment.
The effect of amplitude-modulated (AM) noise on speech recognition in listeners with normal and impaired hearing was investigated in two experiments. In the first experiment nonsense syllables were presented in high-pass steady-state or AM noise to determine whether the release from masking in AM noise relative to steady-state noise was significantly different between normal-hearing and hearing-impaired subjects when the two groups listened under equivalent masker conditions. The normal-hearing subjects were tested in the experimental noise under two conditions: (a) in a spectrally shaped broadband noise that produced pure tone thresholds equivalent to those of the hearing-impaired subjects, and (b) without the spectrally shaped broadband noise. The release from masking in AM noise was significantly greater for the normal-hearing group than for either the hearing-impaired or masked normal-hearing groups. In the second experiment, normal-hearing and hearing-impaired subjects identified nonsense syllables in isolation and target words in sentences in steady-state or AM noise adjusted to approximate the spectral shape and gain of a hearing aid prescription. The release from masking was significantly less for the subjects with impaired hearing. These data suggest that hearing-impaired listeners obtain less release from masking in AM noise than do normal-hearing listeners even when both the speech and noise are presented at levels that are above threshold over much of the speech frequency range.
The focus of the present investigation was to study, via molecular biology techniques, the character of the DNA present in individual archival celloidin-embedded human temporal bone sections. Polymerase chain reaction (PCR) amplification of 92 base pair (bp), 121 bp, and 471 bp regions of mitochondrial DNA (mtDNA) extracted from a single archival celloidin-embedded human temporal bone section was used to assess the length of the template DNA extracted. The effects of digestion time and sample motion during the extraction method on DNA concentration was also studied. These data are crucial to determine the limits of applying PCR technology to amplify specific genomic DNA targets located within the human inner ear. Further development of these methods will allow additional molecular temporal bone pathologic studies to be completed and, more specifically, hypotheses regarding the molecular etiopathogenesis of many auditory, vestibular, and facial nerve disorders, such as autoimmune hearing loss, congenital hearing losses, Meniere's disease, otosclerosis, or Bell's palsy could be tested. The results described should be of great value to those investigators extracting DNA from archival individual human temporal bone sections for PCR assays of specific genetic alterations or infectious agents associated with temporal bone pathologies.
Reported baseline findings from the neurological assessment component of the Hemophilia Growth and Development Study (HGDS). HIV-positive (HIV+; n = 207) and HIV-negative (HIV-; n = 126) young males with hemophilia ages 6 to 18 years, were enrolled in a prospective study of their growth and development. At baseline, HIV+ and HIV- subjects were not significantly different in test performance. The number of subjects exhibiting below-average performance in three or more areas assessed was about 25% overall. For both groups, mean test scores were within the average range. Academic and adaptive skills were lower than expected based on mean IQ scores, and more behavioral/emotional problems than expected were reported by parents. Absolute CD4 cell counts per mm3 were not related to neuropsychological performance at baseline. Results suggest that the subjects with HIV were relatively free of HIV-related neuropsychological impairment at baseline and that observed differences from a general population reflect effects of hemophilia as a chronic illness.
Papillary squamous neoplasms of the upper respiratory tract are rare variants of squamous cell carcinoma and are related temporally to proliferative verrucous leukoplakia. Fifty-two cases of papillary squamous neoplasms were selected from 2366 cases of squamous cell carcinoma. This is the first study to characterize the biological behavior of papillary squamous neoplasms. Papillary squamous neoplasms exhibit two distinct, yet sometimes overlapping, histologic patterns including an exophytic papillary and an inverting verrucous morphologic appearance. A high rate of synchronous or metachronous lesions were found, especially with the inverting-type of papillary squamous neoplasm. Stage T3 and T4 lesions had a high rate of neck metastasis. Early surgical intervention and close long-term follow-up is mandatory.
The relative importance and absolute contributions of various spectral regions to speech intelligibility under conditions of either neutral or predictable sentential context were examined. Specifically, the frequency-importance functions for a set of monosyllabic words embedded in a highly predictive sentence context versus a sentence with little predictive information were developed using Articulation Index (AI) methods. Forty-two young normal-hearing adults heard sentences presented at signal-to-noise ratios from -8 to +14 dB in a noise shaped to conform to the peak spectrum of the speech. Results indicated only slight differences in 1/3-octave importance functions due to differences in semantic context, although the crossovers differed by a constant 180 Hz. Methodological and theoretical aspects of parameter estimation in the AI model are discussed. The results suggest that semantic context, as defined by these conditions, may alter frequency-importance relationships in addition to the dynamic range over which intelligibility rises.
Invariance of error patterns in confusion matrices of varying dimensions were examined. Normal-hearing young adults were presented closed-set arrangements of digitized syllable tokens, spoken by 1 male and 1 female talker, and selected from a set of 14 consonants (stops and fricatives). Each consonant was paired with the vowel/a/ in a vowel-consonant format and presented at three intensity levels. Patterns of errors among voiceless stops and among voiced fricatives were dependent on the set of alternatives. Voiceless fricatives and voiced stops were not significantly affected by the number of response alternatives. Speaker differences, individual differences among listeners, and implications relating to the generalization of confusion data collected in small closed-set arrangements are discussed.
Confusion patterns among English consonants were examined using log-linear modeling techniques to assess the influence of low-pass filtering, shaped noise, presentation level, and consonant position. Ten normal-hearing listeners were presented consonant-vowel (CV) and vowel-consonant (VC) syllables containing the vowel /a/. Stimuli were presented in quiet and in noise, and were either filtered or broadband. The noise was shaped such that the effective signal level in each 1/3 octave band was equivalent in quiet and noise listening conditions. Three presentation levels were analyzed corresponding to the overall rms level of the combined speech stimuli. Error patterns were affected significantly by presentation level, filtering, and consonant position as a complex interaction. The effect of filtering was dependent on presentation level and consonant position. The effects stemming from the noise were less pronounced. Specific confusions responsible for these effects were isolated, and an acoustical interaction is suggested, stressing the spectral characteristics of the signals and their modification by presentation level and filtering.
Flaccid laryngeal nerve paralysis may be treated by vocal fold augmentation with Teflon injection, which is successful to various degrees depending on the subjective interpretation of the patient or clinician. A new material, Phonogel, consisting of cross-linked bovine collagen, is available but not approved for human use in this area. Ten dogs were submitted to videostroboscopy, photoglottography, electroglottography, and acoustic analysis in the normal state, with stimulated recurrent laryngeal nerve paralysis, and with injection of either Teflon or Phonogel. A statistical comparison and the advantages and disadvantages of each material are discussed in relation to this study and its clinical use.
The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS.
In the present study, speech-recognition performance was measured in four hearing-impaired subjects and twelve normal hearers. The normal hearers were divided into four groups of three subjects each. Speech-recognition testing for the normal hearers was accomplished in a background of spectrally shaped noise in which the noise was shaped to produce masked thresholds identical to the quiet thresholds of one of the hearing-impaired subjects. The question addressed in this study is whether normal hearers with a hearing loss simulated through a shaped masking noise demonstrate speech-recognition difficulties similar to those of listeners with actual hearing impairment. Regarding overall percent-correct scores, the results indicated that two of the four hearing-impaired subjects performed better than their corresponding subgroup of noise-masked normal hearers, whereas the other two impaired listeners performed like the noise-masked normal listeners. A gross analysis of the types of errors made suggested that subjects with actual and simulated losses frequently made different types of errors.
The present article is divided into four major sections dealing with the application of acoustical indices to the prediction of speech recognition performance. In the first section, two acoustical indices, the Articulation Index (AI) and the Speech Transmission Index (STI), are described. In the next section, the effectiveness of the AI and the STI in describing the performance of normal-hearing and hearing-impaired subjects listening to spectrally distorted (filtered) and temporarily distorted (reverberant) speech is examined retrospectively. In the third section, the results of a prospective investigation that examined the recognition of nonsense syllables under conditions of babble competition, filtering and reverberation are described. Finally, in the fourth section, the ability of the acoustical indices to describe the performance of 10 hearing-impaired listeners, 5 listening in quiet and 5 in babble, is examined. It is concluded that both the AI and the STI have significant shortcomings. A hybrid index, designated mSTI, which takes the best features from each procedure, is described and demonstrated to be the best alternative presently available.
Log-linear models, in conjunction with the G2 statistic, were developed and applied to several existing sets of consonant confusion data. Significant interactions of consonant error patterns were found with signal-to-noise ratio (S/N), presentation level, vowel context, and low-pass and high-pass filtering. These variables also showed significant interactions with error patterns when categorized on the basis of feature classifications. Patterns of errors were significantly altered by S/N for place of articulation (front, middle, back), voicing, frication, and nasality. Low-pass filtering significantly affected error patterns when categorized by place of articulation, duration, or nasality; whereas, high-pass filtering only affected voicing and frication error patterns. This paper also demonstrates the utility of log-linear modeling techniques in applications to confusion matrix analysis: specific effects can be tested; variant cells in a matrix can be isolated with respect to a particular model of interest; diagonal cells can be eliminated from the analysis; and the matrix can be collapsed across levels of variables, with no violation of independence. Finally, log-linear techniques are suggested for development of parsimonious and predictive models of speech perception.
Three investigations were conducted to determine the application of the articulation index (AI) to the prediction of speech performance of hearing-impaired subjects as well as of normal-hearing listeners. Speech performance was measured in quiet and in the presence of two interfering signals for items from the Speech Perception in Noise test in which target words are either highly predictable from contextual cues in the sentence or essentially contextually neutral. As expected, transfer functions relating the AI to speech performance were different depending on the type of contextual speech material. The AI transfer function for probability-high items rises steeply, much as for sentence materials, while the function for probability-low items rises more slowly, as for monosyllabic words. Different transfer functions were also found for tests conducted in quiet or white noise rather than in a babble background. A majority of the AI predictions for ten individuals with moderate sensorineural loss fell within +/- 2 standard deviations of normal listener performance for both quiet and babble conditions.
The purpose of this experiment was to determine the applicability of the Articulation Index (AI) model for characterizing the speech recognition performance of listeners with mild-to-moderate hearing loss. Performance-intensity functions were obtained from five normal-hearing listeners and 11 hearing-impaired listeners using a closed-set nonsense syllable test for two frequency responses (uniform and high-frequency emphasis). For each listener, the fitting constant Q of the nonlinear transfer function relating AI and speech recognition was estimated. Results indicated that the function mapping AI onto performance was approximately the same for normal and hearing-impaired listeners with mild-to-moderate hearing loss and high speech recognition scores. For a hearing-impaired listener with poor speech recognition ability, the AI procedure was a poor predictor of performance. The AI procedure as presently used is inadequate for predicting performance of individuals with reduced speech recognition ability and should be used conservatively in applications predicting optimal or acceptable frequency response characteristics for hearing-aid amplification systems.
Between April 1979 and August 1983, 49 nearly drowned children in serious condition were admitted to Childrens Hospital of Los Angeles (CHLA) with Glasgow coma scores of 3, 4, or 5 and underwent intracranial pressure monitoring and brain resuscitative therapy. Of the 49 patients, 29 (59%) died in the hospital 1 day to 3 months after admission, 13 (27%) were discharged in vegetative states, and 7 (14%) made good recoveries. No patient made a partial neurological recovery. The sustained mean highest intracranial pressure was significantly higher and the sustained lowest cerebral perfusion pressure was significantly lower for those who died than for survivors (P less than 0.05), but these data did not significantly distinguish between intact and vegetative survivors. Pupillary reactivity noted on arrival at CHLA also significantly discriminated survivors and fatalities (P less than 0.05), but not between intact and vegetative survivors. The presence of any motor activity after arrival at CHLA, even posturing or twitching, indicated a significant chance for intact survival (P less than 0.05), although such activity did not discriminate between death and vegetative survival. Extensive neuropsychological testing indicated that the apparently intact recovered patients generally showed nearly average levels of cognitive functioning, with mild residual gross motor and coordination deficits.