Biomedical subjects
Publications and source records attributed to E Borg.
In a bilateral paired comparison study 39 patients with plaque psoriasis completed a 4 week study using hydrocolloid dressing alone, twice daily Betamethasone propionate cream alone, or both therapies combined and applied every 7 days.
The human alpha-tectorin (TECTA) gene has recently been cloned and proposed to be involved in autosomal dominant non-syndromic hearing impairment (NSHI) in two families linked to the DFNA12 locus. We have studied a Swedish pedigree with autosomal dominant NSHI with possible digenic inheritance of the disease, involving locus DFNA12 in chromosome 11 and locus DFNA2 in chromosome 1. Mutation analysis of the TECTA gene in this family has identified eight nucleotide substitutions indicating that TECTA is highly polymorphic. One of the changes results in a cysteine to serine (C 1057 S) mutation, in the zonadhesin domain of TECTA; this segregates with the disease haplotype on chromosome 11 and is not present in a control population. The mutation results in the replacement of a cysteine in one of the repeats of the zonadhesin/Von Willebrand domain of the protein and might cause a change in the crosslinking of the polypeptide. These findings add support to the involvement of TECTA in hearing disabilities. However, the three families carrying different TECTA mutations also show phenotypic differences: the hearing loss ranges from prelingual to progressive with late onset. The explanation for the different phenotypes and some clues regarding the functions of TECTA may lie in the localization of the mutations in the different modules of the protein. Another possibility is that the phenotype in the Swedish family is the result of two defective genes.
OBJECTIVE: To evaluate the performance of 4 intraoral direct digital sensors regarding their fundamental physical characteristics. The sensors are made by Schick Technologies Inc (Long Island City, NY) and Gendex Dental Systems (Milan, Italy). STUDY DESIGN: The sensors were exposed by using a Prostyle dental x-ray machine (Planmeca Oy, Helsinki, Finland) operating at 50 kV, 8 mA and various exposure times. Three test phantoms were used: a homogeneous 10-mm thick aluminum block, an aluminum block with a pattern of holes of varying sizes, and a resolving power target. Digital images were transferred as 8 bit TIFF files and analyzed by using a personal computer. RESULTS AND CONCLUSIONS: Some improvements could be observed in the physical performance of the new generation of direct digital radiographic sensors when compared with the earlier generation. Smaller pixels and higher quantum efficiency have improved sensor performance.
The problems that deaf-blind subjects have with monitoring the environment and the strategies they use were identified using structured interviews. The use of the vibratory sense did not appear to be highly developed, but some individuals indicated that it has great potential. We describe here the design of a computerized laboratory device for sound localization, based on a three-microphone system with a cross correlation algorithm. It was found to have reasonable precision and sufficient reliability to allow the detection and localization of a person approaching a deaf-blind subject in an ordinary room. The next step is to miniaturize the equipment and build a portable prototype.
The general aim of the study was to evaluate and compare different solid-state and photo-stimulable phosphor systems for digital intra-oral radiography and to compare different generations of some of the systems. The evaluations concerned physical and psychophysical performance, subjective image quality and the influence of image processing. Physical performance was tested by means of large area transfer characteristics, noise, contrast, and modulation transfer function. For the physical performance it was found that grey level values in images from solid-state systems decreased faster with increasing exposure than in images from photo-stimulable phosphor systems. Noise increased with increased exposure for both solid-state and photo-stimulable phosphor systems. Solid-state systems reached their highest contrast index at lower doses than the photo-stimulable phosphor systems. Solid-state systems had better resolving power due to higher contrast and smaller pixel sizes than the PSP systems. The resolving power of the photo-stimulable phosphor systems improved when the images were enhanced. Psychophysical tests were performed by determining the sensitivity of the systems for detecting small mass differences in test objects. It was found that when contrast enhancement were applied lower exposures could be used to detect low contrast objects in images from both solid-state and photo-stimulable phosphor systems. Blooming effects deteriorated images from solid-state systems at lower doses than burn-out effects deteriorated conventional radiographs or images from a photo-stimulable phosphor system. Some improvement in physical and psychophysical performance could be seen in the new generation of solid-state systems. Subjective image quality was tested by visual grading analysis in which observers graded the visibility of structures important for the diagnosis of common dental diseases. All systems produced diagnostically acceptable image quality but the photo-stimulable phosphor systems over a much wider exposure range than the solid-state systems. Histogram equalization did not improve image quality. A common diagnostic task; measurement of marginal bone level around implants, was used to study the influence of image processing. Radiographic measurements of bone height around implants in images from a photo-stimulable phosphor system was as accurate and precise as film images. Image processing was found to be task dependent. For a specific task, related to marginal bone height measurements around implants, a strong edge enhancement algorithm was found to be best.
The underlying assumption in the present study is that the individual's speech and hearing communicative ability is composed of three components, each corresponding to different functional systems of the brain: afferent functions (A) represent the auditory activity and sound perception largely corresponding to activity in the ascending auditory pathways. The central functions (C) include cortical auditory and language abilities controlled in parts of the left temporal lobe and subcortical centres. The efferent functions (E) consist of speech motor processes and articulation. A test battery of 20 tests measuring several aspects of afferent, central and efferent functions was applied to 11 hearing-impaired post-secondary school students and several control groups. All data were normalized with the normal materials as references. Individual communicative profiles were obtained from these primary data, which consisted of audiometric tests (tone and speech audiometry, impedance tests, brainstem response audiometry and phase audiometry), sound environmental tests with hearing aids (directional speech-in-noise, word localization, sound environment identification test), and language tests (reading tests, prosody, auditory memory and recall, phonology and articulation). Since the central functions cannot truly and directly be determined in hearing-imparied subjects, they were assessed under optimal listening conditions. Furthermore, central functions were estimated according to three different models: distributive, parallel model (model 1), multiplicative, serial model (model 2) and compensatory model (model 3). On the basis of these models, a three-component description of the communicative ability consisting of A,C and E functions was obtained. It was found that C and E functions were largely independent of the adult afferent functions, but C functions were negatively correctly to hearing in childhood. A preliminary comparison between the tests and a comparison between the models was performed by predicting benefit of hearing aid. Model 3 gave the best prediction. Beyond the three-component A,C, and E characterization of the students, a total communicative ability score could be calculated giving values from 37% to 79% of the normal mean. On the basis of the conceptual and statistical analyses, the test battery could be reduced to include tone 0-12 years, tone adults, word localization test (afferent); word chain, lecture test (central), articulatory test (efferent) and audiovisual test. The simple algorithm of adding the normalized loss of afferent (peripheral) function to the normalized results of the acoustic central tests seems to be promising for isolation for the central auditory capacity even in cases with peripheral impairment. It is concluded that a wider perspective is desirable in the diagnostic evaluation of the hearing-impaired individual in order to understand his communicative abilities and form a cornerstone in the planning of rehabilitation in conjunction with social and psychological factors.
OBJECTIVES: The purpose of this study was to evaluate observers' ability to detect simulated root resorption cavities in conventional radiographs and digital radiographs from a charge-coupled device system and a storage phosphor system and to determine whether the detectability was influenced by resorption size and exposure. STUDY DESIGN: In teeth from dry mandibular jaw specimens, resorptive defects 1.2 mm in diameter and two different depths (0.6 and 0.9 mm) were prepared in the buccal root surface. Each tooth was radiographed at a number of different exposure settings. Observers were asked to rate their confidence that a resorption was or was not present using a five-graded confidence scale. Receiver operating characteristic analysis was used to evaluate the results. RESULTS AND CONCLUSION: Given optimal exposures, all systems reached what might be considered clinically acceptable Az values (> 0.75). The storage phosphor system reached this value at considerably lower exposures than those required for both the film and charge-coupled device systems. There was a tendency to better detect the deeper lesions and to identify them at lower exposures.
An acoustic laboratory for reproduction of speech and acoustic environments is presented along with two sound field tests. Its design has been inspired by the LEDE (Living End Dead End) principle for construction of radio and music control rooms. The equipment and the 12 loudspeakers can simultaneously reproduce several stereophonic and monophonic recordings. The interesting feature is that the delayed first reflex in the LEDE room allows for a realistic perception of the recording room. A preliminary presentation of two newly developed tests for sound field listening is given. In DSIN. Directional Speech In Noise, the JFC (just follow conversation) threshold for continuous discourse is determined in 12 directions in quiet and in noise from +/- 60 degrees azimuth. In SEIT (Sound Environmental Identification Test), stereophonic acoustic environments are presented and the subject is asked to identify specific components and to characterize each environment as closely as possible. Results from tests with normal hearing subjects and examples of results with hearing impaired subjects are presented. The potential of the technique for use in aural rehabilitation, functional definition of auditory communication and quality assessment of hearing aids is discussed. It is pointed out that the term ecological audiology is suitable for describing the interaction between the communicating individual and the environment in a broad sense.
The conceptual framework for describing an audiological communication handicap and its underlying processes is built in analogy to a biological, ecological system and uses the following primary concepts: interaction, internal milieu, preferendum (preferred communication features) and optimal resource utilization. From these primary concepts secondary concepts and processes are formulated: signal, message/dialogue and behavior are three levels of interaction; adjustment and release of mental resources are specifications for preferendum (influenced by contextual and social conditions); specificity and facilitation underlie optimal resource utilization. The internal environment contains afferent, central and efferent speech and language processing, cognitive and emotional processes. The main components of audiology and rehabilitation (impairment, disability, handicap) are deduced from these concepts and processes. Examples of studies based on this conceptual framework are presented briefly. These include an environmental test chamber where realistic acoustic environments and communication situations can be directly studied, and a rehabilitation programme based on tutorial education for structured interaction at the behaviour level between hearing-impaired and normal-hearing persons. A vibratory-based event localization system for deaf-blind is described which improves specificity and thereby mental resource utilization.
We investigated a Swedish family with nonsyndromic progressive bilateral sensorineural hearing loss. Thirteen candidate loci for autosomal dominant nonsyndromic hearing loss were tested for linkage in this family. We found significant LOD scores (>3) for markers at candidate locus DFNA12 (11q22-q24) and suggestive LOD scores (>2) for markers at locus DFNA2 (1p32). Our results for markers on chromosome 11 narrowed down the candidate region for the DFNA12 locus. A detailed analysis of the phenotypes and haplotypes shared by the affected individuals supported the notion that two genes segregated together with hearing impairment in the family. Severely affected family members had haplotypes linked to the disease allele on both chromosomes 1 and 11, whereas individuals with milder hearing loss had haplotypes linked to the disease allele on either chromosome 1 or chromosome 11. These observations suggest an additive effect of two genes, each gene resulting in a mild and sometimes undiagnosed phenotype, but both together resulting in a more severe phenotype.
A sample of 22 subjects was studied from a population of adults who had suffered from bacterial meningitis in childhood. Audiovestibular, oculomotor and neuropsychological investigations were performed and quality of life was assessed. An age-matched control group of 20 subjects was recruited. In the meningitis group, nine subjects had abnormal pure tone audiograms. One was previously undiagnosed and a progression was found in four. There was an overrepresentation of subclinical vestibular pathology (6 out of 9 (67%)) in this group. Audiovestibular test results showed a peripheral pattern and oculomotor tests were normal. The quality of life scores of those with hearing loss were significantly higher than those in the control group. Neuropsychological tests of brain dysfunction were abnormal in six out of 22 (27%) who had recovered from meningitis. The prevalence of such dysfunctions was not related to audiovestibular disorder. The quality of life scores of those with brain dysfunctions were similar to those of the control group. The findings of reduced auditory memory and tone level perception in four out of 22 (18%), suggest that lesions of central auditory pathways may follow from bacterial meningitis. The results support the idea that inner ear damage is the major cause of hearing loss after bacterial meningitis. Despite the absence of brainstem involvement, central nervous system lesions with disturbed auditory processing and language functions can be of significance. The high frequency of discrete brain dysfunctions indicate that a thorough neuropsychological investigation is required after bacterial meningitis.
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The goal of the present study was to analyze the distribution of efferent 8th nerve synaptic endings in a surface preparation of the guinea pig cochlea using synaptophysin antibodies. Employing light and confocal microscopy synaptophysin immunoreactivity was found exclusively at the base of the outer hair cells (OHCs) and the inner hair cells (IHCs) axosomatic efferent synapses. Qualitative and quantitative differences were found between the OHCs and the IHCs immunoreactivity. Efferent nerve endings innervating IHCs were comparatively smaller, more numerous and densely packed. Efferent terminals demonstrated a longitudinal gradient for the IHCs and a longitudinal and radial gradient for the OHCs. Quantitative analysis of synaptophysin immunofluorescence demonstrated a higher percentage of efferent terminals innervating the IHCs and the OHCs in the mid and basal segments of the cochlea than in the apical regions. In addition, a radial gradient from the 1st to 3rd row of OHCs was evident. The results from the present study show that the analysis of synaptophysin immunoreactivity on cochlear surface preparations allows the efferent innervation to be determined throughout the entire cochlea. This technique allows for a rapid assessment of the normal cochlea as well as after cochlear insult.
The aim of this in vitro study was to compare bone loss measurements in the furcation area of mandibular molars in digital radiographs from a CCD-(Sens-A-Ray) and a storage phosphor (Digora) system, 10 1st and 7 2nd mandibular molars, with intact lingual but reduced buccal bone with furcation involvements, were used. Radiographs were first taken with lead markers at the most apical part of the buccal bone and at the cemento-enamel junction. These radiographs were used to establish a radiographically true distance between the CEJ and the buccal bone level. The lead marker at the CEJ served as a reference point for the observers' subsequent estimates of the extent of bone removed, which were made in radiographs without lead markers at the bone level. 1 exposure (400 ms) for the CCD- and 5 (160 ms, 200 ms, 250 ms, 320 ms, 400 ms) for the storage phosphor system were used. Measurements were made in unprocessed (original) and processed images (contrast enhanced and/or high pass filtered). The results showed underestimation of bone loss, but smaller than previously reported for film radiographs. No significant difference was found between the 2 systems when compared at the same exposure. Nor were any significant differences found between unprocessed and processed images or between storage phosphor images from different exposures. We conclude that digital radiographs are comparable to film based radiographs for measurement of buccal bone loss but that lower exposures can be used, especially with the storage phosphor system.
A review and tutorial on the potential use of the skin for sound localization are presented. Some basic physical and psychophysical properties are reviewed; special properties and phantom perceptions associated with cutaneous stimulation are presented; experiments by Békésy, Gescheider, Frost, Richardson and Weisenberger on different instrumentation for/and results on localization of sound sources with skin stimulation are analysed. The best results have been obtained using intensity differences between two vibrators. Sound source localization precision approaching that of the auditory sense in quiet surroundings has been obtained, particularly when free head movements are allowed. Significant results have also been obtained with temporal differences, provided the natural sound delay between the ears is increased to fit the coding characteristics of the skin. As yet, no portable equipment has been designed and tested in realistic environments.
Birth hypoxia, asphyxia and ischemia have often been thought to be major causes of early hearing loss or deafness. The purpose of the present review is to focus on the role of these particular factors for perinatal auditory disorders. On the whole, only a small proportion of neonatal hearing loss is caused by perinatal factors. The exact etiology of neonatal hearing loss in children with complicated deliveries is difficult to evaluate due to the large number of causative factors that might be involved. After reviewing the literature covering the past 15-20 years, it is not possible to say that we understand the relative importance of different factors and their interactions. However, in the majority of studies, birth asphyxia is not correlated with hearing loss in babies with complicated deliveries Prolonged artificial ventilation, the presence of severe hypoxic ischemic encephalopathy or persistent pulmonary hypertension are important factors. The brain is more susceptible to anoxia than the ear and both are more likely to be damaged after prolonged pre-, peri- and postnatal hypoxia-ischemia than pure hypoxia during delivery. Perinatal hypoxia is more likely to cause a temporary hearing loss than a permanent one. Preterm babies are more vulnerable than term babies. The total number of risk factors, e.g. medicated by total length of stay in the neonatal intensive care unit and length of artificial ventilation, is the best predictor of risk for hearing loss of perinatal origin. The similarities between hearing loss and cerebral palsy are pointed out; only 8% of the cases of cerebral palsy are considered to be caused by conditions during delivery.
BACKGROUND: Cisplatin is known to create an acute dose-related ototoxic effect. There are unanswered questions regarding the long term effect of cisplatin on hearing in gynecologic cancer patients. METHODS: A retrospective review of 59 to 115 months' duration was performed on 184 women with gynecologic cancer who were treated with cisplatin-based chemotherapy between 1982 and 1986. Twenty-six of 40 survivors were again tested audiometrically with the same audiologic equipment. RESULTS: Fourteen patients (54%) had significantly progressive hearing loss (> or = 15 decibels) at long term follow-up compared with the posttreatment control. These changes were generally small and restricted to three frequencies or fewer in one of the patient's ears. The changes corresponded to the expected age effect upon hearing. Only 2 patients (8%) showed more severe hearing threshold changes. The hearing loss in one of the two patients might represent degenerative changes induced by cisplatin treatment, whereas in the other patient the etiologic background to the hearing loss remains unknown. CONCLUSIONS: This study does not provide any strong evidence for a delayed ototoxic effect of cisplatin that should influence therapeutic strategy. Patients who receive moderate dose cisplatin therapy, 50 mg/m2 per body surface area every 4 weeks, have a negligible long term risk of a drug-induced social hearing handicap.
Topographic maps of late auditory evoked potentials (AEPs) were obtained in a group of 20 children, aged 9-15 years, with severe language impairment (LI) and an age-matched control (C) group of 20 normal children. The study was focused on differences in the latency, amplitude and topography of the N1 component between the two groups and the potential diagnostic value of these variables. The stimulus was a pure tone at 500 Hz with a duration of 100 msec and a rise and fall time of 20 msec. The intensity was 75 dB HL. Six test sequences of 50 stimuli at an interval of 1.0 sec were presented to the left and right ear separately. The AEPs were recorded and analyzed with the Bio-Logic Brain Atlas III program. In the topographic maps a focus corresponding to N1 (FN1) was seen in 15 subjects after left-ear stimulation and in 17 subjects after right-ear stimulation in the LI group. In the C group FN1 was identified in all 20 subjects after left-ear stimulation and in 19 subjects after right-ear stimulation. The position of FN1 was in front of the interaural line and with a dominance on the side contralateral to the ear stimulated in both groups. Among the subjects with an FN1, 6 in the LI group and 4 in the C group had deviating topography. Non-focal maps were seen in 5 LI subjects and 1 C subject. The latencies of N1 were longer in the LI group and there was no decrease in latency with age. There were no differences in FN1 amplitudes between groups. The prolonged latencies in the LI subjects compared to the C subjects may be explained by a slower processing in central auditory pathways and the lack of decrease in latencies with age in the LI subjects might indicate that the disturbance persists and is not a pure delay of maturation. The diagnostic sensitivity of N1 latency, amplitude and topography, in selecting the LI subjects, was 40% with a specificity of 90%. Statistical mapping of a time epoch of 70-140 msec and corresponding to FN1 in the map showed regions of > or = 3 S.D. in 10 LI and 2 C subjects, which corresponds to a sensitivity of 50% and a specificity of 90%. The variability of results within the LI group may reflect different pathophysiological factors underlying the language impairment. In conclusion, topographic evaluation of auditory long-latency potentials may become a diagnostic tool in speech and language disorders.