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Biomedical subjects

E Borg

Publications and source records attributed to E Borg.

At least 37 records · Page 2Linked to original sources
PubMed1998

Evidence for digenic inheritance of nonsyndromic hereditary hearing loss in a Swedish family.

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.

Adult↗
PubMed1997

Audiovestibular and neuropsychological outcome of adults who had recovered from childhood bacterial meningitis.

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.

Adult↗
PubMed1997

Pattern of synaptophysin immunoreactivity in the efferent nerve terminals of the guinea pig cochlea.

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.

Animals↗
PubMed1997

Marginal bone level buccal to mandibular molars in digital radiographs from charge-coupled device and storage phosphor systems. An in vitro study.

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.

Alveolar Bone Loss↗
PubMed1997

Cutaneous senses for detection and localization of environmental sound sources: a review and tutorial.

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.

Auditory Perception↗
PubMed1997

Perinatal asphyxia, hypoxia, ischemia and hearing loss. An overview.

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.

Asphyxia Neonatorum↗
PubMed1996

Cisplatin administration to gynecologic cancer patients. Long-term effects on hearing.

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.

Adult↗
PubMed1996

Topography of auditory evoked cortical potentials in children with severe language impairment: the N1 component.

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.

Adolescent↗
PubMed1996

Impact of lossy image compression on accuracy of caries detection in digital images taken with a storage phosphor system.

Image compression may reduce storage needs whether in the lossless (reversible) or lossy (irreversible) form. The aims of the study were to evaluate (1) storage needs, (2) subjective image quality, and (3) accuracy of caries detection in digital radiographs compressed to various levels by a lossy compression method. The material consisted of 116 extracted human premolars and molars. The teeth were mounted three in a line and radiographed by the Digora system (Sorodex Medical Systems, Helsinki, Finland). The images were exported in tagged image file format and compressed with the Lempel-Ziv-Welch reversible and the Joint Photographic Experts Group irreversible compression algorithm on four levels. The total of 580 images were assessed by five observers on a 5-rank confidence scale for caries diagnosis. The observers subjectively judged image quality on an 11-point rank scale. With the reversible compression, images could be compressed to less than 50% of the original storage needs whereas the four irreversible compression factors compressed to 20%, 8%, 5%, and 3%, respectively. For occlusal surfaces, when receiver operating characteristic curve areas were increasingly smaller and the compression rate was higher. The difference between the original and the most compressed images was 14% (p = 0.1). The median quality score was above middle on the 11-point rank scale for all except the most compressed images (median score = 1). In conclusion, for caries diagnosis, compression ratio rates of 1:12 can be justified before accuracy and image quality is significantly affected.

Dental Caries↗
PubMed1996

Endodontic measurements in digital radiographs acquired by a photostimulable, storage phosphor system.

Digora is a newly developed digital system for intraoral radiography utilizing photostimulable storage phosphor image plates. The aim was to test the quality of the system in respect to the visibility of endodontic files and root apices at different exposures. In teeth from five dry mandibular jaw sections, Hedstrom files no. 15 were placed with the file tip at varying distances from the apex. The specimens were covered with soft tissue equivalent material and placed behind a 2-cm thick polymethyl methacrylate cylinder filled with water. Distance from focus to image plate was 30 cm. Exposures were made at 60 kV and 7 mA at 7 timer settings from 16 ms to 1000 ms in 50% increments. All images were viewed from the monitor by each of 8 observers allowed to use available contrast enhancement facilities to obtain subjectively good image quality. Utilizing built-in measurement functions, distances from file tip and root apex, respectively, to a reference line were measured in 0.1 mm. For measurements between file tip and reference line, and root apex and reference line, there was no statistically significant difference between measurements made at the lowest exposure, compared to the second lowest exposure but there was a statistically significant difference compared to the 5 highest. Measurements at the second lowest exposure were not significantly different from those obtained at the 5 highest exposures. Interobserver variability expressed as standard deviation between observers showed the largest value for measurements obtained at the lowest exposure. The mean observed distances between the tip of the file and the root apex were calculated and showed no statistically significant differences between different exposures. We concluded that the Digora intraoral image plate system provided reliable endodontic measurements even at very low exposures.

Analysis of Variance↗
PubMed1996

On the dynamic range of different X-ray photon detectors in intra-oral radiography. A comparison of image quality in film, charge-coupled device and storage phosphor systems.

OBJECTIVE: To compare film for intra-oral radiography with two charge-coupled device (CCD) and one storage phosphor system for digital imaging in respect of subjective image quality, detectability of small mass differences and appearance of burn-out effects and blooming phenomena at various exposure times. METHODS: Dried mandibles with teeth from different areas were radiographed at exposures covering a relative range from 1 to 100. Image quality was subjectively evaluated after image processing, when applicable, using a visual grading scale from 0 to 10. The number of visible holes in an aluminium block was used to measure the detectability of small mass differences. Burn-out effects and blooming were evaluated by measuring widths of roots and of aluminium and plastic cylinders. RESULTS: Radiographs with the storage phosphor system achieved image quality scores similar to those of film but over a larger exposure range, while CCD images were rated lower and over a smaller range. All holes in the aluminium block were only detected with the storage phosphor system. While the widths of roots were strongly affected by sensor saturation in CCD images and by burn-out in film images, smaller effects were seen with the storage phosphor system. Similar results were obtained with aluminium and plastic cylinders. CONCLUSIONS: Higher image quality was achieved over a much wider exposure range with the storage phosphor system than with either film or the CCD systems.

Humans↗
PubMed1996

An image plate system for digital intra-oral radiography.

Direct image acquisition of intra-oral images using digital, filmless, techniques has been possible only since the late 1980s, although indirect methods have been available since the late 1970s. The techniques possible so far have had a number of limitations, making them cumbersome to use. A new system, the Digora system, has recently been developed in Finland, which overcomes many of these shortcomings. The principles and uses of this system are described here.

Equipment Design↗
PubMed1995

Topography of auditory evoked long-latency potentials in normal children, with particular reference to the N1 component.

Topographic maps of late auditory evoked potentials were obtained with the Brain Atlas III system in 34 healthy, normal hearing children aged 8-16 years. The stimulus was a 100 msec, 500 Hz tone burst, presented separately to the left and right ears, at 75 dB HL. The resulting auditory evoked potentials showed a prominent N1, after about 100 msec, and a topographic map with a corresponding fronto-lateral focus designated as the focus of N1 (FN1). Foci with varying positions and amplitudes were identified in 33 of 34 subjects after left ear stimulation and in 29 of 32 subjects after right ear stimulation. The topography showed a high degree of stability in most subjects, with the position of the negative "peak" of FN1 in front of the interaural line and with a dominance contralateral to the ear stimulated. There was a significant decrease in the latency of N1 with increasing age. FN1 tended to change position with age and some differences from adults were also observed. In conclusion, a distinct topographic pattern of the N1 component of the late auditory evoked potentials was seen in the majority of children. It remains to be established to what extent this method may be clinically useful for disclosing functional disturbances in the central auditory pathways.

Acoustic Stimulation↗
PubMed1995

Extra inner hair cells: prevalence and noise susceptibility.

A total of 39 cochleae, 10 non-exposed and 29 noise exposed cochleae, were analyzed in a scanning electronmicroscope. Inner hair cells (IHCs) localized on the modiolar side of the ordinary row of IHCs were described. The mean number of such extra IHCs was 11 per cochlea both for non-exposed and exposed ears, ranging from 0-37. They showed a bimodal distribution with a maximum number at apex and 6-9 mm from apex. The dimension of the cuticular plate was slightly but significantly larger than for the ordinary IHCs. The extra IHCs suffered significantly less damage to their stereocilia than the ordinary IHCs after short-term high-level noise exposure. There was a significant negative correlation between the number of extra IHCs and the size of the post exposure permanent threshold shift. There was no evidence of postexposure generation of extra IHCs in or near the region of hair cell damage. It was concluded that extra IHCs normally occur in rabbits and that they are less susceptible to noise trauma than ordinary IHCs. The negative correlation between extra IHC occurrence and noise susceptibility needs further analysis.

Acoustic Stimulation↗
PubMed1995

Accuracy of caries diagnosis in digital images from charge-coupled device and storage phosphor systems: an in vitro study.

OBJECTIVES: To evaluate the diagnostic accuracy of carries detection with four intra-oral digital radiographic systems in vitro and to investigate the impact of image compression. METHODS: 116 extracted human premolars and molars mounted three in a line with approximal contacts were radiographed with four digital systems (Digora, RVG, Sens-A-Ray, and Visualix) and imported into a Windows-based program. Sixteen images from each system were compressed (JPEG, irreversible compression). The total of 528 images was assessed by six radiologists using a 5-point confidence scale for the detection of approximal and occlusal caries. Caries was validated histologically. The disease threshold was caries in enamel for approximal surfaces and in dentine for occlusal surfaces. RESULTS: Mean ROC curve areas for approximal surfaces were 0.611 (DIG), 0.572 (RVG), 0.594 (SAR), and 0.596 (VIX), and for occlusal surfaces 0.794 (DIG), 0.819 (RVG), 0.751 (SAR), and 0.761 (VIX). There were no significant differences between the areas under the ROC curves (p > 0.05); nor were there any significant differences between the compressed and uncompressed images (p > 0.05). CONCLUSIONS: The four digital systems performed almost equally well for detection of caries in vitro, and compressed images were as accurate as uncompressed.

Bicuspid↗
PubMed1995

[Multipoint video-conference. An option for highly specialized education].

Video-conferencing via the PST (Public Switched Telephone) network is a good and economical alternative for use in education. If the universities cooperate, instruction by the best lecturers can be made available to small groups of students distributed over great distances. Travel costs will be minimised and teachers under pressure of time will be able to use their time rationally. Although the social intercourse of a study group promotes the students' mental energy to the benefit of instruction, such technical advances as more rapid transmission and audiovisual integration will be needed. Last but not least, efficient course secretaries will be required to coordinate the work both of lecturers and studio and telephone personnel, as well as the participation of the various study groups.

Education, Medical↗