GRAS-1 is a novel regulator of early meiotic chromosome dynamics in C. elegans

Chromosome movements and licensing of synapsis must be tightly regulated during early meiosis to ensure accurate chromosome segregation and avoid aneuploidy, although how these steps are coordinated is not fully understood. Here we show that GRAS-1, the worm homolog of mammalian GRASP/Tamalin and CYTIP, coordinates early meiotic events with cytoskeletal forces outside the nucleus. GRAS-1 localizes close to the nuclear envelope (NE) in early prophase I and interacts with NE and cytoskeleton proteins. Delayed homologous chromosome pairing, synaptonemal complex (SC) assembly, and DNA double-strand break repair progression are partially rescued by the expression of human CYTIP in gras-1 mutants, supporting functional conservation. However, Tamalin, Cytip double knockout mice do not exhibit obvious fertility or meiotic defects, suggesting evolutionary differences between mammals. gras-1 mutants show accelerated chromosome movement during early prophase I, implicating GRAS-1 in regulating chromosome dynamics. GRAS-1-mediated regulation of chromosome movement is DHC-1-dependent, placing it acting within the LINC-controlled pathway, and depends on GRAS-1 phosphorylation at a C-terminal S/T cluster. We propose that GRAS-1 coordinates the early steps of homology search and licensing of SC assembly by regulating the pace of chromosome movement in early prophase I.

Upstream open reading frames control PLK4 translation and centriole duplication in primordial germ cells

Centrosomes are microtubule-organizing centers comprised of a pair of centrioles and the surrounding pericentriolar material. Abnormalities in centriole number are associated with cell division errors and can contribute to diseases such as cancer. Centriole duplication is limited to once per cell cycle and is controlled by the dosage-sensitive Polo-like kinase 4 (PLK4). Here, we show that PLK4 abundance is translationally controlled through conserved upstream open reading frames (uORFs) in the 5' UTR of the mRNA. Plk4 uORFs suppress Plk4 translation and prevent excess protein synthesis. Mice with homozygous knockout of Plk4 uORFs (Plk4 Δu/Δu ) are viable but display dramatically reduced fertility because of a significant depletion of primordial germ cells (PGCs). The remaining PGCs in Plk4 Δu/Δu mice contain extra centrioles and display evidence of increased mitotic errors. PGCs undergo hypertranscription and have substantially more Plk4 mRNA than somatic cells. Reducing Plk4 mRNA levels in mice lacking Plk4 uORFs restored PGC numbers and fully rescued fertility. Together, our data uncover a specific requirement for uORF-dependent control of PLK4 translation in counterbalancing the increased Plk4 transcription in PGCs. Thus, uORF-mediated translational suppression of PLK4 has a critical role in preventing centriole amplification and preserving the genomic integrity of future gametes.

PLK1 depletion alters homologous recombination and synaptonemal complex disassembly events during mammalian spermatogenesis

Homologous recombination (HR) is an essential meiotic process that contributes to the genetic variation of offspring and ensures accurate chromosome segregation. Recombination is facilitated by the formation and repair of programmed DNA double-strand breaks. These DNA breaks are repaired via recombination between maternal and paternal homologous chromosomes and a subset result in the formation of crossovers. HR and crossover formation is facilitated by synapsis of homologous chromosomes by a proteinaceous scaffold structure known as the synaptonemal complex (SC). Recent studies in yeast and worms have indicated that polo-like kinases (PLKs) regulate several events during meiosis, including DNA recombination and SC dynamics. Mammals express four active PLKs (PLK1-4), and our previous work assessing localization and kinase function in mouse spermatocytes suggested that PLK1 coordinates nuclear events during meiotic prophase. Therefore, we conditionally mutated Plk1 in early prophase spermatocytes and assessed stages of HR, crossover formation, and SC processes. Plk1 mutation resulted in increased RPA foci and reduced RAD51/DMC1 foci during zygonema, and an increase of both class I and class II crossover events. Furthermore, the disassembly of SC lateral elements was aberrant. Our results highlight the importance of PLK1 in regulating HR and SC disassembly during spermatogenesis.

Evaluation of the Intubating Laryngeal Mask Airway™ Used by Occasional Intubators in Simulated Trauma

This observational study assessed the potential role of the intubating laryngeal mask airway (ILMA™ ) for use by emergency care givers with limited laryngoscopy skills.

Six ambulance officers with advanced airway training, five doctors with intubation experience and five doctors without intubation experience were given a short instruction course on the use of the ILMA. They subsequently used the device on 80 consenting subjects anaesthetized for elective surgery after the application of cricoid pressure and manual in-line stabilization of the cervical spine. All patients were successfully ventilated via the ILMA. Mean (SD) times in seconds to ventilation were 27 (10), 33 (18) and 47 (22) respectively in the occasional intubator ambulance officers, occasional intubator doctor and naï ve intubator groups. The numbers (percentage) failures to intubate via the ILMA in each group were 2 (7%), 5 (20%) and 4 (16%) respectively. Mean (SD) times in seconds to intubation were 32 (23), 32 (17) and 36 (25). There was no evidence of “learning” with repeated use. The feedback forms were strongly supportive of a prehospital trial and also of having an ILMA available during all intubations. Participants almost universally rated the ILMA as easy to use. This study supports further evaluation of the ILMA in a large pre-hospital trial.

The Patient Reported Outcomes, Burdens and Experiences (PROBE) Project: development and evaluation of a questionnaire assessing patient reported outcomes in people with haemophilia

Background

The interest of health care agencies, private payers and policy makers for patient-reported outcomes (PRO) is continuously increasing. There is a substantial need to improve capacity to collect and interpret relevant PRO data to support implementation of patient-centered research and optimal care in haemophilia. The Patient Reported Outcomes, Burdens and Experiences (PROBE) Project aims to develop a patient-led research network, to develop a standardized questionnaire to gather patient-reported outcomes and to perform a feasibility study of implementing the PROBE questionnaire.

Methods

A pilot questionnaire was developed using focus group methodology. Content and face validity were assessed by a pool of persons living with haemophilia (PWH) and content experts through interactive workshops. The PROBE questionnaire was translated with the forward-backward approach. PROBE recruited national haemophilia patient non-governmental organizations (NGOs) to administer the questionnaire to people with and without haemophilia. PROBE measured the time to complete the questionnaire and gathered feedback on its content and clarity; staff time and cost required to implement the questionnaire were also collected.

Results

The PROBE questionnaire is comprised of four major sections (demographic data, general health problems, haemophilia-related health problems and health-related quality of life using EQ-5D-5L and EQ-VAS). Seventeen NGOs participated in the pilot study of the PROBE Project, recruiting 656 participants. Of these, 71% completed the questionnaire within 15 min, and all participants completed within 30 min. The median total staff and volunteer time required for the NGOs to carry out the study within their country was 9 h (range 2 to 40 h). NGO costs ranged from $22.00 to $543.00 USD per country, with printing and postage being the most commonly reported expenditures.

Conclusions

The PROBE questionnaire assesses patient-important reported outcomes in PWH and control participants, with a demonstrated short completion time. PROBE proved the feasibility to engage diverse patient communities in the structured generation of real-world outcome research at all stages.

Trial registration

Trial registration: NCT02439710.

Electronic supplementary material

The online version of this article (10.1186/s40814-018-0253-0) contains supplementary material, which is available to authorized users.

Building our global family--achieving treatment for all

SUMMARY

Building our global family by reaching out to women, children and youth and those in sub-Saharan Africa to achieve Treatment for All. The World Federation of Hemophilia (WFH) has committed to recognizing and incorporating the critical and important challenges that are faced by women with bleeding disorders within our global family. The next crucial steps include the development of outreach and registry programmes which can be adapted globally to accelerate the identification of such women, and to educate and guide them to the appropriate clinical care setting. Equally important, awareness must be raised within the broader medical community where women would typically first present with clinical symptoms. Family practitioners, nurse-midwives, obstetricians, gynaecologists and community health clinics will increasingly be strategic and central to WFH outreach efforts, in addition to serving as new care partners essential to the multidisciplinary model of care. Adapting and implementing the WFH development model regionally within Africa is proving to be a successful approach both for the introduction as well as the development of sustainable national care programmes for patients with bleeding disorders. The targeted development of solid national programmes such as in South Africa, Senegal and Kenya has expanded the training capacity of the WFH, as well as providing key regional examples. Local medical professionals are now responsible for providing the training in many regional programmes. Children with bleeding disorders in low-income countries are at great risk of dying young. WFH data demonstrate that among such patients, as the economic capacity of a country decreases so does the ratio of adults to children. The organization of care, training of a multi-disciplinary healthcare team, and education of patients and their families lead to improved mortality independent of economic capacity or increased clotting factor concentrate availability. Additionally, through enhanced youth education, awareness and engagement, we will assure continuity within WFH national member organizations, build greater unity within our global family and capture the innovation and creativity of their ideas to improve Treatment for All.

Treatment for all: a vision for the future

The World Federation of Hemophilia (WFH) has defined a new strategic plan which maps out where the organization is going and what it can do for our members. The plan embraces the vision of Treatment for All; i.e. one day, treatment will be available for all those with inherited bleeding disorders, regardless of where they live. Treatment for All means proper diagnosis, management, and care by a multidisciplinary team of trained specialists. It means safe, effective treatment products are available for all people with inherited bleeding disorders. It means expanding services beyond haemophilia, to those with von Willebrand's disease, rare factor deficiencies, and inherited platelet disorders. Today, more than 75% of the global bleeding disorders community receive either inadequate or no treatment whatsoever. Our mission is to improve treatment where it is limited or does not exist. At the same time, we must sustain the many gains we have achieved thus far. The challenge is immense. Making our vision a reality requires us to be focused and deliberate about the programmes we undertake and the commitments we make. Building on past strategic plans, this plan presents a vision for the continued success of the WFH over the next 3-5 years.

What is a cure and how do we get there?

The absence of adequate treatment for most of the world's 400 000 individuals with haemophilia makes the development of a cure compelling. Advances in the basic molecular sciences over the past 20 years have resulted in the feasibility of curing haemophilia through the application of gene therapy. However, the reality of this therapeutic strategy is highly complex. In addition, challenges to achieving a cure exist beyond the basic scientific hurdles. Thoughtful attention must also be given to a number of interrelated issues, including ethical considerations in patient recruitment, informed consent and geographical variables of global clinical trials. The global inequalities in healthcare mean that the ethics of international medical research, especially when it includes countries where people usually do not receive quality care, become much more complicated. The majority of haemophiliacs lives in developing countries and is a valuable resource of human subjects who could be enrolled in clinical trials. When recruiting subjects globally, investigators must be ever mindful that the patient population is a precious resource, which must be treated with respect and care. This presents a major challenge for investigators engaged in trials of haemophilia gene therapy to ensure that the informed consent process is current and comprehensive, that therapeutic misconceptions are appropriately managed, and that the roles of the researcher and physician are clear. Global clinical gene-therapy trials are an important and appropriate component in the quest to achieve a cure for haemophilia. When trials follow identical internationally accepted standards, a successful outcome can be achieved for trials including developing countries, if country specific cultural and economic aspects are considered.

Cochlear implants: three-dimensional localization by means of coregistration of CT and conventional radiographs

With use of radiopaque implanted objects as internal fiducial markers, the authors developed and evaluated a technique for coregistering computed tomographic (CT) and computed radiographic images to help determine three-dimensional location information for implant electrodes in the cochlea in phantoms and patients. Three-dimensional positional data from CT were assigned on a radiograph, which permitted identification of individual cochlear electrode locations that were not depicted at CT.

Do anaesthetists need to wear surgical masks in the operating theatre? A literature review with evidence-based recommendations

Many operating theatre staff believe that the surgical face mask protects the healthcare worker from potentially hazardous biological infections. A questionnaire-based survey, undertaken by Leyland' in 1993 to assess attitudes to the use of masks, showed that 20% of surgeons discarded surgical masks for endoscopic work. Less than 50% did not wear the mask as recommended by the Medical Research Council. Equal numbers of surgeons wore the mask in the belief they were protecting themselves and the patient, with 20% of these admitting that tradition was the only reason for wearing them. Policies relating to the wearing of surgical masks by operating theatre staff are varied. This indicates some confusion about the role of the surgical mask in modern surgical and anaesthetic practice. This review was undertaken to collate current evidence and make recommendations based on this evidence.

The societal costs of severe to profound hearing loss in the United States

OBJECTIVE

Severe to profound hearing impairment affects one-half to three-quarters of a million Americans. To function in a hearing society, hearing-impaired persons require specialized educational, social services, and other resources. The primary purpose of this study is to provide a comprehensive, national, and recent estimate of the economic burden of hearing impairment.

METHODS

We constructed a cohort-survival model to estimate the lifetime costs of hearing impairment. Data for the model were derived principally from the analyses of secondary data sources, including the National Health Interview Survey Hearing Loss and Disability Supplements (1990-91 and 1994-95), the Department of Education's National Longitudinal Transition Study (1987), and Gallaudet University's Annual Survey of Deaf and Hard of Hearing Youth (1997-98). These analyses were supplemented by a review of the literature and consultation with a four-member expert panel. Monte Carlo analysis was used for sensitivity testing.

RESULTS

Severe to profound hearing loss is expected to cost society $297,000 over the lifetime of an individual. Most of these losses (67%) are due to reduced work productivity, although the use of special education resources among children contributes an additional 21%. Lifetime costs for those with prelingual onset exceed $1 million.

CONCLUSIONS

Results indicate that an additional $4.6 billion will be spent over the lifetime of persons who acquired their impairment in 1998. The particularly high costs associated with prelingual onset of severe to profound hearing impairment suggest interventions aimed at children, such as early identification and/or aggressive medical intervention, may have a substantial payback.

Digital X-ray stereophotogrammetry for cochlear implantation

Multielectrode, intracochlear implant systems are effective treatment for profound sensorineural hearing loss. In some cases, these systems do not perform well, which may be partially due to variations in implant location within the cochlea. Determination of each electrode's position in a patient's inner ear provides an in vivo basis for both the cochlear modeling of electrical fields and the future design of electrode arrays that deliver electrical stimulation to surviving auditory neurons, and may improve speech processor programming for better speech recognition. We developed an X-ray stereophotogrammetric approach to localize implanted electrodes in three dimensions. Stereophotogrammetry of implanted electrodes is formulated in weak perspective geometry, with knowledge of a three-dimensional (3-D) reference structure and electrode positions in each of two digital stereo-images. The localization error is theoretically, numerically, and experimentally quantified. Both numerical and experimental results demonstrate the feasibility of the technique.

Three-dimensional modeling and visualization of the cochlea on the Internet

Three-dimensional (3-D) modeling and visualization of the cochlea using the World Wide Web (WWW) is an effective way of sharing anatomic information for cochlear implantation over the Internet, particularly for morphometry-based research and resident training in otolaryngology and neuroradiology. In this paper, 3-D modeling, visualization, and animation techniques are integrated in an interactive and platform-independent manner and implemented over the WWW. Cohen's template shape with mean cross-sectional areas of the human cochlea is extended into a 3-D geometrical model. Also, spiral computer tomography data of a patient's cochlea is digitally segmented and geometrically represented. The cochlear electrode array is synthesized according to its specification. Then, cochlear implantation is animated with both idealized and real cochlear models. Insertion length, angular position, and characteristic frequency of individual electrodes are estimated online during the virtual insertion. The optimization of the processing parameters is done to demonstrate the feasibility of this technology for clinical applications.

Localization of cochlear implant electrodes in radiographs

Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programming for better speech recognition. The prerequisite for 3-D localization of the electrodes is their 2-D localization in x-ray radiographs. In this paper, we develop a practical method to localize the electrodes with high efficiency, accuracy, and reproducibility. In this method, a priori knowledge of the electrodes and their approximate positions are utilized, an intelligent thresholding and segmentation mechanism is embedded, and the electrode center is computed as the weighted geometric center of segmented electrode pixels. Experiments with physical phantoms and human data demonstrate the feasibility and utility of this method. The PC-based program developed for this project is disseminated on the Web.

Effect of stimulation rate on cochlear implant recipients' thresholds and maximum acceptable loudness levels

Clinically, speech processor programs are created using electrical thresholds and maximum acceptable loudness levels (MALs) at several different stimulation rates to determine what rate will provide cochlear implant recipients with the best speech recognition when using fast-rate speech coding strategies. This study was designed to determine the difference in thresholds and MALs (expressed in the clinical unit, Current Level [CL]) for pairs of six rates spanning those available with the Nucleus 24 device (i.e., 250 to 2,400 pps/ch) using monopolar, 25 microsec/phase stimulation. Test-retest measures of threshold and MAL for each rate were obtained from seven adult Nucleus 24 recipients on each of 11 electrodes. The difference in threshold and in MAL between pairs of rates was dependent on the absolute CL. Below approximately 190 CL, thresholds and MALs decreased with increasing rate; above 210 CL, there was little change in threshold or MAL with increasing rate. Based on these findings, an approach to estimating threshold and MAL from one rate to another is suggested, pending further research.

Identification of speech by cochlear implant recipients with the multipeak (MPEAK) and spectral peak (SPEAK) speech coding strategies II. Consonants

OBJECTIVE

The major objective of this study was to evaluate differences in consonant recognition with the Multipeak (MPEAK) and the Spectral Peak (SPEAK) speech coding strategies of the Nucleus-22 Cochlear Implant System. This objective was addressed by comparison of acoustic and electrode activation analyses of consonants with cochlear implant recipients' responses to these same consonant tokens when they used the two speech coding strategies.

DESIGN

Nine subjects identified 14 English consonants with the MPEAK and SPEAK speech coding strategies. These strategies were compared with an ABAB design. Evaluation occurred during two weekly sessions after subjects used each strategy for at least 3 wk in everyday life.

RESULTS

Group medial consonant [aCa] identification scores with the SPEAK strategy were significantly higher than with the MPEAK strategy (76.2% versus 67.5%; p < 0.001). This improvement was largely due to the significant increase in information transmitted for the place feature (p < 0.001) through accurate tracking of second formant transitions and spectrally specific stimulation patterns to differentiate [s] from [symbol see text] and [n] from [m], and the stop consonant bursts. For this reason, more nasal consonants were correctly identified with SPEAK, but there also were more non-nasal error responses when the nasal murmur was of unusually low amplitude. Consequently, significantly less information was transmitted for the nasality feature with SPEAK than MPEAK (p < 0.001).

CONCLUSIONS

Electrical stimulation with the SPEAK strategy provided better spectral representation of the stop consonant bursts, tracking formant transitions into the following vowel, frication in the consonant [symbol see text], and the formants for the nasals [m] and [n] than with the MPEAK strategy. The marked improvement in recognition of the velar consonants, [g] and [k], which cannot be seen during speechreading, should allow greater ease and accuracy of communication with SPEAK than MPEAK.

Effect of speech processor program modifications on cochlear implant recipients' threshold and maximum acceptable loudness levels

This study's purpose was to determine whether or not modifications in speech processor electrical stimulation levels were associated with changes in five Nucleus 22 cochlear implant recipients' thresholds or maximum acceptable loudness levels (MALs). These modifications in minimum and maximum stimulation levels were made to optimize hearing in everyday life. One threshold and one MAL were obtained on each active electrode during six, weekly test sessions, three before and three after program modification. Only one participant had a significant change in threshold after program modification; this participant and four others had significant changes in MAL. Participants' threshold variability was the same, but MAL variability was higher than that observed in other studies. Because these participants had no experience making MAL judgments prior to this study, this result suggests that implant recipients should be given sufficient practice in making MAL judgments to provide a stable clinical estimate of the upper boundary of the electrical dynamic range.

Comparison of two methods for selecting minimum stimulation levels used in programming the Nucleus 22 cochlear implant

Minimum stimulation levels for active electrodes in a Nucleus 22 cochlear implant were set at threshold (clinical default value) and raised levels (M = +2.04 dB) to determine if raised levels would improve recipients' understanding of soft speech sounds with the SPEAK speech coding strategy. Eight postlinguistically deaf adults participated in a 4-phase A1B1A2B2 test design. Speech recognition was evaluated with consonant-vowel nucleus-consonant (CNC) words in quiet and sentences in noise, both presented at 50, 60, and 70 dB SPL during 2 weekly sessions at the end of each phase. Group mean scores were significantly higher with the raised level program for words and phonemes at 50 and 60 dB SPL and for sentences at 50 and 70 dB SPL. All participants chose to use the raised level program in everyday life at the end of the study. The results suggest that clinical use of a raised level program for Nucleus 22 recipients has the potential to make soft sounds louder and, therefore, more salient in everyday life. Further research is needed to determine if this approach is appropriate for other cochlear implant devices.

In vivo measures of cochlear length and insertion depth of nucleus cochlear implant electrode arrays

Three-dimensional cochlear canal lengths, electrode array intracochlear insertion depths, and characteristic frequency ranges were estimated for 20 Nucleus implant recipients on the basis of in vivo computed tomography (CT) scans. Ultra-high resolution images were reconstructed from spiral CT data with 0.1-mm slicing and expanded attenuation scales. Canal length estimates (mean 33.01 mm; SD 2.31) were consistent with previous findings for normal human temporal bones. Intracochlear array insertion depths estimated by 3-dimensional (3-D) spiral calculations (mean 20.19 mm; SD 2.86) and by a computerized array tracking algorithm (mean 20.36 mm; SD 2.66) were not significantly different. Estimates from surgical observations were significantly longer (mean 21.03 mm; SD 2.31) because array compressions were not detectable. Characteristic frequencies at apical electrodes estimated from Greenwood's equations ranged from 387 Hz to 2,596 Hz. The results show that significant variations in cochlear anatomy and array distribution among implant patients that may impact implant performance can be reliably detected and quantified by using in vivo high-resolution CT and 3-D reconstructions.

Spiral CT image deblurring for cochlear implantation

Cochlear implantation is the standard treatment for profound hearing loss. Preimplantation and postimplantation spiral computed tomography (CT) is essential in several key clinical and research aspects. The maximum image resolution with commercial spiral CT scanners is insufficient to define clearly anatomical features and implant electrode positions in the inner ear. In this paper, we develop an expectation-maximization (EM)-like iterative deblurring algorithm to achieve spiral CT image super-resolution for cochlear implantation, assuming a spatially invariant linear spiral CT system with a three-dimensional (3-D) separable Gaussian point spread function (PSF). We experimentally validate the 3-D Gaussian blurring model via phantom measurement and profile fitting. The imaging process is further expressed as convolution of an isotropic 3-D Gaussian PSF and a blurred underlying volumetric image. Under practical conditions, an oblique reconstructed section is approximated as convolution of an isotropic two-dimensional (2-D) Gaussian PSF and the corresponding actual cross section. The spiral CT image deblurring algorithm is formulated with sieve and resolution kernels for suppressing noise and edge artifacts. A typical cochlear cross section is used for evaluation, demonstrating a resolution gain up to 30%40% according to the correlation criterion. Physical phantoms, preimplantation and postimplantation patients are reconstructed into volumes of 0.1-mm cubic voxels. The patient images are digitally unwrapped along the central axis of the cochlea and the implanted electrode array respectively, then oblique sections orthogonal to the central axis formed. After deblurring, representation of structural features is substantially improved in all the cases.

Optimization of speech processor fitting strategies for Chinese-speaking cochlear implantees

OBJECTIVES

To compare speech recognition performance in Chinese-speaking cochlear implant patients with a speech processor program selected by the clinical audiologist in Taiwan and with a new speech processor program based on the Washington University clinical procedure developed by Skinner et al.

STUDY DESIGN

Six adult Chinese-speaking patients implanted with the Nucleus cochlear implant system participated in this study.

METHODS

A fitting procedure developed in 1995 by Skinner et al. at Washington University School of Medicine was used to create a new speech processor program to optimize each patient's hearing in everyday life. Speech tests (vowels, consonants, tones, and words), sound-field thresholds, and a self-report questionnaire were used to evaluate each patient's performance with his or her previous speech processor program and a new one.

RESULTS

Four of the six patients had significant changes from the previous to the new speech processor program. These changes were associated with improvement in score on at least one speech test, more sensitive sound field thresholds, and reported improvement in some everyday listening situations on the questionnaire.

CONCLUSIONS

These results suggest that use of this procedure with adult cochlear implantees may improve benefit in everyday life. Analysis of the speech test stimuli and patients' responses provides a basis for modification or creation of new Mandarin Chinese speech tests for preoperative and postoperative evaluation of adult cochlear implant patients.

Effects of formant bandwidth on the identification of synthetic vowels by cochlear implant recipients

OBJECTIVE

The main objective was to investigate whether the broadening and narrowing of formant bandwidths had a significant effect on the identification of vowels often confused by Nucleus cochlear implant recipients using the Spectral Peak (SPEAK) speech coding strategy. Specifically, identification performance for synthetic vowels with the first two formants (F1 and F2) parametrically varied in bandwidth was explored.

DESIGN

Eight implanted subjects identified synthetic versions of the isolated vowel sounds [I, epsilon, lambda, [symbol: see text]] with F1 and F2 bandwidth manipulations, as well as foil tokens of [i, u, a, ae, [symbol: see text]]. Identification performance was examined in terms of percent correct as well as error patterns. Further analyses compared patterns of electrode activation.

RESULTS

In general, broader F1 bandwidths yielded poorer performance and narrower F1 bandwidths yielded better performance relative to identifications for the reference stimuli. However, similar manipulations of F2 bandwidths resulted in less predictable performance. Comparison of electrode activation patterns indicated a distinct sharpening or flattening in the F1 frequency region for subjects with the greatest performance extremes.

CONCLUSIONS

Manipulation of F1 bandwidth can result in concomitant changes in electrode activation patterns and identification performance. This suggests that modifications in the SPEAK coding strategy for the F1 region may be a consideration. Similar manipulations of F2 bandwidth yielded less predictable results and require further investigation.

Parameter selection to optimize speech recognition with the Nucleus implant

Speech coding strategy, frequency boundary assignment table, and speech processor program minimum and maximum stimulation levels are parameters of the Nucleus Cochlear Implant System whose selection affects speech recognition performance in adults and children. Research studies show that speech recognition is significantly better with (1) the Spectral Peak than with the Multipeak speech coding strategy and (2) frequency boundary assignment Table 7 than with Table 9 in an individual's speech processor program (MAP). Minimum and maximum stimulation levels in this MAP are based on psychophysical measurements on each electrode but often need to be modified for optimum use in everyday life. Many children and adults have increases, decreases, or fluctuations in electrical hearing that require changes in the MAP minimum and maximum levels to maintain their ability to recognize speech and other sounds.

Speech recognition at simulated soft, conversational, and raised-to-loud vocal efforts by adults with cochlear implants

Ten postlinguistically deaf adults who used the Nucleus Cochlear Implant System and SPEAK speech coding strategy responded to vowels, consonants, words, and sentences presented sound-only at 70, 60, and 50 dB sound-pressure level. Highest group mean scores were at a raised-to-loud level of 70 dB for consonants (73%), words (44%), and sentences (87%); the highest score for vowels (70%) was at a conversational level of 60 dB. Lowest group mean scores were at a soft level of 50 dB for vowels (56%), consonants (47%), words (10%), and sentences (29%); all except subject 7 had some open-set speech recognition at this level. For the conversational level (60 dB), group mean scores for sentences and words were 72% and 29%, respectively. With this performance and sound-pressure level, it was observed that these subjects communicated successfully in a variety of listening situations. Given these subjects' speech recognition scores at 60 dB and the fact that 70 dB does not simulate the vocal effort used in everyday speaking situations, it is suggested that cochlear implant candidates and implantees be evaluated with speech tests presented at 60 dB instead of the customary 70 dB sound-pressure level to simulate benefit provided by implants in everyday life. Analysis of individuals' scores at the three levels for the four speech materials revealed different patterns of speech recognition among subjects (e.g., subjects 1 and 5). Future research on the relation between stimuli, sound processing, and subjects' responses associated with these different patterns may provide guidelines to select parameter values with which to map incoming sound onto an individual's electrical dynamic range between threshold and maximum acceptable loudness level to improve speech recognition.

Speech recognition with the MPEAK and SPEAK speech-coding strategies of the Nucleus Cochlear Implant

The Spectra 22 Speech Processor and spectral peak (SPEAK) speech-coding strategy provide Nucleus 22 Channel Cochlear Implant (Cochlear, Corp., Englewood, Colo.) users with a better understanding of speech than the previous Mini Speech Processor and Multipeak (MPEAK) speech-coding strategy. On the NU-6 Monosyllabic Word Test, subjects scored 13% higher for words and 14% higher for phonemes with the SPEAK strategy than with the MPEAK strategy. On the Connected Speech Test and the CID Everyday Sentence Test, subjects scored 32% and 37% higher, respectively, with SPEAK than with MPEAK.

Speech Recognition with the MPEAK and SPEAK Speech-Coding Strategies of the Nucleus Cochlear Implant

The Spectra 22 Speech Processor and spectral peak (SPEAK) speech-coding strategy provide Nucleus 22 Channel Cochlear Implant (Cochlear, Corp., Englewood, Colo.) users with a better understanding of speech than the previous Mini Speech Processor and Multipeak (MPEAK) speech-coding strategy. On the NU-6 Monosyllabic Word Test, subjects scored 13% higher for words and 14% higher for phonemes with the SPEAK strategy than with the MPEAK strategy. On the Connected Speech Test and the CID Everyday Sentence Test, subjects scored 32% and 37% higher, respectively, with SPEAK than with MPEAK.

Unwrapping Cochlear implants by spiral CT

Multielectrode, intracochlear implants were designed for individuals with profound sensorineural hearing loss who derive little or no benefit form acoustic hearing aids. Determination of each electrode's position in a patient's inner ear may improve speech processor programming to maximize speech recognition. In this paper, an approach is described to use as input a volumetric spiral computed tomography (CT) image of the Nucleus electrode array (Cochlear Pty. Ltd, Lane Cove, NSW, Australia) to unwrap it, and to measure its implanted length given starting and end points. Representative curvilinear structures were digitally synthesized in image volumes of isotropic 0.1-mm voxels. The electrode array was spirally CT-scanned in vitro and in vivo, and reconstructed on an isotropic grid in 0.1-mm steps. Two algorithms were constructed to track and measure these curvilinear structures. The first algorithm is Karhunen-Loeve (K-L)-transform based, in which the K-L transform is locally applied at a current main axis position to determine the eigenvectors of the main axis voxels, the next main axis position is estimated from the current position along the principal eigendirection, adjusted to the mass center of the orthogonal cross section passing through the estimated position, and then scaled to have a prespecified step. The second algorithm is similar to the first one but avoids use of the K-L transform. In the second algorithm, the next position is directly estimated along the local direction and then processed with the same correction and scaling operations. With user-specified starting and end points as well as a local direction at the starting point, a curvilinear structure can be automatically tracked using either of the algorithms. The first algorithm is more robust, while the second one is more efficient. In the numerical and in vitro studies, the lengths of the curvilinear structures were accurately measured. Given local directions determined in the tracking process, an electrode array image can be unwrapped into a linear array with the central electrode axis as the abscissa. The unwrapping approach allows longitudinally and cross-sectionally accurate measurement and better visualization of cochlear implant images. With preimplantation knowledge of length, width, and center electrode distance, the position of individual electrodes can be estimated after unwrapping.

Identification of speech by cochlear implant recipients with the Multipeak (MPEAK) and Spectral Peak (SPEAK) speech coding strategies. I. Vowels

OBJECTIVE

The main objective was to evaluate differences in performance associated with the two speech coding strategies. To achieve this objective, acoustic and electrical analyses of vowels identified by cochlear implant recipients were compared with their responses when they used the Multipeak (MPEAK) and the Spectral Peak (SPEAK) speech coding strategies of the Nucleus Cochlear Implant System.

DESIGN

Nine subjects identified pure and r-colored English vowels with the two speech coding strategies. The two processing strategies were compared using an ABAB design. Evaluations were conducted at two weekly sessions after at least 3 wk of use with each strategy.

RESULTS

Group vowel identification scores with the MPEAK versus the SPEAK strategy were not significantly different (72.3% and 73.4%, respectively). However, hierarchical loglinear analysis of group data showed that transmitted information of r-color, duration, and second-formant features was significantly better with the SPEAK than with the MPEAK strategy. In contrast, identification of the first formant feature was significantly better with the MPEAK than with the SPEAK strategy. Individual subjects had different error patterns in response to the 14 vowels.

CONCLUSIONS

Electrical stimulation with the SPEAK strategy provides clearer spectral representation of second formant and duration information as well as second and third formant change in r-colored vowels than with the MPEAK strategy. Consequently, there was marked improvement in recognition of r-colored vowels with SPEAK compared with MPEAK. In contrast, transmitted information for first-formant features was significantly less with SPEAK than with MPEAK. This may have occurred because four instead of six to eight electrodes were assigned to first formant frequencies with SPEAK versus MPEAK.

Temporal bone volumetric image deblurring in spiral computed tomography scanning

RATIONALE AND OBJECTIVES

We developed a method for volumetric image deblurring in spiral (helical) computed tomography (CT) scanning with a three-dimensional (3D) Gaussian point spread function (PSF) to improve the quality of temporal bone spiral CT images for assessing the position of cochlear implants electrodes.

METHODS

A patient was scanned after cochlear implantation, and the temporal bone was reconstructed into a volume with 128 voxels per dimension, 0.1 mm per voxel side, and x 10 gray-scale expansion. The 3D PSF in spiral CT imaging was assumed to be Gaussian separable transversely and longitudinally. Standard deviations of the PSF were derived and subjectively adjusted. The image was then deconvolved using Wiener filtering and maximum-likelihood deconvolution methods. Image quality was assessed both visually and quantitatively using cross-sectional area at half of the maximum (CAHM) of the implanted array as the figure of merit.

RESULTS

Substantial image deblurring was achieved via deconvolution. Subjectively, anatomic structures were more clearly shown. Deconvolution reduced the CAHM by approximately one third, on average. Three-dimensional deconvolution had better image quality than two-dimensional deconvolution. The maximum-likelihood method produced superior image quality but took longer to process relative to Wiener filtering.

CONCLUSION

Volumetric image deblurring is practical with a Gaussian PSF. The maximum-likelihood method is preferred if time permits. Deconvolution facilitates the study of fine details of the temporal bone and cochlear implant.

Comparison of procedures for obtaining thresholds and maximum acceptable loudness levels with the nucleus cochlear implant system

Two stimulus paradigms and two presentation methods were combined to form three procedures (keyboard, knob, and ascending loudness judgments with knob [ALJK]) to obtain detection thresholds and maximum acceptable loudness levels (MALs) from 11 adults with the Nucleus cochlear implant. Thresholds at which subjects correctly counted the number of stimulus bursts also were obtained. Keyboard detection thresholds were higher (Scheffé, p = .01) than knob and ALJK detection thresholds. Counted thresholds were obtained most efficiently by using keyboard detection thresholds as the initial level for testing. Keyboard MALs were highest, knob MALs intermediate, and ALJK MALs lowest (Scheffé, p = .001). MALs were obtained most efficiently with the ALJK procedure. Implications of these results for clinical practice are discussed.

Use of test-retest measures to evaluate performance stability in adults with cochlear implants

OBJECTIVE

This study was designed to evaluate performance stability with test-retest measures of electrical thresholds, electrical maximum acceptable loudness levels, sound-field thresholds, and audition-only speech tests. The hypothesis was that the standard error of measurement differs from one individual to another for each test, and therefore test-retest measures need to be obtained from each subject.

DESIGN

Test-retest data were obtained in three sets. For the first two sets, data were obtained over 4 successive weeks to determine day-to-day variability. The third set was obtained on 2 successive days, 2 to 10 months later at each subject's annual evaluation. The seven subjects were recipients of the Nucleus cochlear implant and used the Mini Speech Processor at least one year. They were selected because they were available for research testing.

RESULTS

The ranges of electrical thresholds and maximum acceptable loudness levels obtained from each subject during the first two sets were substantially larger on some electrodes than on others. Between set 1 and set 2 for each subject, there were significant differences between thresholds and between maximum acceptable loudness levels on some electrodes. For thresholds as well as maximum acceptable loudness levels, the standard error of measurement across the three sets and 10 electrodes differed among subjects. The group standard error of measurement for sound-field thresholds was small (2 dB). The group standard error of measurement for the NU-6 word test scored according to phonemes (2.75%) was less than half that for the vowel (6.06%) and consonant (5.67%) tests. The standard error of measurement for each speech test differed among subjects.

CONCLUSIONS

The standard error of measurement for thresholds as well as maximum acceptable loudness levels varies among electrodes in the same subject and among subjects across electrodes. The standard error of measurement also varies among speech tests for the group as well as among subjects for each speech test. There is little variation in test-retest measures of sound-field thresholds among subjects. These results suggest the clinical importance of obtaining test-retest measures for evaluating the stability of electrical thresholds, electrical maximum acceptable loudness levels, and speech tests.

Evaluation of a new spectral peak coding strategy for the Nucleus 22 Channel Cochlear Implant System

Sixty-three postlinguistically deaf adults from four English-speaking countries participated in a 17-week field study of performance with a new speech coding strategy, Spectral Peak (SPEAK), and the most widely used strategy, Multipeak (MPEAK), both of which are implemented on wearable speech processors of the Nucleus 22 Channel Cochlear Implant System; MPEAK is a feature-extraction strategy, whereas SPEAK is a filterbank strategy. Subjects' performance was evaluated with an experimental design in which use of each strategy was reversed and replicated (ABAB). Average scores for speech tests presented sound-only at 70 dB SPL were higher with the SPEAK strategy than with the MPEAK strategy. For tests in quiet, mean scores for medial vowels were 74.8 percent versus 70.1 percent; for medial consonants, 68.6 percent versus 56.6 percent; for monosyllabic words, 33.8 percent versus 24.6 percent; and for sentences, 77.5 percent versus 67.4 percent. For tests in noise, mean scores for Four-Choice Spondees at +10 and +5 dB signal-to-noise ratio (S/N) were 88.5 percent versus 73.6 percent and 80.1 percent versus 62.3 percent, respectively; and for sentences at +15 dB, +10, and +5 dB S/N, 66.5 percent versus 43.4 percent, 61.5 percent versus 37.1 percent, and 60.4 percent versus 31.7 percent, respectively. Subjects showed marked improvement in recognition of sentences in noise with the new SPEAK filterbank strategy. These results agree closely with subjects' responses to a questionnaire on which approximately 80 percent reported they heard best with the SPEAK strategy for everyday listening situations.

Determination of the position of nucleus cochlear implant electrodes in the inner ear

Accurate determination of intracochlear electrode position in patients with cochlear implants could provide a basis for detecting migration of the implant and could aid in the selection of stimulation parameters for sound processor programming. New computer algorithms for submillimeter resolution and 3-D reconstruction from spiral computed tomographic (CT) scans now make it possible to accurately determine the position of implanted electrodes within the cochlear canal. The accuracy of these algorithms was tested using an electrode array placed in a phantom model. Measurements of electrode length and interelectrode distance from spiral CT scan reconstructions were in close agreement with those from stereo microscopy. Although apparent electrode width was increased on CT scans due to partial volume averaging, a correction factor was developed for measurements from conventional radiographs and an expanded CT absorption value scale added to detect the presence of platinum electrodes and wires. The length of the cochlear canal was calculated from preoperative spiral CT scans for one patient, and the length of insertion of the electrode array was calculated from her postoperative spiral CT scans. The cross-sectional position of electrodes in relation to the outer bony wall and modiolus was measured and plotted as a function of distance with the electrode width correction applied.

Study of the performance of four prelinguistically or perilinguistically deaf patients with a multi-electrode, intracochlear implant

Individuals who are born deaf or become deaf in early childhood and are implanted as adults (or in late adolescence) with a multi-electrode, intracochlear implant often cannot understand speech by audition alone. Test results of four implanted patients were analyzed to determine 1. if there was a difference in performance between patients; 2. if there was a relation between performance and history of auditory stimulation; and 3. which tests revealed performance differences. On audition-only and audition-plus-vision tests, overall performance was rank-ordered from lowest to highest for patients 1, 2, 3, and 4, respectively. Patient 4 recognized a few words audition-only. Patients 1 and 2 had long periods of no auditory stimulation; patients 3 and 4 had long periods of auditory stimulation with hearing aids prior to implantation. Tests not revealing differences in performance were identified.

Recent trends in the selection and fitting of hearing aids

A large segment of the hearing impaired population does not utilize amplification. this paper reviews several factors which may account for the under-utilization of hearing aids by the hearing impaired population. In addition, this paper reviews several recent developments in procedures used to select and fit hearing aids.

Benefit provided by a multi-electrode intracochlear implant to a prelinguistically deaf adult

The authors describe the therapy and performance of a prelinguistically deaf adult using a multi-electrode, intracochlear implant. The post-operative test results show that this patient receives greater benefit with the cochlear implant than he received with a hearing aid.

Performance of postlinguistically deaf adults with the Wearable Speech Processor (WSP III) and Mini Speech Processor (MSP) of the Nucleus Multi-Electrode Cochlear Implant

Seven postlinguistically deaf adults implanted with the Nucleus Multi-Electrode Cochlear Implant participated in an evaluation of speech perception performance with three speech processors: the Wearable Speech Process (WSP III), a prototype of the Mini Speech Processor, and the Mini Speech Processor. The first experiment was performed with the prototype and Wearable Speech Processor both programmed using the F0F1F2 speech coding strategy. The second experiment compared performance with the Mini Speech Processor programmed with the Multi-Peak speech coding strategy and the Wearable Speech Processor programmed with the F0F1F2 speech coding strategy. Performance was evaluated in the sound-only condition using recorded speech tests presented in quiet and in noise. Questionnaires and informal reports provided information about use in everyday life. In experiment I, there was no significant difference in performance using the Wearable Speech Processor and prototype on any of the tests. Nevertheless, six out of seven subjects preferred the prototype for use in everyday life. In experiment II, performance on open-set tests in quiet and noise was significantly higher with the Mini Speech Processor (Multi-Peak speech coding strategy) than with the Wearable Speech Processor. Subjects reported an increase in their ability to communicate with other people using the Mini Speech Processor (Multi-Peak speech coding strategy) compared with the Wearable Speech Processor in everyday life.

Comparison of benefit from vibrotactile aid and cochlear implant for postlinguistically deaf adults

Four postlinguistically deaf adults were evaluated presurgically with a one- or two-channel vibrotactile aid and postsurgically with a multichannel, multielectrode, intracochlear implant. Although the vibrotactile aid provided awareness of sound and enhanced flow of conversation, benefit to lipreading was small on videotaped tests and speech tracking. Scores on recorded, sound-only speech tests were not significantly above chance except in discrimination of noise from voice. With the cochlear implant, benefit to lipreading was significantly greater than with the vibrotactile aid, and scores on sound-only tests were significantly above chance. Communication was markedly better with the implant than with the vibrotactile aid. In counseling those who get no benefit from a hearing aid, the results of this study provide data on the amount of benefit one- or two-channel vibrotactile aids provide postlinguistically deaf adults who are subsequently implanted.

Effect of amplification on the intelligibility of speech produced with an electrolarynx

The purpose of this study was to look at the effect of orolabial amplification on the intelligibility of speech spoken with a neck model electrolarynx for two distance conditions, three noise conditions, and in relative quiet. A speaker using a neck model electrolarynx read single-answer questions to six listeners. The questions were read with and without amplification at 1.5 and 2.5 m distance, in relative quiet as well as in 66 dB, 72 dB, and 76 dBSPL (A-weighted) prerecorded cafeteria noise. The results of the study showed that speech-to-noise ratios were improved for amplified speech, with improvement in intelligibility for speech spoken in moderate background noise (66 and 72 dBSPL). The effect of the "buzz" of the artificial larynx is reduced, and speakers are better understood in moderate background noise with this amplification system.

Recent advances in hearing aid selection and adjustment

Recent research has shown that speech is most intelligible for hearing-impaired individuals when it is amplified to a comfortable level in specific frequency regions between 250 and 6,000 Hz, and is limited below the discomfort level. If commercial hearing aids and earmold coupling are adjusted appropriately, they will provide amplified sound within these parameters for most hearing-impaired individuals. A clinical procedure is described 1) to preselect an aid and earmold with the approximate electroacoustic characteristics that are needed, 2) to determine the gain actually provided by this hearing aid/earmold combination, and 3) to adjust the hearing aid and/or earmold if the gain and maximum output do not meet the prescribed criteria, or if the wearer finds the sound quality unacceptable.

Auditory function in children with diabetes mellitus

Fifty-one insulin-dependent diabetics and 13 nondiabetics between the ages of 8 and 21 years, without a history of exposure to noise, ototoxic drugs or ear disease, were evaluated to examine the relation between auditory function and diabetes, diabetic control and diabetic complications. Audiologic assessment included pure-tone audiometry, speech audiometry, impedance measures and brainstem evoked response audiometry. No statistically significant differences in auditory function were noted between insulin-dependent diabetics and normal controls, between the diabetics in good or poor control or between diabetics with or without neurologic or vascular complications.

Amplification bandwidth and intelligibility of speech in quiet and noise for listeners with sensorineural hearing loss

The intelligibility of speech mixed with noise (+6 dB S/N) and in quiet was measured as a function of its audible bandwidth for 7 listeners with moderate sensorineural hearing losses. Words were presented at three levels in the field (50, 60 and 70 dB SPL) and amplified with a Limiting Master Hearing Aid (LMHA) which allows independent control of gain and maximum power output in each of nine, half-octave channels. The frequency gain characteristics were chosen so the speech spectrum (60 dB SPL) at the input was shaped to approximate the individual listener's contour of most comfortable listening levels at the output. At each level and for the words in noise as well as quiet, the LMHA was set for four bandwidths (266-6 000, 375-4 242, 530-3 000 and 750-2 121 Hz). For these conditions, the listeners all obtained the highest mean score with the LMHA set for the widest bandwidth. The listener's ability to understand the words, after adjustment for individual differences, was well correlated (0.77-0.91) with the articulation index. Preliminary observations on the acceptability of amplified sounds, that is, loud speech, impact noise, an air-horn blast, and a party ratchet, are included.

Amplification bandwidth and speech intelligibility for two listeners with sensorineural hearing loss

The intelligibility of speech as a function of its bandwidth was measured for two listeners with similar, moderately severe sensorineural hearing losses. The shape of the speech spectrum was adjusted to approximate the individual listener's contour of most comfortable listening levels (MCLs) and the overall level was set so that the levels in each band were below (-7 dB), near to (+3 dB), or above (+13 or +18 dB) the MCLs. At each level, nine pairings of three low-frequency and three high-frequency cutoffs (266, 375 and 530 Hz; 3,000, 4,242 and 6,000 Hz) were used. These conditions were achieved by passing the speech through a Limiting Master Hearing Aid (LMHA) which allows independent control of gain and maximum output in each of nine, half-octave bands. It was found that the wider the bandwidth, the higher the score, and the greater the amount of speech energy above threshold, the higher the score. Listeners' ability to understand the test material, after adjustment for listener differences, was correlated (0.7 and 0.8) with the articulation index.

Speech intelligibility in noise-induced hearing loss: effects of high-frequency compensation

The speech-recognition ability of six listeners with permanent noise-induced hearing losses above 1 kHz was evaluated with the Pascoe High-Frequency Work List spoken by a female talker and presented in the field. In experiment I the words were presented at five intensity levels through five different amplification systems (one with a uniform response and four with increasing amounts of high-frequency emphasis). In experiment II the frequency response of the system associated with the highest scores in experiment I was modified in four ways: elimination of frequences above 6.3 kHz, addition and deletion of 1/3-octave emphasis at the low-frequency boundary of the hearing loss, and addition of 6-dB high-frequency emphasis. The frequency response that was associated with the highest word-identification score for each listener had between 20 and 33 dB more gain in the frequency region of the hearing loss than did the uniform response. Three major factors were found to affect the work-identification scores: audibility of the speech energy, separation of the third-octave-band levels of the words from the discomfort threshold, and balance between the low- and high-frequency levels of the speech signal.