Assessment of the ability to model proteins with leucine-rich repeats in light of the latest structural information

The three-dimensional structures of leucine-rich repeat (LRR) -containing proteins from five different families were previously predicted based on the crystal structure of the ribonuclease inhibitor. using an approach that combined homology-based modeling, structure-based sequence alignment of LRRs, and several rational assumptions. The structural models have been produced based on very limited sequence similarity, which, in general. cannot yield trustworthy predictions. Recently, the protein structures from three of these five families have been determined. In this report we estimate the quality of the modeling approach by comparing the models with the experimentally determined structures. The comparison suggests that the general architecture, curvature, interior/exterior orientations of side chains. and backbone conformation of the LRR structures can be predicted correctly. On the other hand. the analysis revealed that, in some cases. it is difficult to predict correctly the twist of the overall super-helical structure. Taking into consideration the conclusions from these comparisons, we identified a new family of bacterial LRR proteins and present its structural model. The reliability of the LRR protein modeling suggests that it would be informative to apply similar modeling approaches to other classes of solenoid proteins.

Interlabial contact pressures exhibited in dysarthria following traumatic brain injury during speech and nonspeech tasks

A miniature pressure transducer was used to assess the interlabial contact pressures produced by a group of 19 adults (mean age 30.6 years) with dysarthria following severe traumatic brain injury (TBI) during a set of speech and nonspeech tasks. Ten parameters relating to lip strength, endurance, rate of movement and lip pressure accuracy and stability were measured from the nonspeech tasks. The results attained by the TBI group were compared against a group of 19 age- and sex-matched control subjects. Significant differences between the groups were found for maximum interlabial contact pressure, maximum rate of repetition of maximum pressure, and lip pressure accuracy at 50 and 10% levels of maximum pressure. In regards to speech, the interlabial contact pressures generated by the TBI group and control group did not differ significantly. When expressed as percentages of maximum pressure, however, the TBI group's interlabial pressures appeared to have been generated with greater physiological effort. Copyright (C) 2002 S. Karger AG, Basel.

Transient evoked otoacoustic emissions in children studying in special schools

Objectives: The present study aimed to investigate the feasibility and practicalities or testing children in special school settings using transient evoked otoacoustic emissions (TEOAE) and tympanometry. Children studying in special schools, particularly those with intellectual impairment, may be highly susceptible to hearing pathologies and can be difficult to assess using traditional test batteries. Researchers have recently suggested the possible applicability of TEOAE testing. in lieu of conventional behavioral methods, as a hearing screening device for persons with intellectual impairment. However, to date. few publications have detailed the particulars and results of such testing. Methods: A total of 489 children, with a mean age of 9.6 years, were tested in 15 special schools. Case information was obtained regarding birth history, medical history and type,degree of impairment, for later comparison with screening results. TEOAEs were collected using Quickscreen mode of the ILO292 Otodynamics Analyzer, whilst tympanometry was performed utilizing a Madsen Zodiac 901 Middle Ear Analyzer. Results: In total, 80% of students were able to be tested using TEOAEs. Average test time per ear was 2 min. However, a large proportion (40 of those able to be tested) failed TEOAE testing in at least one ear. No significant effects were found between could-not-test (CNT) cases and case history factors, A significant difference in TEOAE failure rates was found across history of neonatal special care nursery residency and history of parental concern regarding possible hearing impairment. Failure rates were higher for those who indicated positive histories. A total of 74% of subjects could be tested using tympanometry, with 25% of those able to be tested failing in at least one ear. Notably, neither type nor degree of impairment had any significant bearing on CNT or failure rates for tympanometry or TEOAE screening. Conclusions: Findings of the present investigation lend support to the review of hearing screening programs for children in special schools. with TEOAEs presenting as a potential alternative procedure. Further examination of the performance measures of protocols incorporating TEOAEs would now be advantageous. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

The association between auditory memory span and speech rate in children from kindergarten to sixth grade

This study reexamined the association between speech rate and memory span in children from kindergarten to sixth grade (N = 152) in order to potentially account for the inconsistencies within the published literature on this topic. Some of the inconsistencies in past research may reflect the different methods adopted in assessing speech rate. In particular, repeating word triples may itself involve memory demands, contaminating the correlation between speech rate and memory span in younger children. Analyses using composite speech rate and memory span measures showed that speech rate for word triples shared variance with memory span that was independent of speech rate for single words. Moreover, speech rate for word triples was largely redundant with age in explaining additional variation in memory span once the effects of speech rate for single words were controlled. (C) 2002 Elsevier Science.

Kinematic analysis of lingual fatigue in myasthenia gravis

This study describes a preliminary examination of the viability and suitability of the physiologic technique electromagnetic articulography (EMA) in investigating lingual fatigue in myasthenia gravis (MG). A 52.9-year-old female diagnosed with MG at the age of 18 years, but who was in remission, participated in the study with a matched control subject. Changes in the duration, speed, and range of tongue-tip and tongue-back movements during repetition of /taka/ over two minutes were investigated. Results revealed that the MG subject did not exhibit significant changes in duration, maximum velocity, maximum acceleration, or the distance travelled by her tongue as measured by EMA over the task. The kinematic results were, in part, expected since the MG subject was in remission. The results, therefore, may not be representative of the majority of individuals with active MG. The examination of the current case did highlight, however, the potential advantages of EMA in providing detailed, objective information regarding lingual kinematics for future investigations of individuals with MG. It also showed that EMA may be sensitive in detecting subclinical kinematic features of fatigue in individuals who are in remission from MG. Finally, EMA led to the identification of possible physiologic factors underlying the CV transform effect, which was evident for the MG subject's syllable productions. In the past, the effect had been assumed to be a purely perceptual-based phenomenon.

Detection of swallowing sounds: Methodology revisited

Cervical auscultation is in the process of gaining clinical credibility. In order for it to be accepted by the clinical community, the procedure and equipment used must first be standardized. Takahashi et al. [Dysphagia 9:54-62, 1994] attempted to provide benchmark methodology for administering cervical auscultation. They provided information about the acoustic detector unit best suited to picking up swallowing sounds and the best cervical site to place it. The current investigation provides contrasting results to Takahashi et al. with respect to the best type of acoustic detector unit to use for detecting swallowing sounds. Our study advocates an electret microphone as opposed to an accelerometer for recording swallowing sounds. However, we agree on the optimal placement site. We conclude that cervical auscultation is within reach of the average dysphagia clinic.

A role for the dominant thalamus in language? A linguistic comparison of two cases subsequent to unilateral thalamotomy procedures in the dominant and non-dominant hemispheres

Background: Thalamotomy has been reported to be successful in ameliorating the motor symptoms of tremor and/or rigidity in people with Parkinson's disease (PD), emphasising the bona fide contribution of this subcortical nucleus to the neural circuitry subserving motor function. Despite evidence of parallel yet segregated associative and motor cortico-subcortical-cortical circuits, comparatively few studies have investigated the effects of this procedure on cognitive functions. In particular, research pertaining to the impact of thalamotomy on linguistic processes is fundamentally lacking. Aims: The purpose of this research was to investigate the effects of thalamotomy in the language dominant and non-dominant hemispheres on linguistic functioning, relative to operative theoretical models of subcortical participation in language. This paper compares the linguistic profiles of two males with PD, aged 75 years (10 years of formal education) and 62 years (22 years of formal education), subsequent to unilateral thalamotomy procedures within the language dominant and non-dominant hemispheres, respectively. Methods & Procedures: Comprehensive linguistic profiles comprising general and high-level linguistic abilities in addition to on-line semantic processing skills were compiled up to 1 month prior to surgery and 3 months post-operatively, within perceived on'' periods (i.e., when optimally medicated). Pre- and post-operative language performances were compared within-subjects to a group of 16 non-surgical Parkinson's controls (NSPD) and a group of 16 non-neurologically impaired adults (NC). Outcomes & Results: The findings of this research suggest a laterality effect with regard to the contribution of the thalamus to high-level linguistic abilities and, potentially, the temporal processing of semantic information. This outcome supports the application of high-level linguistic assessments and measures of semantic processing proficiency to the clinical management of individuals with dominant thalamic lesions. Conclusions: The results reported lend support to contemporary theories of dominant thalamic participation in language, serving to further elucidate our current understanding of the role of subcortical structures in mediating linguistic processes, relevant to cortical hemispheric dominance.

Perception or synthesized voice quality in connected speech by Cantonese speakers

Perceptual voice analysis is a subjective process. However, despite reports of varying degrees of intrajudge and interjudge reliability, it is widely used in clinical voice evaluation. One of the ways to improve the reliability of this procedure is to provide judges with signals as external standards so that comparison can be made in relation to these anchor signals. The present study used a Klatt speech synthesizer to create a set of speech signals with varying degree of three different voice qualities based on a Cantonese sentence. The primary objective of the study was to determine whether different abnormal voice qualities could be synthesized using the built-in synthesis parameters using a perceptual study. The second objective was to determine the relationship between acoustic characteristics of the synthesized signals and perceptual judgment. Twenty Cantonese-speaking speech pathologists with at least three years of clinical experience in perceptual voice evaluation were asked to undertake two tasks. The first was to decide whether the voice quality of the synthesized signals was normal or not. The second was to decide whether the abnormal signals should be described as rough, breathy, or vocal fry. The results showed that signals generated with a small degree of aspiration noise were perceived as breathiness while signals with a small degree of flutter or double pulsing were perceived as roughness. When the flutter or double pulsing increased further, tremor and vocal fry, rather than roughness, were perceived. Furthermore, the amount of aspiration noise, flutter, or double pulsing required for male voice stimuli was different from that required for the female voice stimuli with a similar level of perceptual breathiness and roughness. These findings showed that changes in perceived vocal quality could be achieved by systematic modifications of synthesis parameters. This opens up the possibility of using synthesized voice signals as external standards or anchors to improve the reliability of clinical perceptual voice evaluation. (C) 2002 Acoustical Society of America.

Orthographic/phonological facilitation of naming responses in the picture-word task: An event-related fMRI study using overt vocal responding

In the picture-word interference task, naming responses are facilitated when a distractor word is orthographically and phonologically related to the depicted object as compared to an unrelated word. We used event-related functional magnetic resonance imaging (fMRI) to investigate the cerebral hemodynamic responses associated with this priming effect. Serial (or independent-stage) and interactive models of word production that explicitly account for picture-word interference effects assume that the locus of the effect is at the level of retrieving phonological codes, a role attributed recently to the left posterior superior temporal cortex (Wernicke's area). This assumption was tested by randomly presenting participants with trials from orthographically related and unrelated distractor conditions and acquiring image volumes coincident with the estimated peak hemodynamic response for each trial. Overt naming responses occurred in the absence of scanner noise, allowing reaction time data to be recorded. Analysis of this data confirmed the priming effect. Analysis of the fMRI data revealed blood oxygen level-dependent signal decreases in Wernicke's area and the right anterior temporal cortex, whereas signal increases were observed in the anterior cingulate, the right orbitomedial prefrontal, somatosensory, and inferior parietal cortices, and the occipital lobe. The results are interpreted as supporting the locus for the facilitation effect as assumed by both classes of theoretical model of word production. In addition, our results raise the possibilities that, counterintuitively, picture-word interference might be increased by the presentation of orthographically related distractors, due to competition introduced by activation of phonologically related word forms, and that this competition requires inhibitory processes to be resolved. The priming effect is therefore viewed as being sufficient to offset the increased interference. We conclude that information from functional imaging studies might be useful for constraining theoretical models of word production. (C) 2002 Elsevier Science (USA).

Comparison of lumbar range of movement and lumbar lordosis in back pain patients and matched controls

Inconclusive findings have been shown in previous studies comparing lumbar range of movement (LROM) and lumbar lordosis between back pain patients and healthy subjects. In these studies, confounding variables such as age, gender, height, obesity, and pain level were usually not well controlled. The present study aimed to compare LROM and lumbar lordosis between back pain patients and matched controls. Fifteen male back pain patients and 15 age-, height-, obesity-, and physical activity-matched male controls were investigated. To minimize the effect of pain on the measurements, only patients with minimal or no pain at the time of testing were included in the study. Inclinometer technique was used for the evaluation of LROM in flexion, extension and lateral flexion as well as lumbar lordosis. A lumbar rotameter was used for measuring axial rotation. Pelvic motion was limited by a pelvic restraint device during LROM measurements. Results showed that there were no significant differences between the back pain and control groups in flexion, extension, lateral flexion and axial rotation LROM and also in lumbar lordosis. This may indicate that when a back pain patient is not in pain, LROM and lumbar lordosis may not be the measures that distinguish between back pain patients and subjects without back pain.