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Biomedical subjects

P Howell

Publications and source records attributed to P Howell.

At least 19 recordsLinked to original sources
PubMed1999

Exchange of stuttering from function words to content words with age.

Dysfluencies on function words in the speech of people who stutter mainly occur when function words precede, rather than follow, content words (Au-Yeung, Howell, & Pilgrim, 1998). It is hypothesized that such function word dysfluencies occur when the plan for the subsequent content word is not ready for execution. Repetition and hesitation on the function words buys time to complete the plan for the content word. Stuttering arises when speakers abandon the use of this delaying strategy and carry on, attempting production of the subsequent, partly prepared content word. To test these hypotheses, the relationship between dysfluency on function and content words was investigated in the spontaneous speech of 51 people who stutter and 68 people who do not stutter. These participants were subdivided into the following age groups: 2-6-year-olds, 7-9-year-olds, 10-12-year-olds, teenagers (13-18 years), and adults (20-40 years). Very few dysfluencies occurred for either fluency group on function words that occupied a position after a content word. For both fluency groups, dysfluency within each phonological word occurred predominantly on either the function word preceding the content word or on the content word itself, but not both. Fluent speakers had a higher percentage of dysfluency on initial function words than content words. Whether dysfluency occurred on initial function words or content words changed over age groups for speakers who stutter. For the 2-6-year-old speakers that stutter, there was a higher percentage of dysfluencies on initial function words than content words. In subsequent age groups, dysfluency decreased on function words and increased on content words. These data are interpreted as suggesting that fluent speakers use repetition of function words to delay production of the subsequent content words, whereas people who stutter carry on and attempt a content word on the basis of an incomplete plan.

Adolescent↗
PubMed1999

Utterance rate and linguistic properties as determinants of lexical dysfluencies in children who stutter.

Two important determinants of variation in stuttering frequency are utterance rate and the linguistic properties of the words being spoken. Little is known how these determinants interrelate. It is hypothesized that those linguistic factors that lead to change in word duration, alter utterance rate locally within an utterance that then gives rise to an increase in stuttering frequency. According to the hypothesis, utterance rate variation should occur locally within the linguistic segments in an utterance that is known to increase the likelihood of stuttering. The hypothesis is tested using length of tone unit as the linguistic factor. Three predictions are confirmed: Utterance rate varies locally within the tone units and this local variation affects stuttering frequency; stuttering frequency is positively related to the length of tone units; variations in utterance rate are correlated with tone unit length. Alternative theoretical formulations of these findings are considered.

Child↗
PubMed1999

Toxic bile acids in gastro-oesophageal reflux disease: influence of gastric acidity.

BACKGROUND: Bile acid toxicity has been shown in the gastric, colonic, and hepatic tissues; the effect on oesophageal mucosa is less well known. AIMS: To determine the spectrum of bile acids refluxing in patients with gastro-oesophageal reflux disease and its relation to oesophageal pH using a new technique of combined oesophageal aspiration and pH monitoring. METHODS: Ten asymptomatic subjects and 30 patients with symptoms of gastro-oesophageal reflux disease (minimal mucosal injury, erosive oesophagitis (grade 2 or 3 Savary-Miller), Barrett's oesophagus/stricture; n=10 in each group) underwent 15 hour continuous oesophageal aspiration with simultaneous pH monitoring. Bile acid assay of the oesophageal samples was performed using modified high performance liquid chromatography. RESULTS: The peak bile acid concentration and DeMeester acid scores were significantly higher in the patients with oesophagitis (median bile acid concentration 124 micromol/l; acid score 20.2) and Barrett's oesophagus/stricture (181 micromol/l; 43. 3) than patients with minimal injury (14 micromol/l; 12.5) or controls (0 micromol/l; 11.1). The predominant bile acids detected were cholic, taurocholic, and glycocholic acids but there was a significantly greater proportion of secondary bile acids, deoxycholic and taurodeoxycholic acids, in patients with erosive oesophagitis and Barrett's oesophagus/stricture. Although bile acid reflux episodes occurred at variable pH, a temporal relation existed between reflux of taurine conjugates and oesophageal acid exposure (r=0.58, p=0.009). CONCLUSION: Toxic secondary bile acid fractions have been detected in patients with extensive mucosal damage. Mixed reflux is more harmful than acid reflux alone with possible toxic synergism existing between the taurine conjugates and acid.

Adult↗
PubMed1998

Phonological words and stuttering on function words.

Stuttering on function words was examined in 51 people who stutter. The people who stutter were subdivided into young (2 to 6 years), middle (6 to 9 years), and older (9 to 12 years) child groups; teenagers (13 to 18 years); and adults (20 to 40 years). As reported by previous researchers, children up to about age 9 stuttered more on function words (pronouns, articles, prepositions, conjunctions, auxiliary verbs), whereas older people tended to stutter more on content words (nouns, main verbs, adverbs, adjectives). Function words in early positions in utterances, again as reported elsewhere, were more likely to be stuttered than function words at later positions in an utterance. This was most apparent for the younger groups of speakers. For the remaining analyses, utterances were segmented into phonological words on the basis of Selkirk's work (1984). Stuttering rate was higher when function words occurred in early phonological word positions than other phonological word positions whether the phonological word appeared in initial position in an utterance or not. Stuttering rate was highly dependent on whether the function word occurred before or after the single content word allowed in Selkirk's (1984) phonological words. This applied, once again, whether the phonological word was utterance-initial or not. It is argued that stuttering of function words before their content word in phonological words in young speakers is used as a delaying tactic when the forthcoming content word is not prepared for articulation.

Child↗
PubMed1998

Assessment of combined bile acid and pH profiles using an automated sampling device in gastro-oesophageal reflux disease.

BACKGROUND: Bile acid reflux is an important component of duodenogastro-oesophageal reflux but there is no effective method of quantifying it. The contribution of bile acids to oesophageal pH is unknown. METHODS: Oesophageal aspirates were collected over 15 h using a new automated suction device and pH was monitored in ten asymptomatic volunteers (group 1) and 30 patients with reflux oesophagitis (group 2, minimal mucosal injury; group 3, erosive oesophagitis; group 4, stricture or Barrett's oesophagus). Bile acid assay was performed by high-performance liquid chromatography. RESULTS: The concentration of bile acids was significantly higher in group 3 (median (interquartile range) 124 (50-301) mumol/l) and group 4 (181 (85-591) mumol/l) compared with group 1 (0 mumol/l) and group 2 (14 (0-100) mumol/l). Patients in groups 3 and 4 also had significantly greater DeMeester acid scores. Combined bile acid and oesophageal acid reflux was observed in eight of ten patients with stricture or Barrett's oesophagus. There was no correlation between total bile acid concentration and oesophageal acid or alkaline exposure. CONCLUSION: This study supports the theory of toxic synergism between acid and bile acids in reflux oesophagitis. Bile acids may contribute to the pathogenesis of Barrett's metaplasia.

Adult↗
PubMed1998

IgG anti-Jka/Jkb antibodies are unlikely to fix complement.

Antibodies in the Kidd blood group system show a great deal of serological variability, are notoriously elusive and hence evoke difficulties in detection. However, they have been regularly reported as causing severe immediate or delayed haemolytic transfusion reactions and this clinical potential has been largely attributed to their complement binding ability. In initial investigations on 43 anti-Jka/Jkb sera with a range of titres of IgG antibody only a few seemed to fix complement, though following repeated tests on 20 of these sera a further five were shown to bind complement, making a total of 12 (27.9%) showing evidence of complement binding. Twenty-three sera were unavailable for re-testing. Subsequent tests revealed that only those sera which showed direct agglutination or were positive with an anti-IgM reagent in an indirect antiglobulin test (IAT) fixed complement. Evaluations on the IgG fractions of six selected potent anti-Jka sera failed to reveal any complement-fixing ability although all the original sera bound complement avidly and contained variable amounts of IgM antibody, some at very low subagglutinating levels. These findings challenge past perceptions and give cause for reflection on the changing methodologies and strategies which could unduly compromise the detection of these potentially clinically damaging antibodies.

Antibodies↗
PubMed1998

Crop failure in Dalocha, Ethiopia: a participatory emergency response.

This case study of an NGO's response to a food crisis due to crop failure focuses on the extent of active community participation at each stage of the project. With the current debate on the relationship between relief and development, and in particular the focus on encouraging more active community participation in relief responses, this study has relevance both in the Ethiopian context and beyond. In this example the participation process was greatly facilitated by the prior relationship between the international NGO and the communities, and also by the high level of staff input into the project. Where resources or conditions are less favourable, as might be the case in similar responses by local NGOs or government agencies, the paper suggests that the participatory approach can be adapted or partially implemented and still result in a more effective and locally relevant operation.

Agriculture↗
PubMed1998

Methods of interval selection, presence of noise and their effects on detectability of repetitions and prolongations.

Accurate methods for locating specific types of stuttering events are necessary for diagnosis, treatment, and prognosis. A factor that could add variability to assessment of stuttering is noise on recordings. The effects of noise were assessed by adding noise to intervals of speech containing all fluent material, fluent material with a repetition, or fluent material with a prolongation. These intervals allow a unique dysfluency response to be made. A statistical analysis of the occurrence of such intervals in spontaneous speech showed that only a limited number of intervals met these criteria. This demonstrated that selecting intervals at random from spontaneous speech (as in time interval analysis procedure) will infrequently lead to a unique and unambiguous dysfluency specification for the interval. Intervals were selected for testing from the intervals that met the stipulated criteria. These were presented for dysfluency judgment when the position of the stuttering within an interval was varied and with different amounts of added noise (no added noise, 3 dB, and 6 dB of noise relative to mean speech amplitude). Accuracy in detecting stuttering type depended on noise level and the stuttering's position in the interval, both of which also depended on the type of stuttering: Noise level affected detection of repetitions more than prolongations: Repetitions were more difficult to detect when they occurred at the end of an interval whereas prolongations were more difficult to detect when they were at the beginning of an interval. The findings underline the importance of adopting rigorous recording standards when speech is to be employed to make stuttering assessments.

Child↗
PubMed1997

Development of a two-stage procedure for the automatic recognition of dysfluencies in the speech of children who stutter: I. Psychometric procedures appropriate for selection of training material for lexical dysfluency classifiers.

This program of work is intended to develop automatic recognition procedures to locate and assess stuttered dysfluencies. This and the following article together, develop and test recognizers for repetitions and prolongations. The automatic recognizers classify the speech in two stages: In the first, the speech is segmented, and, in the second, the segments are categorized. The units that are segmented are words. Here assessments by human judges on the speech of 12 children who stutter are described using a corresponding procedure. The accuracy of word boundary placement across judges, categorization of the words as fluent, repetition or prolongation, and duration of the different fluency categories are reported. These measures allow reliable instances of repetitions and prolongations to be selected for training and assessing the recognizers in the subsequent paper.

Adolescent↗
PubMed1997

Development of a two-stage procedure for the automatic recognition of dysfluencies in the speech of children who stutter: II. ANN recognition of repetitions and prolongations with supplied word segment markers.

This program of work is intended to develop automatic recognition procedures to locate and assess stuttered dysfluencies. This and the preceding article focus on developing and testing recognizers for repetitions and prolongations in stuttered speech. The automatic recognizers classify the speech in two stages: In the first the speech is segmented and in the second the segments are categorized. The units segmented are words. The current article describes results for an automatic recognizer intended to classify words as fluent or containing a repetition or prolongation in a text read by children who stutter that contained the three types of words alone. Word segmentations are supplied and the classifier is an artificial neural network (ANN). Classification performance was assessed on material that was not used for training. Correct performance occurred when the ANN placed a word into the same category as the human judge whose material was used to train the ANNs. The best ANN correctly classified 95% of fluent, and 78% of dysfluent words in the test material.

Adolescent↗
PubMed1997

Speaking clearly for the hearing impaired: intelligibility differences between clear and less clear speakers.

The clarity of the speech of 12 speakers was assessed by intelligibility tests with hearing impaired subjects and from self-ratings about the speaker's ability to communicate with such listeners. The results of these tests correlate positively. Self-ratings account for approximately 60% of the variance. Thus self-ratings can be used as a convenient practical way of establishing an individual speaker's clarity.

Adult↗
PubMed1995

Carotid artery trauma: a review of contemporary trauma center experiences.

PURPOSE: Many issues surrounding the management and outcome of carotid artery injuries remain controversial. The purpose of this study was to review a large contemporary experience with such injuries in the setting of designated trauma centers. METHODS: A statewide computerized trauma registry was used to identify all patients with injuries to the common or internal carotid arteries from October 1987 to June 1993. The records of 82 such patients were retrieved and analyzed. RESULTS: Overall mortality and stroke rates were 17% and 28%, respectively. Patients presenting with coma or shock had a particularly bad prognosis (50% and 41% mortality, respectively). Internal carotid injuries resulted in mortality and stroke rates of 21% and 41%, respectively, compared with 11% each for common carotid injuries. Patients with blunt injuries had a much higher stroke rate (56% vs 15%) but had lower mortality (7% vs 22%) than did patients with penetrating injuries. Airway compromise and associated injuries did not affect prognosis. Operative repair and percutaneous balloon occlusion had the best survival and functional outcomes. CONCLUSIONS: Operative repair offers the best chances for recovery in all categories of patients regardless of injury mechanism. Ligation is useful only as a last-resort lifesaving effort. Shock and neurologic impairment are poor prognostic factors but should not negate repair.

Adolescent↗
PubMed1994

Epidural butorphanol does not reduce side effects from epidural morphine after cesarean birth.

In this prospective, double-blind, randomized study of women undergoing elective cesarean birth, the hypothesis that epidural butorphanol in various doses could effectively reduce or eliminate the side effects caused by epidural morphine was tested. Patients were randomly assigned to one of four groups. All received a standard epidural anesthetic and 20 min after delivery each received 3 mg epidural morphine with either 1 mg butorphanol (Group A), 2 mg butorphanol (Group B), 3 mg butorphanol (Group C), or 3 mL normal saline (Group D). Patient evaluations were made preoperatively and 2, 8, and 24 h after delivery. These consisted of visual analog scores for pain, satisfaction, nausea, itch, and somnolence. At each evaluation, a CO2 challenge test, using portable equipment, was performed. Data from 71 patients were analyzed and all four groups were comparable in terms of age, height, weight, level of sensory block, and volume of local anesthetic used. There were no significant differences among groups in terms of pain, satisfaction, nausea, or pruritus. Groups A, B, and C had significantly higher somnolence scores at 8 h compared to Group D (P < 0.001). There were no significant differences among groups in CO2 challenge test data at any point during the study, but overall a reduced sensitivity to CO2 after opioid administration was observed across all groups. There were no clinically significant incidents of respiratory depression. Epidural butorphanol, in doses of 1-3 mg, failed to reduce the side effects from 3 mg epidural morphine given after cesarean birth. Patients who received epidural butorphanol reported significantly higher levels of somnolence.

Anesthesia, Epidural↗
PubMed1993

Patient-controlled epidural analgesia in labour: varying bolus dose and lockout interval.

This double-blind prospective study was designed to determine the best dose variables for patient-controlled epidural analgesia (PCEA) and to compare bolus-only PCEA with continuous infusion epidural analgesia (CIEA) during the first stage of labour. Five groups of parturients self-administered 0.125% bupivacaine with 1:400,000 epinephrine and fentanyl 2.5 micrograms.ml-1 using PCA pumps programmed as follows: Group A, 2 ml bolus/10 min lockout interval (LI); Group B, 3 ml bolus/15 min LI; Group C, 4 ml bolus/20 min LI; Group D, 6 ml bolus/30 min LI; Group E, 8 ml.hr-1 continuous infusion. Hourly assessments included: VAS scores for pain and satisfaction, sensory and motor block, bupivacaine and fentanyl consumption. Blood samples were collected at birth for maternal and fetal fentanyl concentrations. Data from 68 patients showed no differences among groups in pain relief or maternal satisfaction. Most patients received excellent analgesia and those requiring extra epidural supplements were evenly distributed across groups. There was higher consumption of bupivacaine and fentanyl in Group E than in any of the other four groups: bupivacaine mg.hr-1, mean (SD), 9.4 (2.7) in Group E vs 5.2 (1.7) in Groups A-D inclusive (P < 0.0001); fentanyl microgram.hr-1, 19.6 (4.6) in group E vs 12.6 (7.5) in Groups A-D inclusive (P < 0.05). Motor block was minimal, whereas sensory levels were higher at the 3- and 4-hour assessments in Groups D and E than in all other groups (P < 0.05). Plasma fentanyl concentrations were < 0.5 ng.ml-1 in all samples and no sequelae from fentanyl were observed, apart from mild pruritus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Cue trading in the production and perception of vowel stress.

The distinction between stressed and unstressed vowels in noun/verb pairs differentiated by stress (e.g., as in the word "misprint") is known to be cued by the acoustic attributes fundamental frequency, intensity, and duration. The role of these cues and vowel centralization measures in perception is ordered differently from that in production. It is not known what variability there is between speakers, whether the acoustic factors vary with speech clarity that a speaker produces on different occasions, or what the relationship is between the various speech attributes. Importantly, no studies have been performed in which production and perception of materials is compared with respect to these questions. In the current study, noun/verb pairs differentiated by stress were produced by four speakers, and measures of produced and perceived clarity obtained for these subjects. The importance of the acoustic factors to the contrast was modeled in perception and production, and the results compared. Additionally, the variation with produced or perceived clarity was ascertained. Finally, comparison between cue trading in production and perception was made. The results are discussed in connection with models of speech perception and production.

Adult↗