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Biomedical subjects

G D Allen

Publications and source records attributed to G D Allen.

At least 19 recordsLinked to original sources
PubMed1992

A fitness analysis system with an intelligent interface.

This paper describes the development of a system with an intelligent interface for analysis of physiological correlates of athletes' physical performance capacities. The system improves the interface between the physiologist and the coach and provides scientific information in a systematic and coherent fashion. The recommendations provided are based on the results of a series of physiological tests. The implementation of the system is described with emphasis placed on recognition of the internal structure of the knowledge, independence from a particular shell, design for future expansion and maintenance and the integration with existing information resources.

Artificial Intelligence↗
PubMed1992

The relationship between paroxetine and the sparteine oxidation polymorphism.

The relationship between the selective serotonin reuptake inhibitor paroxetine and the sparteine oxidation polymorphism was investigated in a combined single-dose (30 mg) and steady-state (30 mg/day for 2 weeks) study including a panel of nine extensive metabolizers and eight poor metabolizers of sparteine. The median area under the plasma concentration-time curve (AUC) after the first paroxetine dose was about seven times higher in poor metabolizers than in extensive metabolizers (3910 versus 550 nmol.hr/L), whereas at steady state the median AUCss tau interphenotype difference was only twofold (4410 versus 2550 nmol.hr/L). Plasma half-life and steady-state plasma concentration were significantly longer and higher, respectively, in poor metabolizers than in extensive metabolizers (41 versus 16 hours and 151 versus 81 nmol/L). Paroxetine pharmacokinetics were linear in poor metabolizers and nonlinear only in extensive metabolizers. Sparteine metabolic ratio (MR = 12 hour urinary ratio of sparteine/dehydrosparteine), increased during treatment with paroxetine in subjects who were extensive metabolizers, and after 14 days treatment two extensive metabolizers were phenotyped as poor metabolizers and the remaining extensive metabolizers were changed into extremely slow extensive metabolizers with sparteine MRs of 5.7 to 16.5. The inhibition of sparteine metabolism was rapidly reversed after cessation of paroxetine administration. In the poor metabolizers there were no significant changes in MRs during the study. It is concluded that paroxetine and sparteine metabolism cosegregates, but the interphenotype difference in metabolism was less prominent at steady state than after a single dose, presumably because of saturation of the sparteine oxygenase (CYP2D6) in subjects who were extensive metabolizers. Paroxetine is a potent inhibitor of sparteine oxidation by CYP2D6 in vivo.

Adult↗
PubMed1992

Grammatical morphology and speech perception in children with specific language impairment.

Many English-speaking children with specific language impairment have been found to be especially weak in their use of grammatical morphology. In a separate literature, many children meeting the same subject description have shown significant limitations on tasks involving the perception of rapid acoustic changes. In this study, we attempted to determine whether there were parallels between the grammatical morphological limitations of children with specific language impairment and their performance profiles across several perceptual contrasts. Because most English grammatical morphemes have shorter durations relative to adjacent morphemes in the speech stream, we hypothesized that children with specific language impairment would be especially weak in discriminating speech stimuli whose contrastive portions had shorter durations than the noncontrastive portions. Results from a group of eight children with specific language impairment with documented morphological difficulties confirmed these predictions. Several possible accounts of the observed morphology-perception parallels are offered.

Child↗
PubMed1992

Etiology of low back pain in elite boardsailors.

Seven elite boardsailors reporting nonradiating low back pain without leg pain during sailing volunteered for detailed examination. In these subjects, the onset of pain was limited to those occasions when sailing positions were held for a significant period of time, e.g., close hauled sailing or in light winds. No pain was described at any other time. The determination of possible antecedent factors was based on the results of clinical assessment, radiological evaluation, and computer tomography (CT) scanning. Apart from limited flexibility in some subjects, the clinical examination of these athletes was normal; CT changes in this group were limited to disc protrusions and bulges, and pars interarticularis defects. Despite the small number of subjects in the present report, it appears that the frequency of these problems exceeds that in the normal population. It may be possible to suggest that risk factors such as body position during prolonged sailing, particularly under light wind conditions without a harness, and limited flexibility may be associated with the radiological findings and may be implicated in the presence of low back pain, although further investigations appears warranted.

Adult↗
PubMed1990

Intelligibility of synthetic speech for normal-hearing and hearing-impaired listeners.

This study examined the perceived intelligibility of synthetic speech. Participants were adults aged 49-69, one group with normal hearing and one group with acquired sensorineural hearing impairment. Word lists were presented in two speech types: DECtalk (a high-quality speech synthesizer) and a natural male speaker. Results revealed differences between groups, with normal-hearing listeners scoring higher than hearing-impaired listeners, and between speech types, with higher scores for natural speech than for synthesized speech. There was no significant interaction of hearing level and speech type.

Aged↗
PubMed1989

Unusual phonological behavior and the avoidance of homonymy in children.

Young children sometimes make use of unusual phonological patterns even when they already possess the appropriate sound or a suitable substitute in their phonological systems. In this investigation, we attempted to determine whether in such instances unusual sound changes enable children to avoid potential homonymy with other words in their lexicons. Novel words were presented to children, half serving as potential homonyms, half as unlikely homonyms. The children's acquisition of these words was monitored. For a group of normally developing children, unusual sound changes were found to be more frequent in the words with the potential for homonymy. In contrast, a group of children with specific language impairment showed the same degree of unusual usage for both types of words. The findings suggest that children with specific language impairment are especially limited in their ability to capitalize on the phonetic regularities of the language.

Child, Preschool↗
PubMed1989

The mechanisms of nitrous oxide scavenging devices.

A recent publication discussing the concern with nitrous oxide pollution in dental offices and the methods available to reduce this risk aroused interest in scavenging systems. This is the first in a series of three articles and will explain the mechanisms of the nitrous oxide systems available. The second describes the testing of these systems under ideal conditions and the third will assess their efficiency in various dental offices and the factors which were found to detract from that efficiency.

Air Pollution↗
PubMed1988

Cues for intervocalic /t/ and /d/ in children and adults.

One naturally spoken token of each of the words petal and pedal was computer edited to produce stimuli varying in voice onset time (VOT), silent closure duration, and initial /e/ vowel duration. These stimuli were then played, in the sentence frame "Push the button for the----," to four adult and four 6-year-old listeners who responded by pressing a button associated with a flower (petal) or a bicycle (pedal). Among the findings of interest were the following: (a) VOT was statistically the strongest cue for both listener groups, followed by closure duration and initial vowel duration; (b) VOT was relatively stronger for children than for adults, whereas closure and initial vowel durations were relatively stronger for adults than for children; (c) except for a probable ceiling/floor effect, there were no statistically significant interactions among the three acoustic cues, although there were interactions between those cues and both listener group (adults versus children) and the token for which the stimulus had been derived (petal versus pedal).

Acoustic Stimulation↗
PubMed1986

The disposition of clavulanic acid in man.

Following oral administration of potassium 14C-clavulanate to four human subjects, at least 73% of the radioactive dose was absorbed. The mean absolute bioavailability was 64%. Absorption was rapid with peak plasma concentrations of radioactivity and clavulanic acid (2-6 micrograms/ml) occurring between 45 min and three hours after dosing. Values for the volume of distribution at steady-state and terminal half-life of clavulanic acid in the plasma were 12.01 and 0.8 h respectively. Following intravenous administration of clavulanic acid to the same subjects, the clearance, and volume of distribution at steady-state were 0.21 l/min, and 12.01, respectively. Clavulanic acid was the major radioactive component present in 0-24 h urine following oral dosing (23% of the dose). The two major metabolites were 2,5-dihydro-4-(2-hydroxyethyl)-5-oxo-1H-pyrrole-3-carboxylic acid (15% of the dose) and 1-amino-4-hydroxybutan-2-one (8.8% of the dose). Clavulanic acid and 1-amino-4-hydroxybutan-2-one were the major components in plasma following oral administration (52 and 21% of plasma radioactivity respectively at two hours after dosing). The major route of excretion of radioactivity following oral administration was via the urine (73% of the dose). Most of this radioactivity was excreted in the first 24 h after dosing (68% of the dose). The renal clearance of clavulanic acid was 0.1 l/min. Elimination of radioactivity also occurred via the expired air (17% of the dose) and the faeces (8% of the dose).

Chromatography, Thin Layer↗
PubMed1979

The relationship between nitrous oxide conscious sedation and the hypnotic state.

To evaluate the hypothesis that inhalation of low levels of nitrous oxide-oxygen produces an altered state of consciousness similar to hypnosis, 20 subjects were given three suggestions (analgesia, compulsive behavior, and amnesia) during double-blind administration of either nitrous oxide-oxygen or oxygen. Results suggest that administration of nitrous oxide-oxygen may be of increased clinical usefulness if it is combined with careful use of suggestion.

Anesthesia, Dental↗
PubMed1978

Nitrous oxide pollution levels in oral surgery offices.

Nitrous oxide pollutant levels, surveyed in oral surgery offices in Southern California, were lower than previously reported. These evaluations were related to rebreathed gas samples obtained from the operator and assistants, and appear to correlate well with exposure to nitrous oxide contamination. The lower levels in the hallway were tenfold less than those previously reported. Better air-conditioning in these offices and better airway control could be responsible, in part, for the difference.

Air Pollutants↗
PubMed1977

Timing control accuracy in normal speakers and stutterers.

This study attempted to assess the abilities of 10 normal speakers, five stutterers in therapy, and five stutterers no longer in therapy, to control the time program of repeated utterances. The speech sample comprised repeated sentences, paragraphs, and nursery rhymes, and a finger-tapping task was included as a control. Temporal accuracy was measured. Results suggest that (1) there is a wide range of timing abilities, even among the normal speakers, with considerable overlap between the different groups of speakers; (2) on most of the experimental tasks, normal speakers are more accurate timers than are stutterers; (3) stutterers released from therapy are more accurate timers than are stutterers still in therapy, whenever these groups differ; and (4) subjects' speech timing scores correlate moderately with their tapping scores. These results are discussed in terms of (1) theoretical timing control processes, such as a neural clock for controlling speech segment durations, and a speech motor output buffer, whose capacity may be limited in stutterers, and (2) known effects of rhythmic constraints and respiratory irregularity on fluency.

Female↗
PubMed1977

The efficacy of the laryngeal reflex in conscious sedation.

The Jorgensen technique and nitrous oxide-oxygen sedation were evaluated for the risk of aspiration. Volunteers and patients were studied in the supine, semisupine, and Trendelenburg positions. Aspiration occurred in a single patient under the Jorgensen technique and could be related to the presence of a narcotic in the mixture. The incidence of tracheal soiling was lower than that with other intravenous techniques and could be attributed to the use of the semisupine position or the baseline concept of narcotic dosage in the Jorgensen technique. In the nitrous oxide-oxygen sedation technique, aspiration was not noted. The study suggests that use of a narcotic in an intravenous sedative technique increases the hazard of aspiration.

Adolescent↗