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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 1,063 records · Page 59Linked to original sources
PubMed1986

Relationship between amplitude of tremor and reflex responses of the human jaw-closing system.

Jaw-closing force was transduced while subjects maintained a biting force of 9.8 N. To estimate the amplitude of tremor in each subject's force record, the average spectrum of the force was computed, and the definite integral of the averaged spectrum in the frequency range from 3.5 to 10 Hz was calculated. For the same subjects, the amplitude of reflex responses to innocuous mechanical stimuli delivered to intraoral and perioral sites was measured as the peak-to-peak change in jaw-closing force following application of the stimulus. Force responses produced by stimulation at each site were used to compute an average reflex response measure for each subject. Large intersubject variability was observed in the amplitudes of jaw tremor and reflex responses. A correlation coefficient computed between the tremor and reflex measures revealed that subjects with large amplitude tremor tended also to have large reflex force responses. This correlation is consistent with the suggestion that activity in cutaneous reflex pathways contributes to tremor of the human mandible.

Electromyography↗
PubMed1986

Clinical experience with 50 cases of first-trimester fetal diagnosis by chorionic biopsy.

Prenatal diagnosis by chorionic biopsy was undertaken between the eighth and 12th weeks of pregnancy in 50 patients at risk of chromosomal or genetic abnormalities. Samples from 45 patients were karyotyped. A DNA analysis for the detection of homozygous beta-thalassaemia was undertaken in five patients. The sample from one patient at risk of haemophilia in the fetus was subjected to DNA analysis after a male fetus was confirmed on karyotyping. Abnormal karyotypes were detected in four fetuses while three had homozygous beta-thalassaemia.

Abortion, Spontaneous↗
PubMed1986

Translation of Broca's 1865 report. Localization of speech in the third left frontal convolution.

Modern texts continue to cite Broca's 1861 study of a single patient, Tan, as the first definitive localization of a cerebral function, specifically, articulate speech. We describe the development of Broca's theory from his initial support in 1861 for Bouillaud's view that speech is localized in both frontal lobes to his description in 1865 of a center for articulate speech in the third left frontal convolution. We have translated Broca's 1865 French report. Despite the revival of "classical" anatomically based concepts of discrete aphasic syndromes, numerous clinicoanatomical correlation studies have failed to confirm the specific language impairment described by Broca. Broca's own descriptions of language development in the third right frontal convolution following left hemisphere damage also raise questions about the validity of theories of brain-behavior relationships based on punctate localization of specific mental functions.

Aphasia↗
PubMed1986

Factors influencing bowel function after ileal pouch-anal anastomosis.

Seventeen patients were studied 3-31 months (median 6.4 months) after mucosal proctectomy and ileal pouch-anal anastomosis for ulcerative colitis (n = 15) or adenomatous polyposis (n = 2). Seven had a triplicated pouch, and ten a duplicated pouch. Clinical bowel function was determined by detailed questionnaire, and correlations sought between clinical end-points such as frequency of defaecation, urgency of defaecation and continence, and the results of laboratory investigations, comprising anal manometry, capacity and compliance of the pouch, completeness of emptying, faecal bacteriology and mucosal inflammation. Frequency of defaecation was found to be inversely correlated with both the capacity (rs = -0.66, P less than 0.01) and the compliance (rs = -0.53, P less than 0.05) of the pouch. Patients who could postpone defaecation for greater than 30 min had higher anal squeeze pressures (P less than 0.05) than patients who had greater urgency of defaecation. Patients with perfect anal continence had higher resting anal pressure (P less than 0.05) and emptied the pouch more completely (P less than 0.01) than patients who experienced minor leakage. The faecal flora of the pouches showed a greater predominance of anaerobes (P less than 0.01) and increased numbers of bacteroides (P less than 0.01) compared with the faecal flora of ileostomies, but the changes in the flora did not correlate with any aspect of bowel function. The best clinical results (i.e. perfect continence, low frequency of defaecation and little urgency) were associated with high anal pressure and with large volume, high compliance and complete emptying of the pouch. The completeness of emptying was similar for both designs of pouch, but the capacity and compliance of triplicated pouches were greater than the capacity and compliance of duplicated J pouches (P less than 0.05), and this was associated with a better clinical result in the triplicated pouches.

Adolescent↗
PubMed1986

The significance of pericentric inversions of chromosome 2.

Thirteen new cases of a pericentric inversion 2 collected from different laboratories are reported. In addition 41 cases of a pericentric inversion 2 were reviewed from the literature. The pooled data were analysed using Weinberg's proband method to evaluate the risk of a carrier for either children with congenital anomalies or reproductive wastage. In the "corrected" sample of 166 lifeborn offspring of carriers of a pericentric inversion 2 there were five who showed phenotypic anomalies and two died a few hours after delivery. The reported anomalies are heterogeneous and probably reflect the basic risk of any couple for abnormal lifeborn offspring. There has been no observation of a lifeborn who inherited an unbalanced recombination of a parental pericentric inversion 2. A carrier of a pericentric inversion 2 obviously has an increased risk for reproductive wastage. This is indicated by (1) an increase of the rate of spontaneous abortions and (2) an increase of the rate of index patients ascertained because of previous miscarriages. The risk of a carrier of a pericentric inversion 2 for a spontaneous abortion or a stillbirth may be about twice the basic risk of the general population.

Abortion, Spontaneous↗
PubMed1986

Isochromosome 15 with behaviour disorder.

An isochromosome of 15(q12) was found in a mentally retarded patient with behaviour disorders which included hyperactivity, short attention span, aggression, and autistic behaviour. There were only minor physical anomalies; he did not have the Prader-Willi syndrome.

Adolescent↗
PubMed1986

An apparatus for collecting blood samples by radiotelemetry from horses during exercise.

An apparatus was designed to collect four consecutive blood samples from exercising horses. The collection of each sample was controlled by valves activated by radiotelemetry signals transmitted by an observer. Using the device, venous blood samples were collected from ten thoroughbred racehorses before, during and after a 400 m training gallop. Blood glucose increased markedly post-exercise. Both phosphorus and potassium concentrations increased during exercise, decreased post-exercise and recovered to pre-exercise levels within 120 minutes. The system was modified to collect anaerobic samples of arterial and venous blood, and the efficiency of the modified system was investigated in a standing conscious horse. Blood gas values of samples collected by means of the apparatus were compared with those collected manually and simultaneously, directly from the neck of the intravascular catheter. For eight pairs of arterial and venous samples, the coefficients "r" were 0.998 and 0.997 for PO2 and PCO2 respectively. It was concluded that the system worked efficiently and that the anaerobic sealing of the modified version was adequate.

Animals↗
PubMed1986

The use of a single daily theophylline dose and metered-dose albuterol in asthma treatment.

Sustained-release, 24-hour theophylline preparations have been formulated and may provide for convenient once-a-day dosing, although the use of such products in clinical asthma has yet to be fully established. This study compared single daily versus twice daily dosing with a 24-hour theophylline, Uniphyl, in asthma and further evaluated for the additional effect of metered-dose albuterol on each theophylline regimen. Twenty-eight patients with asthma were enrolled in this randomized crossover trial. Before enrollment, all demonstrated at least a 15% improvement in FEV1 after a beta-adrenergic aerosol and had serum theophylline levels ranging from 5 to 20 micrograms/ml with a predetermined 800 mg daily dose of Uniphyl. The patients were then randomly entered into four treatment regimens for one week each: Uniphyl, 800 mg four times a day (qd); metered-dose albuterol, active, 180 micrograms four times a day (qid); Uniphyl, 400 mg twice daily; metered-dose albuterol, active, 180 micrograms qid; Uniphyl, 800 mg qd; placebo, two puffs qid; and Uniphyl, 400 mg twice daily; placebo, two puffs qid. On the morning of the seventh day of each treatment regimen, pulmonary functions and a trough serum theophylline level were measured. The patient then received the same medication that he had taken for the preceding week. Spirometry was measured hourly, and a serum theophylline level was measured 6 hours later. The daily symptom scores, peak flow values, and pulmonary functions on the test day were similar with either single or twice daily Uniphyl dosing. Routine administration of albuterol by metered dose did not enhance asthma control in an unequivocal fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

An anatomical study of the patterns of the coronary arteries and sinus nodal artery in complete transposition.

The origin and course of the main coronary arteries and the sinus nodal artery are relevant to both intra-atrial and arterial relocation operations for complete transposition (the combination of concordant atrioventricular and discordant ventriculo-arterial connexions). The patterns of the main coronary arteries in 148 hearts with complete transposition have been documented together with the patterns of the sinus nodal artery in 105 of these. The terminology which has been used to describe these arteries has been explained. The findings illustrate the wide variation which exists in the origin and course of all these arteries in complete transposition and indicate areas where they are most at risk.

Arteries↗
PubMed1986

Piracetam and event-related potentials in dyslexic males.

The effect of piracetam on visual event-related potentials (ERP) was investigated in a double-blind placebo-controlled study. Eight- to 12-year-old dyslexic males were randomly assigned to 3.3 g/day of piracetam or matching placebo in two divided doses over a 12-week period. Children performed a vigilance task in which they pressed a key when two alphabetic letters or shapes occurred in sequence. ERPs to letters and shapes, for active and passive responses, were recorded at the vertex and left and right parietal areas of the scalp. Performance measures included letter- and form-hits, misses, commission errors and reaction times. Piracetam increased the amplitude of a late positive component (believed to correspond to P300) at the vertex for letter-hits. Piracetam also increased the latency of this component in both hemispheres, but only for active responses (letter-hits) in the left hemisphere and passive responses (correct rejections and misses) in the right hemisphere. Although piracetam did not significantly affect performance, reaction time to letter-hits was significantly correlated with the latency of the P300 component, suggesting that letters created increased effort or attentional demand on the subjects compared with forms. An early ERP component (P225) also showed increased amplitude to piracetam in both hemispheres and effects were limited to form-hits. These effects were thought to possibly reflect slow negative potentials arising from stimulus anticipation in the CNV-like paradigm. In view of the small sample size, the results were cautiously interpreted as indicating a facilitation of verbal processing mechanisms responsible for analyzing the verbal significance of visual stimuli.

Brain↗
PubMed1986

Prevalence of speech and language disorders in 5-year-old kindergarten children in the Ottawa-Carleton region.

A representative sample of 5-year-old kindergarten children was assessed for speech and/or language disorder. Of the 1,655 children tested, 180 were identified as having speech or language impairment. It is estimated that within the total reference population, between 16.2% and 21.8% would show some impairment; for the boys, the rate would be 15.5% to 20.7% and for the girls, between 19.1% and 25.1%. Most of these children would show some language impairment as opposed to speech problems only. Approximately 36% of the identified boys and 30% of the girls would have speech problems only, the remainder having speech and language problems or language problems only. Followup studies of these children are needed to ascertain their outcome and language status in middle childhood.

Articulation Disorders↗
PubMed1986

EMG recording in human lip muscles: can single muscles be isolated?

Electromyography, recording the electrical activity of muscles, is an electrophysiological method that has been used widely in the study of movement performance by human subjects. Borrowing from the tradition of electromyographic studies of limb muscles, investigators interested in speech production have used the method to address many important experimental questions. Unfortunately, data recorded from craniofacial muscles generally have been discussed without reference to problems of interpretation that could arise due to the unique anatomical features of the muscles, particularly the lip muscles. Anatomical data show that the fibers of different muscles of the lips are interdigitated so that fibers with differing spatial orientation typically are found within a small section of lower lip tissue. The anatomical data are consistent with results of physiological studies of the lower lip muscles that have suggested that motor units with different physiological characteristics are found within a single recording site. Together, the anatomical and electrophysiological data suggest that, even with intramuscular electrodes, the probability of recording from a single muscle of the lip in isolation is extremely low. The fact that the activity of more than one muscle is likely to be sampled critically determines the nature of the conclusions that can be drawn from the data.

Electromyography↗