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Biomedical subjects

D Kurtz

Publications and source records attributed to D Kurtz.

At least 73 records · Page 4Linked to original sources
PubMed1984

Characterization of tongue shape.

Mathematical techniques are described for analyzing tongue shapes obtained with ultrasound images. The surface of the mid-sagittal section of the tongue was approximated by discrete points. In turn, these points were used to approximate position, slope and curvature of the tongue surface at a fixed time during speech. Two approaches were employed. The first method involved the use of finite difference approximations to derivatives of the function of tongue position. The second utilized a curve fit. Both methods were examined for reliability. Results of these analyses on a simple, single speech sound are discussed.

Humans↗
PubMed1984

Use of a microcomputer to store information on radiology cases.

A microcomputer program for storage of qualitative patient data has been applied to CT and special procedures case data. Different vocabularies have been established and utilised for these two case categories. Experience over two years involving more than 10,000 cases is discussed. Utility for statistical, research, and patient care purposes is demonstrated.

Computers↗
PubMed1984

[A genetic form of petit mal absence in Wistar rats].

One-third of the Wistar rats bred in the Centre of Neurochemistry in Strasbourg, France, develop spontaneous epileptic seizures which from their clinical manifestations, pharmacological responses, and electroencephalographic findings are suggestive of Petit Mal absences. These fits are genetically determined since in two lines selected from affected animals they occurred in 90 p. cent of three generations. The selection of a pure strain should assist in the use of this pharmacologic and neurophysiologic model of Petit Mal epilepsy.

Animals↗
PubMed1983

A microcomputer approach to storage of qualitative patient data using key words.

A microcomputer program is presented which stores and retrieves qualitative patient information, such as diagnosis and physical findings. Users can design and enter a key word list and modify it as needed. Using those key words, up to 5000 patient entries can be made on a single floppy disk. Application of the program to CT scan study results is discussed.

Computers↗
PubMed1983

[Sodium valproate: a hyperammonemic drug. Study in the epileptic and healthy volunteer].

Sodium valproate (VPA) consistently induces an arterial hyperammonemia in epileptics tolerant of this drug and in normal subjects. The hyperammonemia appears with the first oral or intravenous dose of the drug, 15-25 mg/kg, and is established within minutes following drug absorption. In 20 epileptics treated with VPA alone for 4 days, the mean arterial ammonemia measured 2-3 h after breakfast and the day's first VPA dose was 72 +/- 9 mumols/l in non-alcoholics, and 77 +/- 7 mumols/l in alcoholics. Hyperammonemia persisted during chronic treatment; in 10 epileptics who had had received only VPA for over a month, the mean hyperammonemia was 87 +/- 6 mumols/l (normal value means +/- 2 SD = 28 +/- 12 mumols/l). The ammonemia varied in the course of the day; sharp peaks 7 or more times the base value were observed. These variations, differing among subjects, depended on the VPA plasma concentration, and above all on the meal composition and the relative timing of the meal and the drug administration. No secondary effects were seen; in particular, hepatic and pancreatic tests were normal. The hyperammonemia would seem to be due to physiopathological mechanisms other than those giving rise to the hepatic complications occasionally observed with VPA. The permanence and the extent of the hyperammonemia raise questions as to its origin, its relation to the stuporous states induced by VPA, and its eventual repercussions on the functioning of neurons.

Ammonia↗
PubMed1983

[Recording ventilation during sleep using pneumotachography: drawbacks and disadvantages].

Pneumotachographic recording of ventilation requires an air-tight nasobuccal face-mask which might disturb the subjects' sleep and thereby modify their breathing pattern. In a cross-over randomised study we compared recordings obtained with and without a face-mask in 20 healthy normal volunteers (10 males, 10 females, mean age = 21.7 +/- S.E.M. = 0.5). The sleep modifications that resulted from the presence of the face-mask were a lengthening of the REM-sleep latency (+ 38%; P less than 0.01), an increase in intra-sleep waking-time (+ 65%, P less than 0.05), an increase in stage I duration (+ 40%, P less than 0.02), and a decrease in REM-sleep duration (- 20%, P less than 0.01), resulting in a decrease in total sleep duration (- 9%, P less than 0.05). The sleep latency, the number of awakenings, the stage II duration, the deep slow-wave sleep duration, the sleep stability, and the number of sleep cycles were not significantly modified.

Adult↗
PubMed1983

Breathing during sleep in normal young and elderly subjects: hypopneas, apneas, and correlated factors.

Polysomnograms were obtained from two groups of normal subjects (20 medical students and 20 elderly persons). The recordings included the usual sleep parameters (electroencephalograph, electrooculograph, and electromyograph of chin muscles) and respiratory data obtained by means of a pneumotachygraph (tidal volumes and respiratory frequency) and thoracic and abdominal strain gauges. In the older group, sleep was more disturbed and respiratory events (hypopneas and apneas) were more frequent both in non-rapid eye movement (NREM) and in REM sleep. The apneas were predominantly of the obstructive type. A correspondence analysis carried out on the 40 subjects showed that a high frequency of hypopneas and obstructive apneas was linked to old age and age-related parameters (disturbed sleep and obesity) both during NREM and REM sleep. A high frequency of central apneas during light slow-wave sleep was linked to the male sex; a high frequency of central apneas during REM sleep was linked to the amount of REM sleep. No relationship could be demonstrated between the decrease of minute ventilation from wakefulness to steady sleep and the incidence of sleep respiratory events.

Adult↗
PubMed1983

Sodium valproate associated with phenobarbital: effects on ammonia metabolism in humans.

Treatment with sodium valproate (VPA) in association with phenobarbital (PB) is accompanied by a greater systemic hyperammonemia than treatment by VPA alone. The anatomical origins of this difference were studied by injecting a dose of 1,500 mg VPA i.v. into six unmedicated patients and six epileptics chronically treated with PB and measuring the ammonium (NH4+) concentration difference between arterial blood and renal, hepatic, internal jugular, and femoral venous blood. In unmedicated patients, arterial [NH4+] rose moderately, secondary to an increased amount of NH4+ released into the general circulation by the kidney; the hepatic metabolism of NH4+ remained normal. In epileptics treated with PB, arterial [NH4+] rose massively, partly as a result of the increased NH4+ release by the kidney and partly because of disturbance of the hepatic metabolism of NH4+. These results provide a clearer understanding of the potentiation of the secondary effects of VPA by PB.

Adult↗
PubMed1983

Effects of midazolam on sleep in normal subjects.

The effects of a single dose of 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a] [1,4]benzodiazepine (midazolam, Ro 21-3981, Dormicum), 15 mg, on both self-evaluated and all-night EEG-recorded sleep parameters were studied in 10 normal young volunteers. All self-evaluated parameters were modified under midazolam compared with placebo: the sleep onset latency was estimated to be shorter, the sleep duration longer, the sleep quality better. Furthermore, the feeling on awakening in the morning was rated better after midazolam. Yet, when compared with prestudy values, two of these parameters (sleep onset latency and sleep duration) were altered under placebo, despite an adaptation night, but unchanged under midazolam. All-night recordings showed a decrease in intra-sleep awakenings, an increase in stage II and III-IV and a decrease in stage I, mainly during the first sleep cycle whereas REM-sleep was not modified. No sleep latency was significantly modified. The correspondence between self-evaluated and measured sleep-duration was different under placebo and under midazolam, suggesting that an additional effect of the drug might be to modify the subjects' perception of their own sleep.

Adult↗
PubMed1983

[Effect of oral almitrine on the sleep apnea syndrome].

Almitrine stimulates breathing by activating peripheral chemoreceptors and was given orally in a dose of 200 mg/day to nine patients with sleep apnoea syndrome, after a single blind placebo sequence. No reduction in the number of respiratory events per hour of sleep was observed. On the other hand Almitrine led to a significant fall in the mean duration of respiratory events (p less than 0.02). This fall occurred principally in the obstructive apnoea group and in those with mixed apnoea only during light slow wave sleep. These results are in agreement with the hypothesis that the arousal response to hypoxia mediated by the chemoreceptors could be responsible for the termination of sleep apneas.

Aged↗
PubMed1982

Further analysis S-R separation effects on visual discrimination performance of normal rhesus monkeys and monkeys with superior colliculus lesions.

Rhesus monkeys discriminated between two color-differentiated stimuli presented on a screen only when they fixated the center of the screen. The stimuli were presented 8 degrees, 20 degrees, or 32 degrees from the screen's center, for 2 sec or 100 msec, a duration too brief to permit their fixation. Performance declined when the response sites, located either centrally (8 degrees eccentricity) or peripherally (32 degrees eccentricity), were separated from the stimuli, whether they were presented for 2 sec or 100 msec. These findings suggest that the stimulus-response separation effect is due to selective attention to the response sites and not to fixating them during stimulus presentation. Following superior colliculus lesions, the monkeys were impaired in discriminating between peripheral stimuli, but only when they responded centrally. This deficit was not due to (a) a failure to fixate the stimuli, for it occurred when the stimuli were 100 msec or 2 sec or (b) reduced sensory capacities, for it disappeared when the subjects responded peripherally. This deficit may reflect deficient attentional shifts from the response sites to the stimuli.

Animals↗