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Biomedical subjects

J Krieger

Publications and source records attributed to J Krieger.

At least 181 records · Page 10Linked to original sources
PubMed1984

[Sleep apnea syndromes. Treatment with continuous positive pressure by the nasal route].

Nine patients with severe, predominantly obstructive sleep apnoea syndromes were treated during one night by continuous positive pressure under polygraphic monitoring. Three patients did not tolerate the treatment for either mechanical reasons (2 cases) or ventilatory reasons (1 case). In the remaining 6 patients, continuous positive pressure resulted in reorganization of sleep and disappearance of obstructive and central apnoeic episodes. This effect was incomplete at low pressure (2 cm H2O) and complete at pressures of 6 to 10 cm H2O. The fact that continuous positive pressure was effective against both obstructive and central apnoea suggests that its mode of action is not purely mechanical but involves the central ventilatory control, probably by a reflex mechanism. In view of its effectiveness, continuous positive pressure appears to be the treatment of choice for sleep apnoea syndromes.

Aged↗
PubMed1983

A marathon: the immediate effect on female runners' luteinizing hormone, follicle-stimulating hormone, prolactin, testosterone, and cortisol levels.

This study was designed to measure the changes that occur in luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, testosterone, and cortisol levels in women at the immediate conclusion of a marathon and to compare the results with those in women on the United States Women's Water Polo Team at the conclusion of a strenuous practice session. Thirty-one women runners were included in this study, and each woman served as her own control. Thirteen women were studied from the United States Women's Water Polo Team. In the postmarathon group, cortisol levels showed a mean increase of 211% (p = less than 0.005), FSH levels were unchanged; LH levels, contrary to other published reports, were reduced by 36% (p = less than 0.005); and prolactin levels showed a mean increase of 327% (p = less than 0.005). These results were analyzed in the age groups 20 to 30, 30 to 40, and 41 +. All age groups had similar changes. In members of the United States Women's Water Polo Team, there were no significant changes in cortisol, FSH, LH, or testosterone levels. Prolactin levels showed an average increase of 70% (p = less than 0.002). These data indicate that acute exercise by running a marathon does alter the immediate hormonal profile. The data also indicate that acute exercise in an aquatic program results in a different response.

Adolescent↗
PubMed1983

Sodium valproate-induced hyperammonemia in the rat: role of the kidney.

The intravenous injection of sodium valproate (VPA) 200 mg/kg provoked in fasting rats a 100% increase in the arterial NH+4 concentration by the 10th min. The increase persisted at this level for at least 100 min. Simultaneous measurements of NH+4 and glutamine concentrations in the carotid artery, renal vein and suprahepatic vein showed that there were increases in the release of NH+4 and the uptake of glutamine by the kidney while the [NH+4] of suprahepatic venous blood remained stable. In binephrectomized rats injected with VPA, NH+4 levels did not change. These results suggest that the VPA-induced arterial hyperammonemia depended on the accelerated catabolism or possibly the reduced synthesis of glutamine by the kidneys. The liver of fasting rats does not seem to play a preponderant role in the VPA-induced hyperammonemia.

Ammonia↗
PubMed1983

Single and repeated dose kinetics of the hypnotic agent loprazolam in healthy volunteers.

The pharmacokinetics of loprazolam have been studied in eight healthy male volunteers after single and repeated 2 mg oral doses taken at night, for eight nights. The absorption and disposition of unchanged drug (HPLC-GC assay) and receptor active benzodiazepine-type materials (radioreceptor assay) were examined after the first and eighth dose. Maximum levels of approximately 10 ng ml-1 (range 3.6 to 15.5 ng ml-1) were reached within about 2.5 h after dosing. The post-peak levels declined in a single exponential fashion with an overall mean +/- SD half-life of 7.06 +/- 1.98 h and total areas under the curve ranging from 35.9 to 189.0 ng ml-1 h. There were no statistical differences between the values for the first and eighth doses. There was no evidence to suggest that significant accumulation of parent drug or receptor active benzodiazepine-type materials had occurred, and it is concluded that the kinetics of loprazolam would allow repeated daily doses of 2 mg.

Adult↗
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

Matrix isolation of free radicals from myo-inositol formed by H reaction in acidic glasses.

Reaction of H.-atoms produced photolyticaly in acid glasses with myo-inositol initially results in the formation of three different radical intermediates, two of which give rise to discernable hyperfine interactions in electron spin-resonance spectra whereas one is a non-specific singlet. The two former species correspond to loss of H. from all carbon-positions of the polyalcohol. Both intermediates transform into the same secondary radical upon thermal annealing by water elimination.

Electron Spin Resonance Spectroscopy↗
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

The renal origin of sodium valproate-induced hyperammonemia in fasting humans.

Acute administration of 1,500 mg of sodium valproate or chronic administration of 30 mg/kg/24 hours induced a more than twofold increase of renal ammoniagenesis in fasting subjects. Hyperammonemia was moderate, as normal hepatic ammonia detoxification persisted. Renal uptake of glutamine increased simultaneously.

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↗