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Biomedical subjects

K Meier-Ewert

Publications and source records attributed to K Meier-Ewert.

At least 19 recordsLinked to original sources
PubMed1995

Effects of vitamin B12 on human circadian body temperature rhythm.

To clarify the effect of vitamin B12 on the human circadian clock, five healthy male adults participated in two constant routine procedures, 2 or 3 weeks apart. In one, subjects received intravenous saline injections (placebo trial) and in the other, intravenous injections of methylcobalamin (MB12) (drug trial). Intravenous administration of MB12 increased rectal temperature in the later hours of the daytime during the constant routine. The activity did not change between treatments in any period during the constant routine. During the later hours of the constant routine, alertness assessed with visual analog scale was higher in the drug trial than in the placebo trial. The period in which drug treatment produced greater alertness almost coincided with that in which MB12 elevated rectal temperature. These results may provide evidence of an effect of vitamin B12 on the circadian clock.

Adult↗
PubMed1995

Cephalometric predictors for orthopaedic mandibular advancement in obstructive sleep apnoea.

The cephalometric analysis of two groups: 30 sleep apnoea patients, and 30 age- and sex-matched control patients, established predictors for the orthopaedic mandibular advancement by means of the Esmarch device (ED) in treating obstructive sleep apnoea (OSA). Polysomnographic sleep and ventilation data gathered for each patient with and without mandibular advancement by means of the ED were compared. Cephalometric data and treatment efficacy for each patient were submitted to a regression analysis. Maximal efficacy is predicted by: 1. The combination of an orthognathic to prognathic maxilla (SNA larger than or equal to 83 degrees) with an orthognatic to retrognathic mandible (SNB less than or equal to 77 degrees) 2. An anterior superior displacement of the mandible, with the supramentale situated at a distance from the anterior part of second cervical vertebra (B-HWK 2 longer than or equal to 95.5 mm) and a narrow angle between the skull and the mandibular ramus (SN/B-Go equal to or less than 1.5 degrees) 3. Short oral height (TB-PNS equal to or less than 35.5 mm), with the uvula not extending beyond the tongue base (UT-PNS, equal to or less than 30 mm). 4. A narrow oropharynx (PAS equal to or less than 3.4 mm). The narrower the SNB-angle, the wider the SNA-angle, and the shorter the uvula, the more effective the device.

Adult↗
PubMed1995

[Differential therapeutic aspects in treatment of obstructive sleep apnea syndrome].

We report the case of a 43-year-old man who suffered from obstructive sleep apnea with excessive daytime sleepiness and nocturnal sweating. His initial apnea index of 60/h improved under treatment with an Esmarch device. Apneas were totally suppressed by nCPAP application with a pressure of only 4 mb, but the patient rejected nCPAP therapy. After two years with the Esmarch device he reported increasing temporomandibular joint pain and Esmarch therapy had to be stopped. A cephalometric evaluation showed good prognosis for maxillomandibular advancement osteotomy, which was performed and which suppressed the apneas completely over a period of more than one year. Indication, surgical technique, and risks are discussed.

Adult↗
PubMed1994

Differential effects of extended sleep in narcoleptic patients.

The aim of the present study was to investigate the effects of extended night sleep on subsequent daytime sleep propensity in narcoleptic patients. The possible differentiation between REM and NREM sleepiness was of particular interest. Ten unmedicated narcoleptic inpatients (8 men, 2 women) aged 23-61 years (mean, 47.9 years) participated in this study. Adapting the patients to the hospital schedule (nocturnal sleep period from 22:00 to 6:00 h and ad lib, nap during daytime) for at least 2 weeks, we conducted a baseline PSG from 22:00 to 6:00 h and subsequent 5-trial daytime sleep recordings with naps (lying on the bed for 20 min light-out period) at 9:30, 11:30, 13:30, 15:30 and 17:30 h (the baseline condition: BC). After a 1-5 day interval, we conducted an extended PSG from 22:00 to 10:00 h. Subsequent to the extended PSG, we carried out 5-trial daytime sleep recordings. We adjusted the start time of the first nap trial at least 90 min after waking time and start time in the 5th nap trial before 19:00 h (the extended condition: EC). Mean TST was 417.0 min in the baseline PSG, and 595.2 min in extended PSG. Mean number of daytime naps per subject exhibiting a sleep latency shorter than 10 min was decreased in EC. Mean sleep latency in EC was significantly prolonged in comparison with that in BC. This prolongation of mean sleep latency per subject was positively correlated with S4 duration and % S4 obtained in the morning of the extended PSG (from 6:00 to wake time).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Striatal dopamine D2 receptors in patients with narcolepsy measured with PET and 11C-raclopride.

We investigated in vivo D2 receptor binding using 11C-raclopride and PET in the striatum of 17 subjects with the narcoleptic syndrome. Putamen and caudate nucleus 11C-raclopride uptake was comparable in the total patient group and controls, and the tracer uptake was similar in the HLA-DR2-positive (n = 12) and HLA-DR2-negative (n = 5) narcoleptic subjects. There was a significant increase in 11C-raclopride uptake in the putamen of narcoleptic subjects older than 31 years (n = 11) when compared with age-matched controls (n = 15). There was no evidence of involvement of the striatal D2 dopaminergic neurotransmitter system in the basic pathophysiology of the narcoleptic syndrome despite an age-related increase in putaminal 11C-raclopride uptake.

Adolescent↗
PubMed1993

A deletion in the second exon of an HLA-DRB1 allele found in a DR2-negative narcolepsy patient.

In this report, we describe a new allele of the HLA-DRB 1 gene carrying a form of mutation that has not been observed before. It appeared in an HLA-DR2-negative narcolepsy patient who, besides HLA-DR4, revealed a serologic HLA-DR blank segregating with HLA-DQ1. Oligotyping showed that the new allele belongs to the HLA-DR8 group. Restriction analysis and DNA sequencing revealed the deletion of 12 bp as well as the substitution of 9 flanking base pairs between codons 36 and 43. The expression of the mutated gene was demonstrated by the presence of its messenger RNA and a few positive reactions with DR8 sera. Without interrupting the reading frame, the mutation leads to a gene product composed of a modified amino acid sequence. We anticipate that the mutation influences the conformation of the molecule with possible consequences concerning immune response.

Alleles↗
PubMed1991

[Abnormal daytime drowsiness--attempt at typology].

Abnormal drowsiness during the day is defined on the basis of three criteria: 1. subjective feeling of increased tiredness, 2. objective observation of attacks of falling asleep, 3. detection of premature falling asleep in the multiple sleep latency test. About 3 to 4% of the population of modern industrial countries complain of this symptom which very quickly leads to inability to work in numerous occupations (driving instructors, lorry drivers, airline pilots). In many cases, the symptoms can be eliminated by effective methods of treatment. Early diagnosis and therapy is hence an important task of physicians. Clinically suitable tools and methods of measurement for appraising the phenomena are at present: 1. the multiple sleep latency test (Richardson et al., 1978), 2. the multiple staying awake test (Mitler et al., 1982), 3. the vigilance test according to Quatember and Maly from the Vienna test system. In neurophysiological terms, an attempt is made to differentiate between: REM drowsiness, non-REM drowsiness, hypofunction of the arousal systems of the reticular formation, and hyperfunction and overstimulation of the arousal systems of the reticular formation (over-aroused tiredness). Approaches to a clinical typology of abnormal drowsiness are available from two points of departure: 1. Forms of permanent somnolence which are not alleviated but intensified by a brief restorative sleep and resemble the 'oversleeping syndrome' of the healthy individual. 2. Attacks of imperative falling asleep in narcoleptic patients. The characteristic of this form of abnormal drowsiness during the day is that in the interval between the attacks of falling asleep patients can take on any healthy person with regard to alertness, reaction capacity and ready wit. After a brief restorative sleep of less than 5 min., they immediately feel fresh, alert and fit again.

Arousal↗
PubMed1989

Bright white light does not improve narcoleptic symptoms.

Bright white light (500lx) for 4 h/day was applied to seven narcoleptic patients (age 47-65 years, mean 55 years). The effects of the light on the disturbed sleep-wake cycle in narcoleptics were investigated by the measurement of the following parameters: (1) excessive daytime sleepiness and sustained attention (multiple sleep latency test); (2) rest-activity cycles; (3) self-ratings (mood, anxiety, tiredness); (4) urinary cycles of 6-OH melatonin sulphate and cortisol; (5) sleep EEG. Treatment with bright light showed neither objective nor subjective changes in the clinical symptoms of narcolepsy. While similar "dosage" light applications can phase shift human circadian rhythms and improve depression and hypersomnia in winter depression, it is not an appropriate treatment for narcolepsy.

Aged↗
PubMed1988

Cellular approach for detecting narcolepsy-specific alterations in DR2 haplotypes.

In an attempt to detect disease-associated genetic variations and/or exogenously induced alterations in DR2 haplotypes of narcolepsy patients, primed lymphocytes (PLs) were generated in nine families against DR2 haplotypes of narcolepsy patients and healthy family members. Twenty-four PL reagents were obtained and restimulated by cells of unrelated narcolepsy patients and DR2/Dw2-positive healthy individuals. The mean restimulation rates triggered by cells of patients or healthy controls, respectively, never differed significantly. In primary MLC as well as PLT combinations of patients and their HLA-identical siblings no significant stimulation was observed in both directions. We conclude that narcolepsy-specific alterations of class II molecules cannot be cellularly detected or do not exist on peripheral lymphocytes.

Female↗
PubMed1988

[ENT medical findings in obstructive sleep apnea syndromes].

Correlations between the manifestation of obstructive sleep apnoea syndrome (OSAS) and anatomical or functional changes in the upper respiratory tract remain controversial. The correlation between obstruction of the upper respiratory tract and the degree of sleep apnoea syndrome was investigated in 60 patients with obstructive sleep apnoea (diagnosed by polysomnography) and in 55 healthy controls. After clinical examination, rhinomanometry and determination of the size of the lower jaw and oropharynx, the motility of the pharyngeal walls during Mueller's manoeuvre was evaluated by flexible endoscopy. No significant anatomical or functional differences were observed between OSAS patients and healthy controls. There was no correlation between the degree of OSAS (expressed by the apnoea index) and pharyngeal size. Although no specific statement concerning diagnosis or degree of OSAS can be made on the basis of an otolaryngological examination, OSAS patients should always undergo otolaryngological examination to exclude pharyngeal disease.

Airway Obstruction↗
PubMed1987

Rapid eye movements, muscle twitches and sawtooth waves in the sleep of narcoleptic patients and controls.

Seventeen unmedicated patients with narcolepsy-cataplexy and 17 age- and sex-matched controls were recorded polygraphically for 3 consecutive nights. Rapid eye movements (REMs), m. mentalis twitches and sawtooth waves in the EEG were visually scored. REM and twitch densities during REM sleep were significantly higher in the patients than in the controls. The distribution pattern of REMs and twitches was altered in the patients: twitch density peaked in the first REM period and density of REMs showed an even distribution across all the REM periods of the night. In the controls both REM and twitch density increased from the first to the second REM period. We therefore assume that in the narcoleptics phasic activity of REM sleep is disinhibited. Densities of REMs, twitches and sawtooth waves did not correlate with one another in patients and controls. They appear to be independently regulated. The REM periods of the patients contained 3 times as many waking epochs as those of the controls. This suggests that in narcolepsy the transition REM/waking is selectively facilitated. The REM/NREM ratio of twitch and sawtooth wave densities was the same in patients and controls.

Adult↗
PubMed1987

Possible male segregation distortion of DR2 haplotypes in narcolepsy patients.

Segregation of disease-associated DR2-linked haplotypes from patients with narcolepsy was studied in 18 German families. Of these, 13 were informative, as transmission could be traced from DR2 heterozygous patients to their healthy offspring. Although the composition of extended haplotypes was equal in males and females, DR2 was transmitted to 78.6% of the offspring by diseased fathers but only to 57.1% by diseased mothers. Compared to an expected 1:1 ratio according to Mendelian segregation this means a statistically significant deviation (p less than or equal to 0.03) for male but not for female patients. In contrast, transmission distortion was not observed with 30 DR2 haplotypes in 27 healthy families. These data represent a new example of male segregation distortion in an HLA-associated disorder.

Female↗
PubMed1986

[Therapy of obstructive sleep apnea syndrome].

Symptomatology and sequelae, as well as diagnosis and therapy of the obstructive sleep apnea syndrome are discussed. The Esmarch prosthesis, which we developed for the prosthetic treatment of obstructive sleep apnea syndrome, was tested in 7 patients. Patients were polysomnographically recorded during two sequential nights with and without Esmarch prosthesis. All apnea parameters improved significantly (apnea time by 78%, apnea index by 67% of baseline values). The mean duration of the remaining apnea phases diminished by 31%. Improvement of O2 saturation of haemoglobin and O2 partial pressure in the tissue paralleled that of the apnea parameters. The severely disturbed sleep profile of the patients showed a clear tendency towards normalization. The Esmarch prosthesis is an efficient method for the treatment of the obstructive sleep apnea syndrome.

Adult↗
PubMed1986

HLA and narcolepsy in a German population.

In this paper the first MHC data including HLA-A, B, C, DR, DQ and complement BF, C4A, C4B determinants in German narcoleptics are presented together with the first family studies in European Caucasoids. 57 out of 58 unrelated patients (98.3%) were positive for DR2 and DQw1, respectively. In contrast to all other reports, one patient with typical signs of narcolepsy was found to be DR2/DQw1 negative. Data showing significant increase in the frequency of B7, and normal frequencies of B35 were discordant with data from Japanese patients. Definition of the extended DR2 linked haplotypes, deduced from 6 families, revealed that 5 out of 12 were DQw1, DR2, BFS, C4B1, C4A3, B7 (Cw7), while 11/12 had DR2, DQw1, BFS, C4A3, C4B1 in common. In one multiple case family two genotypically different DR2 haplotypes were identified in affected siblings. Results from the family study were concordant with a dominant mode of inheritance with incomplete penetrance of a hypothetical disease susceptibility gene.

Complement C4↗
PubMed1985

Propranolol: long-term treatment in narcolepsy-cataplexy.

Forty-eight sequential narcoleptic patients were treated with propranolol (80-240 mg/day) for an average period of 18.4 months. Initially all patients received single drug therapy; after 10 days or longer, however, 50% of patients also received tricyclics or stimulants because propranolol alone did not sufficiently suppress the narcoleptic symptoms. Fifty percent of patients judged the initial effectiveness of propranolol on daytime sleepiness to be good to very good; in these patients the effects seemed comparable to that of pemoline. Within 6 months, however, the effectiveness started to decrease, and after 26 months only 8% (2 out of 24) of those patients taking the single drug were satisfied with propranolol therapy alone. Side effects included disturbed night sleep, decreased blood pressure, increased lethargy, allergic skin rash, and asthma; 58% of the patients dropped out of the study after 26 months. Vigilance tests during the first 4 months (16 patients) showed significant improvements in all test criteria, including a shorter reaction time. All-night polygraphic electroencephalogram recordings of 14 patients on the eighth and ninth day of medication showed that average total sleep time decreased by 5.7%, but other sleep characteristics did not change significantly.

Arousal↗