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Biomedical subjects

E Naumann

Publications and source records attributed to E Naumann.

At least 19 recordsLinked to original sources
PubMed2005

Alteration of cerebral perfusion in patients with idiopathic normal pressure hydrocephalus measured by 3D perfusion weighted magnetic resonance imaging.

OBJECTIVE: It is controversial whether alteration of cerebral perfusion plays an important role in the pathophysiology of patients with idiopathic normal pressure hydrocephalus (NPH) and can help to predict the outcome after shunt surgery. MATERIALS AND METHODS: 28 patients with suspected NPH were examined clinically (Homburg Hydrocephalus Scale, walking test, incontinence protocol) and by 3D dynamic susceptibility based perfusion weighted magnetic resonance imaging (PWI-MRI) before and after cerebrospinal fluid release (spinal tap test, STT). The perfusion parameters (negative integral (NI), time of arrival (T0), time to peak (TTP), mean transit time, and the difference TTP-T0 were analysed. RESULTS: Three different groups of patients were identified preoperatively: In group 1 seven patients showed an increase in the cerebral perfusion and a clinical improvement after STT. The second group (9 patients) also revealed an increase of the cerebral perfusion, but no significant alteration of the clinical assessment could be found. In the third group neither the cerebral perfusion nor the clinical assessment changed. 14 of the 16 patients (group 1 and 2) were examined three months after shunt placement. 11 patients showed a good or excellent result, 2 patients revealed a fair assessment, and only 1 patient had transiently improved. No patient was downgraded after shunting. In the patient group 1 and 2 the NI increased significantly (effect size: 34%), whereas in group 3 no significant alteration of NI was observed. CONCLUSION: PWI-MRI improves the prediction of outcome after shunt placement in patients with NPH and can offer new insights into the pathophysiology.

Adult↗
PubMed2002

Suppression of interleukin-6 to interleukin-10 ratio in chronic alcoholics: association with postoperative infections.

OBJECTIVE: To investigate the interleukin-6 (IL-6) to interleukin-10 (IL-10) ratio and levels of sE-selectin in patients undergoing elective surgery of the upper digestive tract and to define the differences in the perioperative immune response between chronic alcoholic and non-alcoholic patients. DESIGN: Prospective pilot study. SETTING: Single center, interdisciplinary intensive care unit (ICU) at a university hospital. MEASUREMENT AND MAIN RESULTS: The study compared chronic alcoholics ( n=25) and non-alcoholics ( n=20) before and after surgery for resection of upper digestive tract tumors. White blood cell counts, C-reactive protein and circulating levels of sE-selectin, the pro-inflammatory cytokine IL-6 and the inhibitory cytokine IL-10, were obtained at hospital admission, preoperatively, postoperatively at ICU admission and 2 and 4 days later. Rates of postoperative infectious complications including pneumonia and sepsis were determined. sE-selectin only differed between chronic alcoholics and non-alcoholics preoperatively. Compared to non-alcoholics, chronic alcoholic patients showed a fourfold increase in circulating levels of IL-10 ( p<0.01) and a suppression of the IL-6/IL-10 ratio ( p=0.001) immediately after surgery. Coincident with the immune alterations, chronic alcoholics had a prolonged ICU stay ( p<0.01) and a threefold increased rate of wound infections ( p<0.05) and pneumonia ( p<0.01). Lower IL-6/IL-10 ratios were associated with increased rates of infectious complications ( p<0.05). CONCLUSION: Chronic alcoholics had decreased IL-6/IL-10 ratios at ICU admission and increased rates of infectious complications in the postoperative ICU course. This may indicate immediate postoperative immune suppression before the onset of infections and may help to identify chronic alcoholic patients at risk.

Aged↗
PubMed2002

[Treatment of idiopathic headache in childhood - recommendations of the German Migraine and Headache Society (DMKG)].

According to the principles of evidence-based medicine, the controlled studies on the treatment of idiopathic headache in childhood have been analysed and compiled to treatment recommendations. For the acute treatment of migraine attacks or tension-type headache, ibuprofen (10 mg per kg body weight) or acetaminophen (15 mg per kg body weight) are recommended with highest evidence, intranasal sumatriptan (10 to 20 mg) can be given as second choice. For the prophylaxis of migraine, betablockers (propranolol and metoprolol), flunarizine, and valproic acid are recommended. Flunarizine is the drug of first choice in the treatment of migraine-related disorders. No controlled studies are available for the treatment of further headache types. First line methods for the non-drug treatment of headache in childhood are relaxation therapies, biofeedback, and specific training schedules.

Acetaminophen↗
PubMed2001

The effects of ocular artifacts on (lateralized) broadband power in the EEG.

OBJECTIVE: Empirical evidence suggests that blinks and eye movements do not generate substantial activity outside the delta and theta range, and that the propagation of ocular activity to the EEG is rather symmetrical. These observations suggest that an alteration of the alpha and beta asymmetry of the EEG due to ocular artifacts is not likely to occur. The aim of the present study is to examine the effects of ocular artifacts on broadband EEG parameters. METHODS: EEG and EOG were recorded from 31 participants in a resting condition with eyes open and closed, allowing for spontaneous ocular activity. General effects of ocular artifacts were examined with mean comparisons, and differential effects were examined with correlation analysis of data portions that were selected for a presence or absence of artifacts. RESULTS: At single sites, blinks and eye movements exerted substantial general effects on the whole EEG spectrum, but there were no substantial differential effects of artifacts in the alpha and beta bands, except at the frontopolar sites. The distorting effects of ocular artifacts were smaller in magnitude for asymmetry than for single site measures. CONCLUSIONS: The control of ocular artifacts may be dispensable for correlation analyses of alpha or beta band parameters.

Adult↗
PubMed2001

The quest for the EEG reference revisited: a glance from brain asymmetry research.

Recent findings suggested that the choice of the EEG reference might be a critical issue for the study of anterior asymmetry in the alpha band. The present paper investigates the validity of different reference schemes for the measurement of alpha asymmetry. A 32-channel resting EEG was recorded with a common vertex reference (Cz), and transformed into computer-averaged ears (A1 + A2), average reference (AR), and current source density derivations. A correlation analysis of an alpha asymmetry measure between all derivation schemes indicated a poor convergent validity for anterior sites but an excellent convergent validity for posterior sites. Further analyses suggested the presence of substantial alpha activity at the various reference sites (Cz, A1 + A2, AR), which might be similar in magnitude to anterior but smaller than posterior alpha. These findings suggest that the validity of a reference scheme is a function of the signal-to-noise ratio of the electrical activities at target and reference sites. The limitations of each reference scheme for the measurement of anterior alpha asymmetry are discussed.

Adult↗
PubMed1998

Effects of dehydroepiandrosterone replacement in elderly men on event-related potentials, memory, and well-being.

BACKGROUND: In humans, concentrations of the adrenal steroid hormone dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS) decline with age. Results from studies in rodents have suggested that DHEA administration can improve memory performance as well as neuronal plasticity. However, a first study from our laboratory could not demonstrate beneficial effects of DHEA substitution on cognitive performance and well-being in elderly subjects. To further evaluate whether DHEA replacement has effects on the central nervous system, an experiment using event-related potentials (ERPs) was conducted. METHODS: In this placebo-controlled crossover study, 17 elderly men (mean age, 71.1 +/- 1.7 yr; range 59-81 yr) took placebo or DHEA (50 mg/day) for 2 weeks (double blind). After each treatment period subjects participated in an auditory oddball paradigm with three oddball blocks. In the first two blocks subjects had to count the rare tone silently, whereas, in the third block they had to press a button. In addition, memory tests assessing visual, spatial, and semantic memory as well as questionnaires on psychological and physical well-being were presented. RESULTS: Baseline DHEAS levels were lower compared with young adults. After 2-week DHEA replacement, DHEAS levels rose 5-fold to levels observed in young men. DHEA substitution modulated the P3 component of the ERPs, which reflects information updating in short-term memory. P3 amplitude was increased after DHEA administration, and only selectively in the second oddball block. DHEA did not influence P3 latency. Moreover, DHEA did not enhance memory or mood. CONCLUSIONS: A 2-week DHEA replacement in elderly men results in changes in electrophysiological indices of central nervous system stimulus processing if the task is performed repeatedly. However, these effects do not appear to be strong enough to improve memory or mood.

Aged↗
PubMed1998

Frontal brain asymmetry and affective style: a conceptual replication.

Recent studies have demonstrated that positive and negative affective reactivity can be predicted by resting electroencephalographic (EEG) asymmetry in frontal brain regions. These studies used different methods to assess asymmetry and affectivity. The goal of the present study was a conceptual replication of these results and to investigate their independence of employed procedures. Resting EEG of 37 subjects was recorded and affective slides were presented to obtain ratings of subjects' emotional reactions. Different procedures were applied to the data to assess the relation between asymmetries and affective reactivity. Depending on the particular analysis procedure, there were associations between anterior asymmetry and affectivity in line with the published findings, opponent to those findings, or no relation between anterior asymmetry and affective reactivity.

Adult↗
PubMed1997

[Event related potentials and emotional pictures:effect of stimulus presentation time].

The perception of the emotional content of a stimulus is a preattentive automatic process which causes an emotional reaction. As the ongoing stream of behavior might be disturbed by the emotional reaction, a controlled process is initialited at the same time, which normally leads to an inhibition of the emotional response. By means of event related potentials it should be possible to observe these controlled processes. In a first study using photographs from the International Affective Picture System, Diedrich et al. (1997) reported enhanded P300 amplitudes for emotional stimuli, even when the task distracted from the emotional content of the stimuli. This was interpreted as an index of the additional, controlled information processing elicited by the emotional content of the stimuli. Additionally, Diedrich et al. observed a frontel slow positivity, which might indicate the inhibition of the emotional response. However, this frontal slow wave might also be explained by the stimulus presentation time, which lasted 500 ms. This study is a conceptual replication of the experiment of Diedrich et al. Stimulus presentation time of neutral and emotional slides was varied in three steps (250 ms, 500 ms and 2000 ms). Subjects either performed a structural or an emotion-focused task on the stimuli. The results for the P300 component were exactly replicated. However, the variation of slow frontal positivity differed from that in the first study. Differences in the intensity of the emotional stimuli are discussed as a reason für this result.

Adult↗
PubMed1992

The scalp topography of P300 in the visual and auditory modalities: a comparison of three normalization methods and the control of statistical type II error.

This study was designed to replicate recent findings suggesting that the P3 component of the event-related potential is dependent on the modality of the eliciting stimulus. When assessing this research hypothesis two methodological problems are of special interest: first, the amplitudes have to be normalized, due to problems with the model of the analysis of variance; second, special care has to be taken regarding the beta error, which is the probability of falsely accepting the null hypothesis of a statistical test. A possible modality independence is associated with the acceptance of a null hypothesis. The first problem was assessed by using different normalization procedures and comparing their results. The second was solved by controlling the beta error. Results for P3 amplitudes from two sessions in which 61 subjects performed in each session an auditory and a visual oddball task (EEG measured at 11 locations) showed no influence of modality on the P3 elicited by the rare, task relevant, stimulus. Influences of modality were observed for the P3 elicited by the frequent stimulus. As it is quite unlikely that P3 generating sources are strongly active during the processing of the frequent stimulus, this effect is possibly due to a component overlap from the vertex potential.

Adult↗
PubMed1989

[The effect of a submaximal physical load on the beta 2-adrenoreceptor-dependent adenylate cyclase system of the lymphocytes in hypertension].

Effects of dynamic exercise on lymphocyte beta 2-adrenoreceptor density (BARD) and adenylate cyclase activity (ACA) basal and stimulated by isoproterenol (I). Gpp(NH)p, Gpp(NH)p+I, and forskolin (F), on plasma adrenaline and noradrenaline levels, renin activity (PRA) were compared in 6 healthy donors and 12 patients with essential hypertension (EH). Acute stimulation of sympathetic activity by dynamic exercise leads to a rapid increase in lymphocyte BARD in normotensive and hypertensive subjects. The rise in BARD was accompanied by a significant increase in lymphocyte basal ACA in normotensive subjects, but not hypertensive patients. In patients with EH, basal ACA changed after exercise according to their renin status: patients with low baseline PRA showed a decrease in basal ACA after exercise, whereas patients with normal baseline PRA showed an increase as did normotensive subjects. Patients with decreased basal ACA after exercise also showed a lower ACA stimulation by IPR, F, Gpp (NH)p and Gpp(NH)p+IPR, which did not change after exercise. These patients also exhibited substantial rises in PRA with exercise. These was an inverse relationship between exercise-induced changes in PRA and basal ACA. So the acute regulation of lymphocyte BARD-ACA system is changed in a subset of patients with EH. The pattern of the regulation of this lymphocyte system is associated that of baseline renin activity and of its response to exercise in patients with EH.

Adenylyl Cyclases↗
PubMed1988

Nitrendipine treatment in so-called therapy-resistant arterial hypertension; effect as monotherapy and in combination with propranolol on blood pressure, heart rate, other hemodynamic parameters, plasma renin activity, and catecholamines.

Twenty-three patients [mean age 49.7 +/- 5.6 years (WHO II-III)] with severe hypertension and not responding to previous drug treatment were included in the study to evaluate the effect of nitrendipine (NTP) as monotherapy and also in combination with propranolol (PRO). After a control period of 10 days, NTP was started with 20 mg twice a day and titrated to the maximal dosage of 2 X 40 mg/day. After 1 week of NTP treatment, PRO was added in increasing dosage to a maximal 2 X 100 mg/day. NTP lowered systolic and diastolic blood pressure (BP) significantly (supine BP from 182/119 +/- 19/9 to 157/98 +/- 16/9 mm Hg). After combination with PRO, systolic BP was decreased additionally (supine BP from 157/98 +/- 16/9 to 150/97 +/- 19/9 mm Hg). Plasma norepinephrine (NE) was increased by NTP (from 1.82 +/- 0.78 to 2.38 +/- 1.08 nmol/l, p less than 0.01) and remained elevated during PRO treatment (2.76 +/- 1.10 nmol/l). Plasma renin activity (PRA) showed no significant changes by NTP. Additional effect of PRO on BP correlated significantly with NE and PRA after the NTP period. Plasma epinephrine and dopamine beta-hydroxylase remained unchanged. NTP decreased systemic resistance, calculated from isotope dilution technique (p less than 0.05); after combination with PRO no additional significant changes were registered. Nitrendipine is an effective alternative in so-called therapy-resistant hypertension.

Blood Pressure↗
PubMed1988

Alpha 2 adrenoceptors of blood platelets from hypertensive and normotensive rhesus monkeys.

Hypertension may cause activation of blood platelets in vivo. One of the possible mechanisms could be adrenergic activation of platelets by catecholamines. Therefore, we have studied specific binding of the alpha 2-adrenoceptor blocker, 3H-yohimbine, to platelets in order to elucidate the role of alpha 2-adrenoceptors of platelets in hypertensive animals. Particularly, competitive inhibition of 3H-yohimbine binding to platelets by hydergine, and plasma catecholamine levels were investigated in hypertensive (stress induced) and normotensive monkeys. It was demonstrated that 3H-yohimbine binds to platelets from rhesus monkeys with high affinity and specificity. The binding was found to be saturable and reversible. Additionally, it was shown that hydergine inhibits specific binding of 3H-yohimbine to platelets from hypertensive monkeys more potent that to those from normotensive animals. The obtained data suggest that the total number of the number of available, free alpha 2-adrenoceptors were reduced on the platelets from hypertensive monkeys. The latter was confirmed by the decreased adrenaline level in the plasma of hypertensive animals.

Animals↗
PubMed1987

Substance P in human essential hypertension.

Substance P (SP) plays an important role in central nervous and peripheral blood pressure regulation. Its effects include modulating influence on the adrenergic system and inhibition of stress-induced plasma noradrenaline increase in animal studies. In patients with essential hypertension (n = 45, WHO stages 1 and 2) the SP-like immunoreactivity (SPLIR) was found significantly (p less than 0.01) lower (1.36 +/- 0.23 pg/100 microliters) than in 24 normotensive subjects (4.54 +/- 0.72 pg/100 microliters). Furthermore, the influence of a mental stress test on SPLIR was investigated in patients with essential hypertension (n = 11, WHO stage 1) and compared with nine normotensive subjects. Whereas in normotensive subjects plasma SP increased under a standardized mental arithmetic test (4.03 +/- 0.48 to 4.74 +/- 0.56 pg/100 microliters), in hypertensive patients a decrease of SP from lower baseline levels (2.85 +/- 0.54 to 2.57 +/- 0.54 pg/100 microliters) was demonstrated. The significantly different changes of plasma SP in normotensive and hypertensive subjects under mental stress conditions had the opposite direction in comparison with the adrenergic reaction [higher and prolonged increase of plasma noradrenaline (NA) in the hypertensive group]. Under antihypertensive drug treatment with prazosin (4.5 mg/day, n = 10) or with captopril (450 mg/day, n = 10) an increase of plasma SP was registered. The results support the participation of SP in the pathogenesis of human hypertension and in therapeutic mechanisms. Lower plasma levels and decreased responsiveness of SP possibly represent the enhanced stress sensitivity in primary hypertension.

Adult↗
PubMed1987

[Stability of cignolin (dithranol) in ointments containing tar with and without the addition of salicylic acid. Oxidation to danthron and dithranol dimer].

The stability of dithranol in white petrolatum was investigated over a period of 10 weeks in dithranol ointments containing liquor carbonis detergens (LCD) and/or coal tar, in the presence and absence of salicylic acid. Qualitative and semiquantitative analysis using high-pressure liquid chromatography (HPLC) showed that dithranol (0.1%, 0.5%, 1.0%) remained rather stable in white petrolatum for 10 weeks, regardless of the presence or absence of salicylic acid. The addition of 5% LCD or 5% crude coal tar resulted, however, in the rather rapid oxidation of dithranol into its products, danthron and dithranol dimer. The addition of 2% salicylic acid to these combined ointments did not stabilize the dithranol: rather, it reduced the amount of danthron but resulted in a considerable increase in the amount of dithranol dimer. The oxidation of dithranol into its products danthron and dithranol-dimer was almost complete in 0.1% ointments and ranged between 16.3% and 53.8% in 0.5% white petrolatum after 10 weeks. These findings may explain why the addition of tar minimizes dithranol-induced erythema, as reported in clinical studies. Such combinations may have an important influence on the antipsoriatic activity of dithranol and the appearance of brownish discoloration.

Anthralin↗