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Biomedical subjects

N Neumann

Publications and source records attributed to N Neumann.

At least 19 recordsLinked to original sources
PubMed2005

Risk factors for venous thromboembolic events in cancer patients.

BACKGROUND: Cancer patients of the Department of Internal Medicine (Cancer Research) of the Essen University Medical School (Tumor Clinics), Germany, were examined and questioned with the aim of identifying those who run a high risk of deep vein thrombosis (DVT). PATIENTS AND METHODS: Between September 2002 and April 2003, cancer therapy and DVT risk factors of 507 cancer patients (53% males, 47% females, mean age 56+/-12 years) were documented. During a mean follow-up of 8+/-5 months, 60 patients (12%) suffered from new venous thromboembolic events (VTE): 28 at the lower limb, 25 at the upper limb and 13 pulmonary embolisms. RESULTS: The following factors were considered as predictive for an increased VTE risk: inpatient treatment (P<0.0001), prior DVT in medical history (P=0.0275), DVT in family (P=0.0598), chemotherapy (P=0.0080), fever (P=0.0093) and CRP (P<0.001). After combining factors in one variable (number of factors) the predicted VTE risk increased with the number of factors in both outpatients (OR 1.85, 95% CI 1.18-2.88, P=0.0071) and inpatients (OR 2.34, 95% CI 1.63-3.36, P<or=0.0001). In the absence of all these factors the predicted VTE risk was 2.3%, increasing to 72% if all were present. CONCLUSIONS: In cancer patients the risk of VTE steadily increases with the number of risk factors, and identification of patients at high risk is possible.

Anticoagulants↗
PubMed2004

Automatic processing of self-regulation of slow cortical potentials: evidence from brain-computer communication in paralysed patients.

OBJECTIVE: Direct brain-computer communication utilizes self-regulation of brain potentials to select letters, words or symbols from a computer menu. Selection of letters or words with brain potentials requires simultaneous processing of several tasks such as production of certain brain potentials at predefined time points simultaneously with processing of presented letter strings. This study addresses the question of whether the self-regulation of slow cortical potentials (SCP) automatizes with practice and can thus be considered as a skill comparable to motor or cognitive skills. METHODS: Two nearly completely paralysed patients learned over several months to produce electrocortically negative and positive SCP by means of visual feedback. Improved performance and a reduction in performance variability were regarded as behavioural indicators for automaticity, while the topographic focalization of cortical activation was considered as a neurophysiological indicator for automaticity. Different indicators of automaticity were expected to covary along with practice. RESULTS: In patient 1, performance measured as the percentage of correct SCP shifts increased simultaneously with the topographic focalization of cortical activation. His performance became more stable with practice. For this patient the criteria for automaticity were all met. In patient 2, performance also improved, but his cortical activity became topographically less focal. His performance was less stable than that of patient 1. CONCLUSIONS: The present findings, albeit on only two subjects, provide preliminary evidence that SCP self-regulation may automatize with long-term practice and can therefore be considered a skill.

Adaptation, Psychological↗
PubMed2003

Predictors of successful self control during brain-computer communication.

OBJECTIVES: Direct brain-computer communication uses self regulation of brain potentials to select letters, words, or symbols from a computer menu to re-establish communication in severely paralysed patients. However, not all healthy subjects, or all paralysed patients acquire the skill to self regulate their brain potentials, and predictors of successful learning have not been found yet. Predictors are particularly important, because only successful self regulation will in the end lead to efficient brain-computer communication. This study investigates the question whether initial performance in the self regulation of slow cortical potentials of the brain (SCPs) may be positively correlated to later performance and could thus be used as a predictor. METHODS: Five severely paralysed patients diagnosed with amyotrophic lateral sclerosis were trained to produce SCP amplitudes of negative and positive polarity by means of visual feedback and operant conditioning strategies. Performance was measured as percentage of correct SCP amplitude shifts. To determine the relation between initial and later performance in SCP self regulation, Spearman's rank correlations were calculated between maximum and mean performance at the beginning of training (runs 1-30) and mean performance at two later time points (runs 64-93 and 162-191). RESULTS: Spearman's rank correlations revealed a significant relation between maximum and mean performance in runs 1-30 and mean performance in runs 64-93 (r= 0.9 and 1.0) and maximum and mean performance in runs 1-30 and mean performance in runs 162-191 (r=1.0 and 1.0). CONCLUSIONS: Initial performance in the self regulation of SCP is positively correlated with later performance in severely paralysed patients, and thus represents a useful predictor for efficient brain-computer communication.

Adult↗
PubMed2002

A non-invasive communication device for the paralyzed.

An EEG-based communication system has been developed to re-establish communication in severely paralyzed patients who operate the device by generating shifts of their slow cortical potentials. Training to gain control over slow cortical potentials was based on visual feedback and operant conditioning strategies. The vertical movement of a graphic signal on a computer screen informs the patients about the course of their slow cortical potential amplitude. Positive slow cortical potential shifts move the cursor up, negative shifts move it down. These shifts are then translated into binary responses. When a patient has achieved reliable control over his/her slow cortical potential shifts, these responses can be used to select or reject items presented at the bottom of the screen. As learning processes and applications differ considerably between patients, the present paper describes the data from one patient with amyotrophic lateral sclerosis. After about three months of training, this patient gained stable, near-perfect control over his slow cortical potentials. This skill enabled him to operate a specially designed program to communicate messages to his caregivers.

Adult↗
PubMed2001

Self-initiation of EEG-based communication in paralyzed patients.

OBJECTIVES: Severely paralyzed patients could learn to voluntarily generate slow cortical potential (SCP) shifts in their electroencephalogram and to use these signals to operate a communication device. To enhance the patients' autonomy, the present study describes the development of a permanently available communication system that can be turned on and off by locked-in patients without external assistance. A skill necessary for turning the system on is the ability to regulate one's slow potentials in the absence of continuous feedback. METHODS: A stepwise learning approach was employed to train two paralyzed patients to regulate their SCPs without continuous feedback. Elements of the original communication system were gradually removed and elements of the new stand-by mode were introduced. RESULTS: At the end of the learning procedure, both patients achieved correct response rates of above 84% in training sessions without continuous feedback. This skill enabled them to turn the communication device on and off without assistance from others. CONCLUSIONS: These findings suggest that severely paralyzed individuals can learn to operate an EEG-based communication device autonomously.

Adult↗
PubMed2001

Brain-computer communication: self-regulation of slow cortical potentials for verbal communication.

OBJECTIVE: To test a training procedure designed to enable severely paralyzed patients to communicate by means of self-regulation of slow cortical potentials. DESIGN: Application of the Thought Translation Device to evaluate the procedure in patients with late-stage amyotrophic lateral sclerosis (ALS). SETTING: Training sessions in the patients' homes. PARTICIPANTS: Two male patients with late-stage ALS. INTERVENTIONS: Patients learned voluntary control of their slow cortical potentials by means of an interface between the brain and a computer. Training was based on visual feedback of slow cortical potentials shifts and operant learning principles. The learning process was divided into small steps of increasing difficulty. MAIN OUTCOME MEASURES: Accuracy of self-control of slow cortical potentials (percentage of correct responses). Learning progress calculated as a function of training session. RESULTS: Within 3 to 8 weeks, both patients learned to self-regulate their slow cortical potentials and to use this skill to select letters or words in the Language Support Program. CONCLUSIONS: This training schedule is the first to enable severely paralyzed patients to communicate without any voluntary muscle control by using self-regulation of an electroencephalogram potential only. The protocol could be a model for training patients in other brain-computer interface techniques.

Adult↗
PubMed2000

The thought translation device (TTD) for completely paralyzed patients.

The thought translation device trains locked-in patients to self-regulate slow cortical potentials (SCP's) of their electroencephalogram (EEG). After operant learning of SCP self-control, patients select letters, words or pictograms in a computerized language support program. Results of five respirated, locked-in-patients are described, demonstrating the usefulness of the thought translation device as an alternative communication channel in motivated totally paralyzed patients with amyotrophic lateral sclerosis.

Biofeedback, Psychology↗
PubMed1998

Kinetics of photosensitivity in bath-PUVA photochemotherapy.

BACKGROUND: Bath-PUVA is used to treat a variety of dermatoses. However, the kinetics of 8-methoxypsoralen during treatment are not completely clarified. OBJECTIVE: The purpose of this study was to investigate the intensity of the phototoxic response and the persistence of phototoxicity after bath-PUVA. METHODS: Twelve volunteers were exposed to UVA doses ranging from 0.5 to 40 J/cm2 from 10 to 240 minutes after bath-PUVA treatment. The resulting phototoxic response of the skin was determined. RESULTS: Irradiation 10 minutes after the psoralen bath led to the lowest assessed minimal phototoxic dose (MPD) of 1.42 J/cm2 (mean, SD +/- 0.29). Thereafter, the MPD increased significantly and sharply every hour. At 4 hours after the psoralen bath, UVA doses up to 40 J/cm2 failed to induce any phototoxic erythema (MPD). CONCLUSION: For optimal effects, UVA irradiation has to be administered immediately after the psoralen bath; no restrictive behavior is necessary after bath-PUVA treatment.

Adult↗
PubMed1997

Prefrontal asymmetric interictal glucose hypometabolism and cognitive impairment in patients with temporal lobe epilepsy.

Depressions of regional cerebral metabolism beyond the epileptogenic zone have been demonstrated in patients with intractable temporal lobe epilepsy. However, their clinical relevance, and the causes of prefrontal metabolic asymmetries are less well understood. We investigated 96 temporal lobe epilepsy patients by FDG-PET and neuropsychological assessment who had a corresponding unilateral temporal hypometabolism, left hemisphere speech dominance, full scale IQ of > 70 and no extratemporal lesion in MRIs. The regional glucose metabolism was determined in each patient in homologous regions including prefrontal cortex, and normalized to whole brain metabolism. Regional differences of > 10% were regarded as asymmetrical. Prefrontal metabolic asymmetries were more frequent in patients with left temporal lobe epilepsy (21 left, six right) and a history of secondarily generalized seizures. A multivariate analysis of variance revealed a main effect for prefrontal metabolic asymmetry on neuropsychological 'frontal lobe measures', including verbal and performance intelligence measures. Prefrontal metabolic asymmetry was not related to 'measures of episodic memory', presence of psychiatric symptoms or frontal interictal epileptiform discharges. We conclude that prefrontal metabolic asymmetry is associated with cognitive impairment. Patients with temporal lobe epilepsy of the left speech dominant hemisphere and a history of secondarily generalized seizures are at considerable risk of developing prefrontal metabolic asymmetry.

Adult↗
PubMed1994

Safety and efficacy during long-term treatment with moclobemide.

Safety aspects [adverse events, blood pressure and heart rate, weight, and laboratory tests (liver parameters, hemoglobin, leukocytes)] of long-term treatment in 1,120 patients are discussed. Adverse events during this long-term treatment were also compared with those of a subgroup of these patients who, before long-term treatment, were treated on a short-term basis (n = 706). Efficacy [Hamilton Depression Rating Scale (HAM-D), Clinical Global Impression of Efficacy (CGI), and occurrence of relapses and recurrences] in a homogeneous sample of 485 patients is also discussed. The adverse events most frequently observed during long-term treatment were insomnia, headache, and dizziness. Insomnia and headache were also most often occurring in the compared sample of patients with short-term treatment, whereas dizziness during this treatment period ranked at the fifth position. Supine and standing mean blood pressure did not consistently change during long-term treatment, the most prominent increases in comparison with baseline were seen in the period > 1 year of treatment (6.3 mm Hg supine/7.2 mm Hg standing). Comparison of blood pressure values in the hypertensive range at baseline and during long-term treatment revealed no statistical difference (McNemar test p = 0.07829). Mean heart rate slightly decreased during long-term treatment (by a maximum of 6.3 beats/min supine, 8.2 beats/min standing). Mean weight did not change between baseline and treatment end point. There were 23 patients with a weight loss of 10 kg or more and 16 patients with a weight gain of 10 kg or more. For none of the laboratory parameters tested was there a statistical significance regarding shifts from normal to pathological values. HAM-D mean total scores in the above-mentioned subgroup of patients decreased from 25.05 points at baseline (n = 485) to 7.88 points after 1 year of treatment (n = 139). Seventy-five patients who had favorably responded to treatment (total responders n = 300) relapsed during the first 6 months of treatment. During the second half-year of treatment the recurrence rate was 14.8%, and during the third 6 months the recurrence rate was 12.2%. CGI in the same subsample of patients in whom HAMD was evaluated (n = 485) compared with those patients who did not drop out during the short-term period up to 44 days and entered long-term treatment (n = 401) showed that the percentage of the ratings "no change/worse" was higher in the sample that also included patients who withdrew from treatment during the short-term period.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Active control equivalence trials: some methodological aspects.

The therapeutic efficacy of an investigational new drug is best demonstrated in clinical trials against a placebo control. However, ethical requirements increasingly preclude the use of an inactive control substance as a treatment alternative, as clinical testing to compare the effects of active treatments, has become more frequent. The statistical evaluation and interpretation of these trials is complex and requires the demonstration of 'equivalence' or 'at-least equivalence' between the experimental drug and a comparable standard therapy. The design of controlled clinical trials to compare the effects of moclobemide, a new and selective monoamine oxidase-A inhibitor, with those of standard tricyclic antidepressant drugs involved the refinement of selection strategies, formulation of hypotheses, means of statistical analysis and clinical interpretation.

Antidepressive Agents↗
PubMed1992

Differential effects of two dihydropyridine calcium antagonists in humans.

We studied the effects after single doses of niguldipine (0.3, 0.6, and 0.9 mg intravenously; 8 and 16 mg orally) and nifedipine (2 mg intravenously; 20 mg orally) in healthy male volunteers in randomized placebo-controlled experiments. Total peripheral resistance (TPR), heart rate-corrected electromechanical systole (QS2c), and preejection period (PEPc) were assessed noninvasively. Both drugs induced a similar pronounced decreased in TRP, indicating peripheral vasodilation, followed by increasing heart rate and cardiac output, a decrease in diastolic blood pressure, and a shortening of the PEPc. QS2c was unchanged after niguldipine. The prolongation of QS2c after oral nifedipine is suggestive of a negative inotropic effect. We conclude that the vasodilatory effects of dihydropyridines may (as for nifedipine) or may not (as for niguldipine) be associated with changes that are suggestive of negative inotropic effects, and that this difference is detectable by noninvasive methods in healthy subjects.

Administration, Oral↗
PubMed1992

[The effect of UV-A and UV-B irradiation on the skin barrier. Skin physiologic, electron microscopy and lipid biochemistry studies].

In order to gain insight into the effects of UV-irradiation on the skin barrier, functional (skin reactivity), electron microscopic and lipid-biochemical studies were performed. In three different irritation models, both UV-A-irradiated and UV-B-irradiated areas proved to be more resistant to damage than normal skin, providing evidence for improvement of barrier function after UV irradiation. Electron microscopic evaluation showed that UV-B induced a significant increase in horny cell layers, whereas after UV-A no change was detected. However, both UV-B and UV-A exposure resulted in an increase in the amount of all stratum corneum lipids. This was also observed in all major ceramide subfractions, which are believed to be the essential lipid constituents for the epidermal barrier function. These findings may explain the known beneficial effects of phototherapy in dermatoses with impaired barrier function, i.e., atopic dermatitis.

Dose-Response Relationship, Radiation↗
PubMed1991

Photopatch testing: the 5-year experience of the German, Austrian, and Swiss Photopatch Test Group.

A cooperative photopatch test study was conducted by 45 dermatologic centers in Austria, Germany, and Switzerland. Results obtained from 1985 to 1990 are presented. A standard photopatch test tray of 32 substances was applied to the back of patients with suspected photosensivity. After applications for 24 hours, test sites were irradiated with 10 joules/cm2UVA. Unirradiated controls were included. Readings were performed immediately and 24, 48, and 72 hours after irradiation; responses were qualitatively graded on a 4-point scale. All data were stored and processed by a computer. With computer-assisted analysis of reaction patterns photoallergic reactions were identified and distinguished from phototoxic reactions. Data of 1129 patients were evaluated. Among a total of 2859 positive test reactions in 870 patients, 2041 in 778 patients were found to be photoinduced and 818 in 413 patients were contact reactions; 108 reactions in 83 patients were classified as photoallergic. Nonsteroidal anti-inflammatory drugs, disinfectants, sunscreens, phenothiazines, and fragrances caused most often photoallergic reactions. Many unspecific phototoxic reactions were induced by tiaprofenic acid, promethazine, carprofen, chlorpromazine, fenticolar, wood balsam of Peru, and perfumes. Despite the distinction between photoallergic and phototoxic responses, many test reactions lacked relevance for the patients' dermatoses.

Adolescent↗
PubMed1991

[Chronic actinic dermatitis. Concept and case examples].

Two women patients with chronic eczematous dermatitis, who also developed extremely severe, persistent photosensitivity during a course of 10 and over 40 years, are presented. Both patients had an atopic history with positive immediate skin reactions. Patch and photopatch tests revealed sensitization to several contact allergens, and in one case also a photocontact allergy. The action spectrum of the photosensitivity was confined to UV-B; it was possible to provoke eczematous skin reactions with doses smaller than 1 mJ/cm2 UV-B. Both patients were successfully treated with PUVA therapy. These case reports demonstrate the difficulty of nosological classification of chronic eczematous photosensitive dermatoses under the traditional terms persistent light reaction, photosensitive eczema, photosensitivity dermatitis, and actinic reticuloid. Chronic actinic dermatitis is defined clinically by chronic dermatitis on skin exposed to sun, histologically by spongiotic dermatitis, and photobiologically by experimental provocation of spongiotic dermatitis with UV-B and often also longer wavelengths in the absence of a photoallergen. Chronic actinic dermatitis should be used as a general term in addition to the more specific terms listed above.

Biopsy↗
PubMed1990

Early versus late surfactant replacement therapy in severe respiratory distress syndrome.

26 preterm infants with severe respiratory distress syndrome (RDS) have been treated at different ages with a single dose of natural porcine surfactant (Curosurf, 200 mg/kg). Criteria for treatment included clinical and radiological signs of severe RDS (grade III-IV), requirement of artificial ventilation and an FiO2 greater than or equal to 0.6. Nineteen neonates have been subjected to early treatment (2-15 h of age, mean birth weight SD: 1201 +/- 387 g) and 7 patients to late treatment (greater than 15 h to 48 h of age, birth weight SD 1624 +/- 649 g). Average FiO2 before treatment was 0.88 in early-treated patients and 0.8 in late-treated patients, age at treatment was 4.6 h and 36 h, respectively (median). Both early- and late-treated infants exhibited an improvement in oxygenation (more than twofold increase of the PaO2/FiO2 ratio) within 5 minutes after initiation of therapy. Average duration of intermittent pressure ventilation was 15 days in the early treatment group and 19 days in the late treatment group. Total exposition to greater than 21% oxygen was 21 days in early-treated and 48 days in late-treated infants. Pneumothorax occurred in none of the patients. All early treated infants survived without signs of severe bronchopulmonary dysplasia (BPD greater than 21% O2, greater than 90 days plus radiological changes). However, two out of seven late-treated infants developed severe BPD; one patient died as a consequence of cardiopulmonary deterioration. Two patients in the early treatment group died of nonpulmonary complications. We conclude that surfactant replacement therapy should probably be initiated as soon as possible after manifestation of severe RDS.

Birth Weight↗