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R R Engel

Publications and source records attributed to R R Engel.

At least 37 records · Page 2Linked to original sources
PubMed1999

The T102C polymorphism of the 5-HT2A-receptor gene in fibromyalgia.

Based on a possible involvement of serotonergic dysfunction in the pathophysiology of fibromyalgia (FM) and on preliminary reports of a possible genetically driven vulnerability for this disorder we investigated the silent T102C polymorphism of the 5-HT2A-receptor gene in 168 FM patients and 115 healthy controls. Our results showed a significantly different genotype distribution in FM patients with a decrease in T/T and an increase in both T/C and C/C genotypes as compared to the control population (Fisher's Exact test, two-sided, P = 0.008). However, the increase in allele-C102 frequency felt short of significance (P = 0.07). Correlation of genotypes to clinical parameters revealed no influences on age of onset, duration of disease or psychopathological symptoms, measured with the Beck Depression Inventory and the symptom checklist SCL-90-R. In contrast to that the pain score, being a self reported information on pain severity, was significantly higher in patients of the T/T genotype (Mann-Whitney U test, P = 0.028). This suggests that the T102-allele might be involved in the complex circuits of nociception. However, the T102C polymorphism is not directly involved in the aetiology of FM but might be in linkage dysequilibrium with the true functional variant, which has to be unravelled.

Adult↗
PubMed1999

Assessment of adverse drug reactions in psychiatric inpatients with the AMSP drug safety program: methods and first results for tricyclic antidepressants and SSRI.

The AMSP (Arzneimittelsicherheit in der Psychiatrie) study is a new program for continuous assessment of adverse drug reactions (ADR) in psychiatric inpatients under naturalistic conditions of routine clinical treatment. It is based on the preceding drug surveillance study AMUP (Arzneimittelüberwachung in der Psychiatrie). Currently, 29 hospitals are participating in the study. This paper reports on the methods of the AMSP study and the first findings on the comparative risks of tricyclic antidepressants (TCA) and selective serotonin reuptake inhibitors (SSRI) . Data assessment is restricted to "severe" ADR as defined in the study protocol. Drug use is estimated from reference day data. From 1993 to 1997, 896 cases of severe ADR were observed in 48,564 patients (1.84%). SSRI and the new substances mirtazapine and venlafaxine were increasingly used as antidepressants (AD), but TCA were still the most common AD in 1997 (52.1% of all AD patients). Similar rates of ADR were observed for SSRI and TCA (1.7% and 1.5%, respectively, for all cases, 0.9% and 1.0%, respectively, only for cases rated as probable). However, different types of ADR occurred with the two AD subgroups; whereas toxic delirium and increased liver enzymes were the most frequent ADR related toTCA, nondelirious psychic and neurologic ADR predominated with SSRI. The duration of inpatient treatment was considerably longer in patients who experienced an ADR due to TCA or SSRI than in those who did not. The AMSP study promises to contribute greatly to drug safety by providing the relative frequencies of severe ADR from a large-scale database and by improving our knowledge of ADR.

Adult↗
PubMed1998

Phytohemagglutinin-stimulated calcium signal in lymphocytes of alcoholics before, during and after detoxification.

Acute and chronic exposure to ethanol influences intracellular calcium homeostasis via NMDA receptors, direct regulation of calcium channels or the phosphoinositide pathway. To explore the influence of alcohol withdrawal on calcium metabolism, we have investigated the resting and phytohemagglutinin (PHA) stimulated [Ca2+]i in lymphocytes of 10 alcoholics before, during and after withdrawal. Our findings suggest that both compartments of the PHA-stimulated signal are affected in alcoholics, with flattening of the initial peak and sustained calcium influx, as long as severe vegetative signs are present. MANOVA results showed significant interaction effects for both measurement points, for the initial peak, 40 s after stimulation (P = 0.05), and especially for the sustained influx at the end of the observation period (P = 0.001). The detailed mechanisms of this disturbed calcium homeostasis need further investigation.

Adult↗
PubMed1997

Lithium vs carbamazepine in the maintenance treatment of schizoaffective disorder: a randomised study.

In a randomised multicentre study, the prophylactic efficacy of lithium and carbamazepine was compared in schizoaffective disorder. A total of 90 ICD-9 schizoaffective patients were included in the maintenance phase (2.5 years). They were also diagnosed according to RDC and DSM-III-R and classified into subgroups. Mean serum levels were 0.58 +/- 0.12 mmol/l for lithium and 6.4 +/- 1.5 micrograms/ml for carbamazepine (mean dose 643 +/- 179 mg/d). Outcome criteria were hospitalisation, recurrence, concomitant psychotropic medication and adverse effects leading to discontinuation. There were more non-completers under carbamazepine than under lithium (p = 0.02). Survival analyses demonstrated no significant differences between lithium and carbamazepine in treatment outcome. Patient's ratings of side effects (p = 0.003) and treatment satisfaction (p = 0.02) favoured carbamazepine. Following the RDC criteria, patients of the schizodepressive and non-classifiable type did better under carbamazepine (p = 0.055 for recurrence), whereas in the schizomanic patients equipotency of both drugs was found. Applying DSM-III-R, carbamazepine demonstrated a superiority in the patient group with more schizophrenia-like or depressive disorders (p = 0.040 for recurrence), but not in patients fulfilling the DSM-III-R criteria of bipolar disorder. Lithium and carbamazepine seem to be equipotent alternatives in the maintenance treatment of broadly defined schizoaffective disorders. However, in subgroups with depressive or schizophrenia-like features and regarding its long-term tolerability carbamazepine seems to be superior.

Adult↗
PubMed1997

Lithium versus carbamazepine in the maintenance treatment of bipolar disorders--a randomised study.

In a randomised multicentre study, the prophylactic efficacy of lithium and carbamazepine was compared in 144 patients with bipolar disorder (74 vs. 70 patients; observation period: 2.5 years; lithium serum level: 0.63 +/- 0.12 mmol/l, carbamazepine dose: 621 +/- 186 mg/day). Hospitalisations, recurrences, need of psychotropic comedication and adverse effects prompting discontinuation were defined as treatment failures. Survival analyses regarding hospitalisations and recurrences showed no statistically significant differences between both drugs. Results were distinctly in favour of lithium, considering recurrences combined with comedication (P = 0.041) and/or adverse effects (P = 0.007). Whereas adverse effects prompting discontinuation were more frequent under carbamazepine (9 vs. 4, ns), lithium patients reported more often slight/moderate side effects (61% vs. 21% after 2.5 years; P = 0.0006). In completers, recurrences occurred in 28% (lithium) vs. 47% (carbamazepine) of the patients (P = 0.06). Lithium seems to be superior to carbamazepine in maintenance treatment of bipolar disorder, in particular when applying broader outcome criteria including psychotropic comedication and severe side effects.

Adult↗
PubMed1997

Identification of input variables for feature based artificial neural networks-saccade detection in EOG recordings.

Though artificial neural networks (ANN) are excellent tools for pattern recognition problems when signal to noise ratio is low, the identification of decision relevant features for ANN input data is still a crucial issue. The experience of the ANN designer and the existing knowledge and understanding of the problem seem to be the only links for a specific construction. In the present study a backpropagation ANN based on modified raw data inputs showed encouraging results. Investigating the specific influences of prototypical input patterns on a specially designed ANN led to a new sparse and efficient input data presentation. This data coding obtained by a semiautomatic procedure combining existing expert knowledge and the internal representation structures of the raw data based ANN yielded a list of feature vectors, each representing the relevant information for saccade identification. The feature based ANN produced a reduction of the error rate of nearly 40% compared with the raw data ANN. An overall correct classification of 92% of so far unknown data was realized. The proposed method of extracting internal ANN knowledge for the production of a better input data representation is not restricted to EOG recordings, and could be used in various fields of signal analysis.

Algorithms↗
PubMed1996

Comparative efficacy of lithium and amitriptyline in the maintenance treatment of recurrent unipolar depression: a randomised study.

The present study, including 81 depressive patients, compares the prophylactic efficacy of lithium and amitriptyline in recurrent unipolar depression over a treatment period of 2.5 years in a randomised multicentre design. Hospitalisation, re-emergence of depressive or subdepressive recurrences, unwanted side-effects and need of concomitant psychotropic medication were considered to indicate treatment failures. Average dosage for amitriptyline was 98 +/- 37 mg/day, average lithium blood level was 0.59 +/- 0.12 mmol/l. Survival analyses demonstrated a significant superiority of lithium (P = 0.015) regarding the outcome criteria 'recurrences and/or subclinical recurrences' and non-significantly better results of lithium compared to amitriptyline concerning 'recurrence' (P = 0.059) or 'recurrence and/or concomitant medication' (P = 0.066).

Adolescent↗
PubMed1996

ERP changes in alcoholics with and without alcohol psychosis.

The present study compared alterations of event-related brain potentials (ERPs) in subgroups of chronic alcoholics with different complications during alcohol withdrawal. Twenty alcoholics with only mild to moderate alcohol withdrawal symptoms, two groups of alcoholics with histories of either delirium tremens (n = 9) or alcohol hallucinosis (n = 13), and a control group of 38 nonalcoholics were examined. Patients were tested in unmedicated state and not earlier than 14 days after drinking cessation. An auditory Oddball paradigm and a visual Letter Matching paradigm were used as cognitive tasks. In the auditory task, all alcoholic groups exhibited delayed N200 and P300 latencies and a reduced P300 amplitude as compared to nonalcoholics. In the visual task, only P300 amplitude was significantly diminished. Patients having suffered from delirium tremens or alcohol hallucinosis showed greater Oddball P300 amplitudes than alcoholics with uncomplicated withdrawal syndrome. Furthermore, delirium and hallucinosis patients differed in their ERPs, with hallucinosis patients showing an earlier P300 peak in both the auditory Oddball and the Letter Matching task. It is concluded that changes in ERPs during abstinence might reflect specific neurophysiological dysfunctions in alcoholics prone to different alcohol-related psychoses.

Adult↗
PubMed1996

CNV, PINV and probe-evoked potentials in schizophrenics.

Distractibility and temporal modulation of attention in schizophrenics were studied using a visual reaction time task with additional auditory probe stimuli during the forewarning period or between trials. The probes were thought to exert a distracting influence, especially on schizophrenics, and at the same time they generated auditory EPs which allowed to track the modulation of cortical excitability during response preparation. The midline distribution of the terminal contingent negative variation (tCNV) and the amplitude of the postimperative negative variation (PINV) were clearly different in 20 DSM III-R schizophrenics, as compared with 20 alcoholics and 20 normal controls. In schizophrenics, the more frontal distribution of the tCNV was associated with a higher degree of psychopathology (measured with the Brief Psychiatric Rating Scale) and with delayed reactions. Probes between trials reduced tCNV and PINV in all subjects alike. However, this effect could not be attributed to distraction, because reaction times were faster in these trials, possibly due to an alerting effect of the auditory probes. The N100 and P300 amplitudes to probes in the forewarning period, i.e., during the negative potential shift of the CNV, were significantly enhanced in all groups. Apparently there is a state of increased cortical excitability during the CNV which is not selectively "tuned" toward relevant stimuli. In schizophrenia, the temporal and topographical regulation of this excitability is disturbed.

Adult↗
PubMed1995

Information processing during eye tracking as revealed by event-related potentials in schizophrenics, alcoholics, and healthy controls.

To further explore the hypothesis that schizophrenics are more distractable and/or have reduced processing resources available, event-related potentials (ERPs) and smooth pursuit eye movements (SPEM) were investigated in 20 medicated schizophrenics, 19 detoxified chronic alcoholics, and in a control group of 20 healthy subjects. Groups were matched for age and education. Eye tracking tasks and auditory oddball tasks were performed separately as well as simultaneously. In addition, an eye tracking condition with a task-irrelevant tone sequence was used to assess the effect of distraction. Schizophrenics showed a trend for poorer SPEM performance; alcoholics had no dysfunction in this task. Tracking accuracy did not change in either group when additional auditory stimuli were presented. P300 latency was delayed in both schizophrenics and alcoholics. P300 amplitude showed no overall group difference but it increased during the dual task in normals whereas it remained constant in patients. N100 amplitude was generally larger during the more complex conditions indicating heightened unspecific arousal. It is suggested that normals use increased arousal to mobilize additional resources and to allocate them to stimulus evaluation but schizophrenics and alcoholics are unable to do so. Results are more conform to a limited resources concept than to a filter deficit model of cognitive disturbances in schizophrenia and alcoholism.

Adolescent↗
PubMed1995

Carbon monoxide generation from hydrocarbons at ambient and physiological temperature: a sensitive indicator of oxidant damage?

This paper shows that a variety of carbon-containing materials (wool, cotton, wood, paper, latex, Tygon) release CO during incubation at ambient temperature. This CO production was enhanced by aerobic versus anaerobic incubation, increasing temperature, and exposure to fluorescent light. CO production from glucose solutions was enhanced by alkaline pH or prior boiling or autoclaving and reduced by the presence of superoxide dismutase or catalase. We conclude that a variety of materials are constantly undergoing oxidation at ambient or physiological temperature as evidenced by the release of CO. Measurements of this CO production could provide a simple, rapid and sensitive means of assessing oxidative damage.

Carbon Monoxide↗
PubMed1995

Timing of operation for ruptured cerebral aneurysm and long-term recovery of cognitive functions.

Advantage and disadvantages of early and late operation for ruptured cerebral aneurysm are controversially evaluated with regard to peri-operative operation outcome and long-term cognitive recovery. In this retrospective analysis 22 patients with early surgery (ES) within three days after subarachnoid haemorrhage (SAH) and 22 patients with late surgery (LS) at least 14 days after SAH were studied. Patients were pair-wise matched by degree of SAH localisation of aneurysm and age at SAH. On average three years after SAH both groups were examined individually with a comprehensive neuropsychological test battery including tests of premorbid intelligence, concept formation, memory, visuomotor speed, aphasia screening, and mood. ES and LS patients were well comparable in terms of years of education and level of premorbid intelligence. There was a clear influence of patients age on fluid intelligence tests, indicating a general change-sensitivity of tests. No influence of degree of SAH and localisation of aneurysm could be detected. There were also no differences between ES and LS patients in neuropsychological tests sensitive to brain damage, suggesting that the decision for early or late surgery for ruptured cerebral aneurysm can be based upon surgical reasons at the time of the SAH.

Adult↗
PubMed1994

Differentiation of dementia and depression by memory tests. A meta-analysis.

The many tasks used for clinical memory assessment have not been compared systematically for their usefulness in differentiating dementia and depression in old age. The aim of this meta-analysis was to identify those attributes of memory tasks that show high discriminative power. Eighty-nine effect-sizes were calculated out of 16 publications directly comparing demented and depressed patients. Outliers in the effect-size distribution (5% of the highest values) were excluded. The groups could be significantly better differentiated by delayed retrieval tasks rather than immediate retrieval tasks. Tasks with distraction before retrieval reached higher effect sizes than retrieval tasks without distraction. Tasks of high-capacity demand differentiated the groups significantly better than tasks of moderate and low demand. Effect-size magnitude was not influenced by patient characteristics except severity of dementia. Thus, demented and depressed patients may best be differentiated by a memory task that uses delayed retrieval with distraction.

Aged↗