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Biomedical subjects

A Thiel

Publications and source records attributed to A Thiel.

At least 19 recordsLinked to original sources
PubMed1998

Brain plasticity in poststroke aphasia: what is the contribution of the right hemisphere?

The brain may use two strategies to recover from poststroke aphasia: the structural repair of primarily speech-relevant regions or the activation of compensatory areas. We studied the cortical metabolic recovery in aphasic stroke patients with positron emission tomography (PET) at rest and during word repetition. The left supplementary motor area (SMA) showed the most prominent compensatory activation in the subacute state of stroke. The restitution of the left superior temporal cortex determined the long-term prognosis of aphasia. The brain recruited right-hemispheric regions for speech processing, when the left-hemispheric centers were permanently impaired. This strategy, however, was significantly less effective than the repair of the original speech-relevant network.

Adult↗
PubMed1998

Localization of language-related cortex with 15O-labeled water PET in patients with gliomas.

Measurement of relative cerebral blood flow (CBF) with 15O-labeled water PET has been widely used for brain mapping experiments on language functions in normal volunteers and patients with epilepsy. We focused on the question of whether PET during speech activation is an appropriate method for noninvasive determination of language-related cortex in patients with brain tumors. Furthermore, the suitability of the method for determination of hemispheric language dominance was examined and compared to the results of the Edinburgh Handedness Inventory. Ten right-handed and six left-handed patients with gliomas were examined prior to surgery while repeatedly performing word repetition and verb generation tasks. A set of volumes of interest (VOIs) was drawn on coregistered MRI in order to account for anatomic variability as well as anatomical alterations due to tumor mass effect. Repetition of nouns did not produce significant hemispheric differences. During stimulation by verb generation, reliable lateralized activations of Broca's area and supplementary motor area were detected in all right-handed patients. Of the left-handed patients, two showed clear right lateralization, two activated Broca's area bilaterally, and two had a pattern similar to that of right-handers. Patients with bilateral activations showed the strongest tendency toward bihandedness according to the handedness inventory. Lateralization of supplementary motor area in left-handers corresponded to lateralized activity in Broca's area. Tumors in the vicinity of language-related regions did not alter activation responses. In conclusion, measurement of CBF changes during verb generation permits identification of language-related areas in patients with gliomas with strong lateralization related to hemispheric dominance. These findings may be of particular clinical interest for left-handed patients.

Adult↗
PubMed1998

["I have killed my child". Experiences with severe depression in mothers after sudden infant death from the psychiatric and legal medicine viewpoint].

Grief and depressive syndrome belong to normal reaction by parents after a sudden infant death (SID). In the following we report on two cases from the point of view of psychiatry and forensic medicine in which, subsequent to SID, mothers reacted with extremely grave depression and accused themselves of having killed the child. Furthermore, some recommendations are given for the care of parents affected.

Delusions↗
PubMed1998

[Development of the AMDP module for identification of obsessive- compulsive symptoms. Conceptualization and empirical results].

Results of epidemiology and comorbidity studies have recently demonstrated the psychopathological relevance of obsessive-compulsive symptoms. Therefore the "Arbeitsgemeinschaft für Methodik und Diagnostik in der Psychiatrie" (AMDP) has started to develop a rating scale for a quick and precise assessment of obsessive-compulsive symptoms. The actual version of the scale comprises 20 items on the dimensions "description", "distress and impairment" and "emotion and cognition". The results of a first empirical study (n = 137, psychiatric in- and outpatients) demonstrated excellent internal consistency (Cronbach's alpha = 0.92), a split-half reliability of 0.89 (Spearman-Brown), a test-retest reliability of r = 0.86 and good convergent validity with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the Hamburger Zwangsinventar (HZI). The factor-analytical distribution of the 20 items revealed a 4-factor structure of the scale. The results are presented and their implications on further steps of the development of the scale are discussed.

Adult↗
PubMed1998

Disposition and elimination of meropenem in cerebrospinal fluid of hydrocephalic patients with external ventriculostomy.

The broad antibacterial spectrum and the low incidence of seizures in meropenem-treated patients qualifies meropenem for therapy of bacterial meningitis. The present study evaluates concentrations in ventricular cerebrospinal fluid (CSF) in the absence of pronounced meningeal inflammation. Patients with occlusive hydrocephalus caused by cerebrovascular diseases, who had undergone external ventriculostomy (n = 10, age range 48 to 75 years), received 2 g of meropenem intravenously over 30 min. Serum and CSF were drawn repeatedly and analyzed by liquid chromatography-mass spectroscopy. Pharmacokinetics were determined by noncompartmental analysis. Maximum concentrations in serum were 84.7 +/- 23.7 microg/ml. A CSF maximum (CmaxCSF) of 0.63 +/- 0.50 microg/ml (mean +/- standard deviation) was observed 4.1 +/- 2.6 h after the end of the infusion. CmaxCSF and the area under the curve for CSF (AUCCSF) depended on the AUC for serum (AUCS), the CSF-to-serum albumin ratio, and the CSF leukocyte count. Elimination from CSF was considerably slower than from serum (half-life at beta phase [t1/2beta] of 7.36 +/- 2.89 h in CSF versus t1/2beta of 1.69 +/- 0.60 h in serum). The AUCCSF/AUCS ratio for meropenem, as a measure of overall CSF penetration, was 0.047 +/- 0.022. The AUCCSF/AUCS ratio for meropenem was similar to that for other beta-lactam antibiotics with a low binding to serum proteins. The concentration maxima of meropenem in ventricular CSF observed in this study are high enough to kill fully susceptible pathogens. They may not be sufficient to kill bacteria with a reduced sensitivity to carbapenems, although clinical success has been reported for patients with meningitis caused by penicillin-resistant pneumococci and Pseudomonas aeruginosa.

Aged↗
PubMed1998

Permanent cortical damage detected by flumazenil positron emission tomography in acute stroke.

BACKGROUND AND PURPOSE: Therapy of acute ischemic stroke can only be effective as long as neurons are viable and tissue is not infarcted. Since gamma-aminobutyric acid receptors are abundant in the cortex and sensitive to ischemic damage, specific radioligands to their subunits, the central benzodiazepine receptors (BZR), may be useful as indicators of neuronal integrity and as markers of irreversible damage. To test this hypothesis we studied the binding of the BZR ligand [11C]flumazenil (FMZ) early after ischemic stroke in comparison to the extent of final infarcts and hypometabolic cortical areas. METHODS: In 10 patients cerebral blood flow, cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF), and FMZ binding were studied by positron emission tomography 3.5 to 16 hours after onset of their first hemispheric stroke. Early changes in flow, oxygen metabolism, and FMZ binding were compared with permanent disturbances in glucose metabolism, and the size of the final infarcts was determined on MRI or CT 12 to 22 days after the stroke. RESULTS: In all patients except one cerebral blood flow was disturbed, with marked decreases in eight and a hyperperfusion in one patient corresponding to the location of neurological deficits. In these areas CMRO2 was also reduced but to a variable degree, inducing highly variable OEF. Areas with markedly decreased CMRO2 (<60 micromol/100 g per minute) corresponded to regions with decreased FMZ binding (<4.0 times the mean value in the white matter). In all patients the final cortical infarcts were visible on the early FMZ images. Infarcts could be discriminated from noninfarcted cortex by decreased FMZ binding despite a wide range of OEF. In finally hypometabolic cortex FMZ binding was initially decreased or normal, with OEF covering a wide range; this suggested neuronal loss and/or deactivation as the cause of metabolic disturbance. Additionally, a highly significant correlation was found between FMZ distribution within the first 2 minutes after injection and regional cerebral blood flow. CONCLUSIONS: These results demonstrate that permanently and irreversibly damaged cortex can be detected by reduced FMZ binding early after stroke. Since FMZ distribution additionally images regional cerebral perfusion, BZR radioligands have a potential as clinically useful tracers in patients with acute ischemic stroke. The evidence of tissue damage furnished by these tracers might be of relevance for the selection of individual therapeutic strategies.

Aged↗
PubMed1998

Thirty-month outcome in patients with anorexia or bulimia nervosa and concomitant obsessive-compulsive disorder.

OBJECTIVE: The present study examines whether concomitant obsessive-compulsive disorder (OCD) indicates a poorer prognosis for patients with anorexia or bulimia nervosa. METHOD: Seventy-five female inpatients who met DSM-IV criteria for anorexia or bulimia nervosa took part in the follow-up study; 29 of these patients met criteria for concomitant OCD. All patients were investigated twice: during inpatient treatment and at follow-up 30 months after discharge. A semistructured diagnostic interview was used as well as the Eating Disorder Inventory and the Hamburg Obsession-Compulsion Inventory--Short Form. RESULTS: At follow-up, 51% (N = 38) of the patients no longer fulfilled DSM-IV criteria for anorexia or bulimia nervosa, but this improvement was not significantly correlated with the earlier presence of concomitant OCD. Analysis of variance for repeated measures revealed significant improvement over time on six of the eight Eating Disorder Inventory subscales for all patients regardless of OCD presence. Furthermore, no significant group effects or group-by-time interactions were identified. Clinically significant change, as reflected by improvement in scores on the Eating Disorder Inventory, was seen somewhat more often in patients without concomitant OCD, but this trend was not statistically significant. The patients whose eating disorders were most improved at follow-up also showed the highest reduction of obsessions and compulsions. CONCLUSIONS: The results suggest that concomitant OCD does not indicate a significantly poorer prognosis for patients with anorexia or bulimia nervosa.

Adult↗
PubMed1998

Higher prevalence of obsessive-compulsive symptoms in patients with blepharospasm than in patients with hemifacial spasm.

OBJECTIVE: The prevalences of obsessive-compulsive symptoms in patients suffering from blepharospasm and in those with hemifacial spasm were determined. The two conditions have similar symptoms, but only blepharospasm is etiologically linked to basal ganglia dysfunction. METHOD: After being interviewed with the Structured Clinical Interview for DSM-III-R, 13 patients with blepharospasm and 13 with hemifacial spasm completed the SCL-90-R and the Hamburg Obsession/Compulsion Inventory-Short Form. RESULTS: Patients in the blepharospasm group had significantly more obsessive-compulsive symptoms, as indicated by higher scores on the Hamburg Obsession/Compulsion Inventory-Short Form, than the patients with hemifacial spasm. SCL-90-R scores were in the normal range for nine and eight categories, respectively (out of nine). CONCLUSIONS: The findings provide additional support for the hypothesis that obsessive-compulsive symptoms are related to basal ganglia dysfunction.

Aged↗
PubMed1998

11C-methionine PET for differential diagnosis of low-grade gliomas.

Management of low-grade gliomas continues to be a challenging task, because CT and MRI do not always differentiate from nontumoral lesions. Furthermore, tumor extent and aggressiveness often remain unclear because of a lack of contrast enhancement. Previous studies indicated that large neutral amino acid tracers accumulate in most brain tumors, including low-grade gliomas, probably because of changes of endothelial and blood-brain barrier function. We describe 11C-methionine uptake measured with PET in a series of 196 consecutive patients, most of whom were studied because of suspected low-grade gliomas. Uptake in the most active lesion area, relative to contralateral side, was significantly different among high-grade gliomas, low-grade gliomas, and chronic or subacute nontumoral lesions, and this difference was independent from contrast enhancement in CT or MRI. Corticosteroids had no significant effect on methionine uptake in low-grade gliomas but reduced uptake moderately in high-grade gliomas. Differentiation between gliomas and nontumoral lesions by a simple threshold was correct in 79%. Recurrent or residual tumors had a higher uptake than primary gliomas. In conclusion, the high sensitivity of 11C-methionine uptake for functional endothelial or blood-brain barrier changes suggests that this tracer is particularly useful for evaluation and follow-up of low-grade gliomas.

Adult↗
PubMed1997

CD45RA-expressing memory/effector Th cells committed to production of interferon-gamma lack expression of CD31.

It has been considered before that human naive and memory/effector CD4+ T-cells cannot be subdivided solely according to the differential expression of CD45 isoforms. By the lack of expression of CD31 we have identified a subset of CD4+ CD45RA+ CD31- cells which show distinct features of antigen-experienced Th1 cells. Short term stimulation of highly purified human peripheral blood CD4+ T-cells with PMA/ionomycin, followed by the cytometric analysis of intracellular cytokines, showed that a minor subpopulation of CD4+ CD45RA+ CD45RO- cells is able to produce interferon-gamma (IFN-gamma) rapidly, a characteristic of antigen-experienced Th1 cells. Whereas among CD45RA+ CD4+ T-cells both CD31+ and CD31- subsets produce interleukin-2 (IL-2) upon PMA/ionomycin stimulation, only the CD31- subpopulation is able to produce IFN-gamma. Thus, our phenotypic and functional characterization of CD45RA+ CD45RO- Th cells shows that CD45RA+ CD45RO- cells do not represent a homogeneous population of antigen-unexperienced, naive T-cells. We speculate that a certain subset of human CD4+, CD45RO+ memory T-cells reverts to expression of the CD45RA isoform, and that this subset can be identified by the lack of CD31 expression.

Animals↗
PubMed1997

[Transcranial doppler sonography. Effect of sevoflurane in comparison to isoflurane].

METHODS: Using transcranial Doppler sonography (TCD), we studied the effects of sevoflurane compared to equipotent doses of isoflurane on blood-flow velocity in the middle cerebral artery (MCA) before, during, and after general anaesthesia. In random order, 30 patients received sevoflurane (n = 15) or isoflurane (n = 15) given in stepwise-increasing doses of 0.5, 1.0, and 1.5 MAC in oxygen/air (FiO2 = 0.5). Oxygen/air was then replaced by oxygen/nitrous oxide 33%/65% with decreasing doses (1.5, 1.0, 0.5 MAC) of sevoflurane or isoflurane. During each step, ventilation was controlled to provide first normocapnia (end-tidal pCO2 = 38 mmHg) and then hypocapnia (end-tidal pCO2 = 27 mmHg). MCA blood-flow velocity and pulsatility, arterial blood pressure, heart rate, and body temperature were recorded simultaneously at the end of each period. For statistical analysis, within-group comparison was made by one-way ANOVA. Differences between groups were determined by two-way analysis of variance. Age, weight, and height of the patients were compared using Student's t-test; P < 0.05 was considered significant. RESULTS: Groups were comparable regarding age, weight, and height. TCD parameters were not significantly changed by increasing doses of sevoflurane or isoflurane given in oxygen/air when compared to the awake data. However, increasing MCA blood-flow velocity was found with decreasing doses of sevoflurane or isoflurane given in oxygen/nitrous oxide (P < 0.05 for 0.5 MAC, normoventilation) without intergroup, differences. In both groups, hyperventilation always decreased MCA blood-flow velocity. CONCLUSIONS: We conclude from our TCD data that equipotent doses of sevoflurane and isoflurane comparably affect cerebral perfusion, especially when nitrous oxide is given simultaneously.

Adolescent↗
PubMed1997

[Treatment of patients with thromboses of the basilar artery and locked-in syndrome. An ethical dilemma].

Decisions regarding the extent of treatment of severely ill patients can be an ethical dilemma when life-prolonging intensive care contradicts the goal of avoiding unnecessary suffering on the part of the patient. Here we present the results of a written survey of physicians on neurological intensive care units in Germany regarding the treatment of patients with basilar artery thrombosis and locked-in syndrome. 52% of the 93 physicians who replied advocated not treating severe infections with antibiotics, 38% were in favor of stopping intensive care. In contrast, 55% recommended intubating the patient in the presence of swallowing disturbances and imminent aspiration. 58% were in favor of discussing these problems in detail with the patient, and 87% advocated discussing them with relatives. Nearly all physicians (97%) recommended using adequate amounts of opiates and benzodiazepines. In very rare cases, 99% would agree to the use of passive euthanasia and 19% to active euthanasia. These findings illustrate the current disagreement on some of the important treatment decisions among physicians on neurological intensive care units. An open exchange of views on these questions could facilitate the appropriate consideration of ethical matters in the treatment of these patients.

Adult↗
PubMed1997

Slow elimination of mannitol from human cerebrospinal fluid.

OBJECTIVE: The rise of intracranial pressure above the pre-treatment level (rebound phenomenon) is considered, in part, a consequence of osmotherapeutics penetrating into the intracranial compartments. METHODS: The kinetics of mannitol in the ventricular CSF were studied in 10 patients with cerebrovascular stroke after a single i.v. infusion of 37.5 g over 15 min. RESULTS: Maximum mannitol CSF concentrations (mean = 51.1 mg.1-1) were reached 2-12 h after termination of the infusion. Mean t1/2CSF (18.3 h) by far exceeded t1/2S (3.71 h). AUCCSF/AUCS, as a measure of mannitol CSF penetration, ranged from 0.037 to 0.390. CONCLUSION: The slow elimination of mannitol from CSF implies a high risk of accumulation in the central nervous compartments after repeated dosing.

Aged↗
PubMed1997

[Microembolizatoins during heart surgery under extracorporeal circulation].

OBJECTIVE: By means of transcranial Doppler sonography (TCD), microembolic signals (MES) representing embolic events can be registered during cardiac surgery and extracorporeal circulation in a considerable number of patients. We conducted the present study to determine the neuro-psychiatric consequences of MES. METHODS: 25 patients scheduled for elective aorto-coronary bypass grafting (ACBG; n = 10) or aortic valve replacement (AVR; n = 15) were studied pre- and postoperatively with neuropsychiatric testing. Results were related to the number of MES noted intraoperatively. In addition, we registered the intraoperative changes of middle cerebral artery blood flow velocity, mean arterial pressure, arterial blood gases, haemoglobin and haematocrit. Statistics included t-test, two-way analysis of variance, Mann-Whitney-U-test and Spearman correlation with p < 0.05 considered significant. RESULTS: Regarding demographic data and intraoperative parameters, both study groups (ACBG vs. AVR) were comparable except for age. AVR patients showed significantly more MES than those undergoing ACBG (p < 0.012) which was most pronounced in the late state of surgery (aortic clamp off; p < 0.0003). However, MES counts did not correlate with neuropsychiatric test results. CONCLUSIONS: In contrast to recent reports, we were unable to show a deterioration of postoperative neuropsychiatric state related to high intraoperative MES count in our patients. Future TCD studies should focus on the differentiation between gaseous emboli and particles even in the clinical setting, as the latter may well play a major role for the development of cerebral dysfunction following cardiac surgery and extracorporeal circulation.

Analysis of Variance↗