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U Roelcke

Publications and source records attributed to U Roelcke.

36 records · Page 2Linked to original sources
PubMed1997

Intermanual transfer of training: blood flow correlates in the human brain.

In a previous study, we found that relearning of a task with one hand might negatively be influenced by previous, opposite hand training of the analogue task, Thut G., et al., Exp. Brain Res., 108 (1996) 321-327. Drawing of a figure with the right hand, following left hand training, was slower than right hand drawing of an unknown figure. These conditions were termed right hand transfer learning (rTL) and right hand original learning (rOL). The present study aimed to identify the cerebral areas associated with these influences by measuring regional cerebral blood flow (rCBF) in 16 right-handed, healthy subjects during rTL and rOL. Positron emission tomography and statistical parametric mapping were used. Compared with rOL, rTL was associated with increased rCBF in the left medial prefrontal cortex and the right prefrontal convexity. Individual rCBF changes in the area homotopic to the right prefrontal convexity furthermore correlated with individual changes in rTL performance. While the smallest rCBF increases were found in subjects with weakest slowing of rTL relative to rOL, highest rCBF increases were present when rTL slowing dominated. Comparisons between rTL and rOL, however, revealed on average no performance differences. Our data suggest that relearning after previous opposite hand training activates neural mechanisms within the prefrontal convexity which might have an inhibitory function but that inhibition does not have to be the net final behavioral result.

Adult↗
PubMed1997

Influence of spinal cord injury on cerebral sensorimotor systems: a PET study.

OBJECTIVES: To assess the effect of a transverse spinal cord lesion on cerebral energy metabolism in view of sensorimotor reorganisation. METHODS: PET and 18F-fluorodeoxyglucose were used to study resting cerebral glucose metabolism in 11 patients with complete paraplegia or tetraplegia after spinal cord injury and 12 healthy subjects. Regions of interest analysis was performed to determine global glucose metabolism (CMRGlu). Statistical parametric mapping was applied to compare both groups on a pixel by pixel basis (significance level P = 0.001). RESULTS: Global absolute CMRGlu was lower in spinal cord injury (33.6 (6.6) mumol/100 ml/min (mean (SD)) than in controls (45.6 (6.2), Mann-Whitney P = 0.0026). Statistical parametric mapping analysis disclosed relatively increased glucose metabolism particularly in the supplementary motor area, anterior cingulate, and putamen. Relatively reduced glucose metabolism in patients with spinal cord injury was found in the midbrain, cerebellar hemispheres, and temporal cortex. CONCLUSIONS: It is assumed that cerebral deafferentiation due to reduction or loss of sensorimotor function results in the low level of absolute global CMRGlu found in patients with spinal cord injury. Relatively increased glucose metabolism in brain regions involved in attention and initiation of movement may be related to secondary disinhibition of these regions.

Adult↗
PubMed1997

Reduced glucose metabolism in the frontal cortex and basal ganglia of multiple sclerosis patients with fatigue: a 18F-fluorodeoxyglucose positron emission tomography study.

To investigate the pathophysiology of fatigue in MS, we assessed cerebral glucose metabolism (CMR-Glu) in 47 MS patients using PET and 18F-fluorodeoxyglucose. Applying the Fatigue Severity Scale (FSS), we first compared MS patients with severe fatigue (MS-FAT, n = 19, FSS > 4.9) and MS patients without fatigue (MS-NOF, n = 16, FSS < 3.7) on a pixel-by-pixel basis using Statistical Parametric Mapping (SPM95). Second, we compared FSS values of all 47 patients covering the whole range of this scale with CMRGlu using an analysis of covariance (SPM95). In addition, we determined global CMRGlu by region-of-interest analysis. Sixteen healthy subjects served as control subjects (CON). Global CMRGlu was significantly lower in both MS groups compared with CON (CON 43.3 +/- 6.9 mumol/100 mL/min, MS-FAT 34.7 +/- 4.4, MS-NOF 35.4 +/- 4.5) but was not related to fatigue severity. Comparing the two MS groups, SPM95 analysis revealed predominant CMRGlu reductions bilaterally in a prefrontal area involving the lateral and medial prefrontal cortex and adjacent white matter, in the premotor cortex, putamen, and in the right supplementary motor area of MS-FAT. In addition, there were CMRGlu reductions in the white matter extending from the rostral putamen toward the lateral head of the caudate nucleus. FSS values were inversely related to CMRGlu in the right prefrontal cortex. CMRGlu in the cerebellar vermis and anterior cingulate was relatively higher in MS-FAT than in MS-NOF patients. CMRGlu of both regions showed positive correlations with FSS values. Our data suggest that fatigue in MS is associated with frontal cortex and basal ganglia dysfunction that could result from demyelination of the frontal white matter.

Adult↗
PubMed1996

"Sunbath polyneuritis": subacute axonal neuropathy in perazine-treated patients after intense sun exposure.

This article aims at drawing attention to the peculiar association of intense exposure to sunlight and subacute development of sensory neuropathy which was seen in 7 psychiatric patients treated with the phenothiazine derivative, perazine. Three patients additionally developed bilateral VII nerve palsy. Symptoms followed a monophasic course with almost complete remission. Routine neurophysiology suggested axonal neuropathy confirmed by sural nerve biopsy in 1 patient. A toxic origin of neuropathy is supposed, possibly induced by phenothiazine photoproducts, which may cause cell damage via lipid peroxidation.

Adult↗
PubMed1996

Association of rubidium and C-methionine uptake in brain tumors measured by positron emission tomography.

Positron emission tomography (PET) studies have indicated that alteration of active transport contributes to increased net amino acid accumulation into human brain tumors. We compared the uptake of 11C-methionine (MET) and the K+ analog 82Rubidium (RUB) in 30 patients suffering from various brain tumors using PET. MET and RUB accumulated rapidly in tumor tissue and remained on average at a stable level thereafter from which normalized uptake values calculated (tissue radioactivity over injected radioactivity x body weight (NU). K1 (RUB) and K1, k2, k3 (MET) were also estimated using non-linear rate constant fitting in 17/30 patients. NU and K1 values for MET and RUB were higher in meningiomas compared to gliomas and were significantly correlated for the whole spectrum of tumors (p < 0.0001). When meningiomas were excluded, the correlation was maintained. K3 values for MET (metabolic rate) in tumors were in the range of normal brain. No correlation between RUB and MET was found for normal brain. with increasing rub intake the ratio of Nu MET over Nu RUB approached the value of 1.0. These results suggest that apart from active transport, also passive diffusion across the blood-brain barrier (BBB) may account for MET uptake from blood into tumor tissue. This probably limits the use of MET in the differential diagnosis of brain lesions where BBB disruption is present.

Adolescent↗
PubMed1996

Brain tumor iron uptake measured with positron emission tomography and 52Fe-citrate.

Iron and transferrin are required for DNA synthesis and cell division. Cellular iron uptake is mediated by transferrin receptors. In order to investigate whether iron uptake in brain tumors is associated with their histological grade, we studied 24 patients (5 astrocytoma, 11 glioblastoma, 8 meningioma) using positron emission tomography and 52Fe-citrate. Tracer uptake from blood into brain and tumor tissue was assessed 1. using multiple time graphical analysis yielding a measure for unidirectional net tracer uptake (Ki) and 2.) testing a one- and two-tissue kinetic compartment model, where K1 denotes tracer uptake from blood into tissue, k2 efflux from tissue into plasma, and k3 specific tracer binding. In the plasma, 52Fe was bound to a 80 kD protein (transferrin). Ki (in units of 10(-5)/min) was higher in glioblastomas (Ki mean +/- SD 13.6 +/- 6.1) compared with astrocytomas (4.8 +/- 3.5, Mann Whitney p = 0.015) and contralateral brain (2.2 +/- 0.9, Mann Whitney p = 0.009). Highest values were found in meningiomas (no blood-brain barrier (BBB); Ki 33.4 +/- 16.5, Mann Whitney p = 0.008 compared with glioblastomas). Among the compartment models, fitting with K1 and regional plasma volume explained the data best (one-tissue model), data fits were not significantly improved by addition of a k2 or k3 parameter. K1 and Ki values were significantly correlated (Spearman Rank, p = 0.0006). We conclude that 52Fe accumulation in tumors is governed by tracer uptake at the BBB, and does not reflect number of transferrin receptors at the level of tumor cells.

Adult↗
PubMed1995

Alteration of blood-brain barrier in human brain tumors: comparison of [18F]fluorodeoxyglucose, [11C]methionine and rubidium-82 using PET.

The influence of the blood-brain barrier (BBB) on tracer uptake was investigated in 21 patients with gliomas and meningiomas using PET, [18F]fluorodeoxyglucose (FDG), [18C]methionine (MET) and the K+ analog rubidium-82 (RUB) whose uptake into brain is largely prevented if the BBB is intact. Tracer uptake was quantitated by (1) multiple time graphical plotting providing tracer distribution volume (VD), unidirectional tracer uptake (Ki), and (2) normalized uptake (NU) which is a measure of net tissue radioactivity related to administered activity and body weight. VD, Ki and NU of MET were higher in meningiomas compared to gliomas and were significantly correlated with NU RUB (Spearman rank: p < 0.005 (VD), p < 0.05 (Ki), p < 0.001 (NU)). NU MET correlated with VD (p < 0.001) and Ki (p < 0.005) of MET. For FDG, tumor VD was in the range of contralateral cortex. Ki and NU values of FDG were highest in glioblastomas. NU of FDG correlated significantly with Ki of FDG (p < 0.005) but not with VD. The results suggest, that alteration of MET uptake in tumors is governed by changes of tracer influx across the BBB, whereas FDG uptake is related to tracer metabolism. This makes FDG the appropriate tracer particularly for the differential diagnosis of contrast enhancing lesions in operated and irradiated patients.

Adult↗
PubMed1994

PET: brain tumor biochemistry.

Most mechanisms of drugs which are used in brain tumor chemotherapy are well characterized: alkylation of DNA components (nitrosoureas), binding with tubulin protein resulting in metaphase arrest (vincristine), chromatid breaks and chromosome translocations (procarbazine), or inhibition of ribonucleotide reductase (hydroxyurea) [1]. These drugs exert their effects mainly during certain cell cycle phases of proliferating cells, particularly when DNA is synthesized. From this it can be assumed that the efficacy of these drugs depends on the fraction of proliferating cells. Thus it would be of great importance to estimate the proliferation rate of brain tumors which could guide chemotherapy in individual patients. Positron emission tomography (PET) measures quantitatively the in vivo tissue uptake of tracer substances. In tumors, the uptake appears to be altered in a characteristic way determined by biochemical properties of tumor tissue. Some aspects of brain tumor metabolism which are theoretically related to proliferation have been investigated with PET. In the following, the literature is reviewed with regard to: 1) tracer substances whose uptake has been thought to reflect tumor malignancy (11C-methionine, 18F-fluoro-deoxyglucose), and 2) tracers which theoretically could reflect mechanisms specifically related to DNA synthesis (11C-putrescine, ligands for peripheral benzodiazepine receptors).

Animals↗
PubMed1992

Untreated neuroborreliosis: Bannwarth's syndrome evolving into acute schizophrenia-like psychosis. A case report.

In general, meningopolyradiculitis (Bannwarth's syndrome, stage 2 of neuroborreliosis) follows a predictable monophasic self-limiting course. In contrast, we report the case of a patient with an untreated meningopolyradiculitis which evolved into acute schizophrenia-like psychosis due to persistent infection with Borrelia burgdorferi. The psychosis resolved within 1 week of treatment with ceftriaxone. This case shows that the usually benign monophasic meningopolyradiculitis may progress to severe CNS complications, which may have implications on current pathophysiological beliefs.

Acute Disease↗
PubMed1991

[Cogan syndrome. Case report, review of the literature, therapy].

We present a case report of Cogan's syndrome and a review of the literature. Cogan's syndrome is most likely due to autoimmune disease primarily affecting the vestibulocochlear organ and cornea and secondarily resulting in systemic disease. 40% of patients develop bilateral complete deafness and 70% show signs of systemic disease mostly in the form of cardiovascular symptoms. The mortality rate of 10% is mainly due to vasculitis. It is important to consider Cogan's syndrome in the differential diagnosis of sudden hearing loss accompanied by ocular signs in young patients, as high morbidity and mortality rates are effectively lowered by early immunosuppressive treatment.

Adult↗
PubMed1991

[Endogenous paranoid-hallucinatory syndrome caused by Borrelia encephalitis].

We describe a case with no neurological signs but marked psychiatric symptoms induced by borrelia burgdorferi, whose clinical picture was indistinguishable from an endogenous schizophrenia. The symptoms within one week under antibiotic treatment with ceftriaxon, but afterwards the patient showed a mild organic brain syndrome. The case demonstrated the aetiologic nonspecificity of paranoid symptoms and hallucinations and emphasizes that in psychotic patients without psychiatric history additional diagnostic measures should be performed.

Brain Damage, Chronic↗
PubMed1990

Cogan's syndrome.

Cogan's syndrome is a rare systemic autoimmune disease with preeminent ophthalmological and vestibulocochlear manifestations. Untreated, the disease usually results in profound deafness; eye involvement is usually self-remitting. Ten to twenty percent of patients either develop serious aortic valve disease or vasculitis or both. When given early, immunosuppressive therapy has been shown to be effective in treating all aspects of the disease. Thus, early disease recognition is of great significance. We present a patient with Cogan's syndrome and briefly discuss therapeutic implications.

Adult↗
PubMed1989

Meningopolyradiculitis (Bannwarth syndrome) as primary manifestation of a centrocytic-centroblastic lymphoma.

A 65-year-old female presented with Bannwarth's syndrome. Symptoms initially responded to antibiotics but soon progressed despite further adequate antibiotic treatment. Consistently absent antibody titres to Borrelia burgdorferi, repeated CSF examinations combined with an extensive search for tumour, revealed leukaemic meningitis secondary to uterine centrocytic-centroblastic lymphoma. The diagnostic steps required to elucidate the aetiology of meningopolyradiculitis, especially when chronic and progressive, are described.

Diagnosis, Differential↗
PubMed1983

[Cation flux in erythrocytes of patients with essential hypertension].

86Rubidium influx and Na--K-cotransport have been investigated in erythrocytes of mild essential hypertensives and normotensives devoid of familial hypertension. For measurement of cotransport Na-loaded/K-depleted erythrocytes were used while rubidium influx (with and without ouabain) was determined under physiological conditions. Both transport systems were linear in time, the interassay variances in a range of about 10%. The patients with essential hypertension exhibited a decreased rubidium influx compared to the normotensive controls. Ouabain-sensitive fluxes were not significantly different between the two groups, whereas ouabain-resistent rubidium influx was diminished in the group of the patients. Na--K-cotransport was also found to be decreased in essential hypertension. There was no correlation between cotransport and Rb-influx. The results indicate changes in cation fluxes in erythrocytes of essential hypertensives, the Na--K-cotransport being rather more altered than rubidium influx. It is speculated that hypertensive persons with reduced rubidium flux rates may represent a subpopulation of essential hypertension and that their high blood pressure may be additionally influenced by exogeneous factors e.g. enhanced sodium uptake.

Adult↗
PubMedDate not supplied

Fatty acids as markers of the blood-cerebrospinal fluid barrier function in man.

The blood-cerebrospinal fluid barrier (BCB) function in man is derived from the CSF:serum ratio of albumin (QAlb). In order to study other than BCB protein transport we compared CSF:serum ratios of fatty acids in patients revealing normal and increased QAlb values. Ratios of unsaturated fatty acids, which are involved in inflammation, increased significantly in patients with increased QAlb (p < 0.005). In contrast, CSF:serum ratios of saturated fatty acids increased only slightly. We conclude that characterisation of BCB lipid properties may be of particular interest regarding drug penetration into the CSF and lipid metabolism in inflammation.

Adult↗