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T Schulte

Publications and source records attributed to T Schulte.

At least 19 recordsLinked to original sources
PubMed2006

Induction of immediate early gene expression by high-frequency stimulation of the subthalamic nucleus in rats.

Deep brain stimulation is associated with delayed improvement of parkinsonian symptoms, such as hypokinesia with subthalamic nucleus stimulation, or dystonia with globus pallidus internus stimulation. The latency observed is better explained by molecular alterations than immediate electrophysiological processes, and clinical improvement may involve adaptive gene expression. Here, we have studied immediate early gene expression as fast molecular response to subthalamic nucleus stimulation. Bipolar electrodes were implanted bilaterally into the subthalamic nucleus of anesthetized male Wistar rats. High-frequency stimulation (130 Hz or 80 Hz, 60 micros, 300 microA) or low-frequency stimulation (5 Hz, 60 micros, 300 microA) was performed with the right electrode for 15, 60, 120, and 240 min whereas the silent left electrode served as negative control. Brains were fixed by transcardial perfusion and frozen sections were stained with polyclonal antibodies directed against three immediate early gene-encoded proteins, c-Fos, c-Jun, and Krox-24 (NGFI-A, Egr-1, Zif268, Tis8, Zenk). After 120 and 240 h, c-Fos immunoreactivity was strongly upregulated in subthalamic nucleus neurons on the stimulated site. In contrast, no c-Fos immunoreactivity was detected on the non-stimulated site except for single positive cells located in close proximity to the electrode tracks. Furthermore, c-Fos immunoreactivity was induced in subthalamic nucleus projection areas, such as primary and secondary motor cortex, primary somatosensory and insular cortex, lateral and medial globus pallidus, suprageniculate thalamic nucleus, pontine nuclei, medial geniculate nucleus, and substantia nigra. Similarly, c-Jun and Krox-24 were induced at the site of stimulation and in projection areas following high-frequency subthalamic nucleus stimulation. Whereas high frequency stimulation with 80 Hz was similarly effective none of the three immediate early gene-encoded proteins was induced with low-frequency stimulation (5 Hz) for 4 h. This is in accordance with the therapeutic effects of deep brain stimulation which are only elicited with high frequency stimulation. Our data provide evidence that immediate early gene expression in the subthalamic nucleus is rapidly and substantially induced by high-frequency stimulation. The induction of immediate early genes in projection sites suggests ipsilateral transsynaptic modulation of neuronal activity.

Animals↗
PubMed2005

fMRI evidence for individual differences in premotor modulation of extrastriatal visual-perceptual processing of redundant targets.

To perceive the vast array of stimuli in the world around us, the visual system employs parallel processing mechanisms that ensure efficiency in perceiving multiple objects in a scene. A way to test this efficiency is to measure reaction time (RT) to pairs of identical stimuli, presented singly or as doublets; typically, the resulting phenomenon is the redundant targets effect (RTE), which manifests as faster RTs to paired than singly presented stimuli. It is controversial, however, whether the neural locus of the parallel processing mechanisms invoked to produce the RTE is perceptual or motor and why some studies observe a substantial RTE and others do not. To resolve these two issues, we measured the RTE in young adults while undergoing functional MRI. Regarding the question of a perceptual or motor basis for the RTE, we observed that bilateral activation of extrastriate cortex was prominent in paired vs. the sum of the two single stimulus conditions, indicating that the RTE invoked perceptual mechanisms; by contrast, the motor cortex was not disproportionately activated in this comparison. Regarding the magnitude of the RTE, we compared activation patterns in individuals with small vs. large RTEs and observed that frontal and premotor areas were activated with small RTEs. These data indicate that the primary processing level of response facilitation, observed as the RTE, is perceptual, but the modulation of the RTE magnitude is premotor and associated with basic aspects of response selection and preparation.

Adult↗
PubMed2005

Routes towards Anderson-like localization of Bose-Einstein condensates in disordered optical lattices.

We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.

Journal Article↗
PubMed2005

Corpus callosal microstructural integrity influences interhemispheric processing: a diffusion tensor imaging study.

Normal aging and chronic alcoholism result in disruption of brain white matter microstructure that does not typically cause complete lesions but may underlie degradation of functions requiring interhemispheric information transfer. We examined whether the microstructural integrity of the corpus callosum assessed with diffusion tensor imaging (DTI) would relate to interhemispheric processing speed. DTI yields estimates of fractional anisotropy (FA), a measure of orientation and intravoxel coherence of water diffusion usually in white matter fibers, and diffusivity ( ), a measure of the amount of intracellular and extracellular fluid diffusion. We tested the hypothesis that FA and would be correlated with (i) the crossed-uncrossed difference (CUD), testing visuomotor interhemispheric transfer; and (ii) the redundant targets effect (RTE), testing parallel processing of visual information presented to each cerebral hemisphere. FA was lower and higher in alcoholics than in controls. In controls but not alcoholics, large CUDs correlated with low FA and high in total corpus callosum and regionally in the genu and splenium. In alcoholics but not controls, small RTEs, elicited with equiluminant stimuli, correlated with low FA in genu and splenium and high in the callosal body. The results provide in vivo evidence for disruption of corpus callosum microstructure in normal aging and alcoholism that has functional ramifications for efficiency in interhemispheric processing.

Aging↗
PubMed2005

[Surgical treatment of pulmonary aspergilloma].

Invasive pulmonary aspergillosis is a life-threatening disease, developing from infection mostly by Aspergillus fumigatus. It is an opportunistic infection and occurs mostly in immunosuppressed patients, after tuberculosis, in patients with AIDS or malignomas. The most common symptom and complication is hemoptysis up to massive bleeding. Surgical treatment is obligatory on patients with a pulmonary aspergilloma. Time and form of intervention should be discussed between surgeon and pulmonologist. Resection should follow anatomical borders like lobectomy or pneumectomy. Any remaining intrathoracic cavities should be filled either with remaining lung tissue or with muscle flaps of latissimus or pectoralis muscle or omentum majus. Following these rules, intervention can be performed with reasonable mortality and morbidity rate.

Adolescent↗
PubMed2004

Clinical effects of repetitive transcranial magnetic stimulation versus acute levodopa challenge in Parkinson's disease.

We studied the short-term clinical effects of 10-Hz repetitive transcranial magnetic stimulation (rTMS) of the motor hand area contralateral to the more affected limb in 12 non-fluctuating, for at least 12 hours drug free patients with Parkinson's disease (PD). We investigated the efficacy of rTMS in combination with a levodopa challenge test design under double-blind, placebo controlled conditions. Significant reductions of UPDRS III motor scores showed the treatment conditions: placebo/rTMS, levodopa/sham stimulation and levodopa/rTMS. A more detailed evaluation of arm symptoms contralateral to the stimulated brain region showed even more pronounced effects for the three conditions. There were significant differences between the mean response of the UPDRS III arm scores to the four test conditions. In conclusion our study demonstrates short-term beneficial effects of 10-Hz rTMS on motor symptoms in PD patients. A release of endogenous dopamine in subcortical structures, i.e. putamen, in response to rTMS is the most likely mechanism of action.

Adult↗
PubMed2004

Parallel interhemispheric processing in aging and alcoholism: relation to corpus callosum size.

We tested parallel processing of visual information using the redundant targets effect (RTE) in 12 alcoholics and 13 matched controls. The paradigm was a simple reaction time (RT) task with targets presented in the same (uncrossed), opposite (crossed), or both (redundant) visual-fields. In older alcoholics (>50 years) the RT gain invoked by redundant targets did not exceed probability measures, suggesting compromised interhemispheric processing of parallel information in this subgroup compared with controls or younger alcoholics. The difference between crossed and uncrossed reaction times (CUD), an index of interhemispheric transfer time (ITT), was greater in older than younger subjects. Moreover, the CUD was negatively correlated with the corpus callosum (CC) total area and body in controls, supporting the concept of a structure-function relationship of interhemispheric transfer. This relationship was not found in alcoholics, although the midsagittal area of the CC, genu, and body but not intracranial volume (ICV), was significantly smaller in alcoholics than controls. These results suggest that chronic alcohol abuse together with advancing age exert subtle disruption on parallel interhemispheric processing reliant on callosal connections.

Adult↗
PubMed2004

[Changes of the fat/water ratio in the erector trunci muscle in patients with lumbar disc herniation: a comparative study with 1H-MRS].

PURPOSE: To evaluate whether metabolic changes of the erector trunci muscle in patients with lumbar disc herniation can be detected with proton magnetic resonance spectroscopy ( (1)H-MRS). MATERIALS AND METHODS: In 10 patients with lumbar disc herniation and 16 healthy volunteers, proton spectra were obtained from the erector trunci muscle and analyzed for fat-water ratio. The axial images were evaluated for the degree of atrophy of the erector trunci muscle. The muscular tissue was histopathologically examined in 2 patients. RESULTS: The examination was well tolerated by all patients and volunteers and all acquired spectra could be analyzed. Patients with lumbar disc herniation have a significantly increased fat-water ratio of 0.19 compared to 0.09 in the control group, with a p-value of 0.003. This result correlates well with the bioptical findings of increased intracellular lipid deposits and lipomatous transformation of the muscle parenchyma. CONCLUSION: (1)H-MRS is a useful method to detect metabolic changes in lumbar back musculature and, as a non-invasive technique, might play a role in monitoring exercise in lumbar disc herniation. It can be expected that muscle regeneration will be shown as precisely as muscle degeneration. This hypothesis, however, remains to be proven.

Adult↗
PubMed2003

Measurement of the spatial correlation function of phase fluctuating Bose-Einstein condensates.

We measure the intensity correlation function of two interfering spatially displaced copies of phase fluctuating Bose-Einstein condensates. It is shown that this corresponds to a measurement of the phase correlation properties of the initial condensate. Analogous to the method used in the stellar interferometer experiment of Hanbury Brown and Twiss, we use spatial intensity correlations to determine the phase coherence lengths of elongated condensates. We find good agreement with our prediction of the correlation function and confirm the expected coherence length.

Journal Article↗
PubMed2003

Neurophysiological findings in SPG4 patients differ from other types of spastic paraplegia.

The authors examined 12 families with autosomal dominant hereditary spastic paraplegia for phenotypic characteristics predicting the underlying genotype. They found no clinical differences between patients with or without mutations in the spastin gene (SPG4). Motor evoked potentials and nerve conduction studies were almost normal in those with SPG4. In contrast, non-SPG4 families had prolonged central motor conduction times or marked peripheral neuropathy, or both.

Adenosine Triphosphatases↗
PubMed2003

Chronic lumbar epidural haematoma presenting with acute paraparesis.

Chronic spinal epidural haematomas are very rare and have been reported to occur only in the lumbar region. They usually become symptomatic through radicular pain or neurogenic claudication. The epidural bleeding is thought to originate from a rupture of an epidural vein due to a sudden increase in intra-abdominal pressure or due to trauma. The patient reported on here developed acute paraparesis about 8 weeks after a mild fall on the buttocks. MRI showed a spinal epidural mass located dorsolaterally at the level of L3-L5. The mass was surgically removed. Histological and immunohistological studies disclosed an organised haematoma. The clinical, radiological and intra-operative features of this case are described, and the relevant literature is analysed.

Acute Disease↗
PubMed2003

Modulation of disease risk according to a cathepsin D / apolipoprotein E genotype in Parkinson's disease.

Aspartyl protease Cathepsin D (CTSD) has been suggested to play a role in the pathogenesis of sporadic Alzheimer's disease (AD) due to interference with protein degradation mechanisms. A C224T (A38V) polymorphism in exon 2 of the CTSD gene is reported to be associated with an increased risk for AD. The partially overlapping pathology between AD and Parkinson's disease (PD) led us to investigate the role of this polymorphism in PD. Using association studies in 457 German PD patients and 340 controls we found no evidence for direct association between the CTSD genotype and PD. However, stratification for the apolipoprotein E (APOE) epsilon4 allele suggests a protective effect of the CTSD T-allele in PD (OR = 0.24, p = 0.002). Our findings suggest interference of CTSD and APOE polymorphisms in the pathogenesis of PD, in the sense of modulating disease risk.

Aged↗
PubMed2002

Initial study of using a laminar fluid diffusion interface for sample preparation in high-performance liquid chromatography.

This report describes a new microfluidic device called the H Filter for sample preparation prior to HPLC. The H Filters make possible a diffusional transfer of an analyte from a sample stream into a stream of a "receiver" fluid. Existing mathematical models can be used for optimizing experimental conditions. The authors have selected the extraction of the antibiotic cephradine from blood to demonstrate the utility of the new device. The extracts of blood samples spiked with cephradine levels between 0.2 and 100 microg/ml were analyzed using a C8 reversed-phase column and UV detection at 260 nm. The HPLC results were in good agreement with theory. The recovery of 32.2+/-2.8% was uniform over the entire range of cephradine concentrations. The new method completely avoids the use of centrifuges, that is otherwise typical for most current methodologies for the preparation of blood samples prior to HPLC analysis.

Cephradine↗
PubMed2002

Spontaneous bilateral chronic subdural haematoma of the posterior fossa. Case report and review of the literature.

INTRODUCTION: Chronic subdural haematomas of the posterior fossa in adults without a history of trauma are very rare. To our knowledge, only 15 cases have so far been reported in the literature, including those with anticoagulation therapy. A case of spontaneous bilateral infratentorial chronic subdural haematoma associated with anticoagulation therapy in an alive adult is presented and the relevant literature is reviewed. CASE REPORT: A 70 year old female presented with progressive dizziness, vertigo and gait ataxia. She was on anticoagulation therapy for heart disease. Neuro-imaging revealed bilateral infratentorial subdural masses. The subdural masses were suspects for chronic subdural haematomas by neuroradiological criteria. Because of the progressive symptomatology, the haematomas were emptied through burrhole trepanations. Chocolate-colored fluid, not containing clotted components, gushed out under great pressure. The source of bleeding could not be identified. The patient recovered well from surgery, but died 4 months later shortly after admission to another hospital from heart failure. DISCUSSION: The chronic subdural haematomas in this patient may have been due to rupture of bridging veins caused by a very mild trauma not noticed by the patient and possibly aggravated by the anticoagulation therapy. Infratentorial chronic subdural haematoma should at least be a part of the differential diagnosis in elderly patients with cerebellar and vestibular symptomatology even without a history of trauma.

Aged↗
PubMed2001

Double-blind crossover trial of trimethoprim-sulfamethoxazole in spinocerebellar ataxia type 3/Machado-Joseph disease.

OBJECTIVE: To evaluate the efficiency of a combination of trimethoprim and sulfamethoxazole in patients with spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD). DESIGN: Placebo-controlled, double-blind crossover trial in 22 patients with genetically confirmed SCA3/MJD. Study phases of 6 months were separated by a washout period of 4 weeks. Dosages were a combination of trimethoprim, 160 mg, and sulfamethoxazole, 800 mg, twice daily for 2 weeks, followed by a combination of trimethoprim, 80 mg, and sulfamethoxazole, 400 mg, twice daily for 5.5 months. SETTING: Outpatient department of the Neurological Clinic, Ruhr-University, Bochum, Germany. MAIN OUTCOME MEASURES: Ataxia ranking scale, self-assessment score, static posturography, and results of motor performance testing. Effects on the visual system were studied using the achromatic Vision Contrast Test System and the Farnsworth-Munsell 100-hue test for color discrimination. Physical and mental health were documented using the Medical Outcomes Study 36-Item Short-Form Health Survey. Subgroup analyses assessed the influence of age, sex, age at onset, duration of the disease, phenotype, and CAG repeat length on test performance. RESULTS: Twenty of 22 patients completed the study. Dropouts were due to a rash (placebo phase) and an attempted suicide in a family conflict. Trimethoprim-sulfamethoxazole therapy had no significant effect in SCA3/MJD patients in the short-term analysis (2 weeks) or in the long-term interval (6 months). CONCLUSIONS: In contrast to previous reports that studied smaller groups of patients, treatment with trimethoprim-sulfamethoxazole did not improve the diverse and complex movement disorders caused by SCA3/MJD. Trimethoprim-sulfamethoxazole had no effect on the visual system and cannot be recommended as a continuous treatment for SCA3/MJD patients.

Adult↗
PubMed2001

Acute effects of alcohol on divided and covert attention in men.

RATIONALE: While several studies identified divided attention to be sensitive to alcohol effects, the impact of alcohol on covert visual attention is still not clear, despite the latter's important role in perception. OBJECTIVES: The study tests the effect of acute moderate doses of alcohol on divided and covert attention in right-handed, male volunteers. METHODS: The design of the study involved a double-blind trial with an alcohol and a placebo condition; measurements were taken before and after an oral dose of 0.6 g/kg alcohol versus placebo. In the divided-attention task, simultaneous visuo-spatial and auditory stimulation was applied. In a test of covert attention, subjects had to shift their attentional focus according to a central cue, from one location in the visual field to another. RESULTS: Under the divided-attention condition, reaction times were significantly prolonged after alcohol ingestion compared to placebo. Covert attention pre-post change was also significantly different between the alcohol and placebo groups. There is a reduction of false-cueing disturbance for left-appearing stimuli under moderate alcohol but an increase of disturbance for rightward stimuli, i.e. we found a lateralised pattern of reaction for spatial orienting. In the placebo group, no significant differences in right-left performance were obtained. CONCLUSION: The results suggest that sensory-attentional mechanisms play a key role in altered visual perceptual performance after alcohol ingestion. Furthermore, differences between the right and left visual field in the cued target-detection task indicate that alcohol exerts an influence on right-hemispheric attentional priming.

Adult↗
PubMed2001

Deficits of respiratory-cardiac coupling in heavy drinkers.

1. Physiological evidence of chronic alcohol abuse prior to the onset of clinical signs of alcohol dependence is difficult to obtain The purpose of this study was to search for possible non-invasive indicators for chronic alcohol consumption yielding information in addition to conventional biological markers. 2. The authors investigated the relationship between respiratory-cardiac coupling and blood alcohol concentration (BAC) in male subjects who lost their driver's license from drunk driving. 3. We found that subjects who had a high BAC level (0.16-0.31% at the time of offense) show altered respiratory sinus arrhythmia (RSA) and, in particular, an altered heart-rate response to auditory stimulation and compared them to a control group of social drinkers. Normal subjects showed a pronounced acoustic heart-rate response, i.e., particularly during expiration there was a difference between the interbeat-interval (IBI) traces with and without auditory stimulation. Subjects who had lost their driver's license from drunk driving had an overall severely reduced heart-rate response, that was even absent particularly in the subgroup having high BAC values (0.21-0.31%). The authors also found some evidence that in the latter subgroup IBI, RSA, and acoustic heart-rate responses partially recover after a six-month period of abstinence. 4. Specific parameters of the acoustic heart-rate response are changed in our group of alcohol abusers presumably, due to impairment of vagal function. These parameters may therefore be useful to serve as a non-invasive measure of alcohol abuse.

Accidents, Traffic↗