Biomedical subjects

B Conrad

Publications and source records attributed to B Conrad.

At least 19 recordsLinked to original sources

PubMed2005

Structural brain changes in tinnitus.

Tinnitus is a common but poorly understood disorder characterized by ringing or buzzing in the ear. Central mechanisms must play a crucial role in generating this auditory phantom sensation as it persists in most cases after severing the auditory nerve. One hypothesis states that tinnitus is caused by a reorganization of tonotopic maps in the auditory cortex, which leads to an overrepresentation of tinnitus frequencies. Moreover, the participation of the limbic system in generating tinnitus has been postulated. Here we aimed at identifying brain areas that display structural change in tinnitus. We compared tinnitus sufferers with healthy controls by using high-resolution magnetic resonance imaging and voxel-based morphometry. Within the auditory pathways, we found gray-matter increases only at the thalamic level. Outside the auditory system, gray-matter decrease was found in the subcallosal region including the nucleus accumbens. Our results suggest that reciprocal involvement of both sensory and emotional areas are essential in the generation of tinnitus.

Adult↗

PubMed2005

[Doppler sonography suggesting fulminant aortic dissection in initial middle cerebral artery infarction].

Acute aortic dissection is a cardiovascular emergency with a wide spectrum of clinical symptoms making the diagnosis difficult if the leading symptom of thoracic pain is not present. In up to 10% of cases an ischemic stroke may be the first clinical sign. We report a patient with a middle cerebral artery infarction in whom an abnormal signal in the extracranial Doppler sonography revealed the first hint of an aortic dissection. Before the diagnosis could be verified, the patient died due to electromechanical decoupling; autopsy showed an extensive aortic dissection with cardiac tamponade. Based on this case report, we review special problems of diagnosis and therapy in aortic dissection with primary cerebrovascular manifestation.

Aged↗

PubMed2005

Improved cerebral vasoreactivity after statin administration in healthy adults.

BACKGROUND AND PURPOSE: Significant improvements of cerebral vasomotor reactivity during statin treatment were found in patients with cerebral small-vessel disease. The authors analyzed the cerebrovascular CO(2) reactivity before and after statin administration in healthy adults using a case-control study design. METHODS: The mean cerebral blood flow velocity (CBFV) of both middle cerebral arteries and the vasomotor reserve capacity (VMRC) were measured by repeated and simultaneous bilateral transcranial Doppler sonography in 25 healthy adults (7 men, mean age 28.8 years [95% confidence interval (CI): 25.7; 31.9]) before, during (days 1, 3, 7, and 14), and after administration of 40 mg pravastatin for 14 days as compared to 10 healthy control persons (4 men, mean age 30.6 years [95% CI: 22.9; 38.3]). The VMRC was calculated off-line as the percentage change of CBFV per 1% increase in end-tidal CO2 by a blinded investigator. RESULTS: In the statin group, 5 persons were excluded from further analysis. In the remaining 20 volunteers, the authors observed a highly significant effect of statin administration on VMRC (P = .002). The VMRC was significantly increased after statin administration on day 7 as compared to the initial value (3.03 [95% CI: 2.67; 3.38] vs 2.64 [95% CI: 2.41; 2.86]; P = .04). The effect was most pronounced in patients with lower initial VMRC values. In the control group, the VMRC did not differ significantly from baseline at different time intervals. CONCLUSIONS: The findings indicate an improvement of cerebral vasoreactivity even after short-term statin administration in healthy adults. However, this effect was related to baseline vasoreactivity.

Adult↗

PubMed2004

Genetic analysis of the biosynthesis of non-ribosomal peptide- and polyketide-like antibiotics, iron uptake and biofilm formation by Bacillus subtilis A1/3.

The Bacillus subtilis strain A1/3 shows exceptionally diverse antibiotic capacities compared to other B. subtilis strains. To analyze this phenomenon, mutants for the putative pantotheinyltransferase gene (pptS), and for several genes involved in non-ribosomal peptide synthesis and polyketide synthesis were constructed and characterized, using bioassays with blood cells, bacterial and fungal cells, and mass spectrometry. Among at least nine distinct bioactive compounds, five antibiotics and one siderophore activity were identified. The anti-fungal and hemolytic activities of strain A1/3 could be eliminated by mutation of the fen and srf genes essential for the synthesis of fengycins and surfactins. Both pptS- and dhb -type mutants were defective in iron uptake, indicating an inability to produce a 2,3-dihydroxybenzoate-type iron siderophore. Transposon mutants in the malonyl CoA transacylase gene resulted in the loss of hemolytic and anti-fungal activities due to the inhibition of bacillomycin L synthesis, and this led to the discovery of bmyLD-LA-LB* genes. In mutants bearing disruption mutations in polyketide (pksM- and/or pksR -like) genes, the biosynthesis of bacillaene and difficidins, respectively, was inactivated and was accompanied by the loss of discrete antibacterial activities. The formation of biofilms (pellicles) was shown to require the production of surfactins, but no other lipopeptides, indicating that surfactins serve specific developmental functions.

Acyl-Carrier Protein S-Malonyltransferase↗

PubMed2004

Hypothalamic activation in trigeminal autonomic cephalgia: functional imaging of an atypical case.

We report headache induced BOLD changes in an atypical case of trigeminal autonomic cephalgia (TAC). A 68-year-old patient was imaged using fMRI during three attacks of a periorbital head-pain with a average duration of 3 min. During the attacks, left sided conjunctival injection, rhinorrhea, lacrimation, facial sweating and hypersalivation were apparent. These attacks were usually partly responsive to oxygen administration but otherwise refractory to any drug. The patient described either attacks with a duration of one minute or less or longer attacks persisting for maximum of 20 min with headaches occurring up to 100 times a day. When considering the symptoms, frequency, duration and therapeutic response of the patient's headache, no clear-cut classification to one of the subtypes of trigeminal autonomic cephalgias (cluster headache, paroxysmal hemicrania, SUNCT) or trigeminal neuralgia was possible. The cerebral activation pattern was similar but not identical to those previously observed in cluster headache and SUNCT with a prominent activation in the hypothalamic grey matter. This case study underlines the conceptual value of the term TAC for the group of headaches focusing around the trigeminal-autonomic reflex. Our results emphasize the importance of the hypothalamus as key region in the pathophysiology of this entity.

Aged↗

PubMed2003

[Fugue and suicide].

The existence of dissociative fugue is doubted by many psychiatrists. We describe a 22-year-old patient who traveled about 600 km to Munich during a dissociative fugue and then exhibited an irreversible amnesia for a period of 24 h. There was a severe, clearly understandable conflict in the sense of a subjective stalemate situation which has been described as typical for dissociative fugue. The patient had a labile personality structure with insufficient coping strategies. It was possible to rule out other psychiatric or neurological disorders with sufficient certainty, and simulation was very unlikely. The conflict could not be satisfactorily solved, and the patient committed suicide 5 months later by jumping off a bridge.

Adult↗

PubMed2003

Obstacles in the diagnosis and treatment of syphilitic amyotrophy.

The authors describe a case of syphilitic amyotrophy in a 37-year-old man presenting with subacute progressive painless weakness in the right arm. Syphilitic amyotrophy is still an existing differential diagnosis of painless and progressive weakness. The authors explore potential obstacles in the diagnostic workup and finding of adequate therapy.

Adult↗

PubMed2003

[3H]-nociceptin ligand-binding and nociceptin opioid receptor mrna expression in the human brain.

Following the cloning of the novel nociceptin opioid receptor (NOP(1)) and the identification of its endogenous ligand orphanin FQ/nociceptin the distribution and functional role of the NOP(1) receptor system have been studied mainly in the rodent CNS. In the present study the regional distribution and splice variant expression of the NOP(1) receptor was investigated in the adult human brain using [(3)H]-nociceptin autoradiography, NOP(1) reverse transcriptase PCR and mRNA in situ hybridization. Ligand binding revealed strong expression of functional NOP(1) receptors in the cerebral cortex and moderate signals in hippocampus and cerebellum. Interestingly, the NOP(1) receptor specific ligand was also strongly bound in the human striatum. A matching pattern of mRNA expression was observed with high amounts of NOP(1) mRNA in the prefrontal and cingulate cortex as well as in the dentate gyrus of the hippocampus. mRNA levels in the Ammon's horn and cerebellar cortex were moderate and low in the striatum. A considerable expression of N-terminal NOP(1) splice variant mRNAs was not detectable in the human brain by means of in situ hybridization. This suggests that functional NOP(1) receptors in the human brain are encoded by N-terminal full length NOP(1) transcripts. The present data on the anatomical distribution of nociceptin binding sites and NOP(1) receptor mRNA contribute to the knowledge about opioid receptor systems in the human brain and may promote the understanding of function and pharmacology of the orphanin FQ/nociceptin receptor system in the human CNS.

Aged↗

PubMed2003

Differential modulation of subcortical target and cortex during deep brain stimulation.

The combination of electrical deep brain stimulation (DBS) with functional imaging offers a unique model for tracing brain circuitry and for testing the modulatory potential of electrical stimulation on a neuronal network in vivo. We therefore applied parametric positron emission tomography (PET) analyses that allow characterization of rCBF responses as linear and nonlinear functions of the experimentally modulated stimulus (variable stimulator setting). In patients with electrodes in the thalamic ventrointermediate nucleus (VIM) for the treatment of essential tremor (ET) here we show that variations in voltage and frequency of thalamic stimulation have differential effects in a thalamo-cortical circuitry. Increasing stimulation amplitude was associated with a linear raise in rCBF at the thalamic stimulation site, but with a nonlinear rCBF response in the primary sensorimotor cortex (M1/S1). The reverse pattern in rCBF changes was observed with increasing stimulation frequency. These results indicate close connectivity between the stimulated nucleus (VIM) and primary sensorimotor cortex. Likewise, stimulation parameter-specific modulation occurs at this simple interface between an electrical and a cerebral system and suggests that the scope of DBS extends beyond an ablation-like on-off effect: DBS could rather allow a gradual tuning of activity within a neuronal circuit.

Aged↗

PubMed2003

Multiple progressive intracerebral hemorrhages due to an angiosarcoma: a case report.

Identification of intracerebral hemorrhage (ICH) and the underlying cause is a common clinical problem. Rare causes of ICH can be particularly difficult to diagnose. We describe a man on oral anticoagulation with multiple progressive ICHs, who initially showed no signs of a malignant disease. After normalisation of all coagulation tests, the ICHs continued to spread. Autopsy examination revealed an angiosarcoma. Multiple progressive ICHs caused by an angiosarcoma that mainly affects the brain have not yet been described. In the presence of normal coagulation tests, further progression of ICH should raise questions about common causes of ICH such as oral anticoagulation in our case.

Aged↗

PubMed2003

A novel quality of life instrument for deep brain stimulation in movement disorders.

OBJECTIVE: To develop a short instrument to examine quality of life (QoL) which specifically addresses patients with movement disorders treated by deep brain stimulation (DBS). DESIGN: The instrument was developed within an existing concept of a modular questionnaire (questions on life satisfaction: "general life satisfaction" QLS(M)-A, and "satisfaction with health" QLS(M)-G), in which each item is weighted according to its relative importance to the individual. METHODS: Items were generated by interviews with 20 DBS patients, followed by item reduction and scale generation, factor analysis to determine relevant and final questionnaire items, estimation of reliability, and validation based on the medical outcome study 36 item short form health survey (SF-36) and the EuroQol (EQ-5D) (data from 152 patients with Parkinson's disease, essential tremor, or idiopathic torsion dystonia, including 75 patients with DBS). RESULTS: Initial questionnaires were reduced to 12 items for a "movement disorder module" (QLS(M)-MD), and five items for a "deep brain stimulation module" (QLS(M)-DBS). Psychometric analysis revealed Cronbach's alpha values of of 0.87 and 0.73, and satisfactory correlation coefficients for convergent validity with SF-36 and EQ-5D. CONCLUSIONS: QLS(M)-MD and QLS(M)-DBS can evaluate quality of life aspects of DBS in movement disorders. Psychometric evaluation showed the questionnaires to be reliable, valid, and well accepted by the patients.

Activities of Daily Living↗

PubMed2002

Different modes of manual acupuncture stimulation differentially modulate cerebral blood flow velocity, arterial blood pressure and heart rate in human subjects.

The psychophysiological effect of different modes of manual acupuncture stimulation was investigated in 12 healthy, right handed, male subjects (mean age 29). The cerebral blood flow velocity (CBFV) in both middle cerebral arteries, arterial blood pressure (BP), heart rate (HR) and the perceived intensity of the stimulation were monitored while an acupuncture needle in the right dorsal thenar muscle (point Hegu, Li 4) was repetitively rotated with either high frequency (4-8 Hz) and low amplitude (hf-la) or low frequency (1-2 Hz) and high amplitude (lf-ha). Response patterns induced by hf-la and 1f-ha [corrected] stimulation differed significantly (P < 0.05) as tested by Student's t-test: (1), 1f-ha [corrected] stimulation was perceived as more intense and induced a more marked right hemispheric CBFV increase; (2), while hf-la stimulation lead to a slight decrease of BP and HR, lf-ha stimulation induced an initial pressor response (increase of BP, decrease of HR) and a more marked long term decrease of BP. Data indicate that the mode of manual acupuncture stimulation has a differential effect on the perceived stimulation intensity, the cerebral activation and the cardiovascular reflex response.

Acupuncture↗

PubMed2002

[Circumscribed vasculitis with posterior infarct in Hashimoto encephalopathy].

The aetiology of Hashimoto's encephalopathy is still unknown. A 52-year-old woman with so far unspecific thyroid disorder presented with acute onset of right-sided sensory loss and visual disturbances. The neurological examination revealed a right upper quadrant anopsia and subtle right-sided sensory loss and weakness. The cranial MRI showed a left-sided cerebral infarction. MR angiography demonstrated a stenosis of the proximal segment of the left posterior cerebral artery, which was confirmed by conventional catheter angiography. The patient had no cardiovascular risk factors, no signs of systemic vasculitis, and no thromboembolic disorder. Thyroid function tests showed a subclinical hypothyroidism with plasma TSH level of 12.0 mU/ml, and thyroid antibodies were markedly elevated (hTG-AB 3390 U/ml, TPO-AB > 8000 U/ml). Typical features of Hashimoto's disease were demonstrated by ultrasound and scintigraphic examination of the thyroid gland. To the best of our knowledge, this is the first description of Hashimoto encephalopathy with localised vasculitis of the posterior cerebral arteries and left posterior infarction. It could be shown that the MR angiogram is a feasible tool to demonstrate regression of the vasculitis under glucocorticoid therapy.

Cerebral Angiography↗

PubMed2002

[Intervention project on cerebrovascular diseases and dementia in the Ebersberg district (INVADE): rationale and design].

The aim of INVADE (Intervention project on cerebrovascular diseases and dementia in the district of Ebersberg) is to analyse the effect of risk factor evaluation and modification (arterial hypertension, dyslipoproteinaemia, diabetes mellitus,hyperhomocysteinaemie, smoking, adipositas, alcohol abuse, lack of movement and depression) on the incidence of stroke and dementia in a population based sample. Stroke represents the third-common cause of death in the industrialized countries and is together with dementia one of the main causes for dependency in the activities of daily living. The project was performed in an area near to Munich, the district of Ebersberg. Risk factors were evaluated and if necessary modified by means of the primary care concept. INVADE was performed in cooperation with the health insurance company AOK and most of the general practitioners (n=65) of the district. All inhabitants of the district born 1946 and earlier who were also member of the AOK (10548 persons) are able to participate.

Aged↗

PubMed2002

[Investigations on the effect of acupuncture on affective and sensory components of pain in patients with different stages of chronic pain].

OBJECTIVES: The aim of the study was to investigate the effects of acupuncture on the affective and sensory experience of pain in chronic pain patients. Furthermore, the study tried to estimate the therapeutical benefit of acupuncture in relation to the stage of chronic pain according to the Mainz pain staging system for chronic pain (MPSS). METHODS: Patients with chronic pain syndromes who received acupuncture treatment answered a standardized pain questionnaire before and after treatment. The questionnaire included the visual-analogue-scale for the intensity of pain, the pain perception scale for the assessment of affective and sensory components of pain perception, and addressed the patients to the three stages of chronic pain (MPSS). RESULTS: From April 1997 to October 1999, patients (n = 165) suffering from chronic headache and facial pain syndromes (23%), spine associated pain syndromes (48%) or other pain conditions (29%) were subsequently included. Treatment with acupuncture showed a more pronounced reduction of the affective assessment than of the sensory assessment of pain. These effects were particularly pronounced in patients assigned to stage 3 of chronic pain (MPSS). CONCLUSIONS: Acupuncture in patients with high-stage chronic pain syndromes preferentially influences the affective dimension of pain perception. For the estimation of the overall clinical outcome of acupuncture treatment, a differentiation between affective and sensory components of pain is recommended.

Acupuncture Analgesia↗

PubMed2002

A H(2)(15)O positron emission tomography study on mental imagery of movement sequences--the effect of modulating sequence length and direction.

Motor imagery is a state of mental rehearsal of single movements or movement patterns and has been shown to recruit motor networks overlapping with those activated during movement execution. We wished to examine whether the brain areas subserving control of sequential processes could be delineated by pure mental imagery, their activation levels reflecting the processing demands of a sequential task. We studied six right-handed volunteers (39.0 +/- 14 years) with H(2)(15)O positron emission tomography (PET) while they continuously mentally pursued with their right hand one of five sequences differing in complexity (i.e., increases in sequence length, single-finger repetitions, and reversals). Conditions were repeated twice, alternating with two rest scans. Each imagined single motor element was paced at a frequency of 1 Hz. Significant activation increases (P < 0.05, corrected) associated with imagination of right finger movement sequences (conditions I to V combined)--compared to the rest condition--were observed in left sensorimotor cortex (M1/S1) and the adjacent inferior parietal cortex. Further activation increases (P < 0.001, uncorrected) occurred in bilateral dorsal premotor (PMd) cortex, left caudal supplementary motor area, bilateral ventral premotor cortex, right M1, left superior parietal cortex, left putamen, and right cerebellum. Activation decreases occurred in bilateral prefrontal and right temporo-occipital cortex. Activation increases that correlated with sequence complexity were observed only in specific areas of the activated network, notably in left PMd, right superior parietal cortex, and right cerebellar vermis (P < 0.05, corrected). In conclusion, our study, by varying the sequence structure of imagined finger movements, identified task-related activity changes in parietopremotor-cerebellar structures, reflecting their role in mediating sequence control.

Adult↗

PubMed2001

Age-related decrease in paired-pulse intracortical inhibition in the human primary motor cortex.

Using biphasic magnetic stimuli, paired-pulse transcranial magnetic stimulation (TMS) at short interstimulus intervals (ISIs) was employed to investigate age-related changes in the balance between intracortical inhibition and facilitation. In 26 right-handed healthy individuals, motor evoked potentials were recorded from the relaxed right first dorsal interosseus muscle after paired-pulse TMS of the left primary motor hand area. The magnitude of intracortical paired-pulse inhibition at ISIs of 1-5 ms was markedly reduced in elderly individuals, whereas no age effect was observed for intracortical paired-pulse facilitation at ISIs of 11-15 ms. This finding demonstrates that normal aging is associated with a relative decrease in the excitability of intracortical inhibitory circuits. In conclusion, paired-pulse TMS provides a non-invasive means of studying age-related functional changes in the motor cortex.

Adult↗

PubMed2001

Expression of GABA(B1) and GABA(B2) mRNA in the human brain.

GABA(B) receptors are widely expressed in the CNS. The distribution of the recently cloned GABA(B1) receptor is highly concordant with GABA(B) ligand binding sites, but experiments with transfected cell lines indicate that GABA(B1) has to heterodimerize with GABA(B2) to gain the functionality of a native GABA(B) receptor. Using in situ hybridization we investigated the expression of GABA(B1) and GABA(B2) mRNAs in the human brain. Both transcripts were detectable in prefrontal cortex, hippocampus and cerebellum with no apparent mismatch. A distinct expression of GABA(B1) was detected in putative Bergmann glia. In the human striatum GABA(B1) mRNA was expressed in moderate amounts, whereas the GABA(B2) mRNA signal was not clearly above background. According to our data, the current concept on GABA(B) receptor composition needs re-evaluation, at least for certain brain structures.

Aged↗