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Biomedical subjects

A Thiel

Publications and source records attributed to A Thiel.

At least 55 records · Page 3Linked to original sources
PubMed2000

Ectopic thyroid tissue in the left ventricular outflow tract.

Ectopic thyroid tissue in the heart (struma cordis) is rare. The only report from a hemodynamically significant obstruction of the left ventricular outflow tract (LVOT) by a heterotopic thyroid gland was published in 1988. In our patient, a 42-year-old woman with recurrent chest pain, two spheric cardiac tumors were diagnosed by transthoracal echocardiography. One of the tumors, obstructing the LVOT, could successfully be resected under cardiopulmonary bypass. The pathologic examination showed a colloid-filled ectopic thyroid gland. The second tumor, which was entirely located in the submembraneous part of the interventricular septum, had no hemodynamic influence, and was left in situ to avoid surgical damage of adjacent intraseptal structures. The midterm follow-up showed no recurrence.

Adult↗
PubMed2000

Symptoms of eating disorders in obsessive-compulsive disorder.

OBJECTIVE: Despite some empirical evidence suggesting an association between primary OCD and eating disorder (ED) within the 'obsessive-compulsive spectrum', the relationship at a symptomatological level has not been investigated. METHOD: First, comparisons of Eating Disorder Inventory (EDI) scores between 61 patients with primary OCD and 288 control subjects were performed. Secondly, the associations between EDI subscores and Hamburg Obsessive-Compulsive Inventory (HZI) dimensions in OCD patients were investigated by multiple regression analyses, controlling for the impact of general psychopathology. RESULTS: The OCD patients showed significantly higher EDI-scores than controls. However, only distinct OCD symptom dimensions were significantly associated with the core symptoms of ED in females. CONCLUSION: Our results point to a differential gender and symptom-specific relationship between OCD and ED, calling into question a simple dimensional conceptualization of the 'obsessive-compulsive spectrum'.

Adult↗
PubMed2000

Quantitative analysis of gene expression with an improved green fluorescent protein. p6.

The fast and easy in vivo detection predestines the green fluorescent protein (GFP) for its use as a reporter to quantify promoter activities. We have increased the sensitivity of GFP detection 320-fold compared to the wild-type by constructing gfp+, which contains mutations improving the folding efficiency and the fluorescence yield of GFP+. Twelve expression levels were measured using fusions of the gfp+ and lacZ genes with the tetA promoter in Escherichia coli. The agreement of GFP+ fluorescence with beta-galactosidase activities was excellent, demonstrating that the gfp+ gene can be used to accurately quantify gene expression in vivo. However, expression of the gfp+ gene from the stronger hsp60 promoter revealed that high cellular concentrations of GFP+ caused an inner filter effect reducing the fluorescence by 50%, thus underestimating promoter activity. This effect is probably due to the higher absorbance of cells containing GFP+. Thus promoters with activities differing by about two orders of magnitude can be correctly quantified using the gfp+ gene. Possibilities of using GFP variants beyond this range are discussed.

Antiporters↗
PubMed2000

[New antidepressive drugs in comparison with classical tricyclics. Mechanism of action and clinical evaluation].

During the last decade several new agents have been introduced in the treatment of depressive disorders. In comparison to classical tricyclic antidepressants, these agents have less side effects and a very low toxicity. Selective inhibitors of serotonin reuptake do not produce sedation; however, in the initial phase of treatment this is not always an advantage. In contrast, receptor antagonists, such as mirtazapin and nefazodone have moderate sleep-inducing properties. Selective agents are also characterized by certain pharmacologic interactions which can lead to considerable inhibition of the metabolism of other drugs. Classical antidepressants still play an important role in the treatment of severe depressive episodes. Different synaptic effects of new antidepressants lead to an increased availability of monoaminergic neurotransmitters. The article summarizes the most important neurobiological consequences of these acute synaptic effects which might be more closely associated with neurobiological correlates of depression. The authors conclude about the advantages and disadvantages of the different classes of antidepressants from a clinical point of view.

Animals↗
PubMed2000

Respiratory sensitization to diphenyl-methane-4,4'-diisocyanate (MDI) in guinea pigs: impact of particle size on induction and elicitation of response.

The impact of particle size of aerosolized polymeric diphenylmethane-4,4'-diisocyanate (MDI) for the induction and elicitation of respiratory sensitization was evaluated. Four groups of 16 female guinea pigs each received either the vehicle, repeated intradermal (id) injections (3 x 0.3% MDI), one high-level inhalation exposure of 15 min to 135 mg MDI/m(3) air using a small aerosol (MMAD approximately 1.7 microm) or large aerosol (MMAD approximately 3.8 microm). Three weeks later, animals were challenged subsequently with two ramped concentrations of MDI aerosol (average concentrations 16 and 49 mg/m(3) air, each for 15 min) and two different particle sizes, i.e., the MMAD was either approximately 1.6 microm or approximately 5.1 microm for the small- and large-size aerosol, respectively. Respiratory sensitization was assessed by two endpoints: the measurement of respiratory rate, and examination of influx of eosinophilic granulocytes into the mucosa and submucosa of the trachea, bronchi, and lung-associated lymph nodes (LALN). The recruitment of eosinophilic granulocytes into bronchial tissues was subdivided as follows: muscularis mucosae, submucosa, and perivascular. From measurements of respiratory rate, it would appear that guinea pigs sensitized by id injections or by inhalation exposure with the large aerosol tended to display a higher responsiveness than naive controls when challenged with the small aerosol. The recruitment of eosinophilic granulocytes in the bronchial tissue was greater in both inhalation induction groups as compared to the vehicle control. It appears that there was a somewhat greater response in animals sensitized by id injections or by inhalation exposure with the large aerosol and challenged with the small aerosol. Topographically, this difference was apparent only at the bronchial perivascular level and lung-associated lymph nodes (LALN), whereas at the submucosal and muscularis mucosae level the impact on particle size tended to be less pronounced. In summary, this study suggests that a brief, high-level inhalation exposure of MDI aerosol caused a sensitization of bronchial tissues in guinea pigs. The higher sensitization potency of the large aerosol may possibly be related to a dosimetric phenomenon because of the greater fraction of deposition of large particles within the upper respiratory tract. Overall, challenge exposures with this type of irritant aerosol appear to evoke more consistent effects when the MMAD is in the range of approximately 2 rather than approximately 5 microm.

Administration, Inhalation↗
PubMed2000

Late resolution of diffusion-weighted MRI changes in a patient with prolonged reversible ischemic neurological deficit after thrombolytic therapy.

BACKGROUND: Reduced apparent diffusion coefficients (ADCs) correlate with cerebral ischemia. The combination of ADC with techniques to measure cerebral perfusion may help to assess the effect of treatment. CASE DESCRIPTION: The authors describe a patient who experienced an acute stroke with hemianopia, consequently treated with intravenous recombinant tissue plasminogen activator. Positron emission tomographic imaging and MRI, including diffusion-weighted MRI, were performed during and shortly after treatment with recombinant tissue plasminogen activator and 34 to 35 hours later. Cerebral perfusion of the left occipital region was reduced to 74%. Diffusion-weighted MRI detected a territory of restricted water movement in the corresponding area. Further magnetic resonance sequences did not show any pathologies. In follow-up, positron emission tomography demonstrated reperfusion. The volume of diffusion and ADC abnormalities detected by MRI decreased markedly. A few hours later, the patient recovered completely. A third MRI examination 10 days later showed normal findings. CONCLUSIONS: In a patient with prolonged reversible ischemic neurological deficit, resolution of early diffusion changes corresponded to cerebral reperfusion and to the recovery of clinical symptoms.

Acute Disease↗
PubMed2000

Piracetam improves activated blood flow and facilitates rehabilitation of poststroke aphasic patients.

BACKGROUND AND PURPOSE: In a prospective, double-blind, placebo-controlled study, it was investigated whether piracetam improves language recovery in poststroke aphasia assessed by neuropsychological tests and activation PET measurement of cerebral blood flow. METHODS: Twenty-four stroke patients with aphasia were randomly allocated to 2 groups: 12 patients received 2400 mg piracetam twice daily, 12 placebo. Before and at the end of the 6-week treatment period in which both groups received intensive speech therapy, the patients were examined neuropsychologically and studied with H(2)(15)O PET at rest and during activation with a word-repetition task. Blood flow was analyzed in 14 language-activated brain regions defined on reconstructed surface views from MRI coregistered to the PET images. RESULTS: Before treatment, both groups were comparable with respect to performance in language tasks and to type and severity of aphasia. In the piracetam group, increase of activation effect was significantly higher (P:<0.05) in the left transverse temporal gyrus, left triangular part of inferior frontal gyrus, and left posterior superior temporal gyrus after the treatment period compared with the initial measures. The placebo group showed an increase of activation effect only in the left vocalization area. In the test battery, the piracetam group improved in 6 language functions, the placebo group only in 3 subtests. CONCLUSIONS: Piracetam as an adjuvant to speech therapy improves recovery of various language functions, and this effect is accompanied by a significant increase of task-related flow activation in eloquent areas of the left hemisphere.

Adolescent↗
PubMed2000

Cerebral blood flow and glucose metabolism in multi-infarct-dementia related to primary antiphospholipid antibody syndrome.

The primary antiphospholipid antibody syndrome (PAPS) has been described in patients with a history of fetal loss, thrombocytopenia and arterial or venous thrombosis. In PAPS, a prothrombotic state is mediated by antiphospholipid antibodies (aPLs) leading to disseminated thromboembolic vascular occlusion. Today, the presence of aPLs in the serum is considered as a distinct risk factor for recurrent stroke in young adults. Some PAPS patients develop a multi-infarct-syndrome with a stepwise decline of higher cortical functions. We report on a 55-year-old man suffering from progressive dementia and PAPS, in whom cerebral glucose metabolism and blood flow were examined by positron emission tomography (PET). Cerebral atrophy and moderate signs of leukaraiosis were detected in magnetic resonance imaging (MRI), whereas the PET scans showed a considerable diffuse impairment of cortical glucose metabolism combined with a reduced cerebral perfusion in the arterial border zones. These findings indicate that PAPS-associated vascular dementia is accompanied by a cortical neuronal loss, presumably caused by a small-vessel disease with immune-mediated intravascular thrombosis. This case shows that pathological findings in PAPS are congruent to cerebral changes of metabolism and blood flow in systemic lupus erythematosus (SLE).

Antiphospholipid Syndrome↗
PubMed2000

Enhanced accuracy in differential diagnosis of radiation necrosis by positron emission tomography-magnetic resonance imaging coregistration: technical case report.

OBJECTIVE AND IMPORTANCE: To demonstrate the usefulness of positron emission tomography-magnetic resonance imaging (MRI) coregistration for differentiation of radiation necrosis and recurrent tumor in stereotactic planning. CLINICAL PRESENTATION: T1-weighted MRI scans of a 43-year-old woman revealed a contrast-enhancing lesion 4 years after open removal of a recurrent, right parieto-occipital Grade II oligodendroglioma and subsequent external radiation therapy. The suspected contrast-enhancing lesion revealed only moderate tracer uptake (1.3 times the uptake in the contralateral normal cortex) in a coregistered [11C]methionine positron emission tomographic scan. Approximately 15 mm posterior and mesial to the center of the contrast-enhancing lesion, however, an area of higher tracer uptake was found (1.8 times that of the contralateral normal cortex), which exhibited only very minor contrast enhancement on MRI. TECHNIQUE: The coregistered images were used for planning stereotactic serial biopsies, from the contrast-enhancing lesion as well as from the area with higher methionine uptake. Histological examination demonstrated that the contrast-enhancing lesion with low methionine uptake was necrotic tissue, and the nonenhancing area with high methionine uptake was recurrent tumor. CONCLUSION: High-resolution positron emission tomography and modern coregistration techniques allow differentiation of contrast enhancement and methionine uptake in irradiated brain tissue within small areas. High methionine uptake is typical for recurrent tumor tissue and can be differentiated from minor tracer accumulation resulting from disruption of the blood-brain barrier or macrophage activity within the necrotic area.

Adult↗
PubMed2000

Prototype of a JAVA/DICOM image server with integrated findings and data security.

The transfer of medical data within heterogeneous hard- and software infrastructures requires platform-independent standardized protocols and data formats such as DICOM. To avoid costly vendor-specific solutions a DICOM server was implemented in JAVA thereby enabling the data access via internet browser technology. The most important patient and image acquisition information were extracted from the DICOM images and stored into a relational database. For an integrated view patient information such as radiological findings were transferred from the Radiological Information System (RIS) into the data base. Image data were accessed either by a fast preview tool or using a DICOM viewer. Since DICOM does not include inherent data security mechanisms, a second tool allowed the DICOM-conform encryption of DCIOM data for a secure long term storage on CD-R or across unsecure networks.

Computer Security↗
PubMed2000

Realization of security concepts for DICOM-based distributed medical services.

Exploiting distributed hard- and software resources for telemedicine requires a fast, secure, and platform-independent data exchange. Standards without inherent security mechanisms such as DICOM may ease non-authorized data access. Therefore, exemplary telemedical data streams were analyzed within the Berlin metropolitan area network using specialized magnetic resonance imaging techniques and distributed resources for data postprocessing. For secure DICOM communication both the Secure Socket Layer Protocol and a DICOM-conform partial encryption of patient-relevant data were implemented. Partial encryption exhibited the highest transfer rate and enabled a secure long-term storage. Different data streams between secured and unsecured networks were realized using partial encryption.

Berlin↗
PubMed1999

Expression of novel surface antigens on early hematopoietic cells.

The purpose of this report is to demonstrate the expression of very recently identified surface antigens on CD34+ and AC133+ bone marrow (BM) cells. Coexpression analysis of AC133 and defined antigens on CD34+ BM cells revealed that the majority of the CD164+, CD135+, CD117+, CD38low, CD33+, and CD71low cells resides in the AC133+ population. In contrast, most of the CD10+ and CD19+ B cell progenitors and a fraction of the CD71high population are AC133-, indicating that CD34+AC133+ cells are enriched in primitive and myeloid progenitor cells, whereas CD34+AC133- cells mainly consist of B cell and late erythroid progenitors. This corresponds to the highly reduced percentage of CD10+ B cells and the absence of CD71high erythroid progenitors on AC133+ selected BM cells. A portion of 0.2-0.7% of the AC133+ selected cells do not coexpress CD34. These cells are very small and define a uniform CD71-, CD117-, CD10-, CD38low, CD135+, HLA-DRhigh, CD45+ population with unknown delineation. Four color analysis on CD34+CD38- BM cells revealed that virtually all of these primitive cells express AC133. Using an improved liposome-enhanced labeling technique for the staining of weakly expressed antigens, subsets of this population could be identified which express the angiopoietin receptors TIE (67.6%) and TEK (36.8%), the vascular endothelial growth factor receptors FLT1 (7%), FLT4 (3.2%), and KDR (10.4%), or the receptor tyrosine kinases HER-2 (15.4%) and FLT3 (CD135; 77.6%). Our results suggest that the CD34+CD38- population is heterogeneous with respect to the expression of the analyzed receptor tyrosine kinases.

AC133 Antigen↗
PubMed1999

Differential capacity of left and right hemispheric areas for compensation of poststroke aphasia.

As previous functional neuroimaging studies could not settle the controversy regarding the contribution of dominant and subdominant hemisphere to recovery from poststroke aphasia, language performance was related to H2(15)O-positron emission tomographic activation patterns in 23 right-handed aphasic patients 2 and 8 weeks after stroke. In patients classified according to the site of lesion (frontal, n = 7; subcortical, n = 9; temporal, n = 7) and in 11 control subjects, flow changes caused by a word repetition task were calculated in 14 regions representing eloquent and contralateral homotopic areas. These areas were defined on coregistered magnetic resonance imaging scans and tested for significance (Bonferroni corrected t test, alpha = 0.0036). At baseline, differences in test performance were only found between the subcortical and temporal group. The extent of recovery, however, differed and was reflected in the activation. The subcortical and frontal groups improved substantially; they activated the right inferior frontal gyrus and the right superior temporal gyrus (STG) at baseline and regained left STG activation at follow-up. The temporal group improved only in word comprehension; it activated the left Broca area and supplementary motor areas at baseline and the precentral gyrus bilaterally as well as the right STG at follow-up, but could not reactivate the left STG. These differential activation patterns suggest a hierarchy within the language-related network regarding effectiveness for improvement of aphasia; ie, right hemispheric areas contribute, if left hemispheric regions are destroyed. Efficient restoration of language is usually only achieved if left temporal areas are preserved and can be reintegrated into the functional network.

Adult↗
PubMed1999

Intraarticular, epidural, and intravenous analgesia after total knee arthroplasty.

BACKGROUND: After total knee arthroplasty, patients regularly suffer from severe pain. It is unclear whether epidural or systemic pain therapy is superior in terms of postoperative pain relief, patients' comfort and side effects. A new therapeutic approach, intraarticular opioids, has been suggested with the detection of opioid receptors in inflamed tissue. This method has proven suitable for clinical use in small operations (e.g. knee arthroscopy). In this study, we compared epidural analgesia and intraarticular application of morphine plus "on-demand" intravenous analgesia to "on-demand" intravenous analgesia alone. METHODS: Thirty-seven patients, scheduled for total knee arthroplasty, were randomly assigned to three treatment groups: in group 1 (EPI) patients received bolus doses of morphine via an epidural catheter; in group 2 (IA) an intraarticular bolus of 1 mg of morphine was applied at the end of the operation with subsequent use of a patient-controlled analgesia (PCA) pump; group 3 (Control), in which only PCA was provided, served as control for both analgesic procedures. Main outcome measures included visual analogue pain scales, total morphine consumption, and stress hormones. RESULTS: No statistically significant differences in visual analogue pain scales could be detected between the three groups. Application of intraarticular morphine did not reduce the amount of analgesics required for postoperative analgesia as compared to intravenous analgesia alone. Application of epidural morphine significantly suppressed beta-endorphine release, but did not significantly influence other stress hormones as compared to the control group. CONCLUSION: Epidural and intravenous analgesia after total knee arthroplasty are equivalent methods of pain relief. In major orthopaedic procedures, application of intraarticular morphine does not reduce analgesic requirements.

Adrenocorticotropic Hormone↗