Biomedical subjects

F Schmidt

Publications and source records attributed to F Schmidt.

At least 37 records · Page 2Linked to original sources

PubMed2002

Extremely low vertical-emittance beam in the accelerator test facility at KEK.

Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.

Journal Article↗

PubMed2002

[Development of mycotic aneurysms of the superior mesenteric artery after septic embolism].

Mycotic aneurysms of the aorta and the visceral arteries are life-threatening diseases, due to potential rupture and organ or limb ischemia. They occur in endocarditis, immunodeficiency, bacteremia and fungemia, and have a poor prognosis. We report on a case of a 54-year-old male patient suffering from abdominal angina after mitral valve replacement for septic mycotic endocarditis. In presence of a mycotic-embolic occlusion of the left popliteal artery and multiple septic organ infarctions a mycotic aneurysm of the superior mesenteric artery was found in abdominal spiral-CT. Based on sequential spiral-CT examinations, this case demonstrates the development of a septic aneurysm of the superior mesenteric artery.

Aneurysm, Infected↗

PubMed2002

[MR-guided preoperative localization and percutaneous core biopsy of suspected breast lesions. Possibilities and experience on the vertically open 0.5-T-system].

PURPOSE: To evaluate the feasibility of performing breast interventions in a vertically open 0.5 T MR system (SIGNA SP/i, GE Medical Systems). To develop fitted equipment and to establish preoperative wire localization and percutaneous breast core biopsy as clinical routine procedures. PATIENTS AND METHODS: Initially, we applied a localization method with the patient placed in a sitting position in 31 cases using a single loop coil and a self-developed fixation device. Subsequently, 46 wire localizations and 28 percutaneous core biopsies were carried out in prone patient position using an open breast coil with an integrated biopsy device. The used instruments were either MR-compatible (18 G biopsy needle and localization wire, 14 G coaxial needle, prototype of a 16 G double-shoot gun) or MR-safe (double-shoot gun with 16 G needle). RESULTS: After biopsy we found the needle tip (18 G for a wire localization and 14 G for a percutaneous core biopsy, respectively) placed either within or close to the lesions (< 10 mm distance) for all patients. Out of a total of 66 benign lesions and 39 malignant tumors we missed the lesion (12 mm mean diameter, 4-25 mm range) during open biopsy in two cases and obtained a false negative result for one percutaneous biopsy of a 5 mm lesion. CONCLUSION: Preoperative wire localization and percutaneous core biopsy of suspicious breast lesions demonstrated by MRI can be carried out a vertically open 0.5 T MR scanner. The degree of accuracy is comparable with that of X-ray or ultrasound-guided procedures. A follow-up has to be performed in cases with a negative biopsy.

Adult↗

PubMed2002

Myelopathy in primary Sjögren's syndrome: diagnostic and therapeutic aspects.

We report a patient with a myelopathy in primary Sjögren's syndrome, proven by salivary gland biopsy and specific antibodies. Under steroid medication, the patient had a remitting and relapsing clinical course. The severity of clinical symptoms correlated with a transient contrast uptake in spinal magnetic resonance imaging. Under a treatment with azathioprine and prednisone the patient has suffered no relapse within the last 20 months. Although this is only a case report, the combination of azathioprine and prednisone may be a valuable medication in chronic cases of Sjögren's syndrome with neurologic symptoms.

Aged↗

PubMed2001

Modafinil for excessive daytime sleepiness in myotonic dystrophy.

The authors conducted an open-label trial of modafinil for excessive daytime sleepiness in myotonic dystrophy. Eleven patients were evaluated: two were not treated because of obstructive sleep apnea, and nine received 200 to 400 mg modafinil/day for an average of 16.4 weeks. There were no major side effects. Average sleep latency as measured by the Multiple Sleep Latency Test increased from 7.3 to 22.7 minutes ( p = 0.00013), and average Epworth Sleepiness Scale score decreased from 13.25 to 7.75 (p = 0.01028). Modafinil shows evidence of effectiveness for excessive daytime somnolence in myotonic dystrophy and should be investigated further.

Adult↗

PubMed2001

Evidence for a three-nucleon-force effect in proton-deuteron elastic scattering.

Developments in spin-polarized internal targets for storage rings have permitted measurements of 197 MeV polarized protons scattering from vector polarized deuterons. This work presents measurements of the polarization observables A(y), iT11, and C(y,y) in proton-deuteron elastic scattering. When compared to calculations with and without three-nucleon forces, the measurements provide further evidence that three-nucleon forces make a contribution to the observables. This work indicates that three-body forces derived from static nuclear properties appear to be crucial to the description of dynamical properties.

Journal Article↗

PubMed2001

Glioma cell sensitivity to topotecan: the role of p53 and topotecan-induced DNA damage.

Topotecan is a topoisomerase I inhibitor which is currently evaluated as an adjuvant agent for malignant glioma. Here, we analysed the effects of topotecan on 12 human malignant glioma cell lines in vitro. All cell lines expressed topoisomerase I mRNA. High p53 protein levels, but not genetic or functional p53 status, were associated with increased topotecan-induced DNA/topoisomerase I complex formation. Neither functional p53 status, nor p53 protein levels, nor complex formation predicted topotecan-induced growth inhibition. We thus confirm a possible role for p53 protein in modulating topoisomerase I activity but conclude that the major molecular determinants of topotecan sensitivity in glioma cells await identification.

Antineoplastic Agents↗

PubMed2001

The human dopamine transporter gene: the 5'-flanking region reveals five diallelic polymorphic sites in a Caucasian population sample.

The 5'-flanking region of the human dopamine transporter (hDAT) was systematically screened for variants by single strand conformation analysis (SSCA) between -1586 and +97 basepair (bp) relative to the transcription start site. Five diallelic polymorphisms were found, which were shown to be due to single base substitutions: T-67A, G-660C, C-839T, C-1169G, T-1476G. In a population sample of 119 unrelated Caucasians, allele frequencies of the rarer allele were 47% for -67T, 3% for -660C, 45% for -839T, 50% for -1169G, and 8% for -1476G, respectively. Among 15 observed haplotypes, seven haplotypes collected a frequency of about 96% in our sample. T-67A, C-839T, C-1169G, T-1476G were related to potential transcriptional recognition sites. These findings and the occurrence of distinct haplotypes at the hDAT promoter locus in a Caucasian population sample make this region a promising target in the context of linkage and association studies in certain diseases.

5' Untranslated Regions↗

PubMed2001

Transnasal and transsphenoidal MRI-guided biopsies of petroclival tumors.

Magnetic resonance imaging (MRI) allows excellent tissue characterization in the area of the petroclival region and can depict lesions not visualized with ultrasound or computed tomography (CT). The aim of this study was to demonstrate the clinical feasibility and utility of an interactive MR-guidance system to target and biopsy tumors in the petroclival region. MRI-guided biopsies of 10 patients with tumors in the clivus and petrous apex were performed in an open 0.5-T MR system. Lesions were targeted through a transsphenoidal or transnasal approach. Imaging during biopsies was achieved by a combination of standard and interactive mode. T1-weighted spin-echo, T2-weighted fast spin-echo (FSE), and three-dimensional T1-weighted gradient-echo (GRE) scans (standard mode) were selected to provide optimal tissue characterization for both the lesion and surrounding structures and varied according to the anatomic site. For interactive imaging, T1-weighted GRE and T2-weighted FSE sequences were used. We performed MRI-guided transsphenoidal biopsies in 10 patients who had lesions identified by CT (n = 5) and/or MRI (n = 10). The indications for biopsies were to differentiate between suspected malignant processes (n = 4 ) and benign processes (n = 6). Lesions adjacent to structures like the internal carotid artery were accurately targeted in particular. All biopsies were performed successfully and were the basis for selection of further treatment. No complications occurred during the procedures. An open MR system allows interactive control of biopsies in the area of the petroclival region, providing maximum patient safety and diagnostic accuracy not possible in other systems. The advantages of MRI tissue characterization are combined with an interactive, one-step method of localization and targeting, as well as tissue sampling. J. Magn. Reson. Imaging 2001;13:3-11.

Biopsy, Needle↗

PubMed2001

Influence of gender on the diurnal variation of urine production and micturition characteristics of the rat.

The diurnal variation in the frequency/volume characteristics of male and female conscious rats was evaluated with reference to fluid consumption and urine production. Baseline values of the micturition volume and frequency of nine male and 10 female SD adult rats were measured over a 24-hour time period. The level of initial hydration conditions was standardized with 5 ml of water administered orally. With animals in a metabolism chamber having free access to water, the total volume of water consumed, the frequency/volume characteristics during micturition and the urine production rate were derived from the measurements of voided volume as detected by a digital balance. To establish reliability of measurements two separate micturition studies were done per rat at an interval of 1 week. Mean frequency of micturition and mean volume voided per micturition and urine production rate were computed in 3-hour time bins and represented over the 24-hour period. In addition the mean values of the number of micturitions and mean micturated volumes during the day/dark cycle were evaluated. The results show significant gender specificity in water consumption, urine production, and diurnal variations in micturition frequency/volume characteristics. Females consistently consume significantly larger amounts of water (83%) than males while urine production rate was correspondingly higher in females. It is concluded that water consumption and urine production are gender-specific. Because higher volumes of water are imbibed by females than males, the frequency/volume characteristic of micturition in the rat is also gender-specific. Data suggest that the volume voided per micturition depends on the urine production rate.

Animals↗

PubMed2001

[Interferon alpha-associated agranulocytosis during clozapine treatment. Case report and status of current knowledge].

Little is known about possibilities of chronic hepatitis C treatment with interferon-alpha (IFN-alpha) in psychiatric patients continuously taking antipsychotics. We report on a 28-year-old hepatitis C-positive man with paranoid psychosis. He was successfully treated with clozapine, an atypical antipsychotic drug which is known for the risk of granulocytopenia and agranulocytosis. With doses up to 200 mg/day over 3 years, he showed no remarkable changes in WBC. Because of the chronic hepatitis C with genotype 3a, additional treatment was started with IFN-alpha (s.c., 3 x 6 million IU/week). After 2 months of therapy he developed a severe agranulocytosis. Both clozapine and IFN-alpha were discontinued, and his WBC returned to normal. Results from bone marrow examination were compatible with a toxic reaction possibly caused by either or both medications. We discuss possible problems with IFN-alpha during the treatment of psychiatric patients, interactions with psychiatric medication, and hematotoxic side effects like those from clozapine. We recommend combining IFN-alpha with less "toxic" antipsychotics and weekly checks of WBC.

Adult↗

PubMed2001

[Fusion of MRI, fMRI and intraoperative MRI data. Methods and clinical significance exemplified by neurosurgical interventions].

The aim of this work was to realize and clinically evaluate an image fusion platform for the integration of preoperative MRI and fMRI data into the intraoperative images of an interventional MRI system with a focus on neurosurgical procedures. A vertically open 0.5 T MRI scanner was equipped with a dedicated navigation system enabling the registration of additional imaging modalities (MRI, fMRI, CT) with the intraoperatively acquired data sets. These merged image data served as the basis for interventional planning and multimodal navigation. So far, the system has been used in 70 neurosurgical interventions (13 of which involved image data fusion--requiring 15 minutes extra time). The augmented navigation system is characterized by a higher frame rate and a higher image quality as compared to the system-integrated navigation based on continuously acquired (near) real time images. Patient movement and tissue shifts can be immediately detected by monitoring the morphological differences between both navigation scenes. The multimodal image fusion allowed a refined navigation planning especially for the resection of deeply seated brain lesions or pathologies close to eloquent areas. Augmented intraoperative orientation and instrument guidance improve the safety and accuracy of neurosurgical interventions.

Adult↗

PubMed2001

Lovastatin and phenylacetate induce apoptosis, but not differentiation, in human malignant glioma cells.

Induction of differentiation is an attractive approach to the management of infiltrative tumors such as malignant glioma. Here, we report that lovastatin and phenylacetate induce apoptosis, but fail to induce differentiation, in malignant glioma cell lines and untransformed rat astrocytes. Lovastatin and phenylacetate promote p21 accumulation but fail to induce cell cycle arrest. BCL-2 gene transfer inhibits apoptosis induced by lovastatin but not apoptosis induced by phenylacetate. Wild-type p53 gene transfer promotes lovastatin-induced apoptosis in p53 wild-type LN-229 cells but not in p53 mutant T98G cells. Phenylacetate-induced apoptosis is attenuated by wild-type p53 gene transfer in both cell lines. Neither lovastatin nor phenylacetate modulate glioma cell sensitivity to CD95 ligand-induced apoptosis or cancer chemotherapy. Thus, this study provides no rationale for clinical trials of lovastatin or phenylacetate in the differentiation therapy of malignant glioma. We conclude that neoplastic glioma cells as well as untransformed rat astrocytes are refractory to the induction of differentiation by lovastatin and phenylacetate.

Animals↗

PubMed2001

Management of congenital abnormalities of the donor lung.

Congenital abnormalities were encountered in three donor lungs. A donor tracheal bronchus was incorporated into the right bronchial anastomosis. Anomalous pulmonary venous return of the right upper lobe to the superior vena cava and the left upper lobe to the innominate vein were managed by bridging the anomalous veins to the left atrial cuff with autologous pericardium and donor iliac vein, respectively.

Bronchi↗

PubMed2001

Pryce's type I pulmonary intralobar sequestration presenting with massive hemoptysis.

Pryce's type I intralobar sequestration, in which a region of lung exhibits tracheobronchial continuity and aberrant systemic arterial supply, is most frequently asymptomatic and discovered incidentally. While hemoptysis may be a common presenting symptom, massive hemoptysis is rarely seen. We document a case of a 58-year-old man, previously asymptomatic, whose initial presentation was that of massive hemoptysis. The radiographic, intraoperative and pathologic findings in our patient confirm that his sequestration was of Pryce's type I. Ann Diagn Pathol 5:91-95, 2001.

Angiography↗

PubMed2001

Positron emission tomography with [(18)F]fluoro-2-deoxy-D-glucose for diagnosis and staging of bile duct cancer.

Malignant tumors with high glucose metabolic rates accumulate [18F]-fluorodeoxyglucose (FDG), a positron emitting tracer. The aim of this study was to evaluate FDG positron emission tomography (PET) for detection and staging of human cholangiocarcinoma (CC). Patients with adenocarcinoma of the biliary tree (n = 26), with benign lesions of the bile ducts (n = 8), and 20 control patients underwent FDG-PET (370 MBq [18F]-FDG, Siemens ECAT EXACT HR(+)). In a blinded fashion, 4 independent experts evaluated the PET scans visually and semiquantitatively using the standardized uptake value and a tumor/non-tumor ratio. All adenocarcinomas and benign lesions (sclerosing cholangitis, bile duct adenoma, Caroli's disease) were histologically proven and imaged by magnetic resonance imaging and endoscopic retrograde cholangioscopy. True-positive PET scans were obtained in 24 of 26 CC and false-negative scans in the other 2 (sensitivity 92.3%). The PET scan was true-negative in 18 of 20 controls and in all 8 benign biliary lesions (specificity 92.9%). Visual and semiquantitative evaluation using tumor/non-tumor ratios were equally accurate (accuracy 92.6%) whereas evaluation by standardized uptake value revealed lower accuracy (P <.05). Regional or hepatoduodenal lymph node metastases were detected with PET in only 2 of 15 cases whereas distant metastases (peritoneal carcinomatosis, pulmonary metastases) were diagnosed in 7 of 10 cases. In conclusion, PET is highly sensitive and specific for the detection and localization of CC. It can be helpful for diagnosis of distant metastases but is not suitable for detection of regional lymph node metastases.

Adenocarcinoma↗

PubMed2001

[Value of magnetic resonance tomography for interventions in the ENT specialty].

PURPOSE: Presentation of new concepts and applications of MR-guided head and neck surgery are presented. Examples of diagnostic and therapeutic procedures such as evaluation of transseptal tumor biopsies, placement of afterloading catheters for brachytherapy, and microscopic surgery of paranasal sinuses in the open MRI are discussed. MATERIAL AND METHODS: 24 MRI-guided ENT-procedures (14 transsphenoidal biopsies, one transnasal biopsy, 6 placements of brachytherapy catheters, and 3 operations of the paranasal sinuses) were performed in an open 0.5 T MR system. RESULTS: Localisation and/or extension of all lesions as well as the placement of biopsy needles or catheters were determined with great precision during the interventions. CONCLUSIONS: Surgical risk and postoperative morbidity are significantly reduced in MR-guided surgery of the petroclival region and the region of head and neck compared to other, conventional methods. Thus, interventional MRI-guidance optimizes minimal invasive surgery and catheter placement in difficult anatomical regions like the petroclival region.

Adolescent↗

PubMed2001

[Clinical relevance and treatment possibilities of rapid cycling in patients with bipolar disorder].

In the actual version of the WHO diagnostic guidelines, the ICD-10, subtypes of bipolar disorder are not specified, in contrast to the American DSM-IV, where bipolar disorder has already been differentiated in bipolar I (severe manic and depressive episodes) and bipolar II disorder (depressive and hypomanic episodes). Furthermore, aspects of the longitudinal course of the illness, like rapid cycling (RC), are reflected as well. Rapid cycling is defined as four or more affective episodes within one year of the illness. It has been postulated that rapid cycling is related with a poor response to lithium, to the same extent as mixed episodes or an atypical onset (depressive episode first) of the disease. Here, the current status of alternative pharmacological and supportive therapy of rapid cycling is presented and discussed. Furthermore, the article also displays biological parameters associated with rapid cycling like higher prevalence in women, hypothyreoidism, subtype of bipolar disorder, COMT-allele, influence of sleep or risk of antidepressant induced cycling.

Animals↗