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Biomedical subjects

S Krämer

Publications and source records attributed to S Krämer.

At least 19 recordsLinked to original sources
PubMed2006

[Therapeutic possibilities of probiotics in antibiotic-related diarrhea].

One of the major problems associated with the use of antibiotics is the occurrence of antibiotic-related diarrhea. Although most such cases of diarrhea are harmless, in individual cases it may lead on to fulminant colitis. In 10-20% of the patients, the causal factor is infection with Clostridium difficile, which multiplies unhindered in patients on antibiotics. In the meantime, controlled, randomized studies have shown that probiotics can exercise a preventive effect in antibiotic-related diarrhea. The administration of Saccharomyces boulardii or Lactobacillus rhamnosus GG reduces the relative risk of an antibiotic-related diarrhea developing by 0.5. The data are more uniform in children than in adults.

Adult↗
PubMed2005

[Comparison of a T1-weighted inversion-recovery-, gradient-echo- and spin-echo sequence for imaging of the brain at 3.0 Tesla].

PURPOSE: The increased T1 relaxation times at 3.0 Tesla lead to a reduced T1 contrast, requiring adaptation of imaging protocols for high magnetic fields. This prospective study assesses the performance of three techniques for T1-weighted imaging (T1w) at 3.0 T with regard to gray-white differentiation and contrast-to-noise-ratio (CNR). MATERIALS AND METHODS: Thirty-one patients were examined at a 3.0 T system with axial T1 w inversion recovery (IR), spin-echo (SE) and gradient echo (GE) sequences and after contrast enhancement (CE) with CE-SE and CE-GE sequences. For qualitative analysis, the images were ranked with regard to artifacts, gray-white differentiation, image noise and overall diagnostic quality. For quantitative analysis, the CNR was calculated, and cortex and basal ganglia were compared with the white matter. RESULTS: In the qualitative analysis, IR was judged superior to SE and GE for gray-white differentiation, image noise and overall diagnostic quality, but inferior to the GE sequence with regard to artifacts. CE-GE proved superior to CE-SE in all categories. In the quantitative analysis, CNR of the basal ganglia was highest for IR, followed by GE and SE. For the CNR of the cortex, no significant difference was found between IR (16.9) and GE (15.4) but both were superior to the SE (9.4). The CNR of the cortex was significantly higher for CE-GE compared to CE-SE (12.7 vs. 7.6, p < 0.001), but the CNR of the basal ganglia was not significantly different. CONCLUSION: For unenhanced T1 w imaging at 3.0 T, the IR technique is, despite increased artifacts, the method of choice due to its superior gray-white differentiation and best overall image quality. For CE-studies, GE sequences are recommended. For cerebral imaging, SE sequences give unsatisfactory results at 3.0 T.

Brain↗
PubMed2005

Runoff modelling using radar data and flow measurements in a stochastic state space approach.

In urban drainage the estimation of runoff with the help of models is a complex task. This is in part due to the fact that rainfall, the most important input to urban drainage modelling, is highly uncertain. Added to the uncertainty of rainfall is the complexity of performing accurate flow measurements. In terms of deterministic modelling techniques these are needed for calibration and evaluation of the applied model. Therefore, the uncertainties of rainfall and flow measurements have a severe impact on the model parameters and results. To overcome these problems a new methodology has been developed which is based on simple rain plane and runoff models that are incorporated into a stochastic state space model approach. The state estimation is done by using the extended Kalman filter in combination with a maximum likelihood criterion and an off-line optimization routine. This paper presents the results of this new methodology with respect to the combined consideration of uncertainties in distributed rainfall derived from radar data and uncertainties in measured flows in an urban catchment within the Emscher river basin, Germany.

Cities↗
PubMed2003

[Occupational disease 2108. Degenerative changes of the cervical spine as a causality criterion in the assessment of discogenic diseases according to BeKV 2108].

With the second amendment to the Ordinance on Occupational Diseases (BeKV) of 18 December 1992, discogenic diseases of the spine are included in the disease register of occupational diseases for the first time. If occupations that impose stress on the spine have been practised for many years, the possibility exists of recognizing degenerative diseases as an occupational disease. In assessment practice, the radiological data on the spine exposed to stress is compared with that of regions which are remote from the stress (cervical/thoracic spine). This pattern of the distribution of degenerative disease is then used as the basis for determining a causal relationship between the occupation causing the stress and disease of the axial skeleton. The pattern of degeneration of the cervical spine was investigated in two groups, one with ( n =153) and one without ( n =333) occupations that impose stress on the lumbar spine. A cumulative score of degenerative changes was elaborated and presented as a new classification. No differences were found between the groups with regard to either the frequency of occurrence, segmental distribution or severity of disease. In both groups, degenerative changes correlated with age. The prevailing assessment practice is discussed on the basis of these data.

Adult↗
PubMed2003

Plasmon energy mapping in energy-filtering transmission electron microscopy.

In this paper, we demonstrate the two-dimensional mapping of plasmon energies by energy-filtering transmission electron microscopy. The maps are obtained from a series of energy-filtered images in the plasmon energy region. Examples are shown for a nano-crystalline Si-B-C-N ceramic. This material contains SiC and Si(3)N(4) grains as well as intergranular regions composed of hexagonal BN (h-BN) and turbostratic carbon (t-C). The different phases can be clearly identified by their specific plasmon energies. An energy resolution of < or =0.1eV is achieved. In addition, the plasmon map of an amorphous carbon film is used to visualize the non-isochromaticity of the Corrected Omega filter (90 degrees filter) of the SESAM2. A procedure is proposed for the correction of the non-isochromaticity.

Journal Article↗
PubMed2003

[Sonographical breast biopsy: how many core biopsy specimens are needed?].

PURPOSE: To determine the optimum number of specimens of a sonographically guided core biopsy of the breast. MATERIALS AND METHODS: From January 2001 to April 2001, sonographically guided core biopsies (coaxial needle: 11 G; core needle: 12 G) were performed on 106 patients with 115 BI-RADS trade mark 4-5 lesions that had corresponding sonographic findings. Five specimens were obtained in anteroposterior direction parallel to the chest wall and each specimen examined histologically. RESULTS: A total of 575 core biopsies produced 545 specimens (94.8 %), with no material obtained in 30 biopsies (5.2 %). The first and second specimen confirmed the diagnosis in 99 of 115 lesions (86 %), with subsequent specimens confirming the diagnosis in 87 % (3 rd specimen), 88 % (4 th specimen) and 82 % (5 th specimen). The additive accuracy of the five core breast specimens was 86 %, 96 %, 98 %, 99 % and 100 %. The possible volume of 78.9 mm 3 as determined by the sample notch of the core needle only furnished an average volume of 38.1 mm 3 (41.1 mm 3 for the 1 st, 40.1 mm 3 for the 2 nd, 37.5 mm 3 for the 3 rd, 36.7 mm 3 for the 4 th and 35.0 mm 3 for 5 th core specimen). CONCLUSION: Sonographically guided core breast biopsy (coaxial needle: 11 G; core needle: 12 G) may require five passes to achieve a diagnostic accuracy of more than 99 %.

Adult↗
PubMed2003

[First experiences with a new vacuum-assisted device for breast biopsy].

OBJECTIVE AND METHODS: Stereotaxic and sonographically guided vacuum biopsies are standard methods in interventional breast procedures. We report about the newly developed sonographically guided and vacuum-assisted VacuFlash (VF) method for breast biopsy. In comparison to the Mammotome system, all components for vacuum biopsy are integrated in the hand-held gun of the VF biopsy system. Our first preliminary results in 5 patients are reported. RESULTS: VF was performed in five patients with a nonpalpable, sonographically detectable lesion. The histopathological examination diagnosed a fibroadenoma in 4 patients and established unremarkable breast parenchyma in 1 patient. Subsequent sonography immediately after the biopsy revealed that 3 of the 5 lesions were completely removed. CONCLUSION: The VF biopsy system is a new, technically perfected and applicable diagnostic method. Its costs, risks and accuracy have to be compared with high-speed core cut biopsy, hand-held Mammotome system and open surgical biopsy. Indications for the VF-biopsy are lesions that are too small, superficial or deep for conventional core biopsy as well as abnormalities where wide sampling is considered important. Complete removal can only be expected when the lesion is small and plays a secondary role in a diagnostic process. High-speed core cut biopsy remains the standard procedure in percutaneous breast interventions to clarify sonographically detected breast lesions.

Biopsy↗
PubMed2003

Ductal carcinoma in situ of the breast: diagnosis and management.

Currently, no precise morphologic or biologic prognostic factors reliably identify patients with ductal carcinoma in situ (DCIS) who are at high risk of disease progression. DCIS is a disease with an extremely favorable prognosis and a small likelihood of dying from breast cancer, regardless of what type of treatment is received. No retrospective or prospective study to date has demonstrated a significant difference in breast cancer specific mortality regardless of treatment. The similarities between DCIS and invasive cancer suggest that an important area for future research should be elucidating the processes that can either unleash or contain the invasive potential of DCIS cells. Thus, an understanding of the biology of DCIS can assist in the prevention, the assessment, and the diagnosis of invasive breast cancer.

Breast↗
PubMed2003

Virtual intra-arterial angioscopy (VIA) of the carotid artery based on helical CT data.

The purpose of this study was to visualize both the vessel wall and atherosclerotic plaques in virtual intra-arterial angioscopy (VIA) based on helical CT data sets. To achieve this in vitro, the optimal reconstruction threshold of the vessel wall was determined to be 56.4% of the maximum enhancement. Using this threshold, 20 patients suffering from symptomatic carotid disease were examined in a helical CT scanner. The degree of stenosis was defined using the North American Symptomatic Endarterectomy Trial (NASCET) criteria and compared with results from digital substraction angiography (DSA). Grading of stenoses was only possible by adding the separately computed plaque geometry to the geometry of the vessel wall in a second step. Correlation between VIA and DSA in low grade, medium grade and high grade stenosis was 88%, 93% and 71%, respectively. Complete occlusions were diagnosed correctly in all patients. Sensitivity and specificity for the correct diagnosis of high grade stenosis was 93.7% and 91.3%, respectively. A realistic depiction of intraluminal structures in carotid arteries can only be generated by displaying both the vessel wall and plaque structures simultaneously.

Aged↗
PubMed2002

[Neointimal hyperplasia by luminal cell recruitment and not be transmural migration. The role of Bcl-2 and HSP47 after balloon angioplasty].

Restenosis post angioplasty remains the major limitation of several therapeutic interventions including stent implantation. This explains the ongoing interest in its basic pathogenic mechanisms and factors. The aim of the present study was to assess the localization and maximal expression of Bcl-2, a central antiapoptotic protooncogene, and of heat shock protein 47 (HSP47), a marker of early collagen synthesis, in the context with hyperplastic neointima formation as well as concomitant transmural remodeling processes following angioplasty. 0, 4, 24 and 48 hours, 4, 7 and 14 days post balloon traumatization by use of a rat carotid artery model, specific vascular wall compartments were evaluated concerning area, cell density as well as Bcl-2 and HSP47 expression by immunohistochemistry and morphometry, supplemented by electron microscopy (TEM). Neointimal cell accumulation was detected 4 days post angioplasty, characterized by luminal cells adherent to the internal elastic lamina, associated with maximal Bcl-2 and HSP47 expression amounting to 49% and 41%, respectively. With ongoing neointimal formation, a luminal prevalence of both key determinants and a decreasing expression in basal neointimal areas were found. In the media, a temporally reduced cell density was observed significant at 48 hours post trauma. Constitutive HSP47 expression of the media was constant during the entire observation period, whereas sparse Bcl-2 signalling was induced post angioplasty maximal on day 2 with 3% and on day 14 with 5%. The adventitia demonstrated a transient structural separation between day 4 and 7, exhibiting an inner layer with sparse cellularity and an outer layer with extremely high cell density as well as pronounced neovascularization. In this outer adventitia layer, a high frequency of signals for both Bcl-2 and HSP47 were observed amounting to 29% and 57%, respectively. Complementary TEM analysis gave no evidence of transmural migratory events propagated by adventitial cells and thereby supports early neointimal formation by luminal cell recruitment and marked co-expression of anti-apoptotic Bcl-2 and matrix-generating HSP47 as important survival factors. Clinical implications of these findings may be seen in the integration of proapoptotic substances with temporal efficacy in order to prevent restenosis, e.g., by use of coated stents.

Angioplasty, Balloon, Coronary↗
PubMed2002

[Do tissue marker clips after sonographically or stereotactically guided breast biopsy improve follow-up of small breast lesions and localisation of breast cancer after chemotherapy?].

PURPOSE: We wanted to determine if tissue marker clips after sonographically or stereotactically guided breast biopsy improve the follow-up of small breast lesions classified BI-RADS 4/5 and the localisation of breast cancer (TNM stage 2 or 3) after neoadjuvant chemotherapy. MATERIAL AND METHODS: Prospective analysis was performed of 108 breast lesions 1 cm or smaller mammographically classified as BI-RADS 4/5 and 14 breast lesions larger than 2 cm mammographically classified as BI-RADS 5. 33 of the 108 breast lesions 1 cm or smaller underwent sonographic core cut breast biopsy (group 1) and 75 stereotactic vacuum-assisted breast biopsy (group 2). All 14 lesions greater than 2 cm were stereotactically vacuum-assisted breast biopsied (group 3). The centre of the lesion was marked by a clip after the biopsy. Mammographies were performed in all patients of group 1 and 2 with a histologically benign finding (n = 31, n = 69, respectively) and in all patients of group 3 directly after clip placement and after 6 and 12 months. Clip localisation and possible divergence from the original position were verified by a grid. RESULTS: Two patients of group 1 and 6 patients of group 2 had breast conservative surgery (BET) because of the histological diagnosis of a ductal carcinoma in situ or invasive breast cancer. The tissue marker clips of the remaining 31 patients of group 1 and 69 patients of group 2 diverged with a mean value of 0.4 cm (standard deviation +/- 0.23 cm; range 0.1 cm to 0.9 cm) from their placement position after 6 months. After 12 months the marker clips deviated with a mean value of 0.4 cm (standard deviation +/- 0.21 cm; range 0.1 cm to 0.9 cm) in 94 patients and 0.8 cm (standard deviation +/- 0.25 cm; range 0.1 cm to 0.9 cm) in 6 patients from their original location. No tumour progression of the benign lesions in group 1 and 2 was diagnosed in follow-up mammograms. In all patients of group 3 the tissue marker clips were the only possibility to localize the tumour after neoadjuvant chemotherapy as all other diagnostic methods showed inconsistent results. CONCLUSION: Positioning a tissue marker clip in the tumour centre seems to be reasonable after interventional biopsy of breast lesions of 1.0 cm or smaller and before neoadjuvant chemotherapy.

Antineoplastic Agents↗
PubMed2002

[Galactoscopy--is it a new interventional method for breast diagnosis?].

Based on experimental studies with animals we examined 22 patients with pathological (bloody) nipple discharge by cytology, ultrasonography, galactography and the newly developed galactoscopy [Endoscopic-System EndoGnost(R) (Polydiagnost)]. The duct's cannula has an outer/inner diameter of 0.45 mm/0.36 mm and a working length of 30 mm, the endoscope a length of 1200 mm, adapted to a CCD-camera (2500 pixel). All patients underwent surgery and histo-pathological diagnosis. The best diagnostic results were received with galactoscopy (21/22). By using an additional cutter it is possible to obtain a histological sample for diagnosis endoscopically. Galactoscopy is an emerging technique and will expand the spectrum of interventional methods in breast diagnosis.

Biopsy↗
PubMed2002

[Scar or recurrence--comparison of MRI and color-coded ultrasound with echo signal amplifiers].

PURPOSE: MRI is the most reliable method to differentiate scar and recurrent carcinoma of the breast after surgical treatment. This study compares MRI and color-coded ultrasound with and without echo signal amplifier (ESA). MATERIALS AND METHODS: Forty-two patients with suspected recurrent tumors were enrolled in this prospective study, with 38 patients after breast conserving therapy and 4 after mastectomy. All patients had a clinical examination, mammography (n = 38), real time ultrasound (US), color-coded ultrasound without and with ESA (Levovist(R), Schering, Berlin), and dynamic MRI. The criteria used for duplex ultrasound were tumor vascularisation and flow pattern. The results were compared with histologic findings or the results of follow-up examinations for at least 12 months. RESULTS: The detection of penetrating or central vessels proved to be an accurate sign of malignancy in duplex ultrasound. With the application of ESA, additional vessels were detected within the lesions, increasing the diagnostic accuracy (83 % with ESA versus 79 % without ESA). The sensitivity of color-coded ultrasound improved from 64 % to 86 % with echo signal amplifier. The specificity was 86 % without and 82 % with echo signal amplifier. MRI was found to have a sensitivity of 100 % and a specificity of 82 %. The same 5 lesions were false positive on MRI and color-coded US after Levovist(R). No lesion without signs of vascularity within or in its vicinity was malignant. CONCLUSION: Color-coded ultrasound seems to be a promising method in the differentiation between scar and recurrence. Lesions with penetrating or central vessels have a high probability of being malignant, whereas lesions without any signs of vascularity inside or nearby have a high probability of being benign. Advantage of contrast-enhanced US is its ubiquitous availability.

Breast↗
PubMed2001

[Mammography/stereotactically controlled vacuum excisional biopsy. Interventional methods in breast diagnosis].

As well as in the complementary mamma diagnosis (clinical examination, mammography, sonography) including the dynamic MRI and the mammography screening projects the interventional methods like mammographically/stereotactically guided vacuumbiopsy/excisional biopsy are established methods to avoid unnecessary open operations and they are integrated in the clinical routine. By using strict criterias it is a way to improve the specificity and the negative predictive value in the mamma diagnosis. In addition the interventional methods requires less costs, less time and reduces the morbidity in comparison to an open operation.

Biopsy↗
PubMed2001

Endoleaks after endovascular repair of aortic aneurysm: are they predictable?-initial results.

PURPOSE: To evaluate the predictability of endoleak. MATERIALS AND METHODS: Thirteen women and 60 men (mean age, 69.8 years) underwent transfemoral insertion of endoluminal stent-grafts for treatment of aortic aneurysms. Follow-up included helical computed tomography (CT) at 3-month intervals. In the cases of endoleak, angiography also was performed to document the number of leak sites, their size and position, the feeding artery, the size of the aneurysm, the amount of thrombus, and the visualization of the lumbar arteries and inferior mesenteric artery. These data were correlated (Student t test) with the probability of endoleak. RESULTS: A total of seven (10%) endoleaks were identified at CT in 68 patients. The feeding vessels were lumbar arteries in three cases, the inferior mesenteric artery in three cases, and the median sacral artery in one case. Of all factors, only the number of lumbar arteries visualized preoperatively (P <.005) had a significant correlation with probability of endoleak. In 71% (five of seven patients) of the cases of lumbar endoleak, four lumbar arteries were patent, whereas among the 61 patients with successfully repaired aneurysm, only eight (13%) had four patent lumbar arteries. Endoleaks were never found in the primarily thrombosed sections of an aneurysm. CONCLUSION: Prediction of endoleaks with absolute certainty remains elusive. The single correlating risk factor identified from the data was patency of four or more lumbar arteries visualized preoperatively at CT.

Aged↗