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Dive into the research topics where Stefan Handt is active.

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Featured researches published by Stefan Handt.


The Journal of Urology | 1996

Metabolic Imaging of Untreated Prostate Cancer by Positron Emission Tomography with sup 18 Fluorine-Labeled Deoxyglucose

Peter J. Effert; R. Bares; Stefan Handt; J.M. Wolff; Udalrich Büll; G. Jakse

PURPOSE We evaluated positron emission tomograph (PET) with 18fluorine (18F)-labeled deoxyglucose for metabolic grading of untreated primary prostate cancer, and differentiation of benign and malignant prostatic disease. MATERIALS AND METHODS A total of 48 patients with untreated prostate cancer of different stages and 16 with histologically confirmed benign prostatic hyperplasia (BPH) underwent static PET after intravenous injection of 150 to 300 MBq. 18F-deoxyglucose. 18F-deoxyglucose accumulation was quantitated by calculating differential uptake ratios and prostate-to-skeletal muscle ratios. RESULTS Low 18F-deoxyglucose uptake was noted in the majority of primary tumors (81%). 18F-deoxyglucose accumulation did not correlate with increasing tumor grade or stage. There was a significant overlap in uptake values in BPH and malignant prostatic disease. A trend towards statistical significance was noted with lower prostate-to-skeletal muscle ratios in patients with BPH (p < 0.07). Increased 18F-deoxyglucose accumulation was detected in some patients with BPH and malignant prostatic disease, as well as in those with lymph node and bone metastases of prostate cancer. CONCLUSIONS 18F-deoxyglucose PET does not allow for metabolic labeling in the majority of untreated primary prostate cancers. BPH and primary prostate cancer cannot be reliably differentiated on the basis of PET. Increased 18F-deoxyglucose accumulation occurs in some primary prostate tumors and in metastatic deposits of prostate cancer.


Human Pathology | 2000

Benign metastasizing leiomyoma: A cytogenetically balanced but clonal disease

Lothar Tietze; Kalle Günther; Alexandra Hörbe; Christine Pawlik; Bernd Klosterhalfen; Stefan Handt; Sabine Merkelbach-Bruse

Benign metastasizing leiomyoma (BML) is a rare condition, characterized by the occurrence of multiple smooth-muscle nodules, most often located in the lung after previous hysterectomy because of histologically benign appearing leiomyoma. Although the condition resembles a metastatic process, case studies provided evidence that it may be the result of an intravenous leiomyomatosis or an independent and multifocal smooth-muscle proliferation. Comparative genomic hybridization and X-chromosome inactivation analysis were used in a case of BML to determine whether pulmonary and uterine tumors are related one to another. A balanced karyotype, previously reported in leiomyomas and an identical X-chromosome inactivation pattern found in all tumorlets, is most consistent with a monoclonal origin of both uterine and pulmonary tumors and the interpretation that pulmonary lesions are metastatic.


The Journal of Pathology | 2001

Differences in genetic alterations between primary lobular and ductal breast cancers detected by comparative genomic hybridization

Kalle Günther; Sabine Merkelbach-Bruse; Baffour Kwaku Amo-Takyi; Stefan Handt; Willibald Schröder; Lothar Tietze

Infiltrating ductal (DC) and lobular carcinoma (LC) of the breast represent the most frequently observed varieties of invasive breast cancer, characterized by differences in their histological and clinical properties. Although comparative genomic hybridization (CGH) of invasive breast carcinomas has revealed a complex and consistent pattern of DNA copy number changes, the data with regard to type specific aberrations are limited. A comprehensive study was therefore performed on 19 LCs and 29 DCs to ascertain type‐specific differences of unbalanced DNA copy number changes by CGH. Statistical analysis revealed significantly higher frequencies for underrepresentation of chromosomes 16q (p<0.01), 22 (p<0.05), and 17q (p<0.05), and a lower frequency for overrepresentation of chromosome 8q (p<0.01) in LC. Similar frequencies of non‐random chromosomal changes in LC and DC were obtained for gain of 1q (74%/59%) and loss of 19p (53%/52%), parts of 1p (42%/41%) and 11q (21%/24%). Less frequently, gains mainly involving parts of chromosomes 20q, 20p, 3q, and 5p and partial losses of chromosomes 17p and 13 were observed in both groups of tumours. Minimal regions of overlapping amplifications were mapped to 17q23 exclusively in DC (17%) and 11q13–q14 in both DC and LC (21% and 11%, respectively). High occurrences of DNA copy number decreases were detected at the distal part of chromosomes 1p, 19 and 22, but further analysis is required to confirm these imbalances. It is suggested that the observed differences are involved in the development of type‐specific properties of DC and LC. Copyright


European Journal of Obstetrics & Gynecology and Reproductive Biology | 1999

Elevated soluble adhesion molecules in women with pre-eclampsia: Do cytokines like tumour necrosis factor-α and interleukin-1β cause endothelial activation?

Wolfgang Heyl; Stefan Handt; Frank Reister; Johanna Gehlen; Willibald Schröder; Christian Mittermayer; Werner Rath

OBJECTIVE The purpose of the present study was to evaluate the clinical significance of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) for endothelial cell activation in pre-eclampsia. Therefore, we determined and compared the correlations between these cytokines and circulating adhesion molecules in the sera of pre-eclamptic pregnant women, normotensive pregnant women and nonpregnant women. METHODS The soluble adhesion molecules VCAM-1, ICAM-1, E-selectin, and P-selectin were determined in the serum of 38 pre-eclamptic pregnant women and 40 normotensive pregnant and nonpregnant controls using ELISA-techniques. We correlated these serum concentrations with the serum levels of TNF-alpha and IL-1beta, respectively, also determined by ELISA. RESULTS Elevated serum levels of VCAM-1 and E-selectin could be detected in pre-eclamptic patients, with and without HELLP-syndrome. In contrast, no increased serum concentration of ICAM-1, P-selectin, TNF-alpha and IL-1beta were found in these patients. While significant correlation between VCAM-1 and E-selectin could be determined (r=0.604; p<0.001) no unambiguous correlations, however, were found between TNF-alpha or between IL-1beta and the examined adhesion molecules or the selectins. CONCLUSIONS In contrast to in vitro investigations on cultured umbilical vein endothelium, our experimental results indicate that the cytokines TNF-alpha and IL-1beta can not explain endothelial cell activation, and that their measurement in serum is not useful for the detection of pre-eclampsia.


American Journal of Obstetrics and Gynecology | 1999

The role of soluble adhesion molecules in evaluating endothelial cell activation in preeclampsia.

Wolfgang Heyl; Stefan Handt; Frank Reister; Johanna Gehlen; Christian Mittermayer; Werner Rath

OBJECTIVE Adhesion molecules, such as vascular cell adhesion molecule 1, are known to be increased in the serum of patients with preeclampsia, indicating that these molecules are possible markers of endothelial cell activation. We investigated the influence of serum from women with preeclampsia on the expression of adhesion molecules by cultured endothelial cells. STUDY DESIGN Human umbilical vein endothelial cells were cultured in Ham/Iscove modified Dulbeccos medium containing 20% pooled human serum, l -glutamine (200 mmol/L), penicillin, and streptomycin. We stimulated these cells for 24 hours with sera from patients with preeclampsia and then determined the levels of vascular cell adhesion molecule 1, intercellular cell adhesion molecule 1, E-selectin, and P-selectin in the supernatant and in the maternal serum by means of enzyme-linked immunosorbent assay. These results were compared with those of sera obtained from normotensive pregnant and nonpregnant women. In addition, the expressions of these adhesion molecules on the endothelial surface were determined by immunofluo-rescence microscopy. RESULTS Only for vascular cell adhesion molecule 1 and E-selectin were elevated plasma levels found in hypertensive patients, whereas intercellular cell adhesion molecule 1 and P-selectin showed similar plasma levels in all the patients. No differences in the levels of the adhesion molecules were found between the supernatants of endothelial cell cultures after stimulation with sera from patients with preeclampsia and those after stimulation with normotensive control sera. In contrast, with immunofluorescence microscopy we could detect higher amounts of vascular cell adhesion molecule 1, intercellular cell adhesion molecule 1, and E-selectin on the endothelial surface after stimulation with sera from women with preeclampsia. CONCLUSION Although vascular cell adhesion molecule 1 and E-selectin were elevated in maternal serum samples from women with preeclampsia and on the endothelial surface after stimulation with such sera, there were no detectable increases in the levels of both of these adhesion molecules in the supernatant of cultured endothelial cells. We therefore assume that sera from women with preeclampsia may cause endothelial cell activation. Because we could not detect elevated concentrations of any of the investigated adhesion molecules in the supernatant of endothelial cells, we believe that factors other than sera from women with preeclampsia seem to play a major role in the release of soluble forms of adhesion molecules from the endothelial membrane.


Nephron | 2000

Expression of Heat Shock Proteins 72/73 in Human Peritoneal Mesothelial Cells in vivo and in vitro

Cristina López-Cotarelo; Bernd Sellhaus; Hideo A. Baba; Edith Manegold; Johanna Luka; Stefan Handt; Christian Mittermayer; Bernd Klosterhalfen; Lothar Tietze

Leukocyte accumulation during peritonitis leads to an injurious microenvironment which is involved in the host defense reaction but is also thought to cause peritoneal damage. We tested the hypothesis that mesothelial cells (MC) respond to the injurious microenvironment during peritonitis by an increased expression of heat shock proteins (HSP 72/73), a basic way by which cells are protected against injury. Comparison of resting MC and activated MC during peritonitis in vivo by means of immunohistochemistry revealed an increased expression of HSP 72/73. As assessed by Western immunoblotting, incubation of MC in vitro with tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) caused a time-dependent induction of HSP 72/73 expression, which was maximal 6 h after stimulation. We suggest that the increased HSP 72/ 73 expression of MC during peritonitis is in part induced by TNF-α and IL-1β and may exert a cell-protective function, lessening MC damage during peritonitis.


American Journal of Obstetrics and Gynecology | 1999

Different placentation patterns in viable compared with nonviable tubal pregnancy suggest a divergent clinical management

Birgit Kemp; Sonja Kertschanska; Stefan Handt; Andreas Funk; Peter Kaufmann; Werner Rath

OBJECTIVE In contrast to tubal abortions, viable ectopic pregnancies in color Doppler ultrasonography exhibit a signal-intensive ring around the gestational sac. We investigated the underlying differences in implantation and placentation. STUDY DESIGN Histologic sections of fallopian tubes carrying viable tubal pregnancies (13 patients) and tubal pregnancies that aborted (8 patients) were immunostained for cytokeratin, MIB-1, CD-34, and CD-68. The data were studied by computer-aided image analysis followed by statistical evaluation (Student t test, P <.05). RESULTS In contrast to tubal abortions, viable tubal pregnancies are characterized by implantation at the mesosalpingial rather than at the antimesosalpingial side of the organ. They exhibit deeper trophoblast invasion into the thickened tubal wall, more intense trophoblast proliferation (P <.001), and increased villous vascularization (P <.001). CONCLUSION The morphologic findings correlate with preoperative Doppler ultrasonography. They suggest that trophoblast invasion, placental growth, and the fate of tubal pregnancies depend on the implantation site. They encourage a conservative management of anti-mesosalpingially implanted, nonviable ectopic pregnancies in clinically stable patients.


Medizinische Klinik | 1999

Radioprotektion humaner Endothelzellen durch Natriumselenit

Ursula Schleicher; Cristina Lopez Cotarelo; Demetrios Andreopoulos; Stefan Handt; Jürgen Ammon

BACKGROUND Sodium selenite is applied in tumor patients during chemo- or radiotherapy due to its cytoprotective effects. Aim of our study was to evaluate the effect of exposure with sodium selenite on proliferation of human endothelial and tumor cells after irradiation. MATERIALS AND METHODS We studied the proliferative activity of human umbilical vein endothelial cells in comparison to tumor cells of the HeLa, MIA Paca-2 and SiHa cell line after single-dose irradiation with 2 or 10 Gy and controls without irradiation. All cells had been exposed to different concentrations of sodium selenite prior to irradiation. Evaluation was done by BrdU-ELISA. RESULTS Exposure of human endothelial cells with sodium selenite concentrations > or = 100 micrograms/l led to an increase of BrdU proliferation index. This effect was markedly weaker in HeLa cells and not found in SiHa and MIA Paca-2. CONCLUSIONS High concentrations of sodium selenite can counteract the decrease of proliferative activity caused by irradiation in human endothelial cells and thus exert a radioprotective effect on these cells. This effect was observed by far stronger in endothelial cells than in tumor cells, implying the possible clinical use of sodium selenite as a protective agent for normal tissue in radiotherapy.Zusammenfassung□Hintergrund: Natriumselenit wird als zytoprotektive Substanz bei Tumorpatienten häufig parallel zu Chemo- und Radiotherapie eingesetzt. Die vorliegende Arbeit untersucht die Auswirkungen einer Natriumselenitexposition auf die Proliferation menschlicher Endothel- und Tumorzellen nach Bestrahlung.□Material und Methoden: Wir untersuchten die proliferative Aktivität von Endothelzellen aus humanen Umbilikalvenen, HeLa-, MIA Paca-2- und SiHa-Zellen nach Einzeitbestrahlung mit 2 oder 10 Gy sowie von unbestrahlten Kontrollen. Alle Zellen wurden vor der Bestrahlung mit verschiedenen Natriumselenitkonzentrationen inkubiert. Die Auswertung erfolgte mittels BrdU-ELISA.□Ergebnisse: Die Exposition humaner Endothelzellen mit Natriumselenitkonzentrationen ≥100 µg/1 führt zu einem Anstieg des BrdU-Proliferationsindex. Dieser Effekt war bei den HeLa-Zellen deutlich schwächer ausgeprägt und bei SiHa und MIA Paca-2 nicht nachweisbar.□Schlußfolgerungen: Natriumselenit kann der durch die Bestrahlung bedingten Proliferationshemmung humaner Endothelzellen entgegenwirken und übt somit in höheren Konzentrationen einen zytoprotektiven Effekt auf diese Zellen aus. Diese Wirkung ist bei Endothelzellen deutlich stärker ausgeprägt als bei den untersuchten Tumorzellen, was eine klinische Untersuchung von Natriumselenit als Radioprotektivum sinnvoll erscheinen läßt.Abstract□Background: Sodium selenite is applied in tumor patients during chemo- or radiotherapy due to its cytoprotective effects. Aim of our study was to evaluate the effect of exposure with sodium selenite on proliferation of human endothelial and tumor cells after irradiation.□Material and Methods: We studied the proliferative activity of human umbilical vein endothelial cells in comparison to tumor cells of the HeLa, MIA Paca-2 and SiHa cell line after single-dose irradiation with 2 or 10 Gy and controls without irradiation. All cells had been exposed to different concentrations of sodium selenite prior to irradiation. Evaluation was done by BrdU-ELISA.□Results: Exposure of human endothelial cells with sodium selenite concentrations ≥100 µg/l led to an increase of BrdU proliferation index. This effect was markedly weaker in HeLa cells and not found in SiHa and MIA Paca-2.□Conclusions: High concentrations of sodium selenite can counteract the decrease of proliferative activity caused by irradiation in human endothelial cells and thus exert a radioprotective effect on these cells. This effect was observed by far stronger in endothelial cells than tumor cells, implying the possible clinical use of sodium selenite as a protective agent for normal tissue in radiotherapy.


Virchows Archiv | 2000

Simultaneous appearance of an adenomyoma and pancreatic heterotopia of the stomach

H. Erberich; Stefan Handt; Christian Mittermayer; Lothar Tietze

Abstract Adenomyomas of the stomach are rare tumours characterised by duct/gland-like structures embedded within a smooth muscle stroma. Although the histogenesis of adenomyomas remains unclear, the histological appearance has justified the assumption that these are abortive forms of pancreatic heterotopia. We report an unusual case with simultaneous and independent appearance of both adenomyoma and pancreatic heterotopia of the stomach including immunohistochemical characterisation, supporting the concept of a common histiogenetic origin of both lesions.


Microscopy and Microanalysis | 2004

Endothelial Cells Organize Fibrin Clots into Structures That Are More Resistant to Lysis

W. Gray Jerome; Stefan Handt; Patricia G. Yancey; Roy R. Hantgan

Acute myocardial infarction is a major cause of death and disability in the United States. Introducing thrombolytic agents into the clot to dissolve occlusive coronary artery thrombi is one method of treatment. However, despite advances in our knowledge of thrombosis and thrombolysis, survival rates following thrombolytic therapy have not improved substantially. This failure highlights the need for further study of the factors mediating clot stabilization. Using laser scanning confocal microscopy of clots formed from fluorescein-labeled fibrinogen, we investigated what effect binding of fibrin to the endothelial surface has on clot structure and resistance to lysis. Fluorescent fibrin clots were produced over human umbilical vein endothelial cells (HUVEC) and the clot structure analyzed. In the presence of HUVEC, fibrin near the endothelial surface was more organized and occurred in tighter bundles compared to fibrin just 50 microm above. The HUVEC influence on fibrin architecture was blocked by inhibitory concentrations of antibodies to alphaV or beta3 integrin subunits. The regions of the clots associated with endothelial cells were more resistant to lysis than the more homogenous regions distal to endothelium. Thus, our data show that binding of fibrin to integrins on endothelial surfaces produces clots that are more resistant to lysis.

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Axel Kaiser

RWTH Aachen University

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