11 results on '"Tandi C"'
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2. Thermal instability of gas hydrate bearing sediments: Some issues
- Author
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Dangayach, S., Singh, D.N., Kumar, P., Dewri, S.K., Roy, B., Tandi, C., and Singh, J.
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- 2015
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3. State-of-the-Art of Gas Hydrates and Relative Permeability of Hydrate Bearing Sediments
- Author
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Joseph, J., primary, Singh, D. N., additional, Kumar, P., additional, Dewri, S. K., additional, Tandi, C., additional, and Singh, J., additional
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- 2015
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4. State-of-the-Art of Gas Hydrates and Relative Permeability of Hydrate Bearing Sediments.
- Author
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Joseph, J., Singh, D. N., Kumar, P., Dewri, S. K., Tandi, C., and Singh, J.
- Subjects
GAS hydrates ,PERMEABILITY ,SEDIMENTATION & deposition ,METHANE synthesis ,AQUEOUS solutions - Abstract
The methane gas production potential from its hydrates, which are solid clathrates, with methane gas entrapped inside the water molecules, is primarily dependent on permeability characteristics of their bearing sediments. Moreover, the dissociation of gas hydrates, which results in a multi-phase fluid migration through these sediments, becomes mandatory to determine the relative permeability of both gaseous and aqueous fluids corresponding to different hydrate saturations. However, in this context, the major challenges are: (1) obtaining undisturbed in-situ samples bearing gas hydrates; and (2) maintenance of the thermodynamic conditions to counter hydrate dissociation. One of the ways to overcome this situation is synthesis of gas hydrates in laboratory conditions, followed by conducting permeability tests on them. In addition, empirical relationships that relate permeability of the gas hydrate bearing sediments to pore-structure characteristics (viz., pore size distribution and interconnectivity) can also be conceived. With this in view, a comprehensive review of the literature dealing with different techniques adopted by researchers for synthesis of gas hydrates, permeability tests conducted on the sediments bearing them, and analytical and empirical correlations employed for determination of permeability of these sediments was conducted and a brief account of the same is presented in this article. [ABSTRACT FROM PUBLISHER]
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- 2016
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5. Endotheliales P-Selektin als Zielstruktur von Heparinwirkungen bei der Hemmung experimenteller Melanommetastasen der Lunge
- Author
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Ludwig, RJ, primary, Tandi, C, additional, Podda, M, additional, Schultz, JE, additional, Boehme, B, additional, Jäger, E, additional, Henschler, R, additional, Boehncke, WH, additional, Zollner, TM, additional, Kaufmann, R, additional, and Gille, J, additional
- Published
- 2003
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6. Dual energy CT for the assessment of reperfused chronic infarction - a feasibility study in a porcine model.
- Author
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Kerl JM, Deseive S, Tandi C, Kaiser C, Kettner M, Korkusuz H, Lehmann R, Herzog C, Schoepf UJ, Vogl TJ, Bauer RW, Kerl, J Matthias, Deseive, Simon, Tandi, Christa, Kaiser, Christina, Kettner, Mattias, Korkusuz, Huedayi, Lehmann, Ralf, Herzog, Christopher, and Schoepf, U Joseph
- Abstract
Background: Detection of myocardial infarction has been the focus of considerable research over the past few decades. Recently developed dual source computed tomography (DSCT) scanners with dual energy mode have been used to detect myocardial infarction, but the studies on this topic are few.Purpose: To evaluate the feasibility and performance of dual energy CT (DECT) during arterial phase in coronary CT angiography for the detection of chronic infarction compared with late enhancement MRI (LE-MRI) and histopathology in a porcine model of reperfused myocardial infarction.Material and Methods: Myocardial infarctions were induced by 30 min occlusion of the proximal left anterior descending coronary artery in eight minipigs. DECT, post-contrast LE-MRI and histopathology were performed 60 days after infarct induction. The CT scan was performed in dual energy mode using a dedicated protocol. Myocardial iodine distribution was superimposed as color maps on grey scale multiplanar reformats of the heart. Two radiologists in consensus interpreted all imaging studies for presence of gadolinium uptake at LE-MRI reduced iodine content at DECT and hypoenhanced areas in the initial 100 kV coronary CT angiography images that were acquired during the DECT-acquisition. Results were compared with histopathology.Results: Based on evaluable segments, DECT showed a sensitivity and specificity of 0.72 and 0.88; LE-MRI showed a sensitivity and specificity of 0.78 and 0.92; and the 100 kV data-set of the DECT scan showed a sensitivity and specificity of 0.60 and 0.93, respectively, for the detection of histological proved ischemia.Conclusion: DECT during arterial phase coronary CT angiography, which is ordinarily used for coronary artery evaluation, is feasible for the detection of a chronic reperfused myocardial infarction. [ABSTRACT FROM AUTHOR]- Published
- 2011
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7. Dual-energy computed tomography for the detection of late enhancement in reperfused chronic infarction: a comparison to magnetic resonance imaging and histopathology in a porcine model.
- Author
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Deseive S, Bauer RW, Lehmann R, Kettner M, Kaiser C, Korkusuz H, Tandi C, Theisen A, Schächinger V, Schoepf UJ, Vogl TJ, and Kerl JM
- Subjects
- Animals, Contrast Media, Disease Models, Animal, Feasibility Studies, Magnetic Resonance Imaging, Myocardial Infarction diagnostic imaging, Myocardial Infarction pathology, Myocardial Reperfusion, Sensitivity and Specificity, Swine, Swine, Miniature, Myocardial Infarction diagnosis, Tomography, X-Ray Computed
- Abstract
Objectives: To evaluate the performance of late enhancement dual-energy CT (LE-DECT) for the detection of infarcted myocardium as compared with 1.5-T late enhancement magnetic resonance imaging (LE-MRI) in a porcine model of reperfused chronic myocardial infarction (MI), using histopathology as standard of reference., Materials and Methods: In 8 healthy minipigs, MI was induced by 30-minute balloon occlusion of the left anterior descending coronary artery. Sixty-one ± 4 days after left anterior descending coronary artery occlusion, LE-DECT was performed 5, 10, and 15 minutes subsequent to contrast material injection. Therefore, a dual-source CT scanner (Somatom Definition, Siemens Healthcare, Forchheim, Germany) was used in dual-energy mode with the following protocol: tube potential/current 140 kV/95 mAs on tube A and 100 kV/165 mAs on tube B, collimation 2 × 32 × 0.6 mm, 1.5 mL/kg contrast material injected at 3 to 4 mL/s. Myocardial iodine distribution was calculated from the dual-energy data and superimposed on the gray scale multiplanar reformats of the heart in short-axis view. Fifty ± 12 minutes after LE-DECT imaging, 1.5-T LE-MRI (Magnetom Avanto, Siemens Healthcare, Forchheim, Germany) was performed 10 minutes successive to injection of contrast material using phase-sensitive inversion recovery sequences. For all pigs investigated, 2,3,5-triphenyltetrazolium chloride staining and histopathology of stained-tissue samples were acquired. Two experienced radiologists assessed all imaging studies in a random manner and were blinded to the results of the other techniques for the presence of late enhancement (LE). The American Heart Association 17-segment model was used to compare the results of LE-DECT, 100 kV grayscale LE images, LE-MRI, and histopathology. Size of MI was calculated for histopathological findings, LE-MRI, LE-DECT, and 100 kV grayscale LE images 10 minutes after contrast agent injection. Agreement between infarct size assessed with imaging modalities and histopathology was evaluated with Bland-Altman analysis., Results: Of the 136 myocardial segments in 8 minipigs, histopathology found MI in 27 segments. Diagnostic per-segment sensitivities and specificities for 100 kV grayscale LE images, LE-DECT images, and MR images obtained 10 minutes after contrast agent injection for both the readers were 0.62, 0.77, 0.79 and 0.97, 0.92, 0.94, respectively. Although sensitivities were higher for LE-DECT and LE-MRI than for 100 kV grayscale images, no statistically significant difference for the diagnostic accuracies of 100 kV grayscale LE images, LE-DECT images, and MR images (0.9, 0.89, 0.9) existed 10 minutes successive to contrast agent injection (all P > 0.05). Infarct size for LE-MRI, LE-DECT, and 100 kV grayscale LE images correlated well with histopathological findings (r = 0.97, 0.96, and 0.94; all P < 0.01)., Conclusions: This feasibility study shows a high accuracy and a good correlation of LE-DECT and LE-MRI to histopathology for the detection of LE in a porcine model of reperfused chronic MI.
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- 2011
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8. Growth hormone supplementation increased latency to tumourigenesis in Atm-deficient mice.
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Schubert R, Schmitz N, Pietzner J, Tandi C, Theisen A, Dresel R, Christmann M, and Zielen S
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- Animals, Ataxia Telangiectasia complications, Ataxia Telangiectasia Mutated Proteins, Disease Models, Animal, Female, Growth Hormone administration & dosage, Growth Hormone genetics, Humans, Lymphoma etiology, Lymphoma genetics, Lymphoma physiopathology, Lymphoma prevention & control, Male, Mice, Rats, Recombinant Proteins administration & dosage, Recombinant Proteins genetics, T-Lymphocytes immunology, Treatment Outcome, Ataxia Telangiectasia drug therapy, Cell Cycle Proteins genetics, DNA-Binding Proteins deficiency, DNA-Binding Proteins genetics, Growth Hormone therapeutic use, Protein Serine-Threonine Kinases deficiency, Protein Serine-Threonine Kinases genetics, Recombinant Proteins therapeutic use, Thymus Neoplasms etiology, Thymus Neoplasms genetics, Thymus Neoplasms physiopathology, Thymus Neoplasms prevention & control, Tumor Suppressor Proteins deficiency, Tumor Suppressor Proteins genetics
- Abstract
Growth hormone (GH) is important for cell growth and differentiation, has multiple effects on lymphoid tissue and may promote blast cell proliferation and cancer development. We studied the effect of GH on longevity and tumour formation in Atm-deficient mice, an established model of the human cancer prone syndrome ataxia telangiectasia (AT). AT is a devastating recessive disorder that is characterized by progressive cerebellar ataxia, immunodeficiency, chromosomal instability and cancer susceptibility. Since AT patients also show endocrinological abnormalities the question has been raised as to whether GH therapy could be beneficial and/or increase the cancer risk in AT. We found that treatment with GH significantly increased longevity of Atm-deficient mice. In addition, GH ameliorated locomotoric behaviour and improved T-cell immunity. Thus, our data demonstrated that GH treatment is not necessarily accompanied by increased cancer development in diseases with chromosomal instability and cancer susceptibility and might be beneficial for AT patients.
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- 2009
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9. Lowering of tumor interstitial fluid pressure reduces tumor cell proliferation in a xenograft tumor model.
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Hofmann M, Guschel M, Bernd A, Bereiter-Hahn J, Kaufmann R, Tandi C, Wiig H, and Kippenberger S
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- Animals, Cell Division, Cell Line, Tumor, Disease Models, Animal, Female, Humans, Kinetics, Mice, Mice, Nude, Extracellular Fluid physiology, Transplantation, Heterologous pathology, Vulvar Neoplasms pathology
- Abstract
High tumor interstitial fluid pressure (TIFP) is a characteristic of most solid tumors. TIFP may hamper adequate uptake of macromolecular therapeutics in tumor tissue. In addition, TIFP generates mechanical forces affecting the tumor cortex, which might influence the growth parameters of tumor cells. This seems likely as, in other tissues (namely, blood vessels or the skin), mechanical stretch is known to trigger proliferation. Therefore, we hypothesize that TIFP-induced stretch modulates proliferation-associated parameters. Solid epithelial tumors (A431 and A549) were grown in Naval Medical Research Institute nude mice, generating a TIFP of about 10 mm Hg (A431) or 5 mm Hg (A549). Tumor drainage of the central cystic area led to a rapid decline of TIFP, together with visible relaxation of the tumor cortex. It was found by sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot analysis that TIFP lowering yields a decreased phosphorylation of proliferation-associated p44/42 mitogen-activated protein kinase and tumor relaxation. In confirmation, immunohistochemical staining showed a decrease of tumor-associated proliferation marker Ki-67 after TIFP lowering. These data suggest that the mechanical stretch induced by TIFP is a positive modulator of tumor proliferation.
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- 2006
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10. Endothelial P-selectin as a target of heparin action in experimental melanoma lung metastasis.
- Author
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Ludwig RJ, Boehme B, Podda M, Henschler R, Jager E, Tandi C, Boehncke WH, Zollner TM, Kaufmann R, and Gille J
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- Animals, Blood Platelets metabolism, Cell Communication drug effects, Cell Communication physiology, Endothelium, Vascular drug effects, Endothelium, Vascular pathology, Humans, Lung Neoplasms blood, Male, Melanoma blood, Melanoma pathology, Melanoma, Experimental blood, Melanoma, Experimental drug therapy, Melanoma, Experimental pathology, Melanoma, Experimental secondary, Mice, Mice, Inbred C57BL, Neoplasm Transplantation, P-Selectin physiology, Heparin pharmacology, Lung Neoplasms drug therapy, Lung Neoplasms secondary, Melanoma drug therapy, Melanoma secondary, P-Selectin blood
- Abstract
Spontaneous and experimental metastasis can be effectively inhibited by the widely used anticoagulant heparin in different tumor models. At the cellular level, many of the antimetastatic effects of heparin in vivo are due to its action on P-selectin-mediated binding. Whereas previous attention has focused on P-selectin-dependent tumor-cell-platelet interactions in blood-borne metastasis, we sought to address the potential contribution of endothelial P-selectin expression to adhesive events between the microvasculature and melanoma cells in vivo. Transplantation of bone marrow from P-selectin-deficient into wild-type mice conveyed inhibition of ex-perimental melanoma metastasis. However, the extent to which bone marrow-conferred lack of platelet P-selectin expression attenuated melanoma lung metastasis was significantly less than that seen in P-selectin-deficient mice, suggesting that endothelial P-selectin expression may additionally contribute to formation of hematogenous metastases. This assumption was supported by our intravital microscopy studies, in which a significant proportion of melanoma cells were capable of directly interacting with postcapillary venules of the murine ear in a P-selectin-dependent manner. Heparin not only inhibits P-selectin-mediated melanoma cell rolling but also attenuates melanoma metastasis formation in vivo, further supporting the concept that endothelial P-selectin expression may represent an additional target of heparin action in experimental melanoma lung metastasis.
- Published
- 2004
- Full Text
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11. Activated, not resting, platelets increase leukocyte rolling in murine skin utilizing a distinct set of adhesion molecules.
- Author
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Ludwig RJ, Schultz JE, Boehncke WH, Podda M, Tandi C, Krombach F, Baatz H, Kaufmann R, von Andrian UH, and Zollner TM
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- Animals, Humans, Male, Mice, Mice, Inbred C57BL, Platelet Aggregation, Psoriasis blood, Blood Platelets physiology, Leukocytes physiology, Membrane Glycoproteins physiology, P-Selectin physiology, Platelet Activation, Platelet Glycoprotein GPIIb-IIIa Complex physiology, Skin pathology
- Abstract
Selectin-mediated tethering and rolling initiates the multi-step process of leukocyte extravasation which is crucial for the formation of an inflammatory infiltrate. We studied the impact of platelets on this process in the skin. Using intravital microscopy, we analyzed platelet interactions with cutaneous post-capillary venules of mouse ears and observed an increase in platelet rolling if platelets were activated (41.6+/-20.2% vs. 13.1+/-8.5% rolling of resting platelets). Experiments with P-selectin deficient mice and antibodies blocking either P-selectin, GPIIb/IIIa or GPIb showed that rolling depends on platelet PSGL-1 and GPIIb/IIIa on one hand, and endothelial P-selectin on the other. Next, formation of platelet-leukocyte aggregates was demonstrated by simultaneous observation of platelets and leukocytes in vivo utilizing a newly developed two-color technique. Aggregates increased overall leukocyte rolling (leukocytes alone: 27.4+/-11.2%, leukocytes with resting platelets: 25.3+/-10.2%, leukocytes with activated platelets 38.1+/-11.8%). To investigate if activated platelets may contribute to the pathogenesis of chronic cutaneous inflammation, platelet P-selectin expression was studied in 8 patients with psoriasis. A correlation between platelet P-selectin expression and disease severity was established. In summary, we show that activated, not resting, platelets increase leukocyte rolling in murine skin. This increased rolling is due to the aggregate formation of platelets with leukocytes. We also provide evidence for a potential role of this mechanism in the pathogenesis of chronic inflammatory skin diseases.
- Published
- 2004
- Full Text
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