The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Erik Wilander - One of the best experts on this subject based on the ideXlab platform.
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whole body autoradiography of 123i labelled islet amyloid polypeptide iapp accumulation in the Lung Parenchyma and in the villi of the intestinal mucosa in rats
Acta Oncologica, 1993Co-Authors: Mats Stridsberg, Hans Tjälve, Erik WilanderAbstract:Islet amyloid polypeptide (IAPP) is a 37 amino-acid pancreatic islet polypeptide, displaying about 50% amino-acid homology with neuropeptide calcitonin gene-related peptide (CGRP). IAPP is co-stored with insulin in the β-cell secretory granules and co-released with insulin Upon stimulation. Human IAPP has the ability to precipitate in the shape of amyloid in patients with typ II (non-insulin dependent) diabetes but otherwise its functional or pathophysiological role is enigmatic. In the present study 125I-labelled rat IAPP was injected i.v. into female Sprague-Dawley rats and the distribution of the peptide was examined by whole-body autoradiography at intervals from 2 to 30 min after administration. Already after 2 min high radioactivity occurred in the Lung Parenchyma and in the villi of the small intestinal mucosa. The high radioactivity in these tissues persisted at 10 min but at 30 min the radioactive labelling had decreased to a level only slightly higher than that observed in the blood. A high upta...
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whole body autoradiography of 123i labelled islet amyloid polypeptide iapp accumulation in the Lung Parenchyma and in the villi of the intestinal mucosa in rats
Acta Oncologica, 1993Co-Authors: Mats Stridsberg, Hans Tjälve, Erik WilanderAbstract:Islet amyloid polypeptide (IAPP) in a 37 amino-acid pancreatic islet polypeptide, displaying about 50% amino-acid homology with neuropeptide calcitonin gene-related peptide (CGRP). IAPP is co-stored with insulin in the beta-cell secretory granules and co-released with insulin upon stimulation. Human IAPP has the ability to precipitate in the shape of amyloid in patients with type II (non-insulin dependent) diabetes but otherwise its functional or pathophysiological role is enigmatic. In the present study 125I-labelled rat IAPP was injected i.v. into female Sprague-Dawley rats and the distribution of the peptide was examined by whole-body autoradiography at intervals from 2 to 30 min after administration. Already after 2 min high radioactivity occurred in the Lung Parenchyma and in the villi of the small intestinal mucosa. The high radioactivity in these tissues persisted at 10 min but at 30 min the radioactive labelling had decreased to a level only slightly higher than that observed in the blood. A high uptake of radioactivity was also seen in the cortex of the kidney. In other tissues, including the liver, the skeletal muscle, and the exocrine and endocrine pancreas, the radioactivity was low and did not exceed that of the blood. The uptake of 125I-IAPP in the Lungs and in the small intestine was inhibited by simultaneous injections of either an excess of unlabelled rat IAPP or unlabelled rat CGRP. This indicates that the labelled structures observed in the Lung and the small intestine after injection of 125I-IAPP alone was due to binding to receptors for IAPP or CGRP in these tissues. The accumulation of radioactivity in the kidneys was not affected by pretreatment with high doses of unlabelled IAPP or CGRP. This unspecific uptake of radioactivity may be due to reabsorption of labelled IAPP in the proximal tubuli. Our results indicate the presence of receptors binding IAPP in the Lung Parenchyma and in the villi of the small intestinal mucosa. This, in turn, may imply prominent biological activities of IAPP at these sites.
Mats Stridsberg - One of the best experts on this subject based on the ideXlab platform.
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whole body autoradiography of 123i labelled islet amyloid polypeptide iapp accumulation in the Lung Parenchyma and in the villi of the intestinal mucosa in rats
Acta Oncologica, 1993Co-Authors: Mats Stridsberg, Hans Tjälve, Erik WilanderAbstract:Islet amyloid polypeptide (IAPP) is a 37 amino-acid pancreatic islet polypeptide, displaying about 50% amino-acid homology with neuropeptide calcitonin gene-related peptide (CGRP). IAPP is co-stored with insulin in the β-cell secretory granules and co-released with insulin Upon stimulation. Human IAPP has the ability to precipitate in the shape of amyloid in patients with typ II (non-insulin dependent) diabetes but otherwise its functional or pathophysiological role is enigmatic. In the present study 125I-labelled rat IAPP was injected i.v. into female Sprague-Dawley rats and the distribution of the peptide was examined by whole-body autoradiography at intervals from 2 to 30 min after administration. Already after 2 min high radioactivity occurred in the Lung Parenchyma and in the villi of the small intestinal mucosa. The high radioactivity in these tissues persisted at 10 min but at 30 min the radioactive labelling had decreased to a level only slightly higher than that observed in the blood. A high upta...
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whole body autoradiography of 123i labelled islet amyloid polypeptide iapp accumulation in the Lung Parenchyma and in the villi of the intestinal mucosa in rats
Acta Oncologica, 1993Co-Authors: Mats Stridsberg, Hans Tjälve, Erik WilanderAbstract:Islet amyloid polypeptide (IAPP) in a 37 amino-acid pancreatic islet polypeptide, displaying about 50% amino-acid homology with neuropeptide calcitonin gene-related peptide (CGRP). IAPP is co-stored with insulin in the beta-cell secretory granules and co-released with insulin upon stimulation. Human IAPP has the ability to precipitate in the shape of amyloid in patients with type II (non-insulin dependent) diabetes but otherwise its functional or pathophysiological role is enigmatic. In the present study 125I-labelled rat IAPP was injected i.v. into female Sprague-Dawley rats and the distribution of the peptide was examined by whole-body autoradiography at intervals from 2 to 30 min after administration. Already after 2 min high radioactivity occurred in the Lung Parenchyma and in the villi of the small intestinal mucosa. The high radioactivity in these tissues persisted at 10 min but at 30 min the radioactive labelling had decreased to a level only slightly higher than that observed in the blood. A high uptake of radioactivity was also seen in the cortex of the kidney. In other tissues, including the liver, the skeletal muscle, and the exocrine and endocrine pancreas, the radioactivity was low and did not exceed that of the blood. The uptake of 125I-IAPP in the Lungs and in the small intestine was inhibited by simultaneous injections of either an excess of unlabelled rat IAPP or unlabelled rat CGRP. This indicates that the labelled structures observed in the Lung and the small intestine after injection of 125I-IAPP alone was due to binding to receptors for IAPP or CGRP in these tissues. The accumulation of radioactivity in the kidneys was not affected by pretreatment with high doses of unlabelled IAPP or CGRP. This unspecific uptake of radioactivity may be due to reabsorption of labelled IAPP in the proximal tubuli. Our results indicate the presence of receptors binding IAPP in the Lung Parenchyma and in the villi of the small intestinal mucosa. This, in turn, may imply prominent biological activities of IAPP at these sites.
Masaya Takahashi - One of the best experts on this subject based on the ideXlab platform.
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ultrashort echo time ute mri of the Lung assessment of tissue density in the Lung Parenchyma
Magnetic Resonance in Medicine, 2010Co-Authors: Osamu Togao, Riki Tsuji, Yoshiharu Ohno, Ivan E Dimitrov, Masaya TakahashiAbstract:Nonuniform disruption of Lung architecture is usually assessed by CT, which carries potential radiation risk. Here we report our use of a three-dimensional ultrashort echo time MR method to image the Lungs of normal mice at different positive end-expiratory pressures in a 3-T clinical MR system. The ultrashort echo time sequence in conjunction with a projection acquisition of the free induction decay could reduce the echo time to 100 μsec and provide a more inherent MR signal intensity from the Lung Parenchyma, which is usually invisible due to its short T*(2) in conventional MRI methods. The signal intensity and T*(2) was reduced as the positive end-expiratory pressure became higher. Further, these parameters were highly correlated to the changes in Lung volume (% Lung expansion). The results indicated that the MR signal acquired at ultrashort echo time in the Lung Parenchyma represents interstitial tissue density including blood. The capability of acquiring sufficient MR signal would have implications for the direct assessment of Parenchymal architecture in the Lung. Therefore, ultrashort echo time imaging may have the potential to assist detection of early and localized pathological destruction of Lung tissue architecture observed in various pulmonary disorders such as emphysema without incurring the risks of radiation exposure.
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ultrashort echo time ute mri of the Lung assessment of tissue density in the Lung Parenchyma
Magnetic Resonance in Medicine, 2010Co-Authors: Osamu Togao, Riki Tsuji, Yoshiharu Ohno, Ivan Dimitrov, Masaya TakahashiAbstract:Nonuniform disruption of Lung architecture is usually assessed by CT, which carries potential radiation risk. Here we report our use of a three-dimensional ultrashort echo time MR method to image the Lungs of normal mice at different positive end-expiratory pressures in a 3-T clinical MR system. The ultrashort echo time sequence in conjunction with a projection acquisition of the free induction decay could reduce the echo time to 100 μsec and provide a more inherent MR signal intensity from the Lung Parenchyma, which is usually invisible due to its short T*2 in conventional MRI methods. The signal intensity and T*2 was reduced as the positive end-expiratory pressure became higher. Further, these parameters were highly correlated to the changes in Lung volume (% Lung expansion). The results indicated that the MR signal acquired at ultrashort echo time in the Lung Parenchyma represents interstitial tissue density including blood. The capability of acquiring sufficient MR signal would have implications for the direct assessment of Parenchymal architecture in the Lung. Therefore, ultrashort echo time imaging may have the potential to assist detection of early and localized pathological destruction of Lung tissue architecture observed in various pulmonary disorders such as emphysema without incurring the risks of radiation exposure. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc.
Kiaran P Mcgee - One of the best experts on this subject based on the ideXlab platform.
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estimation of the absolute shear stiffness of human Lung Parenchyma using 1 h spin echo echo planar mr elastography
Journal of Magnetic Resonance Imaging, 2014Co-Authors: Yogesh K Mariappan, Kevin J Glaser, Rolf D Hubmayr, Richard L Ehman, David L Levin, Robert Vassallo, Carl Mottram, Kiaran P McgeeAbstract:Purpose To develop a rapid proton MR elastography (MRE) technique that can quantify the absolute shear stiffness of Lung Parenchyma, to investigate the ability to differentiate respiration-dependent stiffness variations of the Lung, and to demonstrate clinical feasibility. Materials and Methods A spin-echo echo planar imaging MRE sequence (SE-EPI MRE) with a very short echo time was developed and tested in a series of five healthy volunteers at three different Lung volumes: (i) residual volume (RV), (ii) total Lung capacity (TLC), (iii) and midway between RV and TLC (MID). At each volume, Lung density was quantified using a MR-based density mapping sequence. For reference, data were acquired using the previously described spin-echo Lung MRE sequence (SE-MRE). MRE data were also acquired in a patient with proven Idiopathic Pulmonary Fibrosis (IPF) to test clinical feasibility. Results The SE-EPIMRE sequence reduced total acquisition time by a factor of 2 compared with the SE-MRE sequence. Lung Parenchyma median shear stiffness for the 5 volunteers quantified with the SE-EPI MRE sequence was 0.9 kPa, 1.1 kPa, and 1.6 kPa at RV, MID, and TLC, respectively. The corresponding values obtained with the SE-MRE sequence were 0.9 kPa, 1.1 kPa, and 1.5 kPa. Absolute shear stiffness was also successfully measured in the IPF patient. Conclusion The results indicate that stiffness variations due to respiration could be measured with the SE-EPIMRE technique and were equivalent to values generated by the previously described SE-MRE approach. Preliminary data obtained from the patient demonstrate clinical feasibility.J. Magn. Reson. Imaging 2014;40:1230–1237. © 2013 Wiley Periodicals, Inc.
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magnetic resonance elastography of the Lung Parenchyma in an in situ porcine model with a noninvasive mechanical driver correlation of shear stiffness with trans respiratory system pressures
Magnetic Resonance in Medicine, 2012Co-Authors: Yogesh K Mariappan, Rolf D Hubmayr, Armando Manduca, Richard L Ehman, Arunark Kolipaka, Philip A Araoz, Kiaran P McgeeAbstract:Quantification of the mechanical properties of Lung Parenchyma is an active field of research due to the association of this metric with normal function, disease initiation and progression. A phase contrast MRI-based elasticity imaging technique known as magnetic resonance elastography is being investigated as a method for measuring the shear stiffness of Lung Parenchyma. Previous experiments performed with small animals using invasive drivers in direct contact with the Lungs have indicated that the quantification of Lung shear modulus with (1) H based magnetic resonance elastography is feasible. This technique has been extended to an in situ porcine model with a noninvasive mechanical driver placed on the chest wall. This approach was tested to measure the change in Parenchymal stiffness as a function of airway opening pressure (P(ao) ) in 10 adult pigs. In all animals, shear stiffness was successfully quantified at four different P(ao) values. Mean (±STD error of mean) pulmonary Parenchyma density corrected stiffness values were calculated to be 1.48 (±0.09), 1.68 (±0.10), 2.05 (±0.13), and 2.23 (±0.17) kPa for P(ao) values of 5, 10, 15, and 20 cm H2O, respectively. Shear stiffness increased with increasing P(ao) , in agreement with the literature. It is concluded that in an in situ porcine Lung shear stiffness can be quantitated with (1) H magnetic resonance elastography using a noninvasive mechanical driver and that it is feasible to measure the change in shear stiffness due to change in P(ao) .
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mr elastography of human Lung Parenchyma technical development theoretical modeling and in vivo validation
Journal of Magnetic Resonance Imaging, 2011Co-Authors: Yogesh K Mariappan, Kevin J Glaser, Rolf D Hubmayr, Armando Manduca, Richard L Ehman, Kiaran P McgeeAbstract:Purpose: To develop a novel MR-based method for visualizing the elastic properties of human Lung Parenchyma in vivo and to evaluate the ability of this method to resolve differences in Parenchymal stiffness at different respiration states in healthy volunteers. Materials and Methods: A spin-echo MR Elastography (MRE) pulse sequence was developed to provide both high shear wave motion sensitivity and short TE for improved visualization of Lung Parenchyma. The improved motion sensitivity of this approach was modeled and tested with phantom experiments. In vivo testing was then performed on 10 healthy volunteers at the respiratory states of residual volume (RV) and total Lung capacity (TLC). Results: Shear wave propagation was visualized within the Lungs of all volunteers and was processed to provide Parenchymal shear stiffness maps for all 10 subjects. Density corrected stiffness values at TLC (1.83 ± 0.22 kPa) were higher than those at the RV (1.14 ± 0.14 kPa) with the difference being statistically significant (P < 0.0001). Conclusion: 1H-based MR elastography can noninvasively measure the shear stiffness of human Lung Parenchyma in vivo and can quantitate the change in shear stiffness due to respiration. The values obtained were consistent with previously reported in vitro assessments of cadaver Lungs. Further work is required to increase the flexibility of the current acquisition and to investigate the clinical potential of Lung MRE. J. Magn. Reson. Imaging 2011;33:1351–1361. © 2011 Wiley-Liss, Inc.
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feasibility of quantifying the mechanical properties of Lung Parenchyma in a small animal model using 1h magnetic resonance elastography mre
Journal of Magnetic Resonance Imaging, 2009Co-Authors: Kiaran P Mcgee, Rolf D Hubmayr, David C Levin, Richard L EhmanAbstract:Purpose To evaluate the feasibility of spatially resolving the shear modulus of Lung Parenchyma using conventional 1H magnetic resonance elastography (MRE) imaging techniques in a small animal model. Materials and Methods A 10-cm diameter transmit-receive radiofrequency coil was modified to include a specimen stage, an MRE pneumatic drum driver, and needle system. MRE was performed on 10 female Sprague–Dawley rats using a 1H spin-echo based MRE imaging sequence with a field of view of 7 cm and slice thickness of 5 mm. Air-filled Lungs were imaged at transpulmonary inflation pressures of 5, 10, and 15 cm H2O while fluid-filled Lungs were imaged after infusion of 4 mL of normal saline. Results The average shear modulus of air-filled Lungs was 0.840 ± 0.0524 kPa, 1.07 ± 0.114 kPa and 1.30 ± 0.118 kPa at 5, 10, and 15 cm H2O, respectively. Analysis of variance indicated that these population means were statistically significantly different from one another (F-value = 26.279, P = 0.00004). The shear modulus of the fluid-filled Lungs was 1.65 ± 0.360 kPa. Conclusion It is feasible to perform Lung MRE in small animals using conventional MR imaging technologies. J. Magn. Reson. Imaging 2009;29:838–845. © 2009 Wiley-Liss, Inc.
Hans Tjälve - One of the best experts on this subject based on the ideXlab platform.
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whole body autoradiography of 123i labelled islet amyloid polypeptide iapp accumulation in the Lung Parenchyma and in the villi of the intestinal mucosa in rats
Acta Oncologica, 1993Co-Authors: Mats Stridsberg, Hans Tjälve, Erik WilanderAbstract:Islet amyloid polypeptide (IAPP) is a 37 amino-acid pancreatic islet polypeptide, displaying about 50% amino-acid homology with neuropeptide calcitonin gene-related peptide (CGRP). IAPP is co-stored with insulin in the β-cell secretory granules and co-released with insulin Upon stimulation. Human IAPP has the ability to precipitate in the shape of amyloid in patients with typ II (non-insulin dependent) diabetes but otherwise its functional or pathophysiological role is enigmatic. In the present study 125I-labelled rat IAPP was injected i.v. into female Sprague-Dawley rats and the distribution of the peptide was examined by whole-body autoradiography at intervals from 2 to 30 min after administration. Already after 2 min high radioactivity occurred in the Lung Parenchyma and in the villi of the small intestinal mucosa. The high radioactivity in these tissues persisted at 10 min but at 30 min the radioactive labelling had decreased to a level only slightly higher than that observed in the blood. A high upta...
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whole body autoradiography of 123i labelled islet amyloid polypeptide iapp accumulation in the Lung Parenchyma and in the villi of the intestinal mucosa in rats
Acta Oncologica, 1993Co-Authors: Mats Stridsberg, Hans Tjälve, Erik WilanderAbstract:Islet amyloid polypeptide (IAPP) in a 37 amino-acid pancreatic islet polypeptide, displaying about 50% amino-acid homology with neuropeptide calcitonin gene-related peptide (CGRP). IAPP is co-stored with insulin in the beta-cell secretory granules and co-released with insulin upon stimulation. Human IAPP has the ability to precipitate in the shape of amyloid in patients with type II (non-insulin dependent) diabetes but otherwise its functional or pathophysiological role is enigmatic. In the present study 125I-labelled rat IAPP was injected i.v. into female Sprague-Dawley rats and the distribution of the peptide was examined by whole-body autoradiography at intervals from 2 to 30 min after administration. Already after 2 min high radioactivity occurred in the Lung Parenchyma and in the villi of the small intestinal mucosa. The high radioactivity in these tissues persisted at 10 min but at 30 min the radioactive labelling had decreased to a level only slightly higher than that observed in the blood. A high uptake of radioactivity was also seen in the cortex of the kidney. In other tissues, including the liver, the skeletal muscle, and the exocrine and endocrine pancreas, the radioactivity was low and did not exceed that of the blood. The uptake of 125I-IAPP in the Lungs and in the small intestine was inhibited by simultaneous injections of either an excess of unlabelled rat IAPP or unlabelled rat CGRP. This indicates that the labelled structures observed in the Lung and the small intestine after injection of 125I-IAPP alone was due to binding to receptors for IAPP or CGRP in these tissues. The accumulation of radioactivity in the kidneys was not affected by pretreatment with high doses of unlabelled IAPP or CGRP. This unspecific uptake of radioactivity may be due to reabsorption of labelled IAPP in the proximal tubuli. Our results indicate the presence of receptors binding IAPP in the Lung Parenchyma and in the villi of the small intestinal mucosa. This, in turn, may imply prominent biological activities of IAPP at these sites.
