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Grasso K, Singha Roy SJ, Osgood AO, Yeo MJR, Soni C, Hillenbrand CM, Ficaretta ED, Chatterjee A. A Facile Platform to Engineer Escherichia coli Tyrosyl-tRNA Synthetase Adds New Chemistries to the Eukaryotic Genetic Code, Including a Phosphotyrosine Mimic. ACS Cent Sci 2022; 8:483-492. [PMID: 35559426 PMCID: PMC9088295 DOI: 10.1021/acscentsci.1c01465] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Indexed: 06/03/2023]
Abstract
The Escherichia coli tyrosyl-tRNA synthetase (EcTyrRS)/tRNAEcTyr pair offers an attractive platform for genetically encoding new noncanonical amino acids (ncAA) in eukaryotes. However, challenges associated with a eukaryotic selection system, which is needed to engineer the platform, have impeded its success in the past. Recently, using a facile E. coli-based selection system, we showed that EcTyrRS could be engineered in a strain where the endogenous tyrosyl pair was substituted with an archaeal counterpart. However, significant cross-reactivity between the UAG-suppressing tRNACUA EcTyr and the bacterial glutaminyl-tRNA synthetase limited the scope of this strategy, preventing the selection of moderately active EcTyrRS mutants. Here we report an engineered tRNACUA EcTyr that overcomes this cross-reactivity. Optimized selection systems based on this tRNA enabled the efficient enrichment of both strongly and weakly active ncAA-selective EcTyrRS mutants. We also developed a wide dynamic range (WiDR) antibiotic selection to further enhance the activities of the weaker first-generation EcTyrRS mutants. We demonstrated the utility of our platform by developing several new EcTyrRS mutants that efficiently incorporated useful ncAAs in mammalian cells, including photoaffinity probes, bioconjugation handles, and a nonhydrolyzable mimic of phosphotyrosine.
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Agrawal M, Hillenbrand CM, Allin KH, Torres J. Early Life Greenspace and the Risk of Pediatric-Onset Inflammatory Bowel Disease: Insights into the Link Between Environmental and Human Health. Gastroenterology 2021; 161:355-357. [PMID: 33865842 DOI: 10.1053/j.gastro.2021.04.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Indexed: 12/02/2022]
Affiliation(s)
- Manasi Agrawal
- The Henry D. Janowitz Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, New York and, Center for Molecular Prediction of Inflammatory Bowel Disease, Department of Clinical Medicine, Aalborg University, Copenhagen, Denmark
| | - Christen M Hillenbrand
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kristine H Allin
- Center for Molecular Prediction of Inflammatory Bowel Disease, Department of Clinical Medicine, Aalborg University, Copenhagen, Denmark
| | - Joana Torres
- The Henry D. Janowitz Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, New York and, Division of Gastroenterology, Hospital Beatriz Ângelo, Loures, Portugal and, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
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Agrawal M, Sabino J, Frias-Gomes C, Hillenbrand CM, Soudant C, Axelrad JE, Shah SC, Ribeiro-Mourão F, Lambin T, Peter I, Colombel JF, Narula N, Torres J. Early life exposures and the risk of inflammatory bowel disease: Systematic review and meta-analyses. EClinicalMedicine 2021; 36:100884. [PMID: 34308303 PMCID: PMC8257976 DOI: 10.1016/j.eclinm.2021.100884] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 04/12/2021] [Accepted: 04/16/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Early life exposures impact immune system development and therefore the risk of immune-mediated diseases, including inflammatory bowel disease (IBD). We systematically reviewed the impact of pre-, peri‑, and postnatal exposures up to the age of five years on subsequent IBD diagnosis. METHODS We identified case-control and cohort studies reporting on the association between early life environmental factors and Crohn's disease (CD), ulcerative colitis (UC), or IBD overall. Databases were search from their inception until May 24th, 2019 until July 14th, 2020. We conducted meta-analyses for quantitative review of relevant risk factors that were comparable across studies and qualitative synthesis of the literature for a wide range of early life exposures, including maternal health and exposures during pregnancy, perinatal factors, birth month and related-factors, breastfeeding, hygiene-related factors and social factors, immigration, antibiotics, offspring health, including infections, and passive smoking. PROSPERO registration: CRD42019134980. FINDINGS Prenatal exposure to antibiotics (OR 1.8; 95% CI 1.2-2.5) and tobacco smoke (OR 1.5; 95% CI 1.2-1.9), and early life otitis media (OR 2.1; 95% CI 1.2-3.6) were associated with IBD. There was a trend towards an association between exposure to antibiotics in infancy and IBD (OR: 1.7, 95% CI 0.97, 2.9), supported by positive data on population-based data. Breastfeeding was protective against IBD. Other early life risk factors had no association with IBD, but data were limited and heterogenous. INTERPRETATION Early life is an important period of susceptibility for IBD development later in life. Tobacco smoke, infections and antibiotics were associated positively, and breastfeeding was associated negatively with IBD. Our findings offer an opportunity to develop primary prevention strategies. FUNDING This study did not receive any funding.
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Affiliation(s)
- Manasi Agrawal
- The Henry D. Janowitz Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - João Sabino
- Gastroenterology Division, University Hospital of Leuven, Leuven, Belgium
| | - Catarina Frias-Gomes
- Division of Gastroenterology, Hospital Beatriz Ângelo, Loures 2674-514, Portugal
| | - Christen M. Hillenbrand
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Celine Soudant
- Levy Library, The Mount Sinai Medical Center, New York, NY, United States
- Medical Library, Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Jordan E. Axelrad
- Division of Gastroenterology, New York University Grossman School of Medicine, New York, NY, United States
| | - Shailja C. Shah
- Division of Gastroenterology, Hepatology, and Nutrition, Vanderbilt University Medical Center, Nashville, TN, United States
- Section of Gastroenterology, Veterans Affairs Tennessee Valley Healthcare System, Nashville campus, Nashville, TN, United States
| | - Francisco Ribeiro-Mourão
- Pediatrics Department, Unidade Local de Saúde do Alto Minho, Viana do Castelo, Portugal
- Pediatrics Department, Centro Materno Infantil do Norte – Centro Hospitalar e Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto, Portugal
| | - Thomas Lambin
- Department of Gastroenterology, Claude Huriez Hospital, University of Lille, Lille, France
| | - Inga Peter
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Jean-Frederic Colombel
- The Henry D. Janowitz Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Neeraj Narula
- Department of Medicine (Division of Gastroenterology) and Farncombe Family Digestive, Health Research Institute, McMaster University, Hamilton, ON, Canada
| | - Joana Torres
- The Henry D. Janowitz Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Division of Gastroenterology, Hospital Beatriz Ângelo, Loures 2674-514, Portugal
- Faculdade de Medicina, Universidade de Lisboa, Portugal
- Corresponding author.
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Grasso KT, Yeo MJR, Hillenbrand CM, Ficaretta ED, Italia JS, Huang RL, Chatterjee A. Structural Robustness Affects the Engineerability of Aminoacyl-tRNA Synthetases for Genetic Code Expansion. Biochemistry 2021; 60:489-493. [PMID: 33560840 DOI: 10.1021/acs.biochem.1c00056] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability to engineer the substrate specificity of natural aminoacyl-tRNA synthetase/tRNA pairs facilitates the site-specific incorporation of noncanonical amino acids (ncAAs) into proteins. The Methanocaldococcus jannaschii-derived tyrosyl-tRNA synthetase (MjTyrRS)/tRNA pair has been engineered to incorporate numerous ncAAs into protein expressed in bacteria. However, it cannot be used in eukaryotic cells due to cross-reactivity with its host counterparts. The Escherichia coli-derived tyrosyl-tRNA synthetase (EcTyrRS)/tRNA pair offers a suitable alternative to this end, but a much smaller subset of ncAAs have been genetically encoded using this pair. Here we report that this discrepancy, at least partly, stems from the structural robustness of EcTyrRS being lower than that of MjTyrRS. We show that the thermostability of engineered TyrRS mutants is generally significantly lower than those of their wild-type counterparts. Derived from a thermophilic archaeon, MjTyrRS is a remarkably sturdy protein and tolerates extensive active site engineering without a catastrophic loss of stability at physiological temperature. In contrast, EcTyrRS exhibits significantly lower thermostability, rendering some of its engineered mutants insufficiently stable at physiological temperature. Our observations identify the structural robustness of an aaRS as an important factor that significantly influences how extensively it can be engineered. To overcome this limitation, we have further developed chimeras between EcTyrRS and its homologue from a thermophilic bacterium, which offer an optimal balance between thermostability and activity. We show that the chimeric bacterial TyrRSs show enhanced tolerance for destabilizing active site mutations, providing a potentially more engineerable platform for genetic code expansion.
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Affiliation(s)
- Katherine T Grasso
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Megan J R Yeo
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Christen M Hillenbrand
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Elise D Ficaretta
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - James S Italia
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Rachel L Huang
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
| | - Abhishek Chatterjee
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, United States
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Italia JS, Peeler JC, Hillenbrand CM, Latour C, Weerapana E, Chatterjee A. Genetically encoded protein sulfation in mammalian cells. Nat Chem Biol 2020; 16:379-382. [PMID: 32198493 PMCID: PMC7564891 DOI: 10.1038/s41589-020-0493-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 12/11/2019] [Accepted: 01/17/2020] [Indexed: 11/14/2022]
Abstract
Tyrosine sulfation is an important post-translational modification found in higher eukaryotes. Here we report an engineered tyrosyl-tRNA synthetase/tRNA pair that co-translationally incorporates O-sulfotyrosine in response to UAG codons in E. coli and mammalian cells. This platform enables recombinant expression of eukaryotic proteins homogeneously sulfated at chosen sites, which was demonstrated by expressing human heparin cofactor II in mammalian cells in different states of sulfation.
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Affiliation(s)
- James S Italia
- Department of Chemistry, Boston College, Chestnut Hill, MA, USA
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Torres Yordán NC, Yost EL, Hillenbrand CM, Robinson JN, McElrath TF, Greenberg J. 411: Effects of labor on metabolic indicators of fetal stress in newborns delivered via cesarean section. Am J Obstet Gynecol 2020. [DOI: 10.1016/j.ajog.2019.11.427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Winchell AM, Taylor BA, Song R, Loeffler RB, Grundlehner P, Hankins JS, Wang WC, Ogg RJ, Hillenbrand CM, Helton KJ. Evaluation of SWI in children with sickle cell disease. AJNR Am J Neuroradiol 2014; 35:1016-21. [PMID: 24263696 DOI: 10.3174/ajnr.a3794] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND AND PURPOSE SWI is a powerful tool for imaging of the cerebral venous system. The SWI venous contrast is affected by blood flow, which may be altered in sickle cell disease. In this study, we characterized SWI venous contrast in patients with sickle cell disease and healthy control participants and examined the relationships among SWI venous contrast, and hematologic variables in the group with sickle cell disease. MATERIALS AND METHODS A retrospective review of MR imaging and hematologic variables from 21 patients with sickle cell disease and age- and sex-matched healthy control participants was performed. A Frangi vesselness filter was used to quantify the attenuation of visible veins from the SWI. The normalized visible venous volume was calculated for quantitative analysis of venous vessel conspicuity. RESULTS The normalized visible venous volume was significantly lower in the group with sickle cell disease vs the control group (P < .001). Normalized visible venous volume was not associated with hemoglobin, percent hemoglobin F, percent hemoglobin S, absolute reticulocyte count, or white blood cell count. A hypointense arterial signal on SWI was observed in 18 of the 21 patients with sickle cell disease and none of the 21 healthy control participants. CONCLUSIONS This study demonstrates the variable and significantly lower normalized visible venous volume in patients with sickle cell disease compared with healthy control participants. Decreased venous contrast in sickle cell disease may reflect abnormal cerebral blood flow, volume, velocity, or oxygenation. Quantitative analysis of SWI contrast may be useful for investigation of cerebrovascular pathology in patients with sickle cell disease, and as a tool to monitor therapies. However, future studies are needed to elucidate physiologic mechanisms of decreased venous conspicuity in sickle cell disease.
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Affiliation(s)
- A M Winchell
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - B A Taylor
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - R Song
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - R B Loeffler
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - P Grundlehner
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - J S Hankins
- Hematology (J.S.H., W.C.W.), St. Jude Children's Research Hospital, Memphis, Tennessee
| | - W C Wang
- Hematology (J.S.H., W.C.W.), St. Jude Children's Research Hospital, Memphis, Tennessee
| | - R J Ogg
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - C M Hillenbrand
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
| | - K J Helton
- From the Departments of Radiological Sciences (A.M.W., B.A.T., R.S., R.B.L., P.G., R.J.O., C.M.H., K.J.H.)
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Sedlacik J, Winchell A, Kocak M, Loeffler RB, Broniscer A, Hillenbrand CM. MR imaging assessment of tumor perfusion and 3D segmented volume at baseline, during treatment, and at tumor progression in children with newly diagnosed diffuse intrinsic pontine glioma. AJNR Am J Neuroradiol 2013; 34:1450-5. [PMID: 23436052 DOI: 10.3174/ajnr.a3421] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE DIPG is among the most devastating brain tumors in children, necessitating the development of novel treatment strategies and advanced imaging markers such as perfusion to adequately monitor clinical trials. This study investigated tumor perfusion and 3D segmented tumor volume as predictive markers for outcome in children with newly diagnosed DIPG. METHODS Imaging data were assessed at baseline, during, and after RT, and every other month thereafter until tumor progression for 35 patients (ages 2-16 years) with newly diagnosed DIPG enrolled in the phase I clinical study, NCT00472017. Patients were treated with conformal RT and vandetanib, a vascular endothelial growth factor receptor 2 inhibitor. RESULTS Tumor perfusion increased and tumor volume decreased during combined RT and vandetanib therapy. These changes slowly diminished in follow-up scans until tumor progression. However, increased tumor perfusion and decreased tumor volume during combined therapy were associated with longer PFS. Apart from a longer OS for patients who showed elevated tumor perfusion after RT, there was no association for tumor volume and other perfusion variables with OS. CONCLUSIONS Our results suggest that tumor perfusion may be a useful predictive marker for the assessment of treatment response and tumor progression in children with DIPG treated with both RT and vandetanib. The assessment of tumor perfusion yields valuable information about tumor microvascular status and its response to therapy, which may help better understand the biology of DIPGs and monitor novel treatment strategies in future clinical trials.
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Affiliation(s)
- J Sedlacik
- Department of Radiological Sciences, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
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Löbel U, Sedlacik J, Reddick WE, Kocak M, Ji Q, Broniscer A, Hillenbrand CM, Patay Z. Quantitative diffusion-weighted and dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging analysis of T2 hypointense lesion components in pediatric diffuse intrinsic pontine glioma. AJNR Am J Neuroradiol 2010; 32:315-22. [PMID: 21087935 DOI: 10.3174/ajnr.a2277] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Focal anaplasia characterized by T2 hypointensity, signal-intensity enhancement on postcontrast T1-weighted MR imaging and restricted water diffusion has been reported in a patient with juvenile pilocytic astrocytoma. We identified T2(HOF) with these MR imaging characteristics in children with DIPG and hypothesized that these represent areas of focal anaplasia; and may, therefore, have increased perfusion properties and should be characterized by increased perfusion. Thus, we used DSC to investigate our hypothesis. MATERIALS AND METHODS We retrospectively reviewed the baseline MR imaging scans of 86 patients (49 girls, 37 boys; median age, 6.1 years; range, 1.1-17.6 years) treated for DIPG at our hospital (2004-2009). T2(HOF) with the described MR imaging characteristics was identified in 10 patients. We used a region of interest-based approach to compare the ADC, FA, rCBV, rCBF, and rMTT of T2(HOF) with those of the typical T2(HRT). RESULTS The ADC of T2(HOF) with the specified MR imaging characteristics was significantly lower than that of T2(HRT) (range, 0.71-1.95 μm(2)/ms versus 1.36-2.13 μm(2)/ms; P < .01); and the FA (range, 0.12-0.34 versus 0.07-0.24; P = .03) and rCBV (range, 0.4-2.62 versus 0.23-1.57; P = .01) values of T2(HOF)s were significantly higher. CONCLUSIONS Our data suggest that T2(HOF) in DIPG may represent areas of focal anaplasia and underline the importance of regional, rather than global, tumor-field analysis. T2(HOF) may be the ideal target when stereotactic biopsy of tumors that present with an inhomogeneous T2 signal intensity is considered.
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Affiliation(s)
- U Löbel
- Department of Radiological Sciences, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105-2794, USA
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Sedlacik J, Löbel U, Kocak M, Loeffler RB, Reichenbach JR, Broniscer A, Patay Z, Hillenbrand CM. Attenuation of cerebral venous contrast in susceptibility-weighted imaging of spontaneously breathing pediatric patients sedated with propofol. AJNR Am J Neuroradiol 2010; 31:901-6. [PMID: 20053806 DOI: 10.3174/ajnr.a1960] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND AND PURPOSE SWI is known for its detailed visualization of the cerebral venous system and seems to be a promising tool for early detection of cerebrovascular pathologies in children, who are frequently sedated for MR imaging. Because sedation influences cerebral hemodynamics, we hypothesized that it would affect cerebral venous contrast in SWI. MATERIALS AND METHODS SWI (125 examinations) of 26 patients (age, 2-16 years) was reviewed in this study. Images were acquired of patients sedated with propofol. Reviewers classified the images by weak or strong venous contrast. Physiologic data, such as etCO(2), BP, age, and CBF by arterial spin-labeling, were monitored and collected during MR imaging. A generalized estimating equation approach was used to model associations of these parameters with venous contrast. RESULTS EtCO(2) and CBF were found to correlate with venous contrast, suggesting that patients with high etCO(2) and CBF have weak contrast and patients with low etCO(2) and CBF have strong contrast. BP was also found to correlate with the venous contrast of SWI, suggesting that patients with high BP have strong venous contrast. No significant correlations were found for any other physiologic parameters. CONCLUSIONS We found that the venous contrast in SWI is affected by propofol sedation in spontaneously breathing patients. We also found that low etCO(2), low CBF, and high BP are associated with strong venous contrast. Reviewing SWI data in light of physiologic measures may therefore help prevent potential misinterpretations of weak venous contrast in SWI examinations under propofol sedation.
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Affiliation(s)
- J Sedlacik
- Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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Abstract
In this contribution, a rapid and robust technique for quantitative T(1) mapping of the human lung is presented. Based on a series of Snapshot FLASH tomograms acquired after a single inversion pulse, high quality and quantitative T(1) parameter maps acquired in under five seconds were obtained from six healthy volunteers. The measured T(1) values are in good agreement with previously reported literature values. T(1) maps were also acquired with the volunteers breathing room air or 100% O(2). The T(1) difference between breathing room air and 100% O(2) is statistically significant at P < 0.0001.
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Affiliation(s)
- P M Jakob
- Department of Physics, University of Würzburg, Würzburg, Germany.
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Brokaw JJ, Hillenbrand CM, White GW, McDonald DM. Mechanism of tachyphylaxis associated with neurogenic plasma extravasation in the rat trachea. Am Rev Respir Dis 1990; 141:1434-40. [PMID: 1693479 DOI: 10.1164/ajrccm/141.6.1434] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Electrical stimulation of the vagus nerve of rats is known to produce plasma extravasation in the trachea, presumably by releasing substance P or other tachykinins from sensory nerves. We sought to determine whether the tachyphylaxis that develops after prolonged vagal stimulation results from an inability of sensory nerves to release tachykinins or from an inability of tracheal blood vessels to respond to tachykinins. To induce tachyphylaxis, we electrically stimulated the right vagus nerve of Long-Evans rats for 5 min (5 V, 1 ms, 20 Hz). Then, 10 min later, we gave intravenous injections of capsaicin (0.3 mumol/kg), histamine (18 mumols/kg), or substance P (2.2 nmol/kg), which produce equivalent amounts of plasma extravasation as assessed by the extravasation of Evans blue dye. We found that vagal stimulation reduced the amount of dye extravasation produced by capsaicin but not the amount produced by either histamine or substance P. We also found that pretreating neonatal rats with capsaicin, which destroys tachykinin-containing sensory nerves, reduced the amount of dye extravasation produced by capsaicin but not the amount produced by either histamine or substance P. This finding suggests that capsaicin produces plasma extravasation in the trachea by releasing tachykinins from sensory nerves, whereas histamine and substance P do so by acting directly on tracheal blood vessels. Taken together, our results indicate that prolonged vagal stimulation reduces the ability of sensory nerves to release tachykinins but that tracheal blood vessels remain fully responsive to both histamine and substance P.
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Affiliation(s)
- J J Brokaw
- Department of Anatomy, Indiana University School of Medicine, Evansville
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