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Sudarshana DM, Nair G, Dwyer JT, Dewey B, Steele SU, Suto DJ, Wu T, Berkowitz BA, Koretsky AP, Cortese ICM, Reich DS. Manganese-Enhanced MRI of the Brain in Healthy Volunteers. AJNR Am J Neuroradiol 2019; 40:1309-1316. [PMID: 31371354 DOI: 10.3174/ajnr.a6152] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 06/13/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND PURPOSE The manganese ion is used as an intracellular MR imaging contrast agent to study neuronal function in animal models, but it remains unclear whether manganese-enhanced MR imaging can be similarly useful in humans. Using mangafodipir (Teslascan, a chelated manganese-based contrast agent that is FDA-approved), we evaluated the dynamics of manganese enhancement of the brain and glandular structures in the rostral head and neck in healthy volunteers. MATERIALS AND METHODS We administered mangafodipir intravenously at a rate of 1 mL/minute for a total dose of 5 μmol/kg body weight. Nine healthy adult volunteers (6 men/3 women; median age, 43 years) completed baseline history and physical examination, 3T MR imaging, and blood work. MR imaging also followed mangafodipir administration at various time points from immediate to 7 days, with delayed scans at 1-3 months. RESULTS The choroid plexus and anterior pituitary gland enhanced within 10 minutes of infusion, with enhancement persisting up to 7 and 30 days, respectively. Exocrine (parotid, submandibular, sublingual, and lacrimal) glands also enhanced avidly as early as 1 hour postadministration, generally resolving by 1 month; 3 volunteers had residual exocrine gland enhancement, which resolved by 2 months in 1 and by 3 months in the other 2. Mangafodipir did not affect clinical parameters, laboratory values, or T1-weighted signal in the basal ganglia. CONCLUSIONS Manganese ions released from mangafodipir successfully enable noninvasive visualization of intra- and extracranial structures that lie outside the blood-brain barrier without adverse clinical effects, setting the stage for future neuroradiologic investigation in disease.
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Affiliation(s)
- D M Sudarshana
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland.,Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (D.M.S.), Cleveland, Ohio
| | - G Nair
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - J T Dwyer
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - B Dewey
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - S U Steele
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - D J Suto
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - T Wu
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - B A Berkowitz
- Department of Ophthalmology (B.A.B.), Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan
| | - A P Koretsky
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - I C M Cortese
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
| | - D S Reich
- From the National Institute of Neurological Disorders and Stroke (D.M.S., G.N., J.T.D., B.D., S.U.S., D.J.S., T.W., A.P.K., I.C.M.C., D.S.R.), National Institutes of Health, Bethesda, Maryland
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Hartter DE, Burton PR, Laveri LA. Distribution and calcium-sequestering ability of smooth endoplasmic reticulum in olfactory axon terminals of frog brain. Neuroscience 1987; 23:371-86. [PMID: 3500427 DOI: 10.1016/0306-4522(87)90297-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In the present study, the structural and functional role of smooth endoplasmic reticulum was investigated in bullfrog olfactory axon terminals. Structural evidence obtained from this study indicated that this vesiculotubular organelle becomes a more elaborate network of anastomosing tubules near the nerve terminal, located in the olfactory lobe of frog brain. Further structural evidence suggested that membranes of the smooth endoplasmic reticulum pinch off to give rise to some electron-lucent vesicles of approximately 50 nm diameter (microvesicles). Ultrastructural cytochemistry was employed in the present study to demonstrate that olfactory axon terminal smooth endoplasmic reticulum actively sequesters Ca2+. However, a variable amount of electron-dense product (calcium oxalate) was associated with microvesicles located at a distance from the synapse, in contrast to those clustered near the synapse which usually did not contain this reaction product. Results from Ca2+-Mg2+-adenosine-5'-triphosphatase (ATPase) cytochemistry showed a similar pattern of distribution, with smooth endoplasmic reticulum being densely labeled with ATPase reaction product (lead phosphate), but aggregated microvesicles in the nerve terminal generally lacking this electron-dense product. Therefore, it is concluded that olfactory axonal smooth endoplasmic reticulum plays a role in the regulation of intraneuronal Ca2+ levels, and that the Ca2+-sequestering activity of this membranous organelle is dependent upon enzymatic hydrolysis of ATP. Conversely, the microvesicles, particularly those accumulated near the synapse, lack this Ca2+-pumping capacity. Thus, if some of the microvesicles originate from smooth endoplasmic reticulum membranes which are capable of pumping Ca2+, but these vesicles themselves lack this capacity, one can postulate that the Ca2+ pumps are either removed from the newly formed microvesicle membranes or are somehow incapacitated in situ in the membrane.
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Affiliation(s)
- D E Hartter
- Department of Physiology and Cell Biology, University of Kansas, Lawrence 66045
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Thiyagarajah P, Lim SC. The (Ca2+ + Mg2+)-stimulated ATPase of the rat parotid endoplasmic reticulum. Biochem J 1986; 235:491-8. [PMID: 2943271 PMCID: PMC1146712 DOI: 10.1042/bj2350491] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A membrane fraction enriched in endoplasmic reticulum was prepared from rat parotid glands by using sucrose-gradient centrifugation. The fraction showed a 10-fold increase in specific activity of NADPH: cytochrome c reductase activity over that of tissue homogenates and minimal contamination with plasma membranes or mitochondria. The endoplasmic reticulum fraction possessed both Mg2+ -stimulated ATPase as well as Ca2+, Mg2+-ATPase [( Ca2+ + Mg2+)-stimulated ATPase]activity. The Ca2+, Mg2+-ATPase required 2-5 mM-Mg2+ for optimal activity and was stimulated by submicromolar concentrations of free Ca2+. The Km for free Ca2+ was 0.55 microM and the average Vmax. was 60 nmol/min per mg of protein. The Km for ATP was 0.11 mM. Other nucleotides, such as GTP, CTP or ADP, could not substitute for ATP in supporting the Ca2+-activated nucleotidase activity. Increasing the K+ concentration from 0 to 100 mM caused a 2-fold activation of the Ca2+, Mg2+-ATPase. Trifluoperazine, W7 [N-(6-aminohexyl)-5-chloronaphthalene-1-sulphonamide] and vanadate inhibited the enzyme. The concentration of trifluoperazine and vanadate required for 50% inhibition of the ATPase were 52 microM and 28 microM respectively. Calmodulin, cyclic AMP, cyclic AMP-dependent protein kinase and inositol 1,4,5-trisphosphate had no effect on the ATPase. The properties of the Ca2+, Mg2+ -ATPase were distinct from those of the Mg2+-ATPase, but comparable with those reported for the parotid endoplasmic-reticulum Ca2+-transport system [Kanagasuntheram & Teo (1982) Biochem. J. 208, 789-794]. The results suggest that the Ca2+, Mg2+-ATPase is responsible for driving the ATP-dependent Ca2+ accumulation by this membrane.
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