Read by QxMD icon Read

Manganese isotope tracer

Stephen A Graves, Reinier Hernandez, Hector F Valdovinos, Paul A Ellison, Jonathan W Engle, Todd E Barnhart, Weibo Cai, Robert J Nickles
Manganese has long been employed as a T1-shortening agent in magnetic resonance imaging (MRI) applications, but these techniques are limited by the biotoxicity of bulk-manganese. Positron emission tomography (PET) offers superior contrast sensitivity compared with MRI, and recent preclinical PET studies employing (52g)Mn (t1/2: 5.6 d, β(+): 29%) show promise for a variety of applications including cell tracking, neural tract tracing, immunoPET, and functional β-cell mass quantification. The half-life and confounding gamma emissions of (52g)Mn are prohibitive to clinical translation, but the short-lived (51)Mn (t1/2: 46 min, β(+): 97%) represents a viable alternative...
June 8, 2017: Scientific Reports
J B Richardson
Manganese (Mn) cycling in the Critical Zone is important because of its role as an essential nutrient and potential toxicity to plants and organisms. Quantifying Mn enrichment in terrestrial environments has been limited since Mn is monoisotopic. However, elemental ratios of Mn/Ca ratios may be used to determine spatial Mn enrichment and in aboveground and belowground pools. The objectives of this study were to quantify the spatial variation in Mn concentrations and Mn/Ca ratios in foliage, bolewood, forest floor, and mineral soil horizons across the northeastern United States and compare Mn/Ca ratios to estimate enrichment...
March 1, 2017: Science of the Total Environment
Andrew J Frierdich, Michael J Spicuzza, Michelle M Scherer
Manganese is biogeochemically cycled between aqueous Mn(II) and Mn(IV) oxides. Aqueous Mn(II) often coexists with Mn(IV) oxides, and redox reactions between the two (e.g., comproportionation) are well known to result in the formation of Mn(III) minerals. It is unknown, however, whether aqueous Mn(II) exchanges with structural Mn(III) in manganese oxides in the absence of any mineral transformation (similar to what has been reported for aqueous Fe(II) and some Fe(III) minerals). To probe whether atoms exchange between a Mn(III) oxide and water, we use a (17)O tracer to measure oxygen isotope exchange between structural oxygen in manganite (γ-MnOOH) and water...
June 21, 2016: Environmental Science & Technology
Christian Vanasschen, Marie Brandt, Johannes Ermert, Heinz H Coenen
Radiolabelling using isotopic mixtures of (52g/55)Mn(ii) offers fast and easy access to new small molecule PET/MR tracers, composed of chemically identical reporting units. trans-1,2-Diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA) was radiolabelled with carrier-added (52g)Mn(ii) in >99% radiochemical yield, producing the first manganese-based bimodal PET/MR probe. The Mn-CDTA chelate was shown to be very stable to air oxidation and sufficiently inert to decomplexation in blood serum. These data sparked our interest in functionalized CDTA ligands for the design of optimized PET/MR tracers...
January 28, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
E Weigand, U Helbig, M Kirchgessner
A conventional balance study with growing rats was conducted to evaluate experimental conditions for determining endogenous fecal manganese (Mn) excretion and, hence, true Mn absorption by the isotope-dilution technique. Thirty-four rats, with a mean initial live weight of 60 g, allotted to three groups of 8 animals and one group of 10 animals, were injected intramuscularly with a(54)Mn tracer dose and sacrificed after 4, 8, 12, and 16 d, respectively.In liver and serum, the specific radioactivity of Mn was the lowest among the tissues analyzed and its exponential rate of decrease over the period of d 4-16 was the highest...
October 1986: Biological Trace Element Research
Sarah A Castine, Dirk V Erler, Lindsay A Trott, Nicholas A Paul, Rocky de Nys, Bradley D Eyre
Settlement ponds are used to treat aquaculture discharge water by removing nutrients through physical (settling) and biological (microbial transformation) processes. Nutrient removal through settling has been quantified, however, the occurrence of, and potential for microbial nitrogen (N) removal is largely unknown in these systems. Therefore, isotope tracer techniques were used to measure potential rates of denitrification and anaerobic ammonium oxidation (anammox) in the sediment of settlement ponds in tropical aquaculture systems...
2012: PloS One
Lev J Spivak-Birndorf, Brian W Stewart, Rosemary C Capo, Elizabeth C Chapman, Karl T Schroeder, Tonya M Brubaker
Sequential leaching experiments on coal utilization by-products (CUB) were coupled with chemical and strontium (Sr) isotopic analyses to better understand the influence of coal type and combustion processes on CUB properties and the release of elements during interaction with environmental waters during disposal. Class C fly ash tended to release the highest quantity of minor and trace elements-including alkaline earth elements, sodium, chromium, copper, manganese, lead, titanium, and zinc-during sequential extraction, with bottom ash yielding the lowest...
January 2012: Journal of Environmental Quality
Gregory A Brennecka, Laura E Wasylenki, John R Bargar, Stefan Weyer, Ariel D Anbar
Previous work has shown uranium (U) isotope fractionation between natural ferromanganese crusts and seawater. Understanding the mechanism that causes (238)U/(235)U fractionation during adsorption to ferromanganese oxides is a critical step in the utilization of (238)U/(235)U as a tracer of U adsorption reactions in groundwater as well as a potential marine paleoredox proxy. We conducted U adsorption experiments using synthetic K-birnessite and U-bearing solutions. These experiments revealed a fractionation matching that observed between seawater and natural ferromanganese sediments: adsorbed U is isotopically lighter by ∼0...
February 15, 2011: Environmental Science & Technology
Alexander V Sobolev, Albrecht W Hofmann, Gerhard Brügmann, Valentina G Batanova, Dmitry V Kuzmin
Recycled subducted ocean crust has been traced by elevated 187Os/188Os in some studies and by high nickel and low manganese contents in others. Here, we show that these tracers are linked for Quaternary lavas of Iceland, strengthening the recycling model. An estimate of the osmium isotopic composition of both the recycled crust and the mantle peridotite implies that Icelandic Quaternary lavas are derived in part from an ancient crustal component with model ages between 1.1 _ 109 and 1.8 _ 109 years and from a peridotitic end-member close to present-day oceanic mantle...
July 25, 2008: Science
Mauro Bonardi, Claudio Birattari, Flavia Groppi, Luigi Gini, Alberto Ghioni, Hae Song Mainardi, Dolores Arginelli, Mario Gallorini, Enrico Rizzio, Enrico Sabbioni
In this paper are presented the production methods for very "high specific activity" radionuclides (HSA-RN) of vanadium, manganese and thallium which have been developed in our laboratories for labelling different chemical forms of these elements present in the echo-systems in ultra-trace amounts, for metallo-toxicological and bio-kinetic studies. Use was made of both cyclotron and thermal nuclear reactor. If the nuclear reaction product has atomic number different from irradiated target, it is possible separating the radioactive nuclide from irradiated target, without addition of isotopic carrier...
April 2003: Annali di Chimica
P L Hagan, S E Halpern, P Stern, J Dabbs, R Gordon
The smallest quantity of carrier Ga and Mn necessary to initiate and maximize a carrier effect was studied in the Morris 7777 rat hepatoma model. The quantity needed for a maximum response did not appear to adversely effect the rats. Not all tissues were equally affected at the same plasma concentrations. If carrier Ga was administered 2 hours following 67Ga injection and the rats sacrificed 30 minutes later, a dramatic change occurred in background activity, which was more pronounced in healthy than malignant tissues...
November 1980: Investigative Radiology
A Veglia, S Keckes
No abstract text is available yet for this article.
September 1971: International Journal of Applied Radiation and Isotopes
A Lauber, M Wolgast
No abstract text is available yet for this article.
July 1972: Physics in Medicine and Biology
C C Ashley, J C Ellory
1. In the large single muscle fibres from the barnacle Balanus nubilus, the total fibre Mg concentration was estimated as 15.1 m-mole/kg wet wt., of which about 3-3.5 m-mole/kg wet wt. was extracellular. The diffusible Mg, measured by internal sampling, was 11.5 m-mole/kg wet wt., of which at least half may be complexed to larger diffusible molecules. The free ionized Mg level was estimated as < 5 m-mole/kg wet wt.2. The loss of [(28)Mg]MgCl(2) from both Maia and Balanus muscle fibres following axial micro-injection approximated to first-order kinetics...
November 1972: Journal of Physiology
J C Evans, R J Evans, A Holmes, R F Hounam, D M Jones, A Morgan, M Walsh
No abstract text is available yet for this article.
June 1973: Environmental Research
E Weigand, M Kirchgessner, A Kiliç
A tracer study with broiler chicks was conducted to determine endogenous Mn excretion in response to graded levels of dietary Mn supply by the isotope-dilution method. Starting with 46 day-old chicks, low-Mn diets were fed for 12 days before 8 chicks were slaughtered for assessing the initial Mn status and 38 chicks each were given an intramuscular injection of 555 kBq 54Mn. Four groups of six birds each were fed, one bird per cage, diets containing 2.8, 9.1, 25.8, and 59.7 ppm Mn for 16 days before slaughter and carcass analyses...
October 1988: Archiv Für Tierernährung
E J Underwood
Twenty-two mineral elements are known to be essential for animal life. These are calcium, phosphorus, sulphur, potassium, sodium, chlorine, magnesium, iron, iodine, copper, manganese, zinc, cobalt, molybdenum, selenium, chromium, tin, vanadium, fluorine, silicon, nickel and arsenic. Naturally occurring and man-made dietary imbalances of many of these elements and their interactions with other minerals are described and their functions and requirements by farm animals are outlined. The nature and importance of metabolic interactions among the mineral elements are discussed and the important concept stressed that there is no single minimum requirement or safe tolerance of a particular mineral, but a series of such minimum requirements and safe tolerances depending on the extent to which other minerals with which it interacts is present or absent from the diet...
December 1976: Atomic Energy Review
C R Bagshaw, D R Trentham
From transient kinetic studies of the Mg2+-dependent adenosine triphosphatase of myosin subfragment 1, prepared from rabbit skeletal muscle, a seven-step mechanism has been proposed. Features of this mechanism include two-step processes for ATP and ADP binding in which the binary complex isomerizes in addition to a rapid nucleotide association step. In the case of ATP a large negative standard free energy change is associated with the isomerization. An overall rate-limiting isomerization of the myosin-product complex prior to product release has been identified...
1975: Journal of Supramolecular Structure
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"