Modelling of seasonal variation in nitrogen retention and in-lake concentration: A four-year mass balance study in 16 shallow Danish lakes

1996 ◽  
Vol 33 (1) ◽  
Author(s):  
J�rgen Windolf ◽  
Erik Jeppesen ◽  
JensPete Jensen ◽  
Peter Kristensen
Keyword(s):  
Seasonal Variation ◽  
Mass Balance ◽  
Nitrogen Retention ◽  
Balance Study ◽  
Mass Balance Study

A 90-day oral (dietary) toxicity and mass balance study of corn starch fiber in Sprague Dawley rats

2016 ◽  
Vol 97 ◽  
pp. 57-69 ◽  
Author(s):  
Christine M. Crincoli ◽  
Andrey I. Nikiforov ◽  
Marisa O. Rihner ◽  
Elizabeth A. Lambert ◽  
Melanie A. Greeley ◽  
...  
Keyword(s):  
Mass Balance ◽  
Corn Starch ◽  
Sprague Dawley ◽  
Balance Study ◽  
Sprague Dawley Rats ◽  
Dietary Toxicity ◽  
Mass Balance Study

Unequal Absorption of Radiolabeled and Nonradiolabeled Drug from the Oral Dose Leads to Incorrect Estimates of Drug Absorption and Circulating Metabolites in a Mass Balance Study

2019 ◽  
Vol 13 (1) ◽  
pp. 37-44
Author(s):  
Ryan H. Takahashi ◽  
Jae H. Chang ◽  
Jodie Pang ◽  
Xiaorong Liang ◽  
Shuguang Ma
Keyword(s):  
Oral Dose ◽  
Mass Balance ◽  
Specific Activity ◽  
The Body ◽  
Total Drug ◽  
Beagle Dogs ◽  
Balance Study ◽  
Drug Concentrations ◽  
Specific Activities ◽  
Mass Balance Study

Background: Mass balance studies conducted using radiolabeled material (14C or 3H) definitively characterize the Absorption, Metabolism, and Excretion (AME) of a drug. A critical aspect of these studies is that the radiotracer maintains its proportion to total drug from its administration to its complete elimination from the body. In the study of GDC-0276 in beagle dogs, we observed that the 14C radiotracer proportion (specific activity) varied through the study. Method: High resolution-accurate mass spectrometric measurements of 12C and 14C isotopes of GDC- 0276 and its metabolites in plasma and excreta samples were used to determine the apparent specific activities, which were higher than the specific activity of the dosing formulation. Drug concentrations were adjusted to the observed specific activities to correct the readouts for GDC-0276 AME and PK. Results: The enrichment of 14C, which resulted in higher specific activities, was consistent with faster and more extensive absorption of the radiotracer from the dosing formulation. This resulted in overestimating the dose absorbed, the extent of elimination in urine and bile, and the exposures to circulating metabolites. These biases were corrected by the specific activities determined for study samples by mass spectrometry. Conclusion: Assuming that the radiotracer was proportional to total drug throughout a radiolabeled study was not valid in a 14C study in beagle dogs. This presumably resulted from unequal absorption of the radiotracer and nonradiolabeled test articles from the oral dose due to inequivalent solid forms. We were able to provide a more accurate description of the AME of GDC-0276 in dogs by characterizing the differential absorption of the radiotracer.

A Phase 1 Mass Balance Study of 14 C‐Labeled Talazoparib in Patients With Advanced Solid Tumors

2019 ◽  
Author(s):  
Yanke Yu ◽  
Chin‐Hee Chung ◽  
Anna Plotka ◽  
Kevin Quinn ◽  
Haihong Shi ◽  
...  
Keyword(s):  
Mass Balance ◽  
Solid Tumors ◽  
Phase 1 ◽  
Advanced Solid Tumors ◽  
Balance Study ◽  
Mass Balance Study

Spatially distributed mass balance of 14 Icelandic glaciers, 1945−2017. Trends and link with climate.

2020 ◽  
Author(s):  
Joaquín M. C. Belart ◽  
Eyjólfur Magnússon ◽  
Etienne Berthier ◽  
Águst Þ. Gunnlaugsson ◽  
Finnur Pálsson ◽  
...  
Keyword(s):  
Mass Balance ◽  
Correction Term ◽  
Statistical Modelling ◽  
Airborne Lidar ◽  
Limited Attention ◽  
Mass Balances ◽  
Balance Study ◽  
Ice Caps ◽  
Mass Balance Study ◽  
Surface Correction

<p>Excluding the three largest ice caps, Icelandic glaciers have, until recently, received limited attention in terms of mass balance observations over the last century. In this study, mass balance estimates from 1945 to 2017 are presented, in decadal time spans, for 14 glaciers (total area 1054 km<sup>2</sup>) subject to different climatic forcing in Iceland. The mass balances are derived from airborne and spaceborne stereo imagery and airborne lidar, and correlated with precipitation and air temperature by a first order equation including a reference-surface correction term. This permits statistical modelling of annual mass balances and to temporally homogenize the mass balances for a region-wide, multidecadal mass balance study. The mean (standard deviation) mass balances of the target glaciers were −0.43 (0.17) m w.e. a<sup>−1</sup> in 1945−1960, 0.01 (0.21) m w.e. a<sup>−1</sup> in 1960−1980, 0.10 (0.23) m w.e. a<sup>−1</sup> in 1980−1994, −0.98 (0.44) m w.e. a<sup>−1</sup> in 1994−2004, −1.23 (0.57) m w.e. a<sup>−1</sup> in 2004−2010 and 0.06 (0.35) m w.e. a<sup>−1</sup> in 2010−2017. The majority of mass loss occured in 1994−2010, accounting for 22.5±1.6 Gt (1.4±0.1 Gt a<sup>−1</sup>). High decadal mass-balance variability is found on glaciers located at the south and west coasts,<br>in contrast to the glaciers located inland, north and northwest. These patterns are likely explained by the proximity to warm (south and west) versus cold (northwest) oceanic currents.</p>

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