Mining-impacted sources of metal loading to an alpine stream based on a tracer-injection study, Clear Creek County, Colorado

Abstract Background Metabolic reprogramming is a common phenomenon in tumorigenesis and tumor progression. Amino acids are important mediators in cancer metabolism, and their kinetics in tumor tissue are far from being understood completely. Mass spectrometry imaging is capable to spatiotemporally trace important endogenous metabolites in biological tissue specimens. In this research, we studied L-[ring-13C6]-labeled phenylalanine and tyrosine kinetics in a human non-small cell lung carcinoma (NSCLC) xenografted mouse model using matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry imaging (MALDI-FTICR-MSI). Methods We investigated the L-[ring-13C6]-Phenylalanine (13C6-Phe) and L-[ring-13C6]-Tyrosine (13C6-Tyr) kinetics at 10 min (n = 4), 30 min (n = 3), and 60 min (n = 4) after tracer injection and sham-treated group (n = 3) at 10 min in mouse-xenograft lung tumor tissues by MALDI-FTICR-MSI. Results The dynamic changes in the spatial distributions of 19 out of 20 standard amino acids are observed in the tumor tissue. The highest abundance of 13C6-Phe was detected in tumor tissue at 10 min after tracer injection and decreased progressively over time. The overall enrichment of 13C6-Tyr showed a delayed temporal trend compared to 13C6-Phe in tumor caused by the Phe-to-Tyr conversion process. Specifically, 13C6-Phe and 13C6-Tyr showed higher abundances in viable tumor regions compared to non-viable regions. Conclusions We demonstrated the spatiotemporal intra-tumoral distribution of the essential aromatic amino acid 13C6-Phe and its de-novo synthesized metabolite 13C6-Tyr by MALDI-FTICR-MSI. Our results explore for the first time local phenylalanine metabolism in the context of cancer tissue morphology. This opens a new way to understand amino acid metabolism within the tumor and its microenvironment.

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Renal function measurements from MR renography and a simplified multicompartmental model

AJP Renal Physiology ◽

10.1152/ajprenal.00347.2006 ◽

2007 ◽

Vol 292 (5) ◽

pp. F1548-F1559 ◽

Cited By ~ 107

Author(s):

Vivian S. Lee ◽

Henry Rusinek ◽

Louisa Bokacheva ◽

Ambrose J. Huang ◽

Niels Oesingmann ◽

...

Keyword(s):

Low Dose ◽

Random Noise ◽

Compartment Model ◽

Parameter Estimates ◽

Imaging Data ◽

Tracer Injection ◽

Multicompartmental Model ◽

Enhancement Curve ◽

Reference Measurements ◽

Single Kidney

The purpose of this study was to determine the accuracy and sources of error in estimating single-kidney glomerular filtration rate (GFR) derived from low-dose gadolinium-enhanced T1-weighted MR renography. To analyze imaging data, MR signal intensity curves were converted to concentration vs. time curves, and a three-compartment, six-parameter model of the vascular-nephron system was used to analyze measured aortic, cortical, and medullary enhancement curves. Reliability of the parameter estimates was evaluated by sensitivity analysis and by Monte Carlo analyses of model solutions to which random noise had been added. The dominant sensitivity of the medullary enhancement curve to GFR 1–4 min after tracer injection was supported by a low coefficient of variation in model-fit GFR values (4%) when measured data were subjected to 5% noise. These analyses also showed the minimal effects of bolus dispersion in the aorta on parameter reliability. Single-kidney GFR from MR renography analyzed by the three-compartment model (4.0–71.4 ml/min) agreed well with reference measurements from 99mTc-DTPA clearance and scintigraphy ( r = 0.84, P < 0.001). Bland-Altman analysis showed an average difference of 11.9 ml/min (95% confidence interval = 5.8–17.9 ml/min) between model and reference values. We conclude that a nephron-based multicompartmental model can be used to derive clinically useful estimates of single-kidney GFR from low-dose MR renography.

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Spinogenesis and pruning in the primary auditory cortex of the macaque monkey (Macaca fascicularis): An intracellular injection study of layer III pyramidal cells

Brain Research ◽

10.1016/j.brainres.2009.12.056 ◽

2010 ◽

Vol 1316 ◽

pp. 35-42 ◽

Cited By ~ 21

Author(s):

Guy N. Elston ◽

Tsuguhisa Okamoto ◽

Tomofumi Oga ◽

Dimity Dornan ◽

Ichiro Fujita

Keyword(s):

Auditory Cortex ◽

Macaca Fascicularis ◽

Primary Auditory Cortex ◽

Pyramidal Cells ◽

Macaque Monkey ◽

Intracellular Injection ◽

Injection Study

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