Competition between palmitate and ketone bodies as fuels for the heart: study with positron emission tomography

1993 ◽  
Vol 264 (3) ◽  
pp. H701-H707 ◽  
Author(s):  
J. L. Vanoverschelde ◽  
W. Wijns ◽  
J. Kolanowski ◽  
A. Bol ◽  
P. M. Decoster ◽  
...  

To test the ability of ketone bodies to inhibit myocardial fatty acid oxidation in vivo, the myocardial clearance kinetics of [1–11C]palmitate was assessed with positron emission tomography in six fasted volunteers and six instrumented dogs, studied repeatedly before and during infusion of 3-hydroxybutyrate (17 mumol.kg-1 x min-1). With the use of multiexponential fitting of tissue time-activity curves, the size, half time (T1/2), and index of the early rapid phase of 11C myocardial clearance, reflecting palmitate oxidation, were calculated. In humans, the relative size (-28%, P < 0.001) and index (-37%, P < 0.01) of the early rapid phase decreased significantly during infusion of 3-hydroxybutyrate, consistent with decreased fatty acid oxidation. Paradoxically, T1/2 decreased from 10.1 +/- 1.6 to 7.4 +/- 1.1 min (P < 0.01). To elucidate possible mechanisms, multiple coronary arteriovenous samples were obtained from the dogs to assess the efflux of oxidized and nonmetabolized tracer. Infusion of 3-hydroxybutyrate resulted in decreased myocardial [11C]CO2 production (-40%, P < 0.05) and reduced palmitate retention (-38%, P < 0.05). In three dogs, the arteriovenous difference in radiolabeled palmitate became negative 10 min after injection, indicating backdiffusion of nonmetabolized tracer from the myocardium. Thus a steady-state infusion of 3-hydroxybutyrate, resulting in physiological plasma levels, alters [1-11C]palmitate kinetics in vivo by decreasing myocardial long-chain fatty acid oxidation and by increasing backdiffusion of nonmetabolized tracer.

2015 ◽  
Vol 35 (11) ◽  
pp. 1827-1835 ◽  
Author(s):  
Isabelle Boileau ◽  
Pablo M Rusjan ◽  
Belinda Williams ◽  
Esmaeil Mansouri ◽  
Romina Mizrahi ◽  
...  

Positron emission tomography with [11C]CURB was recently developed to quantify fatty acid amide hydrolase (FAAH), the enzyme responsible for hydrolyzing the endocannabinoid anandamide. This study investigated the test–retest reliability of [11C]CURB as well as its in vivo specificity and the validity of the kinetic model by using the highly specific FAAH inhibitor, PF-04457845. Five healthy volunteers completed test–retest [11C]CURB scans 1 to 2 months apart and six subjects completed baseline and blocking scans on the same day after PF-04457845 (p.o.) administration (1, 4, or 20 mg; n = 2 each). The composite parameter γ k3 (an index of FAAH activity, γ = K1/ k2) was estimated using an irreversible two-tissue compartment model with plasma input function. There were no clinically observable responses to oral PF-04457845 or [11C]CURB injection. Oral administration of PF-04457845 reduced [11C]CURB binding to a homogeneous level at all three doses, with γ k3 values decreased by ≥91%. Excellent reproducibility and good reliability (test–retest variability = 9%; intraclass correlation coefficient = 0.79) were observed across all regions of interest investigated. Our findings suggest that γ k3/[11C]CURB is a reliable, highly sensitive, and selective tool to measure FAAH activity in human brain in vivo. Moreover, PF-04457845 is a highly potent FAAH inhibitor (>95% inhibition at 1 mg) in living human brain.


2015 ◽  
Vol 14 (9) ◽  
pp. 7290.2015.00024 ◽  
Author(s):  
Yinlin Li ◽  
Tao Huang ◽  
Xinyue Zhang ◽  
Min Zhong ◽  
Natalie N. Walker ◽  
...  

2015 ◽  
Vol 35 (8) ◽  
pp. 1237-1240 ◽  
Author(s):  
Isabelle Boileau ◽  
Rachel F Tyndale ◽  
Belinda Williams ◽  
Esmaeil Mansouri ◽  
Duncan J Westwood ◽  
...  

The common functional single-nucleotide polymorphism (rs324420, C385A) of the endocannabinoid inactivating enzyme fatty acid amide hydrolase (FAAH) has been associated with anxiety disorder relevant phenotype and risk for addictions. Here, we tested whether the FAAH polymorphism affects in vivo binding of the FAAH positron emission tomography (PET) probe [11C]CURB ([11C-carbonyl]-6-hydroxy-[1,10-biphenyl]-3-yl cyclohexylcarbamate (URB694)). Participants ( n = 24) completed one [11C]CURB/PET scan and were genotyped for rs324420. Relative to C/C (58%), A-allele carriers (42%) had 23% lower [11C]CURB binding ( λk3) in brain. We report evidence that the genetic variant rs324420 in FAAH is associated with measurable differences in brain FAAH binding as per PET [11C]CURB measurement.


2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Carlos Velasco ◽  
Adriana Mota-Cobián ◽  
Jesús Mateo ◽  
Samuel España

Abstract Background Multi-tracer positron emission tomography (PET) imaging can be accomplished by applying multi-tracer compartment modeling. Recently, a method has been proposed in which the arterial input functions (AIFs) of the multi-tracer PET scan are explicitly derived. For that purpose, a gamma spectroscopic analysis is performed on blood samples manually withdrawn from the patient when at least one of the co-injected tracers is based on a non-pure positron emitter. Alternatively, these blood samples required for the spectroscopic analysis may be obtained and analyzed on site by an automated detection device, thus minimizing analysis time and radiation exposure of the operating personnel. In this work, a new automated blood sample detector based on silicon photomultipliers (SiPMs) for single- and multi-tracer PET imaging is presented, characterized, and tested in vitro and in vivo. Results The detector presented in this work stores and analyzes on-the-fly single and coincidence detected events. A sensitivity of 22.6 cps/(kBq/mL) and 1.7 cps/(kBq/mL) was obtained for single and coincidence events respectively. An energy resolution of 35% full-width-half-maximum (FWHM) at 511 keV and a minimum detectable activity of 0.30 ± 0.08 kBq/mL in single mode were obtained. The in vivo AIFs obtained with the detector show an excellent Pearson’s correlation (r = 0.996, p < 0.0001) with the ones obtained from well counter analysis of discrete blood samples. Moreover, in vitro experiments demonstrate the capability of the detector to apply the gamma spectroscopic analysis on a mixture of 68Ga and 18F and separate the individual signal emitted from each one. Conclusions Characterization and in vivo evaluation under realistic experimental conditions showed that the detector proposed in this work offers excellent sensibility and stability. The device also showed to successfully separate individual signals emitted from a mixture of radioisotopes. Therefore, the blood sample detector presented in this study allows fully automatic AIFs measurements during single- and multi-tracer PET studies.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Johannes Notni ◽  
Florian T. Gassert ◽  
Katja Steiger ◽  
Peter Sommer ◽  
Wilko Weichert ◽  
...  

Following publication of the original article [1], the authors have reported an error in the ‘Histopathology’ (under ‘Materials and methods’) section of the article that compromises the reproducibility of the paper.


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