In vivo NMR detection of diet-induced changes in adipose tissue composition

Branca, Rosa T.; Warren, Warren Sloan

doi:10.1194/jlr.d012468

Cited by 17 publications

(18 citation statements)

References 28 publications

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“…Influences of nutrition may play a crucial role. Long‐term diet in humans and mice with supplementation of fish oil (high in PUFA) or Lorenzo‐oil (high in MUFA) led to changes in adipose tissue composition, as measured by 13 C MRS. In addition, probable changes in the composition of fatty acids in VAT after weight loss (e.g.…”

Section: Discussionsupporting

confidence: 71%

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined ¹H MRS and volumetric MRI study in male subjects

et al. 2012

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Visceral adipose tissue (VAT) is thought to play an important role in the pathogenesis of obesity and insulin resistance. However, little is known about the composition of VAT with regard to the amount of mono- (MUFAs) and polyunsaturated fatty acids (PUFAs) in triglycerides. Volume-selective MRS was performed in addition to MRI for the quantification of VAT. Analysis comprised proton signals from the vinyl-H group (H-C=C-H), including protons from MUFA+PUFA, and diallylic-H, i.e. methylene-interrupted PUFAs. The methyl (-CH(3) ) resonance, which is the only peak with a defined number of protons/triglyceride (n=9), served as reference. Twenty male subjects participated in this prospective study and underwent MRS of VAT on a 3-T whole-body unit. Spectra were recorded by a single-voxel stimulated echo acquisition mode (STEAM) technique (TE/TM/TR=20/10/4000 ms; volume of interest between 20 × 25 × 20 and 30 × 30 × 20 mm(3); 48-80 acquisitions depending on the size of the volume of interest; bandwidth, 1200 Hz). Post-processing was performed by a Java-based magnetic resonance user interface (jMRUI; AMARES). The volume of VAT was quantified in a separate session on a 1.5-T imager a few days prior to the MRS session by T(1) -weighted imaging. The relative amount of VAT was calculated as a percentage of body weight (%VAT). Ratios of vinyl-H to -CH(3) and diallylic-H to -CH(3) were calculated. All spectra recorded from VAT were of high quality, enabling reliable quantification of the mentioned resonances. %VAT and vinyl-H/CH(3) varied over a broad range (2.8-8.3% and 0.45-0.64, respectively). A strong negative correlation between %VAT and vinyl-H/CH(3) was found (r= -0.92), whereas diallylic-H/CH(3) alone was clearly less well correlated with %VAT (r= -0.21). The composition of VAT shows strong interindividual variations. The greater the total amount of VAT, the less unsaturated the fatty acids. This is a preliminary result in mainly obese male subjects, and it remains to be determined whether this correlation holds for other cohorts of different age, gender and body mass index. Furthermore, changes in VAT composition during weight loss or different forms of diet have yet to be examined.

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Section: Discussionsupporting

confidence: 71%

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined ¹H MRS and volumetric MRI study in male subjects

et al. 2012

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“…For example, by isolating the polyunsaturated lipid signal with a selective conventional multiple quantum coherence transfer technique, an absence of polyunsaturated fats was observed to correlate with invasive ductal carcinoma in the breast, whereas healthy breast tissue showed a continuous distribution of fats . Using intermolecular multiple quantum coherences (iMQCs), fat can be used to image absolute temperature in vivo and detect brown adipose tissue (an important goal for obesity research) . However, the spectrum of fat has at least 10 distinct resonances and many J‐couplings , in many cases between spins with very similar resonance frequencies.…”

Section: Chemical Shifts Intensity Weighting Factors and J‐couplingmentioning

confidence: 99%

Enhanced refocusing of fat signals using optimized multipulse echo sequences

Stokes

Feng

Mitropoulos

et al. 2012

Magnetic Resonance in Med

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Endogenous magnetic resonance contrast based on the localized composition of fat in vivo can provide functional information. We found that the unequal pulse timings of the Uhrig’s Dynamical Decoupling (UDD) multipulse echo sequences significantly alter the signal intensity compared to conventional, equal-spaced Carr-Purcell-Meiboom-Gill (CPMG) sequences. The signal increases and decreases depending on the tissue and sequence parameters, as well as on the interpulse spacings; particularly strong differences were observed in fatty tissues, which have a highly structured morphology and a wide range of chemical shifts and J-couplings. We found that the predominant mechanism for fat refocusing under multipulse echo sequences is the chemical structure, with stimulated echoes playing a pivotal role. As a result, specialized pulse sequences can be designed to optimize refocusing of the fat chemical shifts and J-couplings, where the degree of refocusing can be tailored to specific types of fats. To determine the optimal time delays, we simulated various UDD and CPMG pulse sequence timings, and these results are compared to experimental results obtained on excised and in vivo fatty tissue. Applications to intermolecular multiple-quantum coherence (iMQC) imaging, where the improved echo refocusing translates directly into signal enhancements, are presented as well.

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“…In animal studies, MRS has been used to assess diet impact on lipid composition in the liver ( 15 ) and adipose tissue ( 16,17 ) as well as in the muscle of a diabetic mouse model ( 18 ). Many other animal models are available to investigate steatosis, such as the genetic model ob/ob mouse.…”

Section: Mr Experimental Conditionsmentioning

confidence: 99%

In vivo hepatic lipid quantification using MRS at 7 Tesla in a mouse model of glycogen storage disease type 1a

Ramamonjisoa

Ratiney

Mutel

et al. 2013

Journal of Lipid Research

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This article is available online at http://www.jlr.org Glycogen storage disease type 1 (GSD 1) is an autosomal recessive metabolic disorder resulting in severe impairment of glucose production and large accumulation of lipids within hepatocytes (steatosis) ( 1, 2 ). The phenotype of GSD 1 results from a defect in the glucose-6 phosphatase (G6Pase) complex, leading to severe hypoglycemia due to the loss of endogenous glucose production. Despite a strict diet, patients with GSD 1 develop hepatomegaly and steatosis and may develop, with age, hepatocellular adenoma that can ultimately evolve into hepatocellular carcinoma ( 3, 4 ). Recently, a viable mouse model of GSD 1a with a liverspecifi c deletion of G6Pase catalytic subunit (L-G6pc Ϫ / Ϫ ) has been generated and validated ( 5 ). GSD 1a mice exhibit hepatic pathological features very similar to those observed in GSD 1a patients.The accumulation of lipids in the liver relates to the buildup of neutral lipids, such as triglycerides (TGs) and cholesterol esters, stored as lipid droplets in hepatocytes and leading to hepatic steatosis. This fat accumulation may originate from a ) peripheral fat stored in adipose tissue that fl ows to the liver as plasma nonesterifi ed fatty acids, b ) fatty acids newly made within the liver through de novo lipogenesis, and c ) dietary fatty acids ( 6, 7 ).Steatosis is highly linked to the development of metabolic diseases such as obesity or type 2 diabetes, but it can also result from genetic disorders impacting lipid and glucose metabolism such as in GSD 1a, ␣ 1-antitrypsin defi ciency, Abstract The assessment of liver lipid content and composition is needed in preclinical research to investigate steatosis and steatosis-related disorders. The purpose of this study was to quantify in vivo hepatic fatty acid content and composition using a method based on short echo time proton magnetic resonance spectroscopy (MRS) at 7 Tesla. A mouse model of glycogen storage disease type 1a with inducible liver-specifi c deletion of the glucose-6-phosphatase gene (L-G6pc ؊ / ؊ ) mice and control mice were fed a standard diet or a high-fat/high-sucrose (HF/HS) diet for 9 months. In control mice, hepatic lipid content was found signifi cantly higher with the HF/HS diet than with the standard diet. As expected, hepatic lipid content was already elevated in L-G6pc ؊ / ؊ mice fed a standard diet compared with control mice. L-G6pc ؊ / ؊ mice rapidly developed steatosis which was not modifi ed by the HF/HS diet. On the standard diet, estimated amplitudes from olefi nic protons were found signifi cantly higher in L-G6pc ؊ / ؊ mice compared with that in control mice. L-G6pc ؊ / ؊ mice showed no noticeable polyunsaturation from diallylic protons. Total unsaturated fatty acid indexes measured by gas chromatography were in agreement with MRS measurements. These results showed the great potential of high magnetic fi eld MRS to follow the diet impact and lipid alterations in mouse liver.

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In vivo NMR detection of diet-induced changes in adipose tissue composition

Cited by 17 publications

References 28 publications

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined ¹H MRS and volumetric MRI study in male subjects

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined ¹H MRS and volumetric MRI study in male subjects

Enhanced refocusing of fat signals using optimized multipulse echo sequences

In vivo hepatic lipid quantification using MRS at 7 Tesla in a mouse model of glycogen storage disease type 1a

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In vivo NMR detection of diet-induced changes in adipose tissue composition

Cited by 17 publications

References 28 publications

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined 1H MRS and volumetric MRI study in male subjects

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined 1H MRS and volumetric MRI study in male subjects

Enhanced refocusing of fat signals using optimized multipulse echo sequences

In vivo hepatic lipid quantification using MRS at 7 Tesla in a mouse model of glycogen storage disease type 1a

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Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined ¹H MRS and volumetric MRI study in male subjects

Fraction of unsaturated fatty acids in visceral adipose tissue (VAT) is lower in subjects with high total VAT volume – a combined ¹H MRS and volumetric MRI study in male subjects