Intermuscular and intramuscular adipose tissues: Bad vs. good adipose tissues.
10 Dec 2014-Vol. 3, Iss: 4, pp 242-255
TL;DR: It seems that in the pig and humans, INTMF and VAT share a similar pattern of distribution and a similar association of components dictating insulin sensitivity, while in pigs, the relationship between leanness and higher proportions of IN TMF fat in pigs was not observed in human studies and was not corroborated by other pig studies.
Abstract: Human studies of the influence of aging and other factors on intermuscular fat (INTMF) were reviewed. Intermuscular fat increased with weight loss, weight gain, or with no weight change with age in humans. An increase in INTMF represents a similar threat to type 2 diabetes and insulin resistance as does visceral adipose tissue (VAT). Studies of INTMF in animals covered topics such as quantitative deposition and genetic relationships with other fat depots. The relationship between leanness and higher proportions of INTMF fat in pigs was not observed in human studies and was not corroborated by other pig studies. In humans, changes in muscle mass, strength and quality are associated with INTMF accretion with aging. Gene expression profiling and intrinsic methylation differences in pigs demonstrated that INTMF and VAT are primarily associated with inflammatory and immune processes. It seems that in the pig and humans, INTMF and VAT share a similar pattern of distribution and a similar association of components dictating insulin sensitivity. Studies on intramuscular (IM) adipocyte development in meat animals were reviewed. Gene expression analysis and genetic analysis have identified candidate genes involved in IM adipocyte development. Intramuscular (IM) adipocyte development in human muscle is only seen during aging and some pathological circumstance. Several genetic links between human and meat animal adipogenesis have been identified. In pigs, the Lipin1 and Lipin 2 gene have strong genetic effects on IM accumulation. Lipin1 deficiency results in immature adipocyte development in human lipodystrophy. In humans, overexpression of Perilipin 2 (PLIN2) facilitates intramyocellular lipid accretion whereas in pigs PLIN2 gene expression is associated with IM deposition. Lipins and perilipins may influence intramuscular lipid regardless of species.
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TL;DR: Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation.
Abstract: The ability to accurately measure body or carcass composition is important for performance testing, grading and finally selection or payment of meat-producing animals. Advances especially in non-invasive techniques are mainly based on the development of electronic and computer-driven methods in order to provide objective phenotypic data. The preference for a specific technique depends on the target animal species or carcass, combined with technical and practical aspects such as accuracy, reliability, cost, portability, speed, ease of use, safety and for in vivo measurements the need for fixation or sedation. The techniques rely on specific device-driven signals, which interact with tissues in the body or carcass at the atomic or molecular level, resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively. The electromagnetic signal produced by the instrument may originate from mechanical energy such as sound waves (ultrasound – US), ‘photon’ radiation (X-ray-computed tomography – CT, dual-energy X-ray absorptiometry – DXA) or radio frequency waves (magnetic resonance imaging – MRI). The signals detected by the corresponding instruments are processed to measure, for example, tissue depths, areas, volumes or distributions of fat, muscle (water, protein) and partly bone or bone mineral. Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions. CT, MRI and US can provide volume data, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation. A combination of simple US and more expensive CT, MRI or DXA might be applied for farm animal selection programs in a stepwise approach.
133 citations
Cites background from "Intermuscular and intramuscular adi..."
...Deeper insights into the physiological role of IMF in comparison with intermuscular fat (adipose tissue) are provided by Hausman et al. (2014)....
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TL;DR: Current knowledge of the different ectopic fat depots is updated, focusing on underlying mechanisms and potential clinical implications, Considering the global rise in the prevalence of obesity, the understanding of mechanisms underlying ectopicfat accumulation represents an urgent need.
Abstract: A growing body of evidence is pointing out the pathophysiological role of fat accumulation in different organs. Ectopic fat depots within heart, liver, skeletal muscle, kidney, and pancreas as well as around blood vessels might be more associated to cardiometabolic risk than classical variables, such as body mass index. Among different mechanisms, lipid metabolism appears to be particularly influenced by ectopic fat depots. Indeed, intracellular accumulation of nonesterified fatty acids, and triglycerides promotes endoplasmic reticulum stress, mitochondrial uncoupling, oxidative stress, and altered membrane composition/function, finally promoting inflammatory response and cell death. The dysfunctional adipose tissue was shown to induce both local and systemic effects, with relevant clinical consequences. Epicardial fat and myocardial steatosis have been associated with the development of atrial fibrillation and ventricular dysfunction. Similarly perivascular adipose tissue appears to trigger atherosclerosis and hypertension. Nonalcoholic fatty liver disease has been recognized both as the hepatic manifestation of metabolic syndrome and as a cardiovascular (CV) risk factor. Importantly, the renal sinus fat emerged as a potential player in kidney dysfunction. Finally, both skeletal muscle and pancreatic fat depots have been indicated as potential endocrine modulators of insulin resistance. Considering the global rise in the prevalence of obesity, the understanding of mechanisms underlying ectopic fat accumulation represents an urgent need, with potential clinical implications for CV risk stratification. Here, we attempt to update the current knowledge of the different ectopic fat depots, focusing on underlying mechanisms and potential clinical implications.
103 citations
Cites background from "Intermuscular and intramuscular adi..."
...INTMF significantly increases with aging and BMI and is influenced by exercise and race, being more represented in African‐Americans rather than Caucasian subjects (Hausman et al., 2014)....
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TL;DR: In this paper, the authors examined the relationship of two common sit-to-stand (STS) variants with grip strength, muscle mass and functional measures, and their impact on sarcopenia prevalence in community-dwelling older adults.
Abstract: The sit-to-stand (STS) test has been deployed as surrogate measures of strength or physical performance in sarcopenia diagnosis. This study examines the relationship of two common STS variants – Five Times Sit-to-Stand Test (5TSTS) and 30 s Chair Stand Test (30CST) – with grip strength, muscle mass and functional measures, and their impact on sarcopenia prevalence in community-dwelling older adults. This is a cross-sectional analysis of 887 community-dwelling adults aged ≥50 years. Participants completed a battery of physical fitness tests - 5TSTS, 30CST, grip strength, gait speed, Timed-Up-and-Go (TUG) for dynamic balance and six-minute walk test (6MWT) for cardiorespiratory endurance. Muscle mass was measured using multi-frequency segmental bioelectrical impedance analysis (BIA). We performed correlation analysis between STS performance and other fitness measures and muscle mass, followed by multiple linear regression for the independent determinants of STS performance. Mean participant age was 67.3±7 years, with female predominance (72.9%). STS tests exhibited weak correlations with grip strength (30CST, r = 0.290; 5TSTS, r = − 0.242; both p< 0.01), and stronger correlations with gait speed (30CST, r = 0.517; 5TSTS, r = − 0.533; both p< 0.01), endurance (30CST, r = 0.558; 5TSTS, r = − 0.531; both p < 0.01) and dynamic balance (30CST, r = − 0.501; 5TSTS, r = 0.646; both p< 0.01). Muscle mass correlated with grip strength but not STS. In multiple regression analysis, all fitness measures were independently associated with 30CST performance. Performance in both STS tests remained independent of muscle mass. There was no significant difference in prevalence of possible sarcopenia diagnosis using grip strength or STS (30CST, 25.0%; 5TSTS, 22.1%; grip strength, 22.3%; p = 0.276). When both measures are used, prevalence is significantly higher (42.0%; p = 0.276). Prevalence of confirmed sarcopenia with inclusion of muscle mass was significantly lower using STS compared with grip strength (30CST, 4.6%; 5TSTS, 4.1% vs. grip strength, 7.1%; p< 0.05). In the sarcopenia construct, STS tests better represents muscle physical performance rather than muscle strength. Different subsets of population with possible sarcopenia are identified depending on the test used. The lack of association of STS performance with muscle mass results in a lower prevalence of confirmed sarcopenia compared with grip strength, but may better reflect changes in muscle quality.
65 citations
TL;DR: In this paper, nutritional regulation of adipogenesis, focusing on retinoic acid and its impact on epigenetic modifications of key adipogenic genes, was discussed, and it was shown that vitamin D and folates interact with the retinoid acid receptors to regulate adipogenesis.
58 citations
TL;DR: Myosteatosis may be a useful parameter to predict perioperative outcome in patients undergoing OLT, supporting the role of muscle quality over quantity (muscle mass) in this setting.
58 citations
References
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12,729 citations
"Intermuscular and intramuscular adi..." refers background in this paper
...Another study demonstrated that physical activity can prevent losses in muscle strength and prevent increases in INTMF in the absence of changes in SQF (Table 1).(84) In a study of older individuals with metabolic and mobility impairments, 12 wks of resistance training decreased INTMF and increased lean tissue (Table 1)....
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University of Bristol1, University of Oxford2, Wellcome Trust Centre for Human Genetics3, Churchill Hospital4, National Health Service5, University of London6, Imperial College London7, University of Oulu8, National Institutes of Health9, Medical Research Council10, Wellcome Trust Sanger Institute11, Newcastle University12, Royal London Hospital13, Queen Mary University of London14, Ninewells Hospital15, University of Dundee16
TL;DR: A genome-wide search for type 2 diabetes–susceptibility genes identified a common variant in the FTO (fat mass and obesity associated) gene that predisposes to diabetes through an effect on body mass index (BMI).
Abstract: Obesity is a serious international health problem that increases the risk of several common diseases. The genetic factors predisposing to obesity are poorly understood. A genome-wide search for type 2 diabetes-susceptibility genes identified a common variant in the FTO (fat mass and obesity associated) gene that predisposes to diabetes through an effect on body mass index (BMI). An additive association of the variant with BMI was replicated in 13 cohorts with 38,759 participants. The 16% of adults who are homozygous for the risk allele weighed about 3 kilograms more and had 1.67-fold increased odds of obesity when compared with those not inheriting a risk allele. This association was observed from age 7 years upward and reflects a specific increase in fat mass.
4,184 citations
"Intermuscular and intramuscular adi..." refers background in this paper
...Whole genome association studies in humans provided evidence that three different SNPs in the FTO gene are associated with both childhood and adult obesity.(153,186,187) The FTO gene is located on porcine SSC6 (Table 3), adjacent to a number of QTLs for IM percentage and body lipid content....
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...Three independent whole genome association studies in humans provided evidence that three different SNPs in the FTO (fat mass and obesity-associated) gene intron 1 are significantly associated with both childhood and adult obesity.(153,186,187) FTO gene participates in fat tissue and energy homeostasis and adults homozygous for the risk alleles of SNP rs993939 are linked with increased risk for obesity....
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...FTO gene participates in fat tissue and energy homeostasis and adults homozygous for the risk alleles of SNP rs993939 are linked with increased risk for obesity.(153) Interestingly, the FTO gene was assigned between SW1302 and SWR1130 on SSC6 in the porcine (Table 3), adjacent to the region with a number of QTLs for average daily gain, IM percentage and body lipid content....
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TL;DR: Interest in adipogenesis has increased markedly over the past few years with emphasis on the intersection between extracellular signals and the transcriptional cascade that regulates adipocyte differentiation.
Abstract: Improved knowledge of all aspects of adipose biology will be required to counter the burgeoning epidemic of obesity. Interest in adipogenesis has increased markedly over the past few years with emphasis on the intersection between extracellular signals and the transcriptional cascade that regulates adipocyte differentiation. Many different events contribute to the commitment of a mesenchymal stem cell to the adipocyte lineage including the coordination of a complex network of transcription factors, cofactors and signalling intermediates from numerous pathways.
2,363 citations
TL;DR: Interest in meat fatty acid composition stems mainly from the need to find ways to produce healthier meat, i.e. with a higher ratio of polyunsaturated (PUFA) to saturated fatty acids and a more favourable balance between n-6 and n-3 PUFA.
2,166 citations
"Intermuscular and intramuscular adi..." refers background in this paper
...The effect of a low protein diet on INTMF content and percent muscle was found to be breed specific and only significant for the Berkshire and Large White breeds.(67) Limited studies have examined the genetic control of INTMF fat development and composition....
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TL;DR: The "metabolic syndrome" is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity that is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus.
Abstract: The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.
1,625 citations