Where is intramuscular fat found

Analyzed the data: NVLS. Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Abstract Studies have shown that intramuscular adipogenesis and fibrogenesis may concomitantly occur in skeletal muscle of beef cattle.

This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited Data Availability: All relevant data are within the paper and its Supporting Information files.

Introduction Intramuscular fat IMF is one of the main factors that positively affect the perception of consumers of meat quality due to IMF influence on taste, juiciness, and tenderness [ 1 ]. Download: PPT. Table 1. Ingredient proportion and chemical composition of experimental diet. Collagen content analysis Duplicate samples 3. Intramuscular fat content Powdered freeze-dried muscle samples were analyzed for moisture by the Method Carcass total fat content All carcasses composite samples were frozen using liquid nitrogen and ground into powder using a blender.

Average daily gain and carcass traits of Angus and Nellore cattle Angus cattle had an average daily gain Table 3. Performance and carcass traits of Angus and Nellore cattle. Fig 1. Expression of lipid metabolism markers in skeletal muscle of Angus and Nellore cattle. Fig 2. Intramuscular fat content and expression of adipogenic markers in skeletal muscle of Angus and Nellore cattle.

Fig 3. Collagen content, expression of fibrogenic and collagen remodeling markers in skeletal muscle of Angus and Nellore cattle. Fig 4. Supporting Information. S1 Data. Raw data according to experimental treatments.

References 1. Cellular conditions for intramuscular fat deposition in Japanese Black and Holstein steers. Meat Sci. Meat Science and Muscle Biology Symposium: manipulating mesenchymal progenitor cell differentiation to optimize performance and carcass value of beef cattle. Journal of animal science.

Mesenchymal progenitors distinct from satellite cells contribute to ectopic fat cell formation in skeletal muscle. Nat Cell Biol. Fibrosis and adipogenesis originate from a common mesenchymal progenitor in skeletal muscle. Journal of cell science. Transcriptional control of preadipocyte determination by Zfp Gene regulation and systems biology. Simulated influence of postweaning production system on performance of different biological types of cattle: I. Estimation of model parameters.

Enhancement of adipogenesis and fibrogenesis in skeletal muscle of Wagyu compared with Angus cattle. Bos indicus Young Bulls Finished in a Feedlot. Asian Austral J Anim. View Article Google Scholar The relationship between ultrasound measurements and carcass fat thickness and longissimus muscle area in beef cattle. Journal of Animal Science. Effects of intramuscular collagen and elastin on bovine muscle tenderness. Journal of Food Science. Due to the typically sedentary behaviour observed in this group [ 11 , 12 ], one aspect of muscle composition that may be altered in BSCP is the level of intra- and intermuscular fat.

Fatty infiltration into muscle results in a reduced proportion of contractile tissue per unit muscle volume. Intramuscular fat also may secrete inflammatory cytokines that can reduce the myofibrillar force even in the absence of muscle atrophy [ 13 ]. If present in this group, raised intramuscular fat may have important consequences for physical performance, and implications for exercise regimes employed in their physical management [ 14 ]. Heightened levels of inter- and intra- muscular fat have been shown to be associated with cardiovascular risk [ 15 , 16 ].

Adults with cerebral palsy may have a 2—3 times greater risk of dying from ischemic heart disease than their typically developing peers [ 17 ]. However, there are few studies in the literature that have attempted to document body or muscle composition in this group.

Since individuals with cerebral palsy have reduced muscle mass, even those with body mass index BMI in the normal range may have relatively increased levels of adipose tissue.

Previous studies in children with cerebral palsy have suggested raised levels of fat [ 18 , 19 ]. To date, there have been no studies of intramuscular fat in adults or children with BSCP even though this non-invasively quantified parameter appears to be one of those most associated with cardio-metabolic disease [ 20 ]. T 1 -weighted image segmentation is primarily used to quantify IMAT, with IMAT defined as the MRI-visible fat within the muscles intramuscular fat and between the muscles beneath the fascia intermuscular fat.

Although this method is effective for assessing intermuscular and subcutaneous fat volumes, it is not an accurate method for measuring fat distribution within individual muscles. These techniques utilise the predictable difference in phase evolution between water and fat signals due to their chemical shift difference to enable the calculation of separate water and fat images, permitting the calculation of the fat fraction. The fat fraction is the signal intensity attributable to fat, normalised by the total signal from all mobile proton species.

These techniques have been widely used in studies quantifying the degree of liver fat in hepatic steatosis for review see Reeder [ 22 ] : although, to date, Dixon imaging has only been used in a small number of clinical intramuscular fat quantification studies [ 16 , 23 , 24 ].

The aim of this study is to investigate the intermuscular fat IMAT , subcutaneous fat SF and intramuscular fat IntraMF content in five major muscles of the leg medial and lateral gastrocnemius, soleus, tibialis posterior and tibialis anterior in 10 subjects with BSCP and 10 TD subjects using multi-echo gradient echo chemical shift imaging mDixon. All subjects gave informed consent before they participated.

Patients who had undergone surgery, serial casting or botulinum toxin injections to the lower limbs within the previous year were excluded from the study. This was a convenience sample of individuals attending our hospital department, with consecutive patients that met the inclusion criteria invited to participate in the study. The BSCP subjects had undergone a range of previous interventions see Table 1 but none had undergone surgery, serial casting or botulinum toxin injections to the lower limbs within the previous year.

All TD subjects had no prior significant musculoskeletal trauma or disorders. MR data were acquired on a 3. An 11 cm section of the left leg was scanned, centred at the largest circumference of the calf with the subject prone. Utilising the known chemical shift between water and fat signal constituents, separate water and fat images were calculated within the scanner software. Subject height and body mass were measured in standing before the MRI scan using a stadiometer and calibrated weighing scales.

Patients at our centre are routinely classified according to GMFCS level in their medical record by their consulting physician or surgeon. Regions of interest ROIs were manually drawn around the SF, muscle compartment Figure 1 B , and five individual muscles; the soleus, medial gastrocnemius, lateral gastrocnemius, tibialis anterior, and tibialis posterior Figure 1 C , on the mDixon water images using Osirix version 3. The ROIs around the entire musculature and individual muscles were eroded with a structuring element size of 2 pixels 4.

The reproducibility of the Dixon technique employed was measured using 5 acquisitions of one TD subject imaged over 3 visits, with the scan repeated twice during 2 of these visits. Reproducibility was defined as the average standard deviation of the measured percentage fat, i. The average standard deviation representing reproducibility of intramuscular fat averaged across all muscles was 0. Example images for a case and age-matched control are given in Figure 4.

Error bars represent the standard error of each group. This may be due to decreased physical activity with increasing mobility impairments. The 1. IMAT values cannot be compared between these studies due to the separation by Johnson et al.

Children and young adults with cerebral palsy have been shown to have reduced muscle volumes in their lower limbs [ 2 — 4 , 26 — 30 ] and increased IMAT [ 18 ]. This study demonstrates that these muscles also have greater levels of intramuscular fat that is independent of subcutaneous fat levels.

This combination of morphological and compositional changes may have implications both for the mechanical performance of these skeletal muscles and also for the predisposition of the adult with BSCP to cardio-metabolic disease [ 20 ]. Muscle weakness is a prevalent feature of individuals with cerebral palsy [ 26 , 31 , 32 ].

Muscle weakness, in this group, is in part caused by an inability to fully activate available muscular resources [ 33 ], increased co-activation [ 34 ] and by reduced muscle volume [ 2 — 4 , 26 — 30 ]. For a given muscle volume, a higher intramuscular fat content will correspond to reduced contractile tissue content, resulting in a weaker muscle than predicted from muscle mass alone.

Furthermore, inflammatory cytokines produced by intramuscular fat may interfere with the action of myofibrillar proteins reducing specific force production [ 13 ]. Greater intramuscular fat content in BSCP may expose these individuals to a greater risk of developing cardio-metabolic disease [ 20 ]. There is a strong relationship between intramuscular fat content, insulin resistance and type-II diabetes [ 15 , 35 , 36 ].

EMCL is found within adipose cells adjacent to the muscle fibres, and IMCL is located along with enzymes involved in fatty acid esterification, hydrolysis, and transport into the mitochondria [ 37 ]. Enhanced storage of IMCL occurs due to the combined effects of high concentration of serum insulin and free fatty acids [ 38 ]. In particular, greater IMCL in the soleus correlates with glucose-insulin-lipid metabolism and insulin sensitivity [ 39 — 42 ], with soleus IMCL content being the only differentiating feature in a study of lean insulin-resistant subjects and their TD peers matched for BMI, body fat distribution, percentage body fat and physical fitness [ 42 ].

IMCL has been shown to be unrelated to measures of adiposity [ 39 , 43 ]. The increased intramuscular fat content observed in this study, particularly in the soleus, indicates that patients with cerebral palsy may have a greater risk of developing obesity related diseases, particularly type-II diabetes.

Since IntraMF was observed to be greater with increasing GMFCS level, this risk of obesity-related disease may increase with decreasing functional ability. However, intramuscular fat is only one factor associated with the risk of developing obesity related diseases. Future studies of activity levels, fat levels, and glucose tolerance, are required to investigate the risk developing cardio-metabolic diseases in this patient group.

Greater intramuscular fat can be caused by a chronic mismatch between energy intake and expenditure [ 26 , 45 ]. Such a mismatch would also result in greater subcutaneous fat levels. This suggests that other factors as well as any potential energy mismatch are adversely affecting the intramuscular fat content in BSCP. IntraMF has been correlated with deficits in central muscle activation [ 46 ], increased risk of future mobility loss [ 47 , 48 ], and insulin resistance [ 49 ] in the elderly population.

Preliminary studies have also shown that particular exercise regimes in older adults may prevent and decrease intramuscular fat [ 10 ]. The amount of intramuscular fat significantly increased as the sheep became older and fatter; however, these differences were quantitatively small.

As such, finishing prime lambs to high levels of total carcass fatness would have little effect on any eating quality benefits associated with increased intramuscular fat proportion. The excellent co-operation of employees and management from Junee and Hillside abattoirs is gratefully acknowledged. Journal of Animal Science 60 , — Meat Science 71 , — Crossref GoogleScholar Google Scholar Dikeman ME Fat reduction in animals and the effects on palatability and consumer acceptance of meat products.

Australian Journal of Experimental Agriculture 47 , — Crossref longissimus lumborum muscle depth and GR fat depth to predict half carcass composition in sheep. Consumer acceptability of m. Meat Science 53 , 67— Journal of Lipid Research 20 , — Meat pH, colour and tenderness. Meat Science 49 , — Australian Journal of Experimental Agriculture 45 , — Australian Journal of Experimental Agriculture 46 , —