The Experts below are selected from a list of 19704 Experts worldwide ranked by ideXlab platform
C W J Melling - One of the best experts on this subject based on the ideXlab platform.
-
the effects of exercise training versus intensive insulin treatment on skeletal Muscle Fibre content in type 1 diabetes mellitus rodents
Lipids in Health and Disease, 2021Co-Authors: David P Mcbey, Michelle S Dotzert, C W J MellingAbstract:Intensive-insulin treatment (IIT) strategy for patients with type 1 diabetes mellitus (T1DM) has been associated with sedentary behaviour and the development of insulin resistance. Exercising patients with T1DM often utilize a conventional insulin treatment (CIT) strategy leading to increased insulin sensitivity through improved intramyocellular lipid (IMCL) content. It is unclear how these exercise-related metabolic adaptations in response to exercise training relate to individual Fibre-type transitions, and whether these alterations are evident between different insulin strategies (CIT vs. IIT). Purpose: This study examined glycogen and fat content in skeletal Muscle Fibres of diabetic rats following exercise-training. Male Sprague-Dawley rats were divided into four groups: Control-Sedentary, CIT- and IIT-treated diabetic sedentary, and CIT-exercised trained (aerobic/resistance; DARE). After 12 weeks, Muscle-Fibre lipids and glycogen were compared through immunohistochemical analysis. The primary findings were that both IIT and DARE led to significant increases in type I Fibres when compared to CIT, while DARE led to significantly increased lipid content in type I Fibres compared to IIT. These findings indicate that alterations in lipid content with insulin treatment and DARE are primarily evident in type I Fibres, suggesting that Muscle lipotoxicity in type 1 diabetes is Muscle Fibre-type dependant.
-
The effects of exercise training versus intensive insulin treatment on skeletal Muscle Fibre content in type 1 diabetes mellitus rodents
'Springer Science and Business Media LLC', 2021Co-Authors: David P Mcbey, Michelle S Dotzert, C W J MellingAbstract:Abstract Background Intensive-insulin treatment (IIT) strategy for patients with type 1 diabetes mellitus (T1DM) has been associated with sedentary behaviour and the development of insulin resistance. Exercising patients with T1DM often utilize a conventional insulin treatment (CIT) strategy leading to increased insulin sensitivity through improved intramyocellular lipid (IMCL) content. It is unclear how these exercise-related metabolic adaptations in response to exercise training relate to individual Fibre-type transitions, and whether these alterations are evident between different insulin strategies (CIT vs. IIT). Purpose: This study examined glycogen and fat content in skeletal Muscle Fibres of diabetic rats following exercise-training. Methods Male Sprague-Dawley rats were divided into four groups: Control-Sedentary, CIT- and IIT-treated diabetic sedentary, and CIT-exercised trained (aerobic/resistance; DARE). After 12 weeks, Muscle-Fibre lipids and glycogen were compared through immunohistochemical analysis. Results The primary findings were that both IIT and DARE led to significant increases in type I Fibres when compared to CIT, while DARE led to significantly increased lipid content in type I Fibres compared to IIT. Conclusions These findings indicate that alterations in lipid content with insulin treatment and DARE are primarily evident in type I Fibres, suggesting that Muscle lipotoxicity in type 1 diabetes is Muscle Fibre-type dependant
Ian A Johnston - One of the best experts on this subject based on the ideXlab platform.
-
rapid evolution of Muscle Fibre number in post glacial populations of arctic charr salvelinus alpinus
The Journal of Experimental Biology, 2004Co-Authors: Ian A Johnston, Marguerite Abercromby, Vera L A Vieira, Rakel J Sigursteindottir, Bjarni K Kristjansson, Dean Sibthorpe, Skuli SkulasonAbstract:Thingvallavatn, the largest and one of the oldest lakes in Iceland, contains four morphs of Arctic charr Salvelinus alpinus. Dwarf benthic (DB), large benthic (LB), planktivorous (PL) and piscivorous (PI) morphs can be distinguished and differ markedly in head morphology, colouration and maximum fork length (FLmax), reflecting their different resource specialisations within the lake. The four morphs in Thingvallavatn are thought to have been isolated for approximately 10·000 years, since shortly after the end of the last Ice Age. We tested the null hypothesis that the pattern of Muscle Fibre recruitment was the same in all morphs, reflecting their recent diversification. The cross-sectional areas of fast and slow Muscle Fibres were measured at 0.7·FL in 46 DB morphs, 23 LB morphs, 24 PL morphs and 22 PI morphs, and the ages of the charr were estimated using sacculus otoliths. In fish larger than 10·g, the maximum Fibre diameter scaled with body mass (Mb) 0.18 for both Fibre types in all morphs. The number of myonuclei per cm Fibre length increased with Fibre diameter, but was similar between morphs. On average, at 60·µm diameter, there were 2264·nuclei·cm ‐1 in slow Fibres and 1126·nuclei·cm ‐1 in fast Fibres. The absence of Fibres of diameter 4‐10·µm was used to determine the FL at which Muscle Fibre recruitment stopped. Slow Fibre number increased with body length in all morphs, scaling with Mb 0.45 . In contrast, the recruitment of fast Muscle Fibres continued until a clearly identifiable FL, corresponding to 18‐19·cm in the dwarf morph, 24‐26·cm in the pelagic morph, 32‐33·cm in the large benthic morph and 34‐35·cm in the piscivorous morph. The maximum fast Fibre number (FNmax) in the dwarf morph (6.97� 10 4 ) was 56.5% of that found in the LB and PI morphs combined (1.23� 10 5 ) (P<0.001). Muscle Fibre recruitment continued until a threshold body size and occurred at a range of ages, starting at 4+ years in the DB morph and 7+ years in the LB and PI morphs. Our null hypothesis was therefore rejected for fast Muscle and it was concluded that the dwarf condition was associated with a reduction in Fibre number. We then investigated whether variations in development temperature associated with different spawning sites and periods were responsible for the observed differences in Muscle cellularity between morphs. Embryos from the DB, LB and PL morphs were incubated at temperature regimes simulating cold subterranean spring-fed sites (2.2‐3.2°C) and the general lakebed (4‐7°C). Myogenic progenitor cells (MPCs) were identified using specific antibodies to Paired box protein 7 (Pax 7), Forkhead box protein K1-α (FoxK1-α), MyoD and Myf-5. The progeny showed no evidence of developmental plasticity in the numbers of either MPCs or Muscle Fibres. Juveniles and adult stages of the DB and LB morphs coexist and have a similar diet. We therefore conclude that the reduction in FNmax in the dwarf morph probably has a genetic basis and that gene networks regulating myotube production are under high selection pressure. To explain these findings we propose that there is an optimal Fibre size, and hence number, which varies with maximum body size and reflects a trade-off between diffusional constraints on Fibre diameter and the energy costs of maintaining ionic gradients. The predictions of the optimal Fibre size hypothesis and its consequences for the adaptive evolution of Muscle architecture in fishes are briefly discussed.
-
seasonal differences in Muscle Fibre recruitment of pilchard larvae in the north western mediterranean
Journal of Fish Biology, 2004Co-Authors: Ignacio Alberto Catalan, Ian A Johnston, M P OlivarAbstract:The recruitment of slow and fast myotomal Muscle Fibres with respect to growth in body length in European pilchard larvae Sardina pilchardus [(3� 5–13� 5 mm standard length (LS)] was significantly higher in November 1998 than February 1999. This resulted in a significant seasonal difference in the relationship between Fibre number and LS, particularly for the fast Muscle. Mean sea surface temperature was c .6 � C higher in November than February, whereas the mean abundance of potential prey items (copepod nauplii) was comparable between cruises. Laboratory and field data obtained from other clupeid species have indicated the importance of early thermal experience on Muscle Fibre recruitment patterns. Differences in average sea temperature therefore provide a plausible mechanism for the observed seasonal differences in Muscle growth characteristics. # 2004 The Fisheries Society of the British Isles
-
Muscle Fibre density in relation to the colour and texture of smoked atlantic salmon salmo salar l
Aquaculture, 2000Co-Authors: Ian A Johnston, Richard Alderson, Claire Sandham, Alistair Dingwall, David Mitchell, Craig Selkirk, David Nickell, R T M Baker, Billy Robertson, David WhyteAbstract:Muscle Fibre cellularity was quantified during seawater growth in populations of predominantly early (strain X) and late maturing (strain Y) Atlantic salmon (Salmo salar L.). The Fibre density (number mm−2 white Muscle cross-sectional area) in the fresh fillet was related to pigment concentration, colour as determined with the Roche SalmoFan™, and lipid content. The relationship between Fibre density and the textural characteristics of the smoked fillet, as assessed by trained taste panels, was also determined. There was no significant correlation between astaxanthin concentration and Muscle Fibre density. However, significant positive relationships were obtained between Roche SalmoFan™ score and Fibre density, explaining 33% and 44% of the total variation in colour visualisation in strains X and Y, respectively. Significant positive correlations were observed between Muscle Fibre density and all four measures of texture assessed by the taste panels, “chewiness”, “firmness”, “mouth-feel” and “dryness”. A firm texture was therefore associated with a high Muscle Fibre density. At harvest, the lipid content of the fillet was significantly higher in strain X (11.2%) than strain Y (7.0%). There was, however, no significant correlation found between sensoric “oiliness” score and the percentage lipid content of the fillet. The results indicate that Muscle Fibre cellularity is an important factor in several key flesh quality traits. The potential for manipulating Muscle cellularity to produce desirable flesh quality characteristics is briefly discussed.
-
Muscle Fibre types and size distribution in sub antarctic notothenioid fishes
Journal of Fish Biology, 2000Co-Authors: Daniel A Fernandez, J Calvo, Craig E Franklin, Ian A JohnstonAbstract:The presumptive tonic Muscles Fibres of Cottoperca gobio, Champsocephalus esox, Harpagifer bispinis, Eleginops maclovinus, Patagonothen tessellata, P. cornucola and Paranotothenia magellanica stained weakly or were unstained for glycogen, lipid, succinic dehydrogenase (SDHase) and myosin ATPase (mATPase) activity. Slow, intermediate and fast twitch Muscle Fibres, distinguished on the basis of the pH stability of their mATPases, showed intense, moderate and low staining activity for SDHase, respectively. Slow Fibres were the major component of the pectoral fin adductor profundis Muscle. The proportion of different Muscle Fibre types varied from the proximal to distal end of the Muscle, but showed relatively little variation between species. The myotomes contained a lateral superficial strip of red Muscle composed of presumptive tonic, slow twitch and intermediate Fibres, thickening to a major wedge at the horizontal septum. All species also had characteristic secondary dorsal and ventral wedges of red Muscle. The relative abundance and localization of Muscle Fibre types in the red Muscle varied between species and with body size in the protandric hermaphrodite E. maclovinus. The frequency distribution of diameters for fast twitch Muscle Fibres, the major component of deep white Muscle, was determined in fish of a range of body sizes. The absence of Fibres <20 mu m diameter was used as a criterion for the cessation of Muscle Fibre recruitment. Fibre recruitment had stopped in P, tessellata of 13.8 cm L-T and E, maclovinus of 32.8 cm L-T, equivalent to 49 and 36.5% of their recorded maximum sizes respectively. As a result in 20-cm P. tessellata, the maximum Fibre diameter was 300 mu m and 36% of Fibres were in excess of 200 mu m The unusually large maximum Fibre diameter, the general arrangement of the red Muscle layer and the extreme pH lability of the mATPase of fast twitch Fibres are all common characters of the sub-Antarctic and Antarctic Notothenioids, including Cottoperca gobio, the suggested sister group to the Notothenidae. (C) 2000 The Fisheries Society of the British Isles.
-
influence of temperature on Muscle Fibre development in larvae of the herring clupea harengus
Marine Biology, 1992Co-Authors: V I A Vieira, Ian A JohnstonAbstract:The development of swimming (myotomal) Muscles was studied in herring larvae (Clupea harengus L.) caught in the Firth of Clyde, Scotland, in spring 1990 and reared at either 5, 10 or 15°C. Two Muscle-Fibre types can be distinguished in the myotomes of herring larvae using ultrastructural criteria. A single layer of small-diameter Muscle Fibres, packed with mitochondria, is present beneath the entire surface of the skin (superficial Muscle Fibres). The remaining bulk of the Muscle is composed of larger diameter Fibres (inner Muscle Fibres) containing significantly more myofibrils than the superficial Fibres. In 1 d-old larvae, the number of inner Muscle Fibres in myotomes immediately posterior to the yolk-sac was 311±41 at 15°C, 257±22 at 10°C and 187±22 at 5°C (mean±SD,n=6). The average diameter of inner Muscle Fibres increased with decreasing temperature, so that the total cross-sectional area of Muscle was similar at each temperature. After 6 to 7 d, the number of Muscle Fibres had significantly increased at 15°C (383±25), but not at 10°C (281±32) or 5°C (192±17). In contrast, the average cross-sectional area of inner Muscle Fibres had increased by 19% at 15°C, 34% at 10°C, and 26% at 5°C. Temperature also influenced the relative proportions and spatial distributions of Muscle-Fibre organelles. For example, in 1 d-old larvae, the fraction of Muscle-Fibre volume (volume density) occupied by mitochondria in the superficial Fibres was significantly higher at 15°C (46.0%) than at either 5°C (37.6%) or 10°C (38.8%). In the inner Muscle Fibres, the volume density of mitochondria was 26.1% at 15°C, 20.5% at 10°C and 15.9% at 5°C, whereas the volume density of myofibrils was similar at the three temperatures (33 to 38%). Typically, inner Muscle Fibres from 10°C larvae, but not from 5 or 15°C larvae contained a large central mitochondrion.
David P Mcbey - One of the best experts on this subject based on the ideXlab platform.
-
the effects of exercise training versus intensive insulin treatment on skeletal Muscle Fibre content in type 1 diabetes mellitus rodents
Lipids in Health and Disease, 2021Co-Authors: David P Mcbey, Michelle S Dotzert, C W J MellingAbstract:Intensive-insulin treatment (IIT) strategy for patients with type 1 diabetes mellitus (T1DM) has been associated with sedentary behaviour and the development of insulin resistance. Exercising patients with T1DM often utilize a conventional insulin treatment (CIT) strategy leading to increased insulin sensitivity through improved intramyocellular lipid (IMCL) content. It is unclear how these exercise-related metabolic adaptations in response to exercise training relate to individual Fibre-type transitions, and whether these alterations are evident between different insulin strategies (CIT vs. IIT). Purpose: This study examined glycogen and fat content in skeletal Muscle Fibres of diabetic rats following exercise-training. Male Sprague-Dawley rats were divided into four groups: Control-Sedentary, CIT- and IIT-treated diabetic sedentary, and CIT-exercised trained (aerobic/resistance; DARE). After 12 weeks, Muscle-Fibre lipids and glycogen were compared through immunohistochemical analysis. The primary findings were that both IIT and DARE led to significant increases in type I Fibres when compared to CIT, while DARE led to significantly increased lipid content in type I Fibres compared to IIT. These findings indicate that alterations in lipid content with insulin treatment and DARE are primarily evident in type I Fibres, suggesting that Muscle lipotoxicity in type 1 diabetes is Muscle Fibre-type dependant.
-
The effects of exercise training versus intensive insulin treatment on skeletal Muscle Fibre content in type 1 diabetes mellitus rodents
'Springer Science and Business Media LLC', 2021Co-Authors: David P Mcbey, Michelle S Dotzert, C W J MellingAbstract:Abstract Background Intensive-insulin treatment (IIT) strategy for patients with type 1 diabetes mellitus (T1DM) has been associated with sedentary behaviour and the development of insulin resistance. Exercising patients with T1DM often utilize a conventional insulin treatment (CIT) strategy leading to increased insulin sensitivity through improved intramyocellular lipid (IMCL) content. It is unclear how these exercise-related metabolic adaptations in response to exercise training relate to individual Fibre-type transitions, and whether these alterations are evident between different insulin strategies (CIT vs. IIT). Purpose: This study examined glycogen and fat content in skeletal Muscle Fibres of diabetic rats following exercise-training. Methods Male Sprague-Dawley rats were divided into four groups: Control-Sedentary, CIT- and IIT-treated diabetic sedentary, and CIT-exercised trained (aerobic/resistance; DARE). After 12 weeks, Muscle-Fibre lipids and glycogen were compared through immunohistochemical analysis. Results The primary findings were that both IIT and DARE led to significant increases in type I Fibres when compared to CIT, while DARE led to significantly increased lipid content in type I Fibres compared to IIT. Conclusions These findings indicate that alterations in lipid content with insulin treatment and DARE are primarily evident in type I Fibres, suggesting that Muscle lipotoxicity in type 1 diabetes is Muscle Fibre-type dependant
Tim Snijders - One of the best experts on this subject based on the ideXlab platform.
-
prolonged exercise training improves the acute type ii Muscle Fibre satellite cell response in healthy older men
The Journal of Physiology, 2019Co-Authors: Tim Snijders, Joshua P Nederveen, Kirsten E Bell, Nicole Mazara, Dinesh Kumbhare, Stuart M Phillips, Gianni PariseAbstract:KEY POINTS: Skeletal Muscle stem cells, termed satellite cells, play a crucial role in repair and remodelling of Muscle in response to exercise An age-related decline in satellite cell number and/or function has been hypothesized to be a key factor in the development of sarcopenia and/or the blunted Muscle Fibre adaptive response to prolonged exercise training in older persons We report that performing prolonged exercise training improves the acute type II Muscle Fibre satellite cell response following a single bout of resistance exercise in older men. The observed improvement in Muscle satellite function is associated with an increase in Muscle Fibre capillarization following exercise training suggesting a possible functional link between capillarization and satellite cell function. ABSTRACT: Age-related type II Muscle Fibre atrophy is accompanied by a Fibre type-specific decline in satellite cell number and function. Exercise training restores satellite cell quantity in older adults; however, whether it can restore the impaired satellite cell response to exercise in older adults remains unknown. Therefore we assessed the acute satellite cell response to a single exercise session before and after prolonged exercise training in older men. Fourteen older men (74 ± 8 years) participated in a 12-week exercise training programme (resistance exercise performed twice per week, high intensity interval training once per week). Before and after training, percutaneous biopsies from the vastus lateralis Muscle were taken prior to and following 24 and 48 h of post-exercise recovery. Muscle Fibre characteristics were evaluated by immunohistochemistry and mRNA expression by RT-PCR. Whereas no changes were observed in type II Muscle Fibres, type I Muscle Fibre satellite cell content increased significantly at 24 and 48 h after a single bout of resistance exercise before the exercise training programme (P < 0.01). Following the exercise training programme, both type I and type II Muscle Fibre satellite cell content increased significantly at 24 and 48 h after a single bout of resistance exercise (P < 0.05). The greater acute increase in type II Muscle Fibre satellite cell content at 24 h post-exercise recovery after training was correlated with an increase in type II Muscle Fibre capillarization (r = 0.671, P = 0.012). We show that the acute Muscle satellite cell response following exercise can be improved by prolonged exercise training in older men.
-
Muscle Fibre capillarization is a critical factor in Muscle Fibre hypertrophy during resistance exercise training in older men
Journal of Cachexia Sarcopenia and Muscle, 2017Co-Authors: Sophie Joanisse, Tim Snijders, Joshua P Nederveen, Marika Leenders, Lex B Verdijk, Luc J C Van Loon, Gianni PariseAbstract:Background Adequate Muscle Fibre perfusion is critical for the maintenance of Muscle mass; it is essential in the rapid delivery of oxygen, nutrients and growth factors to the Muscle, stimulating Muscle Fibre growth. Muscle Fibre capillarization is known to decrease substantially with advancing age. However, whether (relative) low Muscle Fibre capillarization negatively impacts the Muscle hypertrophic response following resistance exercise training in older adults is unknown. Methods Twenty-two healthy older men (71 ± 1 years) performed 24 weeks of progressive resistance type exercise training. To assess the change in Muscle Fibre characteristics, percutaneous biopsies from the vastus lateralis Muscle were taken before and following 12 and 24 weeks of the intervention programme. A comparison was made between participants who had a relatively low type II Muscle Fibre capillary-to-Fibre perimeter exchange index (CFPE; LOW group) and high type II Muscle Fibre CFPE (HIGH group) at baseline. Type I and type II Muscle Fibre size, satellite cell, capillary content and distance between satellite cells to the nearest capillary were determined by immunohistochemistry. Results Overall, type II Muscle Fibre size (from 5150 ± 234 to 6719 ± 446 µm2, P < 0.05) and satellite cell content (from 0.058 ± 0.006 to 0.090 ± 0.010 satellite cells per Muscle Fibre, P < 0.05) had increased significantly in response to 24 weeks of resistance exercise training. However, these improvements where mainly driven by differences in baseline type II Muscle Fibre capillarization, whereas Muscle Fibre size (from 5170 ± 390 to 7133 ± 314 µm2, P < 0.05) and satellite cell content (from 0.059 ± 0.009 to 0.102 ± 0.017 satellite cells per Muscle Fibre, P < 0.05) increased significantly in the HIGH group, no significant changes were observed in LOW group following exercise training. No significant changes in type I and type II Muscle Fibre capillarization were observed in response to 12 and 24 weeks of resistance exercise training in both the LOW and HIGH group. Conclusions Type II Muscle Fibre capillarization at baseline may be a critical factor for allowing Muscle Fibre hypertrophy to occur during prolonged resistance exercise training in older men.
Todd A Trappe - One of the best experts on this subject based on the ideXlab platform.
-
single Muscle Fibre contractile properties in young and old men and women
The Journal of Physiology, 2003Co-Authors: S W Trappe, Philip M Gallagher, Matthew P Harber, John A Carrithers, James D Fluckey, Todd A TrappeAbstract:The purpose of this study was to determine whether there was an age-related decline in the isometric and isotonic contractile function of permeabilized slow (MHC I) and fast (MHC IIa) single Muscle Fibres. Vastus lateralis Muscle Fibres from six young men (YM; 25 +/- 1 years), six young women (YW; 25 +/- 1 years), six old men (OM; 80 +/- 4 years) and six old women (OW; 78 +/- 2 years) were studied at 15 degrees C for in vitro force-velocity properties, peak force and contractile velocity. Peak power was 23-28 % lower (P 0.05) among the four groups. These data suggest that differences in whole Muscle strength and function that are often observed with ageing appear to be regulated by quantitative rather than qualitative parameters of single Muscle Fibre contractile function.
