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Biomedical subjects

Stefaan De Smet

Publications and source records attributed to Stefaan De Smet.

11 recordsLinked to original sources
PubMed2006

Lipid metabolism and cellular features of skeletal muscle and subcutaneous adipose tissue in pigs differing in IGF-II genotype.

In pigs, a paternally (pat) imprinted mutation in the IGF-II gene is associated with increased muscle mass and decreased backfat thickness. The aim of this study was to determine whether this mutation influenced cellular, biochemical and metabolic features of skeletal muscle and adipose tissue. Muscle (trapezius) and subcutaneous adipose tissue (SCAT) were collected from pigs (106kg) carrying (Qpat, n=6) or not carrying (qpat, n=7) the mutation. Adipocytes were isolated from those tissues by collagenase treatment. Lipid content and activity of lipogenic enzymes were determined using standard assays. Gene expression levels were determined by real-time PCR. Levels of IGF-II mRNA were higher (P<0.01) in muscle of Qpat than in that of qpat pigs, but they did not differ significantly between the two groups in SCAT. Whereas levels of IGF-I mRNA in muscle were similar in both groups, they were higher (P<0.05) in SCAT of Qpat pigs than in that of qpat pigs. Muscle lipid content and intramuscular adipocyte diameters were not influenced significantly by the IGF-II genotype. In SCAT, the reduction of backfat thickness in Qpat pigs compared with qpat pigs was associated with lower (P<0.05) lipid content and smaller (P<0.05) adipocytes, with no significant genotype-effects on expressions and/or activities of lipogenic enzymes. In summary, our results suggest that the IGF-II mutation altered body composition in pigs by favoring myofiber hypertrophy and repressing adipose cell development in SCAT.

Adipocytes↗
PubMed2006

Readily available porcine aortic valve matrices for use in tissue valve engineering. Is cryopreservation an option?

The clinical use of acellular biological valves as scaffolds in tissue valve engineering would require them to be readily available. This study examines the feasibility of cryopreserving porcine aortic valve matrices for use in tissue valve engineering. Matrices prepared using an enzymatic-detergent decellularization protocol were examined before and after cryopreservation. The biochemical status of tissues were evaluated by collagen and uronic acid (proteoglycan) determination and their mechanical properties were determined using a burst test. The histological and ultrastructural properties were evaluated by light and electron microscopy. Cryopreservation did not significantly affect the collagen and uronic acid content of aortic leaflet matrices. Histological and ultrastructural sections, however, confirmed extensive disruption of the extracellular collagen matrix and inter-fibrillar proteoglycan associations following cryopreservation. Although neither the breakage force nor the maximum force at failure was significantly different in matrices before and after cryopreservation, the strain observed in matrices was significantly higher after cryopreservation. To our knowledge this is the first study to investigate the effects of cryopreservation on aortic valve matrices. Cryopreservation did not significantly alter the biochemical properties of porcine aortic valve matrices. Nevertheless, cryopreservation had significant adverse effects on the structural and mechanical properties of matrices. Cryopreserved matrices showed significantly higher strain when stressed compared to non cryopreserved matrices. While, theoretically matrices are only expected to be functional for a limited time until regenerated in vivo, further mechanical testing is necessary to evaluate the effects of these changes on the durability of porcine aortic valve matrices for use in tissue valve engineering.

Animals↗
PubMed2005

Proteomic analysis of bovine skeletal muscle hypertrophy.

Myostatin plays a major role in muscle growth and development and animals with disruption of this gene display marked increases in muscle mass. Little is known about muscle physiological adaptations in relation to this muscle hypertrophy. To provide a more comprehensive view, we analyzed bovine muscles from control, heterozygote and homozygote young Belgian blue bulls for myostatin deletion, which results in a normal level of inactive myostatin. Heterozygote and homozygote animals were characterized by a higher proportion of fast-twitch glycolytic fibers in Semitendinosus muscle. Differential proteomic analysis of this muscle was performed using two-dimensional gel electrophoresis followed by mass spectrometry. Thirteen proteins, corresponding to 28 protein spots, were significantly altered in response to the myostatin deletion. The observed changes in protein expression are consistent with an increased fast muscle phenotype, suggesting that myostatin negatively controls mainly fast-twitch glycolytic fiber number. Finally, we demonstrated that differential mRNA splicing of fast troponin T is altered by the loss of myostatin function. The structure of mutually exclusive exon 16 appears predominantly expressed in muscles from heterozygote and homozygote animals. This suggests a role for exon 16 of fast troponin T in the physiological adaptation of the fast muscle phenotype.

Animals↗
PubMed2004

Effect of diet and dietary fatty acids on the transformation and incorporation of C18 fatty acids in double-muscled Belgian Blue young bulls.

Three groups of double-muscled Belgian Blue young bulls were fed during different stages of production diets differing in the proportions of linolenic and linoleic acid by including linseed in the concentrate or giving grass silage as main linolenic acid suppliers. Samples of rumen and abomasal contents and of the longissimus thoracis, subcutaneous fat, and liver were taken to analyze the fatty acid pattern with emphasis on the individual trans (t) C18:1 fatty acids and cis-9,trans-11 conjugated linoleic acid (c9t11CLA). Trans C18:1 isomers represented up to 20 g/100 g of total fatty acids in rumen and abomasal contents, whereas the accumulation of c9t11CLA was limited. Total trans C18:1 content in subcutaneous fat and intramuscular fat of the longissimus thoracis comprised 8.4 and 5.2 g/100 g of total fatty acids, respectively, with t11C18:1 being the most abundant one. Compared to rumen contents, subcutaneous and intramuscular fat were enriched in c9t11CLA and contained fewer tC18:1 isomers, resulting in a higher c9t11CLA/t11C18:1 ratio (0.04, 0.22, and 0.22, respectively). This result suggests that the endogenous synthesis of c9t11CLA in adipose tissue by the Delta(9)-desaturase was more important than its ruminal production.

Abomasum↗
PubMed2004

Stable carbon isotope analysis of different tissues of beef animals in relation to their diet.

As part of a larger experiment, 31 young bulls, divided into three groups, were given different diets containing either C(3) plants or a combination of C(3) and C(4) plant-based feeds in three feeding periods before slaughter. Variation in the proportion of C(4) plant material in the diets was made by including or not maize or maize-derived ingredients, whereas the other dietary constituents were from C(3) plants. Analysis of stable carbon isotope ratios (delta(13)C value) was performed on different tissues taken at slaughter: blood, plasma, liver, kidney fat, hair, muscle and ruminal contents. Blood and plasma samples were also taken at the beginning of each period. A highly significant difference was found in the delta(13)C values of blood and plasma samples taken from animals that had received a diet of only C(3) plants or with 59% C(4) material for 70 days. The delta(13)C values of all different samples taken at slaughter were highly significantly different between the three feeding groups that had received diets with 0, 13.5 or 35% C(4) material for on average 137, 139 and 83 days, respectively. For the three groups, samples of hair, muscle, plasma, whole blood and liver were significantly enriched in (13)C compared with the diet (except for liver in one group), whereas kidney fat was significantly depleted. The proportion of C(4) plant material could be accurately estimated from the delta(13)C values of different tissue samples. Stable carbon analysis of different tissues from beef animals can be used to trace back diets containing variable proportions of C(3) and C(4) plant material.

Adipose Tissue↗
PubMed2002

The deposition of conjugated linoleic acids in eggs of laying hens fed diets varying in fat level and fatty acid profile.

The objective of this study was to investigate the incorporation of conjugated linoleic acid (CLA) into eggs and its effect on the fatty acid metabolism when layers are fed diets with different fat sources and fat levels. Layers were fed either a low fat diet (LF) or one of three high fat diets based on soybean oil (SB), animal fat (AF) or flaxseed oil (FSO). CLA was added at a concentration of 1 g/100 g feed from two different CLA premixes with a different CLA profile. For the trial, 144 laying hens were allocated to 12 treatments (4 basal fat sources x 3 CLA treatments) with 3 replicates of 4 hens each. No significant differences were observed in feed intake, egg weight, feed conversion or laying rate between chickens fed control and CLA-supplemented diets. Differences in yolk fat, cholesterol or yolk color were not clearly related to the dietary CLA. However, the supplementation of CLA to the diets had clear effects on the fatty acid composition, i.e., a decrease in monounsaturated fatty acids (MUFA) and an increase in saturated fatty acids (SFA) was observed, whereas the polyunsaturated fatty acids (PUFA) content were essentially unaffected. The results suggest that CLA may influence the activity of the desaturases to a different extent in the synthesis of (n-6) and (n-3) long-chain fatty acids. These effects of CLA depend on the level of (n-6) and (n-3) fatty acids available in the feed. The apparent deposition rate (%) is clearly higher for the c9, t11 isomer than for the t10, c12 isomer. Adding CLA to layers diets rich in (n-3) fatty acids produces eggs that could promote the health of the consumer in terms of a higher intake of (n-3) fatty acids and CLA.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Effect of diets rich in N-3 polyunsatured fatty acids on muscle lipids and fatty acids in Belgian Blue double-muscled young bulls.

The present study was aimed at investigating the effect of duration and time of feeding n-3 fatty acids on the fatty acid composition of intramuscular fat and adipose tissue of bulls at slaughter. Four groups of bulls were given during three periods different diets, mainly differing in the presence of linseed as the predominant n-3 fatty acid source in the concentrate either or not in combination with grass (silage) as the roughage. The results show that the fatty acid composition of the feed during the earlier periods of life of the animal were important and influenced the final intramuscular fatty acid composition. Feeding n-3 PUFA during the phases before the finishing diet increased the long chain n-3 PUFA (C20:5n-3, C22:5n-3 and C22:6n-3) compared to animals which were fed only a C 18:3n-3 rich concentrate in the finishing period. The cis-9,trans-11CLA content was increased by feeding linseed in the fattening period and was mainly deposited in the triacylglycerol fraction of the intramuscular fat.

Adipose Tissue↗