Biomedical subjects

V Mougios

Publications and source records attributed to V Mougios.

At least 19 recordsLinked to original sources

PubMed2006

Does the intensity of an exercise programme modulate body composition changes?

Exercise training is a useful component of weight maintenance programmes. Although energy expenditure, not intensity or duration, seems to determine the amount of weight loss attributable to exercise, it is not clear whether changes in the components of body mass are also insensitive to these parameters. Thus, the aim of the present study was to compare the effect of two isoenergetic exercise training programmes, one of low and one of high intensity, on body composition. Fourteen healthy premenopausal untrained women were divided into two equivalent groups, which exercised on treadmill at 45 or 72 % of V(O2max) four times a week for three months, spending 1548 kJ (370 kcal) per exercise session. No dietary intervention was applied. Body mass decreased significantly in both groups but more in the low-intensity than the high-intensity group (by mean +/- SD, 3.3 +/- 1.3 vs. 1.9 +/- 0.9 kg, p = 0.032). The decrease in fat mass was significant in both groups (3.1 +/- 1.2 vs. 2.4 +/- 1.5 kg, respectively) but not significantly different between them. Fat-free mass did not change significantly in either group, although the difference between groups tended to be significant (decrease by 0.2 +/- 0.7 kg in the low-intensity group vs. increase by 0.5 +/- 0.6 kg in the high-intensity group, p = 0.058). In conclusion, exercise training at 45 % of V(O2max) without dietary restriction produced a higher weight loss than at 72 % of V(O2max), whereas the higher intensity tended to maintain fat-free mass, possibly, in part, through the smaller weight loss. Thus, both programmes may prove useful in eliciting favourable changes depending on which target (weight loss or maintenance of fat-free mass) is of higher priority.

Adult↗

PubMed2006

Mitochondrial phospholipids of rat skeletal muscle are less polyunsaturated than whole tissue phospholipids: implications for protection against oxidative stress.

The fatty acid composition of phospholipids is an important determinant of membrane function. Although the mitochondria play a pivotal role in skeletal muscle function, the fatty acid composition of their individual phospholipids has not been examined. The purpose of this study was to determine the fatty acid profile of each phospholipid in rat skeletal muscle mitochondria and compare it with that of the whole muscle. Lipids were extracted from the gastrocnemius muscles of 10 Wistar rats, and phospholipids were separated by thin-layer chromatography. The fatty acid composition of each phospholipid was then determined by gas chromatography. The same procedure was applied to a mitochondrial preparation from these muscles. We found that the fatty acid composition of the individual mitochondrial phospholipids (phosphatidyl choline, phosphatidyl ethanolamine, cardiolipin, phosphatidyl inositol, phosphatidyl serine, sphingomyelin, and lysophosphatidyl choline) and of the total mitochondrial phospholipids differed markedly (P < 0.05) from the fatty acid composition of the corresponding whole muscle phospholipids. Notably, the mitochondrial phospholipids had higher percentages of MUFA [13.9 (2.1) vs. 10.3 (0.9)] and lower percentages of PUFA [34.8 (4.3) vs. 39.5 (5.2)] and n6 fatty acids [25.0 (2.5) vs. 27.6 (2.5)]. Overall, the mitochondrial phospholipids had a lower unsaturation index than whole muscle phospholipids [135 (20) vs. 161 (26)]. Because PUFA are susceptible to peroxidation, unlike saturated fatty acids and MUFA, we propose that the low polyunsaturation of mitochondrial phospholipids is the result of selective pressure toward membranes that are more resistant to oxidative damage by reactive oxygen species produced in their vicinity. The negative effect of the low polyunsaturation on membrane fluidity may be counterbalanced by the higher percentage of MUFA and the known low cholesterol content of mitochondrial membranes.

Animal Feed↗

PubMed2006

Assessment of brown adipose tissue activity in rats by 99mTc-sestamibi uptake.

Brown adipose tissue (BAT) physiology and imaging have recently attracted considerable attention. BAT is characterized both by enhanced perfusion and increased mitochondrial activity. (99m)Tc-sestamibi is a lipophilic cationic tracer that concentrates in mitochondria. Data on the accumulation of (99m)Tc-sestamibi in BAT are currently lacking. This study investigates the in vivo (99m)Tc-sestamibi uptake in rat BAT. (99m)Tc-sestamibi was administered in male Wistar rats of various age and body size. (99m)Tc-sestamibi uptake was measured in vitro in BAT and white fat (WF) together with cytochrome c oxidase activity. Both (99m)Tc-sestamibi uptake and cytochrome c oxidase activity were higher in BAT than in WF (P<0.05). (99m)Tc-Sestamibi uptake in both BAT and WF was negatively related to body weight (r = -0.96 and -0.89, respectively) as was the BAT/WF uptake ratio (r = -0.85). These data show a higher (99m)Tc-sestamibi uptake in BAT compared to WF, in agreement with the high mitochondrial content and respiratory activity of the former. The strong negative correlation between (99m)Tc-sestamibi uptake in BAT and body weight (negative allometry), is in accordance to increased needs of thermogenesis in smaller animals. Implications of increased (99m)Tc-sestamibi uptake in BAT in radionuclide imaging are also discussed.

Adipose Tissue, Brown↗

PubMed2005

Comparison of the phospholipid and triacylglycerol fatty acid profile of rat serum, skeletal muscle and heart.

Although several studies have analyzed the fatty acid profile of phospholipids (PL) and, to a lesser degree, triacylglycerols (TG) in one or more tissues concurrently, a systematic comparison of the fatty acid composition of different tissues and/or lipid classes is lacking. The purpose of the present study was to compare the fatty acid composition of major lipid classes (PL and TG) in the rat serum, soleus muscle, extensor digitorum longus muscle and the heart. Lipids were extracted from these tissues and analyzed by a combination of thin-layer chromatography and gas chromatography. We found many significant differences in various tissues and lipid classes. Serum had the most distinct fatty acid profile in PL but this "uniqueness" was less apparent in TG, where differences among tissues were in general less frequent than in PL. These two skeletal muscles exhibited similar fatty acid composition in both lipid classes despite their different muscle fiber type composition, denoting that fiber type is not a major determinant of the fatty acid composition of rat skeletal muscle. The fatty acid profile of heart PL was the most different from that of the other tissues examined. PL were rich in polyunsaturated fatty acids, whereas TG were rich in monounsaturated fatty acids. Although the reasons for the differences in fatty acid profile among the tissues examined are largely unknown, it is likely that these differences have an impact upon numerous biological functions.

Acetyltransferases↗

PubMed2005

The effects of muscle damage on running economy in healthy males.

Published information on aspects related to muscle damage and running economy is both limited and contradictory. To contribute to the current debate, we investigated the effects of an eccentric exercise session on selected muscle damage indices in relation to running economy using 10 (mean age 23 +/- 1 years) healthy male volunteers. The eccentric exercise session consisted of 120 (12 x 10) maximal voluntary repetitions by each randomly selected leg at the angular velocity of 1.05 rad . s (-1). Muscle damage (creatine kinase, delayed onset muscle soreness, range of movement, and eccentric, concentric and isometric [at 60 degrees and 110 degrees knee flexion] peak torque) and running economy (oxygen consumption, pulmonary ventilation, respiratory exchange ratio and breaths per minute during treadmill running at 133 and 200 m . min (-1)) indicators, were assessed pre-, 24-, 48-, 72- as well as 96-h after exercise. All muscle damage indicators revealed significant changes at almost all time-points of assessment compared to pre-exercise data (p < 0.05). However, none of the running economy parameters disclosed any significant change throughout the study (p > 0.05). It was concluded that changes in muscle damage and muscle performance as measured in this study are not reflected by concomitant alterations in running economy at submaximal intensities.

Adult↗

PubMed2004

Effect of prior exercise on lipemia after a meal of moderate fat content.

OBJECTIVE: Prior exercise has been repeatedly shown to reduce lipemia after meals of exaggerated fat content (over 60% of total energy). The aim of the present study was to investigate whether the same applies to meals closer to the composition of the typical Western diet and explore whether exercise affects the release of dietary fat into the bloodstream. DESIGN: Randomized counterbalanced. SETTING: Laboratory. SUBJECTS: Nine healthy young male volunteers. INTERVENTION: Subjects consumed a meal of moderate fat content (35% of total energy, 0.66 g/kg body mass) 14 h after having either cycled for 1 h at 70-75% of maximal heart rate or rested. Macadamia nuts were used as the main source of dietary fat to trace its entry into the circulation because of their unusual fatty acid composition. Blood samples were drawn before the meal and for 8 h postprandially. RESULTS: Plasma triacylglycerol concentrations and total area under the triacylglycerol concentration vs time curve (AUC) were significantly lower after exercise (P = 0.001 and 0.003, respectively; effect size for the latter, 0.84). However, incremental (above baseline) AUC was not affected by exercise significantly. When controlling for differences in baseline plasma concentrations, only the fatty acids that were more abundant in the meal than in plasma triacylglycerols were decreased in the early postprandial period following exercise, implying either a suppressive effect of exercise on the rate of triacylglycerol release from the intestine or a more rapid chylomicron clearance after meal consumption. CONCLUSIONS: Exercise performed between 15 and 14 h before a meal of moderate fat content reduced postprandial lipemia, mainly by lowering fasting triacylglycerols. The effect of exercise on postprandial triacylglycerol metabolism may be mediated, at least in part, by attenuated release of dietary fat from the intestine.

Adult↗

PubMed2004

Effects of iron intake through food or supplement on iron status and performance of healthy adolescent swimmers during a training season.

Maintenance of a normal iron status is important for swimming performance during training and competition. The purpose of this study was to investigate whether 1) the iron status of healthy adolescent swimmers changes during a training season of six months, and 2) increasing daily iron intake affects iron status or performance. Forty-two (21 male and 21 female) swimmers, aged 12 - 17, without anemia or iron deficiency were divided into three equal groups. Group A received an iron supplement of 47 mg per day, group B followed a dietary plan rich in iron (providing, on average, 26 mg per day), and group C had a regular diet. Blood samples were taken before the beginning of the study and at the end of each of three training phases (moderate intensity training, high intensity training, and tapering) for the determination of hematological and iron status parameters. To evaluate performance, swimming tests at different distances were conducted along with blood sampling. The results showed significant fluctuations of iron status during the training season, including an increase in erythrocyte parameters during moderate intensity training. No significant differences in iron status or performance were found among the three groups. In conclusion, iron status and performance of healthy adolescent swimmers were affected by training irrespective of iron intake ranging from one to over five times the RDA over a period of six months.

Adolescent↗

PubMed2004

Effect of voluntary exercise on the expression of IGF-I and androgen receptor in three rat skeletal muscles and on serum IGF-I and testosterone levels.

The effects of anabolic agents and training on skeletal muscle are believed to be mediated by a variety of growth and transcription factors. Among these regulatory proteins, insulin-like growth factor-I (IGF-I) and androgen receptor (AR) play a crucial role. The purpose of this study was to investigate the effects of wheel running on IGF-I and AR mRNA expression in three distinct rat skeletal muscles (i.e., gastrocnemius, vastus lateralis, and soleus), as well as on the serum levels of IGF-I and testosterone. Twenty male Wistar rats were housed in cages with free access to running wheels for 12 weeks, while nine rats served as controls. Analysis of the mRNA expression of IGF-I and AR using real time RT-PCR revealed no significant differences between the trained and untrained rats in any of the muscles studied. Enzyme immunoassay showed significantly lower serum levels of IGF-I and testosterone in the trained compared to the untrained animals. These results suggest that chronic exercise in wheels does not affect IGF-I and AR mRNA levels in rat skeletal muscle, while decreasing the circulating levels of two anabolic factors, i.e., IGF-I and testosterone. It is concluded that IGF-I, AR and testosterone seem to play a marginal role during the adaptation process of rat skeletal muscle to long-term wheel running.

Animals↗

PubMed2004

Effect of chronic wheel running on the fatty acid composition of phospholipids and triacylglycerols in rat serum, skeletal muscle and heart.

AIM: The purpose of this study was to examine the effects of long-term wheel running on the fatty acid composition of phospholipids (PL) and triacylglycerols (TG) in rat serum, skeletal muscle (soleus and extensor digitorum longus) and heart. METHODS: To this end, the relevant tissues of 11 trained male Wistar rats were compared with those of 14 untrained ones. RESULTS: There were several significant differences between the two groups regarding the concentrations and percentages of individual fatty acids in serum PL and TG, with most differences appearing in the fatty acid distribution of PL. Monounsaturated fatty acids of muscle PL were significantly lower in the trained rats. Estimated elongase activity was significantly higher, whereas Delta(9)-desaturase activity was significantly lower in the trained muscles. Monounsaturated fatty acids of PL were also significantly lower in the trained hearts. The fatty acid composition of PL in the skeletal muscles and the heart adapted to training in a comparable manner, whereas most of the changes in the fatty acid profile of TG were tissue-dependent. Judging from the magnitude of the effect sizes and the percentage differences between trained and untrained animals, there were many large effects of chronic exercise on the fatty acid composition of the tissues examined. CONCLUSION: Long-term wheel running modified the fatty acid profile of PL and TG in rat serum, skeletal muscle and heart, and could thus be considered as a modulator of tissue fatty acid composition.

Animals↗

PubMed2003

Exercise-induced changes in c-Fos protein levels in skeletal muscle of trained and untrained rats.

We investigated the effect of an acute bout of endurance exercise on c-Fos protein levels in the extensor digitorum longus muscle of trained and untrained rats. Fifty rats were equally divided into a trained and an untrained group. Rats of the trained group ran on a treadmill 45 min/day for 5 days. On the sixth day, 5 rats were killed without exercise, while the remaining 20 ran as above and were killed 0, 3, 6, and 12 h post-exercise (5 rats at each time point). In the untrained group, 5 rats were killed without exercise, while the remaining 20 ran as above only once and were killed at the same time points as the trained group. Western blotting demonstrated no significant changes in c-Fos protein levels in the untrained group. On the contrary, in the trained group, there was a significant increase at 6 and 12 h compared to 3 h post-exercise. The levels of the protein in the trained rats were above the corresponding levels in the untrained ones at all time points, although these differences reached statistical significance only immediately, 6 h and 12 h post-exercise. These results show that trained skeletal muscle exhibits increased levels of c-Fos, probably as a cumulative result of changes occurring during recovery from each exercise bout, and greater c-Fos response after acute endurance exercise compared to untrained skeletal muscle.

Animals↗

PubMed2003

Hematologic and biochemical profile of juvenile and adult athletes of both sexes: implications for clinical evaluation.

The aim of the present study was to compare the values of seventeen hematologic and biochemical parameters between juvenile and adult athletes and non-athletes of both sexes. 579 athletes and 241 non-athletes participated in the study. We measured packed-cell volume, hemoglobin, red blood cell count, white blood cell count, platelet count, iron, glucose, urea, triacylglycerols, total cholesterol, high-density lipoprotein cholesterol, total/high-density lipoprotein cholesterol ratio, calcium, magnesium, creatine kinase, as well as alanine and aspartate aminotransferases. We found significant differences according to age, sex, and physical activity in the majority of the parameters. The effect size of physical activity on most parameters was small (< 0.5); however, that on packed-cell volume, glucose, urea, calcium, magnesium, and creatine kinase was moderate to high (0.5 to 0.8). It is remarkable that three of the highest effect sizes of physical activity appeared on parameters thought to be under tight homeostatic control (i. e., glucose, calcium, and magnesium). We conclude that physical training influences most of the biochemical parameters routinely measured in athletes, although, in some cases, its effect appears to be of limited biological importance. Therefore, clinical assessment on the basis of blood tests has to take into account not only the age and sex, but also the training status of individuals.

Adaptation, Physiological↗

PubMed2003

Estrogen effect on some enzymes in female rats after downhill running.

The study investigates the effect of administered estrogen on plasma creatine kinase (CK) and lactate dehydrogenase (LD) levels in female ovariectomized rats after downhill running. Rats ovariectomized before sexual maturity were subcutaneously implanted with pellets containing 17 beta-estradiol or placebo. Three weeks later they were subjected to a 90-min intermittent downhill running protocol. Blood samples were obtained from the jugular vein immediately after and 72 h after exercise for determination of plasma CK, LD and 17 beta-estradiol levels. A two-way analysis of variance was used for data evaluation. Plasma CK and LD levels were significantly lower (p<0.05) in the estrogen-supplemented, ovariectomized animals which suggests that less muscle damage occurred compared to the controls immediately and 72 h after exercise. Estrogens may have a protective effect on muscle tissue possibly due to their antioxidant and membrane stabilizing properties.

Animals↗

PubMed2001

Effect of supplementation with conjugated linoleic acid on human serum lipids and body fat.

Conjugated linoleic acid (CLA) is a natural component of meat and dairy products with anticarcinogenic, fat lowering, antiatherogenic and anticatabolic activity in animals. The purpose of this study was to examine the effect of CLA supplementation to humans on body fat, certain biochemical parameters of serum, and the CLA content of serum lipids. Twenty-two volunteers were divided into a study group and a control group in a doubly blind design. The study group received 0.7 g of CLA for four weeks and 1.4 g of CLA for the next four weeks, while the control group received placebo. Diet was controlled and no significant differences in energy or macronutrient intake were found between the two groups. Measurements were taken at baseline, four weeks, and eight weeks. The sum of the thickness of ten skinfolds, percentage body fat calculated from it and fat mass was significantly reduced in the CLA group during the second period (P < 0.004) but not overall during the study. Serum HDL-cholesterol decreased significantly (P < 0.001) and triacylglycerols as well as total cholesterol tended to decrease in the CLA group during the first period. The CLA content of serum non-esterified fatty acids, triacylglycerols, phospholipids, and cholesteryl esters increased gradually with supplementation; the CLA content of total serum lipids doubled at the end of the study compared to baseline. Phospholipids had the highest CLA content regardless of supplementation. These data indicate that supplementation with 0.7-1.4 g CLA daily for 4-8 weeks may modulate body fat and serum lipids, as well as increase the CLA content of serum lipids in humans.

Journal Article↗

PubMed1999

Sex-hormone binding globulin from sheep serum: purification and effects of pregnancy and treatment with exogenous estradiol.

Sex-hormone binding globulin (SHBG) is a protein that binds sex steroids in the serum of many species. SHBG binds androgens and estrogens in humans and primates with high affinity, but behaves as an androgen binding protein in other species. Here we purified SHBG from ewe and ram sera to homogeneity, by a simple and rapid method. The K(D) of the purified protein was found to be 3.63 nM for testosterone and around 600 nM for estradiol. We also studied the effect of pregnancy on SHBG levels in ewes and the effect of exogenous estradiol administration either orally or parenterally on SHBG levels in rams. Basal levels of SHBG in sheep are not affected by pregnancy or exposure to exogenous estradiol. It is concluded that SHBG regulation of expression in ewes and rams differs from that in humans in that it is not affected by estrogen and possibly is species specific.

Administration, Oral↗

PubMed1999

Plasma ammonia response to sprint swimming.

BACKGROUND: To study the plasma ammonia response after sprint crawl swimming. METHODS: Nine sprinters (S) and ten non-sprinters (NS) completed a 15-, a 25- and a 50-m crawl at maximal intensity with a 10-min and a 15-min resting period in-between. Capillary blood samples were collected before and at regular intervals after each effort for plasma ammonia determination. RESULTS: Ammonia kinetics differed among distances, but not between groups, with peak values (observed 2-8 min postexercise) being higher after 50 m as compared to shorter distances. Significant differences between S and NS were found in peak ammonia after 50 m (124.5 +/- 58.2 vs 98.7 +/- 6.3 mumoL-1) and in the change of ammonia relative to swim time (delta NH3/delta t) after 25 m (2.66 +/- 1.87 vs 1.49 +/- 0.84 mumol L-1 s-1) and 50 m (1.87 +/- 1.33 vs 1.01 +/- 0.49 mumol L-1 s-1). delta NH3/delta t was highest after 15 m (3.33 +/- 2.53 in S, 3.92 +/- 1.67 mumol L-1 s-1 in NS). CONCLUSIONS: These differences in the plasma ammonia response to sprint swimming according to duration and athlete seem to be connected to distinctions in muscle fiber profile and energy providing processes.

Adult↗

PubMed1998

Effect of exercise on the proportion of unsaturated fatty acids in serum of untrained middle aged individuals.

OBJECTIVES: To examine whether prolonged moderate exercising by untrained middle aged individuals of both sexes affects the plasma ratio of unsaturated to saturated (U/S) fatty acids in the non-esterified fatty acid (NEFA) and triacylglycerol (TG) fractions. METHODS: Twenty two healthy untrained volunteers (eleven men and eleven pre-menopausal women), aged 35-55, exercised on bicycles at 50-55% maximal heart rate reserve (estimated 61% maximal oxygen uptake) for one hour. Pre- and post-exercise blood samples were analysed for lactate, glucose, glycerol, individual NEFAs and TG acyl groups, cholesterol, high density lipoprotein cholesterol, urea, cortisol, and testosterone. Biopsy specimens of adipose tissue were analysed for TG acyl group composition. RESULTS: Serum total NEFAs increased significantly whereas total TG decreased significantly in both sexes. Changes in individual fatty acids, in both the NEFA and TG fractions, generally paralleled changes in the total pool but were not proportionate. As a result, U/S NEFAs increased in both sexes, although significantly only in women. The shift was in the direction of the composition of the major source of blood NEFAs--that is, adipose tissue TG. U/S acyl groups of TG also increased in both sexes, although significantly only in men. CONCLUSIONS: Prolonged moderate exercise increases the U/S ratio of serum NEFAs and TG. This may add to the beneficial effects of exercise given the protective role of unsaturated fatty acids against coronary heart disease.

Adult↗

PubMed1995

Kinetics of the two-step hydrolysis of triacylglycerol by pancreatic lipases.

Pancreatic lipases catalyze the hydrolysis of triacylglycerol in a sequential manner. First, triacylglycerol is hydrolyzed to 1,2-diacylglycerol, which is subsequently converted to 2-monoacylglycerol. We studied the kinetics of trioleoylglycerol hydrolysis by rabbit and human pancreatic lipases. The products (acylglycerols and fatty acid) were analyzed by extraction from the reaction mixture, separation by thin-layer chromatography, and quantification by capillary gas chromatography. The first-order rate constants of trioleoylglycerol and dioleoylglycerol hydrolysis were calculated showing that both enzymes hydrolyze dioleoylglycerol faster than trioleoylglycerol. Using rabbit pancreatic lipase, we found that deoxycholate enhanced dioleoylglycerol hydrolysis to a higher degree than trioleoylglycerol hydrolysis. Colipase increased both rate constants similarly at high deoxycholate concentrations (35 mM), while at low concentrations (5 mM) a selectivity toward trioleoylglycerol was observed. From the variation of the rate constants with respect to temperature, we calculated the apparent activation energies of trioleoylglycerol and dioleoylglycerol hydrolysis to be 59.8 kJ.mol-1 and 53.5 kJ.mol-1, respectively. Upon storage, both rabbit and human pancreatic lipases showed a greater loss of activity toward dioleoylglycerol as compared to trioleoylglycerol, suggesting that different conformational elements of the enzyme molecule are responsible for the interaction with each substrate.

Animals↗

PubMed1995

Exercise-induced changes in the concentration of individual fatty acids and triacylglycerols of human plasma.

Nineteen male handball players played for two 30-minute periods with a 10-minute interval. Blood samples were drawn at rest, at halftime, and at the end of the game. A biopsy of subcutaneous fat was also taken from 14 participants. Mean plasma lactate concentration was not greater than 4 mmol/L at the end of either half. The concentration of nonesterified fatty acids (NEFA) in plasma increased gradually but not uniformly throughout the game. In effect, the percentages of the major NEFA were significantly different at the three time points of sampling: palmitate (16:0) and stearate (18:0) decreased and oleate (18:1) and linoleate (18:2) increased, resulting in an increase of the ratio of unsaturated to saturated fatty acids (U/S) from 1.1 at rest to 1.6 at the end. The concentration of plasma triacylglycerols (TG) declined during the game, but nine of 19 subjects showed increases during one or both halves, implying a stimulation of TG release from the liver during exercise, which can, at times, overcome the increased hydrolysis of TG in muscle capillaries. Changes in the acyl-group distribution of plasma TG were minor but also in favor of unsaturated fatty acids. Changes in NEFA composition tended toward the composition of adipose tissue, in which TG had a U/S ratio of 3.2. Linear regression between changes in the total concentration of plasma NEFA during each half of the game and corresponding changes in the concentration of individual NEFA showed that the contributions (slopes) of myristate (14:0), palmitoleate (16:1), 18:0, and 18:2 were not significantly different from their fractions in adipose tissue TG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗