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C Tsopanakis

Publications and source records attributed to C Tsopanakis.

At least 19 recordsLinked to original sources
PubMed2006

Alterations in antioxidant status, protein concentration, acetylcholinesterase, Na+, K+-ATPase, and Mg2+-ATPase activities in rat brain after forced swimming.

The aim of this study was to investigate whether exercise stress (short [2 h] or prolonged [5 h] forced swimming in rats) could modulate brain total antioxidant status (TAS), tissue protein concentration, and the activities of acetylcholinesterase (AChE), Na +, K +-ATPase, and Mg 2+-ATPase. Protein concentration, TAS and enzyme activities in homogenized rat brain were determined spectrophotometrically. Protein concentration was decreased by 15 % (p < 0.01) and by 30 % (p < 0.001) after 2 h and 5 h of forced swimming, respectively. TAS was decreased by 20 - 25 % after 2 h or 5 h of exercise. AChE was inhibited by 30 % (p < 0.001) and 45 % (p < 0.001) after 2 h and 5 h of forced swimming, respectively. In contrast, Na +, K +-ATPase and Mg 2+-ATPase were stimulated by 80 % (p < 0.001) and 40 % (p < 0.001), respectively, after 2 h of swimming and by 100 % (p < 0.001) and 60 % (p < 0.001), respectively, after 5 h of exercise. Control values in nontreated rats were unaltered (p > 0.05). In conclusion, short or prolonged forced swimming induces oxidative stress in rats, probably resulting in a reduction in brain protein concentration and AChE activity. In addition, a Na +, K +-ATPase and Mg 2+-ATPase activation was observed under the above mentioned experimental conditions. This stress condition may modulate brain intracellular Mg 2+ concentration, neural excitability, metabolic energy production, and neurotransmission.

Acetylcholine↗
PubMed2004

Acute effects of short duration maximal endurance exercise on lipid, phospholipid and lipoprotein levels.

AIM: The acute effects of maximal endurance exercise (15 min) on lipid and lipoprotein levels were examined, in order to determine whether the level of response produced could be affected by maximal exercise intensity (incremental stress test). METHODS: Participants in this cross sectional study were male athletes (n=78) of national level: basketball (n=10), swimming (n=9), long distance (LD) running (n=23) and wrestling (n=35); also a group of non-athlete volunteers as controls (n=19). Athletes had trained an average of 3 h/day and 5 years. The ergometric test used for the determination of maximal oxygen uptake on a treadmill was based on a stepwise stress protocol. RESULTS: Immediately after a maximal effort all groups (controls included) showed significant increases in total cholesterol (TC), triglycerides (TG), phospholipids (PL) and high-density cholesterol (HDL-C), from rest values. Low-density cholesterol (LDL-C) increased significantly in basketball, LD running and wrestling, while it did not change significantly in swimming and controls, after maximal effort. Hemoconcentration was of the order of +12.5%. CONCLUSIONS: The level of these increases might be directly related to the intensity and duration of exercise performed. Acute endurance exercise (100% VO(2max)) may induce acute modification of the above lipid parameters potentiating the systematic chronic exercise effects already present.

Adult↗
PubMed2001

Acute exercise: response of HDL-C, LDL-C lipoproteins and HDL-C subfractions levels in selected sport disciplines.

BACKGROUND: High HDL levels has been shown to be associated with high endurance capacity. The acute effects of maximal endurance exercise (of short duration) (15 min) on low density lipoproteins-cholesterol (LDL-C), high density lipoproteins - cholesterol (HDL-C) and HDL subfractions HDL2 and HDL3 were examined, in order to determine whether the magnitude of response can be affected by maximal intensity of exercise (incremental stress test). METHODS: Male athletes (n=78) of national level, from four sport disciplines, volunteered to participate in this cross-sectional study; basketball (n=10), swimming (n=9), long distance (LD) running (n=23) and wrestling (n=35); also a group of non athletes as controls (n=19). Participants trained at least 2 hrs/day for more than 3 years; they were healthy, non-smokers and fasted 12 hrs before blood sampling. The ergometric test was a test for the estimation of maximal oxygen uptake on a treadmill ergometer based on a stepwise stress protocol. RESULTS: Immediately after a maximal effort all groups (controls included) showed significant HDL-C increases (p<0.001) from rest values, while LD running showed the highest values. HDL2 levels increased in LD running (p<0.001), basketball and wrestling, while HDL3 ones in all groups and controls (p<0.001). The HDL2 of all athletes showed the highest correlation (R=0.37**, p<0.01) with VO2max, even higher than HDL itself. CONCLUSIONS: Acute maximal endurance exercise (100 percent VO2max) may induce acute modifications and intermolecular redistribution of HDL-C and subfractions. It is possible that the increased flux of lipids to HDL-C molecule may result from the regulatory action of lipoprotein lipase (LPL).

Adult↗
PubMed1998

Stress hormonal factors, fatigue, and antioxidant responses to prolonged speed driving.

Oxygen free radicals have been implicated in exercise-induced cell and tissue injury, indicating an oxidative stress. Fatigue accompanied by a number of physiological and metabolic changes is in indication of overtraining. This study aimed to examine the influence of a continuous 24-h intermittent speed driving (1 h driving/1 h stop), on the response of hormones, antioxidative factors, lipid, and enzyme levels. Seven race car drivers of national level were examined before, during, and immediately after the trial of speed driving on a test designed to check endurance to stress. The parameters measured were: testosterone (Tes), cortisol (Cor), IgM, IgA, cholesterol, HDL, billirubin, ceruloplasmin, urea, uric acid, creatine kinase, and transaminases. Stress hormone Cor declined significantly (p < 0.05), while Tes did not change significantly. Fatigue enzyme, aspartate transaminase (GOT) increased significantly (p < 0.05), while alanine transaminase (GPT) did not change and urea declined. Muscle enzyme, creatine kinase (CK) increased to sixfold (p < 0.01). IgA, IgM and lipids did not change. The primary antioxidant ceruloplasmin increased significantly (p < 0.001), while antioxidants uric acid and glucose remained unchanged. Among the factors measured, ceruloplasmin, cortisol, urea, GOT, and CK seem to give a picture of the organism's alertness and defence capabilities in conditions of stress and fatigue.

Adult↗
PubMed1994

Stress adaptation in athletes: relation of lipoprotein levels to hormonal response.

Increased physical stress is produced in acute exercise conditions before and during a physical trial. The effects of the physical stress on lipid and lipoprotein parameters as well as on testosterone and cortisol levels were examined in male elite athletes. In a sample of 22 measured athletes, 11 showed increases and 11 showed decreases in testosterone levels. Subsequently these subjects were treated as two separate groups for statistical purposes in order to characterise the source of individual differences in response to a stressor. Group 1 showed a 16.1% significant increase in testosterone levels, 13.3% in total cholesterol and low density lipoproteins, and a 105% increase in testosterone/cortisol ratio immediately after an acute bout of physical stress of 30 s. Group 2 showed a -25.8% significant decline in testosterone levels and no significant change in either total cholesterol or lipoprotein concentrations, followed by a significant correlation of all lipid and hormonal parameters to psychophysiological factors, such as skin temperature. A measurement of testosterone/cortisol and total cholesterol and high density lipoprotein (HDL-C) levels after a bout of acute physical stress may give a picture of the ability to "respond quickly" to stress, which will be useful in assessing the performance of the elite athlete.

Adult↗
PubMed1991

Cold swimming stress: effects on serum lipids, lipoproteins and LCAT activity in male and female rats.

Effects of consistent cold swimming stress on lipid and lipoprotein metabolism parameters were studied using male and female rats over a period of 60 and 20 days respectively. At the end of treatment serum total cholesterol, high density lipoproteins (HDL-C) and lecithin:cholesterol acetyltransferase (LCAT) activity declined in both male and female rats. TC/HDL-C ratio declined in 20 days in females, while in males it did not change. Free fatty acids increased, while triglycerides remained unchanged in both sexes. %Lipoprotein distribution in male animals did not show any phenotype alteration except in the group of 40 days where %VLDL declined and %LDL-C increased. Body weights did not change, except in males in 60 days. Consistent cold swimming stress by lowering HDL-C and LCAT activity seems to influence lipoprotein metabolism.

Animals↗
PubMed1988

Plasma lecithin: cholesterol acyltransferase activity in elite athletes from selected sports.

The activity of lecithin: cholesterol acyltransferase (LCAT) and the plasma lipoprotein concentrations of elite athletes from 8 selected sports (volleyball, judo, sprinting, wrestling, throwing, cycling, water polo and tennis) were determined and compared with those of a sedentary control group. Plasma LCAT activity levels in the athletes were significantly 2.2-7.0 times higher than in the controls in most sports (p less than 0.01). Judo, sprinting, wrestling and throwing had comparable LCAT values while tennis, volleyball and cycling were considerably higher. HDL-C concentration was significantly higher than controls in the water polo (p less than 0.05), cycling and volleyball (p less than 0.01) groups. Percentage lipoprotein distribution in the athletes in all sports except tennis, throwing and wrestling were similar to the controls. The differences among groups in LCAT activity may be related to the effect of physical exercise and training adaptations to lipid metabolism. This may be of importance when judging the benefit of exercise for atherosclerosis protection.

Adult↗
PubMed1988

Effects of cold stress on serum lipids, lipoproteins, and the activity of lecithin:cholesterol acyltransferase in rabbits.

Effects of prolonged stress on lipid metabolism factors were studied for 9 weeks using four groups of young New Zealand rabbits. Two groups (A,B) were rendered atherosclerotic by administering 1% (w/w) cholesterol. One group (C) was subjected to cold stress together with one of the atherosclerotic groups (B); one group was used as control (N). At the end of treatment serum total cholesterol and total lipids of A and B increased significantly, while in stress group (C) a significant decrease was observed. HDL-C levels were reduced in all experimental groups. Triglycerides did not change in A, while they were reduced in both stress groups (C,B). Serum lecithin:cholesterol acyltransferase (LCAT) activity levels of B and C were decreased. Lipoprotein electrophoresis patterns showed a significant redistribution of percentage values in all experimental groups: %LDL-C increased and %VLDL-C decreased in all groups, %HDL-C declined in A and B and did not change in C. The combination of stress and atherosclerosis in rabbits elicits far greater alterations in lipid and lipoprotein profiles than stress or atherosclerosis alone. A stress and atherosclerotic diet combination may be a hazardous one in relation to CHD and atherosclerosis.

Animals↗
PubMed1986

Evidence for the existence of non-esterified cholesterol carried by albumin in rat serum.

Isolation of non-esterified [14C]cholesterol bound to albumin from rat serum, 8 days after i.p. injection of [14C]cholesterol, was achieved by affinity chromatography, using Cibacron blue F3GA bound to Sepharose 4B and by Sephadex G-150 column chromatography. Both methods permit isolation of large quantities of cholesterol-loaded albumin, free of globulins and lipoproteins. The isolated albumin-cholesterol fraction was estimated to be 4.6 mg/100 ml serum, which represents approx. the 24% of the non-esterified cholesterol present in the rat serum. Albumin-cholesterol, cholesterol glucoside, cholesterol hemisuccinate and hydroxylated derivatives of cholesterol produced a biphasic curve of changes in synaptosomal plasma membranes (SPM)-bound (Na+ + K+)-stimulated ATPase activity. Low concentrations of the ligand progressively increased the enzyme activity, while increasing the ligand concentration above that which maximally stimulated the enzyme activity, produced a progressive inhibition. Lipoproteins did not have any effect on the enzyme activity. The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labeled SPM, increased in albumin-cholesterol derivatives-treated SPM, which is consistent with a general decrease in membrane bilayer fluidity. The results provide evidence that the 'albumin-cholesterol' fraction of the serum may directly affect the cell membrane-bound enzyme activity.

Animals↗
PubMed1986

Lipoprotein and lipid profiles of elite athletes in Olympic sports.

The aim of this work was to obtain an insight into the influence exerted upon plasma lipid parameters by high quality physical training in different specialties of nine Olympic sports. We compared the concentrations of serum cholesterol (TC), total lipids (TL), triglycerides (TG), HDL, LDL, VLDL, and % distribution of HDL, LDL, and VLDL of elite athletes (n = 127, age = 22.0 +/- 3.2 yrs) participating in regular training for over 3 years (2-4 h/day), separated into 11 groups of athletic specialties, with those obtained from a group of selected sedentary controls (n = 26, age = 25.3 +/- 4.5 yrs). We also compared the lipoprotein ratio factor (RF) values TC/HDL and LDL/HDL. The athletic disciplines examined were football, basketball, volleyball, boxing, wrestling, judo, sailing, skiing (slalom), track (two groups), and throwing-jumping. Football, volleyball, judo, SD and LD running, and the total sum of athletes had significantly higher HDL than the controls. Football, basketball, volleyball and all the disciplines taken together showed significantly lower LDL. Boxing, judo, and LD running had significantly lower VLDL and volleyball, SD, and LD running significantly lower %VLDL. Volleyball had significantly lower TL, boxing and volleyball lower TC, while judo, boxing, SD and LD running had lower TG. Sailing had significantly lower %HDL and higher %LDL and TL than the controls; wrestling, skiing, and throwing-jumping did not differ. In all the athletes taken together, VO2 max or relative body weight, with respect to HDL and TC/HDL, were found to be slightly correlated (r = 0.30, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1978

Purification and properties of poly(ADP-ribose) polymerase from pig-thymus nuclei.

The nuclear enzyme poly(ADP-ribose) polymerase has been purified about 9200-fold from pig thymus nuclei with a 46% yield. An aqueous organic solvent system was used for the isolation of the polymerase from nuclei and for its purification by chromatography at sub-zero temperatures. Electrophoretic analysis under both denaturing and non-denaturing conditions revealed a single protein band suggesting that the preparation was homogeneous and that the enzyme is composed of one polypeptide chain. The molecular weight estimated from sodium dodecyl sulphate-/polyacrylamide gel electrophoresis was 63 500 and from gel filtration through columns of Sephadex G-100, 58 000. The enzyme preparation was free from poly(ADP-ribose)-degrading enzymes and from DNA. The purified polymerase showed an absolute requirement for both DNA and histones. The maximal specific activity of the homogeneous preparation measured by the standardized assay, was 20.7 mu mol NAD+ incorporated x min-1 x mg-1 of protein at 37 degree C. Amino-terminal group analysis with dansyl chloride did not reveal a terminal amino acid suggesting that the amino-terminal group may be blocked. In the presence of histones, the Km for NAD+ was 23 micrometer.

Animals↗
PubMed1976

Phage and defective phage of strains of Myxococcus.

1. Phage-like particles were found in the supernatants of cultures of strains of Myxococcus xanthus, M. virescens and M. fulvus. The largest number of such particles was associated with M. virescens V2. Most of the particles were similar in morphology to the virulent Myxococcus phage, MX-1. 2. Several new phages were isolated from soil and animal droppings. A new phage was isolated from cultures of M. virescens V2. All resembled phage MX-1 in morphology and were related to phage MX-1 serologically. One of these phage, om, was characterized by fractionation of its proteins by SDS-polyacrylamide gel electrophoresis and by analysis of restriction fragments of its DNA. The very close relatedness with MX-1 was confirmed by these techniques. Phage om, was found to exist in a state of pseudolysogeny with strains of M. virescens and M. fulvus. 3. Two types of bacteriocin-like activity were found associated with Myxococcus strains. In one case, the activity was extracted from chloroformkilled or from sonicated cells. In the second case it was associated with extracellular material. Strains of Salmonella and Cytophaga were found to be good indicators for this latter activity. These strains were found to be killed by phage MX-1. 4. The significance of these data for origin of the phages of myxococci are discussed and it is proposed that MX-1 and the newly isolated phages may be virulent mutants of a family of lysogenic phages.

Bacteriocins↗