Gene/Protein Disease Symptom Drug Enzyme Compound
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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ten patients with severe dyspnoea and chronic airflow obstruction entered a randomised double-blind crossover trial comparing the effect of carbimazole 80 mg daily for two months with that of placebo. Assessment of thyroid function, lung function, and exercise tolerance was performed monthly. The mean free thyroxine index after two months of carbimazole was significantly lower at 64.1 (+/- 10.5, SEM) than the 89.1 (+/- 3.8) while on placebo. Serum tri-iodothyronine was reduced and thyroid stimulating hormone raised while on the active drug. There was no significant difference in the 12-minute walking distance (TMD), the rating of perceived exertion during the TMD, the oxygen cost score, the dyspnoea grade, the resting arterialised capillary blood gas tensions or the resting minute ventilation. During a progressive exercise test to exhaustion on a cycle ergometer, there was no significant difference in the minute ventilation, heart rate, blood gas tensions at exhaustion, or the total work done. There were no symptoms or signs of hypothyroidism. Lung function (FEV1, FVC, TLC, KCO) was unchanged. Thus a 28% reduction in the free thyroxine index produced no symptomatic or objective benefit in exercise tolerance in patients with severe airflow obstruction. These results provide no support for the use of carbimazole in chronic airflow obstruction.
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PMID:Carbimazole and exercise tolerance in chronic airflow obstruction. 704 24

1. The activity of pyruvate dehydrogenase in its active and inactive forms was measured in biopsy samples obtained from the vastus lateralis muscle of healthy subjects before and after exercise. 2. At rest, 40 +/- 4% (mean +/- SEM) of the enzyme was in the active form. 3. After progressive aerobic exercise to exhaustion (n = 5), 88 +/- 2.3% was in the active form. 4. After intermittent supramaximal short-term exercise (1 min exercise, 3 min rest) to exhaustion (n = 6), 60 +/- 2.2% was in the active form. 5. After isometric maximal exercise of 65 +/- 3.6 s duration (n = 3), only 39 +/- 1% of the enzyme was in the active form. 6. Muscle glycogen depletion was greatest with intermittent exercise and least with isometric maximal exercise; in contrast, the increase in muscle lactate was least with progressive exercise (1.3 to 9.4 mumol/g), intermediate in intermittent maximal exercise (1.2 to 13.1 mumol/g) and greatest after isometric exercise (1.8 to 17.6 mumol/g). There were no significant differences between the three studies in the changes in lactate/pyruvate ratios. 7. In three subjects who exercised with one leg, activation of the enzyme was twice as great in the exercise as in the inactive leg. 8. The ratio of active to total enzyme in biopsies of resting muscle was greater in four well-trained athletes than in four untrained control subjects (70% compared with 41% respectively). 9. The activation of pyruvate dehydrogenase appears to play an important part in regulating the use of glycogen and glucose during exercise in man.
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PMID:Activation by exercise of human skeletal muscle pyruvate dehydrogenase in vivo. 708 70

Twelve asthmatics (ages 8 to 33 yr) with proven exercise-induced asthma (EIA) and allergen-induced asthma (AIA) were investigated in an attempt to elucidate the pathways through which each type of attack develops. All patients were rendered refractory to EIA by repeated exercise at short intervals and were then immediately challenged by inhalation with an allergen known to evoke AIA. After an average of three runs all subjects were rendered refractory to EIA (post-exercise fall in FEV1 of 7 +/- 8% SEM compared with the control postexercise fall of 32 +/- 14%). In this refractory state six patients failed to respond to antigen challenge (6 +/- 4% SEM fall in FEV1 compared with the 30 +/- 3% fall in control study, p less than 0.001), suggesting a common pathway for EIA and AIA, such as the exhaustion of stored chemical mediators. Six other patients developed attacks of AIA while refractory to EIA, which were at least as severe as those in their control study (34 +/- 7% SEM fall in FEV1 compared with 29 +/- 3%). The fact that AIA could develop while EIA was blocked in this group requires an alternate pathway or mechanism for their AIA. The only significant difference between the AIA "blocked" and AIA "nonblocked" groups was a lower baseline level of lung function in all tests in the nonblocked group.
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PMID:Do exercise- and antigen-induced asthma utilize the same pathways? Antigen provocation in patients rendered refractory to exercise-induced asthma. 719 92

1. Five males were studied on three occasions, after oral administration of CaCO3 (control), NH4Cl (acidosis) and NaHCO3 (alkalosis), in a dose of 0.3 g/kg, taken over a 3 h period at rest. The subjects then exercised on a cycle ergometer for 20 min at 33% maximal oxygen uptake (VO2 max.), followed by 20 min at 66% and at 95% VO2 max. until exhaustion. 2. Endurance at 95% VO2 max. was longest with alkalosis (5.44 +/- 1.05 min), shortest with acidosis (3.13 +/- 0.97 min) and intermediate in the control study (4.56 +/- 1.31 min); venous blood pH at exhaustion was 7.33 +/- 0.02 (mean +/- 1 SEM), 7.13 +/- 0.02 and 7.26 +/- 0.02 respectively. 3. Concentrations of plasma lactate at exhaustion were 7.10 +/- 0.8 mmol/1 4.0 +/- 0.5 and 7.9 +/- 0.9 mmol/l in the control, acidosis and alkalosis studies respectively. 4. Muscle lactate increased most from rest to exhaustion with alkalosis to 17.1 +/- 2.5 mumol/g and least with acidosis to 12.2 +/- 1.4 mumol/g. Muscle glycogen depletion was comparable in control and alkalosis studies. 5. The lower plasma lactate concentration during exercise in acidosis compared with control and alkalosis appears to be due to an inhibition of muscle glycolysis combined with a reduction in lactate efflux from muscle.
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PMID:Effect of PH on muscle glycolysis during exercise. 726 54

The contractile properties of the quadriceps muscle were measured in seven healthy male subjects before, during and after prolonged cycling to exhaustion. Special efforts were made to obtain measurements immediately after exercise. The exercise intensity corresponded to about 75% of estimated maximal O2 uptake and time to exhaustion was mean 85 (SEM 9) min. At the end of the cycling heart rate and perceived exertion for the legs were 94% and 97% of maximal values, respectively. Maximal voluntary isometric force (MVC) had decreased after 5 min of exercise to a mean 91 (SEM 4)% of the pre-exercise value (P < 0.05) and decreased further to a mean 82 (SEM 6) and mean 66 (SEM 5)% after 40-min cycling and at exhaustion, respectively. A new finding was that during recovery reversal of MVC occurred in different phases where the half recovery time of the initial rapid phase was about 2 min. The MVC was a mean 80 (SEM 2)% of the pre-exercise value after 30 min and was not affected by superimposed electrical stimulation. Maximal voluntary concentric and eccentric forces decreased to 74% and 80% of initial values at exhaustion (P < 0.05). The kinetics of isometric contraction expressed as the time between 5% and 50% of tension (rise time) and the time between 95% and 50% of tension (relaxation time) were not significantly affected by the prolonged cycling. The electromechanical delay measured as the time between the first electrical stimulus and 5% of tension decreased from a mean 32 (SEM 1) ms at rest to a mean 26.6 (SEM 0.6) ms at fatigue (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of prolonged exercise on the contractile properties of human quadriceps muscle. 758 87

Two studies were conducted to test the validity of an all-out procedure for the assessment of the maximal accumulated oxygen deficit (AOD). Subjects in study 1 (N = 9; VO2max = 57 +/- 3 ml.kg-1.min-1 [+/- SEM]) completed three supramaximal efforts on a cycle ergometer. Exhaustive exercise during an all-out isokinetic procedure (mean intensity of 149% VO2max) was compared with constant intensity exercise at approximately 110% and 125% VO2max. Subjects in study 2 (N = 12; VO2max = 55 +/- 3 ml.kg-1.min-1) completed a constant intensity test to exhaustion at approximately 110% VO2max and a 90 s all-out test on a Monark friction loaded cycle ergometer (mean intensity of 143% VO2max). The AOD within each study were not significantly different (study 1:43.9, 44.1, and 42.0 ml.kg-1 for the 110%, 125%, and all-out tests; study 2: 52.1 and 51.2 ml.kg-1 for the 110% and all-out tests, respectively; P > 0.05). The total amount of work was significantly greater the longer the test, the additional work being attributed to aerobic processes. The rate of both aerobic and anaerobic energy production in the first 30 s of exercise was directly related to exercise intensity and the protocol used. The results indicate that an all-out procedure provides a valid estimate of the maximal AOD and shows potential for a more complete assessment of anaerobic ability as traditional indices of high intensity exercise performance are also obtained.
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PMID:Accumulated oxygen deficit during supramaximal all-out and constant intensity exercise. 772 50

These studies investigated the effects of 2 weeks of either a high-fat (HIGH-FAT: 70% fat, 7% CHO) or a high-carbohydrate (HIGH-CHO: 74% CHO, 12% fat) diet on exercise performance in trained cyclists (n = 5) during consecutive periods of cycle exercise including a Wingate test of muscle power, cycle exercise to exhaustion at 85% of peak power output [90% maximal oxygen uptake (VO2max), high-intensity exercise (HIE)] and 50% of peak power output [60% VO2max, moderate intensity exercise (MIE)]. Exercise time to exhaustion during HIE was not significantly different between trials: nor were the rates of muscle glycogen utilization during HIE different between trials, although starting muscle glycogen content was lower [68.1 (SEM 3.9) vs 120.6 (SEM 3.8) mmol.kg-1 wet mass, P < 0.01] after the HIGH-FAT diet. Despite a lower muscle glycogen content at the onset of MIE [32 (SEM 7) vs 73 (SEM 6) mmol.kg-1 wet mass, HIGH-FAT vs HIGH-CHO, P < 0.01], exercise time to exhaustion during subsequent MIE was significantly longer after the HIGH-FAT diet [79.7 (SEM 7.6) vs 42.5 (SEM 6.8) min, HIGH-FAT vs HIGH-CHO, P < 0.01]. Enhanced endurance during MIE after the HIGH-FAT diet was associated with a lower respiratory exchange ratio [0.87 (SEM 0.03) vs (SEM 0.02), P < 0.05], and a decreased rate of carbohydrate oxidation [1.41 (SEM 0.70) vs 2.23 (SEM 0.40) g CHO.min-1, P < 0.05].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet. 785 62

The purpose of this study was to evaluate the effects on physical performance of three levels of energy intake during a 5-day period of prolonged physical exercise and relative sleep deprivation. A group of 27 male soldiers were randomly assigned to three groups receiving either 1800 kcal.24 h-1 (7560 kJ, LC), 3200 kcal.24 h-1 (13440 kJ, MC) or 4200 kcal.24 h-1 (17,640 kJ, HC). They took part in a 5-day combat course (CC) of heavy and continuous physical activities, with less than 4 h sleep per day. Performance capacity was tested just before and at the end of CC. Maximal oxygen uptake (VO2max) was determined during an exhausting incremental exercise test on a cycle ergometer. Anaerobic performance was measured from the time during which exercise could be maintained at supra maximal loads on a cycle ergometer. After CC, the subjects receiving LC exhibited a 14% decrease in power output at exhaustion in the incremental exercise test [from 325 (SEM 8) to 278 (SEM 9) W, P < 0.001] and a significant decrease in VO2max of 8% [from 3.74 (SEM 0.06) to 3.45 (SEM 0.05) 1.min-1, P < 0.05]. The remaining two experimental groups demonstrated the same mechanical and metabolic performances on days 1 and 5. Anaerobic performance was not influenced by energy intake and the field course. Blood samples were obtained at rest on days 1 and 5. At the end of CC, the data demonstrated a significant decrease in blood glucose concentrated ion (P < 0.01) for LC diet only.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Physical performance and metabolic changes induced by combined prolonged exercise and different energy intakes in humans. 795 46

The aim of this study was to investigate whether, when muscle glycogen is reduced, a pre-exercise infusion of branched-chain amino acids (BCAA) modifies exercise performance or the metabolic and respiratory responses to incremental exercise. Six moderately trained volunteers took part in the following protocol on two occasions. On day 1, at 9 a.m. in the postabsorptive state, they performed a graded incremental exercise (increases of 35 W every 4 min) to exhaustion (Ex-1). A meal of 1,000 kcal (4,200 kJ; 60% protein, 40% fat) was consumed at 12 p.m. No food was then allowed until the end of the experiment (20-21 h later). A 90-min period of exercise at alternating high and moderate intensities, designed to deplete muscle glycogen, was performed between 6 p.m. and 7.30 p.m. The morning after (day 2), the subjects randomly received either a mixed solution of BCAA (260 mg x kg-1 x h-1 for 70 min), or saline. They then repeated the graded incremental exercise to exhaustion (Ex-2). Metabolic and respiratory measurements suggested a muscle glycogen-depleted state had been achieved. No significant differences were observed in total work performed, maximal oxygen uptake or plasma ammonia, alanine, and blood pyruvate concentrations in the two treatments. After BCAA infusion, higher blood lactate concentrations were observed at maximal power output in comparison with those during saline [BCAA 4.97 (SEM 0.41) mmol x l-1, Saline 3.88 (SEM 0.47) mmol x l-1, P < 0.05].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of infusing branched-chain amino acid during incremental exercise with reduced muscle glycogen content. 795 52

The calf and forearm blood flows (Qcalf and Qforearm respectively), blood pressure, heart rate and oxygen uptake of six men and women were studied during combined leg and handgrip exercise to determine whether a reduction of exercise-induced hyperaemia would occur in the active leg when exhausting rhythmic handgrip exercise at 50% maximal voluntary contraction (MVC) was superimposed upon rhythmic plantar flexion lasting for 10 min at 10% MVC (P10) prior to this combined exercise. The Qcalf and Qforearm were measured by venous occlusion plethysmography during 5-s rests interposed during every minute of P10 exercise and immediately after combined exercise. The muscle sympathetic nerve activity (MSNA) changes were also recorded during leg exercise alone and combined exercise. During plantar flexion performed 60 times.min-1 with a load equal to 10% MVC (P10), Qcalf was maintained at a constant level, which was significantly higher than the resting value (P < 0.001). When rhythmic handgrip contraction at 50% MVC (H50) and P10 were performed simultaneously, the combined exercise was concluded due to forearm exhaustion after a mean of 51.2 (SEM 5.5) s. At exhaustion, Qcalf had decreased significantly from 20.6 (SEM 3.0) ml.100 ml-1.min-1 (10th min during P10 exercise) to 15.3 (SEM) ml.100 ml-1.min-1 (P = 0.001), whereas Qforearm had increased significantly (0.001 < P < 0.01) from 8.6 (SEM 1.9) ml.100 ml-1.min-1 (10th min of P10 exercise) to 26.2 (SEM 3.2) ml.100 ml-1.min-1. The mean blood pressure remained at an almost constant level during the 3rd to 10th min of P10 exercise and increased markedly when H50 was added.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Exhausting handgrip exercise reduces the blood flow in the active calf muscle exercising at low intensity. 803 22


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