Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0392674 (exhaustion)
 13,658 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Caffeine is one of the famous ergogenic aids in the athletic field. Caffeine has been known to stimulate lipolysis that spares stored glycogen utilization during moderate intensity exercise. Therefore, we investigated the effects of caffeine ingestion on exercise performance in rats and athletes. Rats were administered the caffeine (6 mg/kg) 1 h prior to the exercise then were run on a treadmill at a speed of 20 m/min. They were decapitated at 0 min, 30 min, 60 min of exercise, and exhausted time point. Human subjects ingested the caffeine (5 mg/kg) 1 h prior to the exercise. They exercised on a cycle ergometer at 60% of their VO2max for 45 min, and then the exercise intensity was increased to 80% of their VO2max until exhaustion. Blood and breathing gas samples were collected and calculated every 10 min during exercise. Respiratory exchange ratio of the caffeine trial was significantly lower than that of the placebo trial in the athletes' study (p<0.05). Blood free fatty acid (FFA) levels in studies of both rats and athletes were increased by caffeine ingestion during exercise (p<0.05). Blood lactate levels were also increased during exercise in both rats and athletes (p<0.05). Increased FFA and glycerol concentrations reduced glycogen utilization during exercise compared with placebo group in rats. In addition, endurance time to exhaustion was significantly increased by the caffeine ingestion in both rats and athletes (p<0.05). These results suggest that the caffeine ingestion enhanced endurance performance resulting from spare stored glycogen with increasing lipolysis from adipose tissues and fat oxidation during exercise both in rats and in athletes.
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PMID:Caffeine as a lipolytic food component increases endurance performance in rats and athletes. 1150 5

Phosphate-limited synthetic culture media were designed to investigate the growth and the pristinamycin production of 'Streptomyces pristinaespiralis' using different nitrogen sources. During balanced growth, either mineral or organic nitrogen sources were readily utilized. However, glutamate and alanine were used as both nitrogen and carbon source, sparing the utilization of the primary carbon source, glucose. Valine was utilized only for its nitrogen and consequently 2-ketoisovalerate was excreted in the medium. Ammonium prevented the utilization of nitrate. Upon phosphate limitation, glycerol, originating from the breakdown of teichoic acids, was released, allowing the recovery of phosphate from the cell wall and the continuation of growth. Under such conditions, ammonium was excreted following the consumption of glutamate and alanine and was later reassimilated after exhaustion of the primary nitrogen source. The mode of utilization of valine prevented the production of pristinamycins due to excretion of 2-ketoisovalerate, one of their direct precursors. For other nitrogen sources, pristinamycin production was controlled by nitrogen catabolic regulation linked to the residual level of ammonium. In the case of nitrate, the negative regulation was alleviated by the absence of ammonium and production then occurred precociously. In the case of amino acids and ammonium, production was delayed until after exhaustion of amino acids and depletion of ammonium.
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PMID:Nitrogen source governs the patterns of growth and pristinamycin production in 'Streptomyces pristinaespiralis'. 1153 85

Oxygen plays a key role in bacterial bioluminescence. The simultaneous and continuous kinetics of oxygen consumption and light emission during a complete exhaustion of the exogenous oxygen present in a closed system has been investigated. The kinetics are performed with Vibrio fischeri, V. harveyi, and Photobacterium phosphoreum incubated on respiratory substrates chosen for their different reducing power. The general patterns of the luminescence time courses are different among species but not among substrates. During steady-state conditions, substrates, which are less reduced than glycerol, have, paradoxally, a better luminescence efficiency. Oxygen consumption by luciferase has been evaluated to be approximately 17% of the total respiration. Luciferase is a regulatory enzyme presenting a positive cooperative effect with oxygen and its affinity for this final electron acceptor is about 4-5 times higher than the one of cytochrome oxidase. The apparent Michaelis constant for luciferase has been evaluated to be in the range of 20 to 65 nM O2. When O2 concentrations are as low as 10 nM, luminescence can still be detected; this means that above this concentration, strict anaerobiosis does not exist. By n-butyl malonate titration, it was clearly shown that electrons enter the luciferase pathway only when the cytochrome pathway is saturated. It is suggested that, in bioluminescent bacteria, luciferase acts as a free-energy dissipating valve when anabolic processes (biomass production) are impaired.
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PMID:Kinetics of light emission and oxygen consumption by bioluminescent bacteria. 1171 Aug 10

Growth and beta-galactosidase activity of the penicillin producer industrial Penicillium chrysogenum NCAIM 00237 strain were examined using different carbon sources. Good growth was observed using glucose, sucrose, glycerol and galactose, while growth on lactose was substantially slower. beta-Galactosidase activity was high on lactose and very low on all the other carbon sources tested. In glucose grown cultures after exhaustion of glucose as repressing carbon source a derepressed low level of the enzyme was observed. cAMP concentration in lactose grown cultures was relatively high, in glucose grown cultures was low. Caffeine substantially decreased glucose consumption and growth but did not increase beta-galactosidase activity and did not prevent glucose repression which rules out the involvement of cAMP in the regulation of beta-galactosidase biosynthesis in Penicillium chrysogenum.
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PMID:Carbon source regulation of beta-galactosidase biosynthesis in Penicillium chrysogenum. 1180 45

It is not known to what extent the muscles use fats and carbohydrates as substrate for oxidation after intense, anaerobic types of bicycling. Six healthy young men therefore bicycled at constant power for 2 min to exhaustion. Blood was drawn from indwelling catheters in the femoral artery and vein at intervals during the 1-h postexercise recovery. The blood samples were analysed for concentrations of O2 and CO2, and for free fatty acids (FFA), triacylglycerols (TG), and glycerol in plasma. The blood flow was also measured, and the rate of leg uptake of FFA, TG, and O2 and the release of CO2 and glycerol as well as its gas exchange ratio were calculated and integrated over the recovery period. The leg gas exchange ratio integrated over the exercise plus 1-h recovery period was 0.67 +/- 0.06 (mean +/- SEM ), suggesting pure fat oxidation. There was no statistically significant arterial-femoral-venous difference of FFA across the leg. The concentration of TG in plasma fell by 0.18 +/- 0.09 mmol L(-1) (32%) during the first 10 min of the recovery period, and the leg took up 18 +/- 8 micromol TG kg(-1) body mass (bm) during the whole 1-h recovery period. Free glycerol was released from the leg throughout the recovery period in excess of that released from hydrolysis of TG from plasma, suggesting that 30 +/- 10 micromol TG kg (-1) bm was hydrolysed, probably from intra-muscular stores. If fully oxidized, the triacylglycerols hydrolysed can account for 101% of the measured O2 uptake. Thus, muscle seems to use only triacylglycerols as substrate for its oxidative energy release after intense exercise.
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PMID:Leg gas exchange, release of glycerol, and uptake of fats after two minutes bicycling to exhaustion. 1208 40

The PKC1 gene in the yeast Saccharomyces cerevisiae encodes protein kinase C that is known to control a mitogen-activated protein (MAP) kinase cascade consisting of Bck1, Mkk1 and Mkk2, and Mpk1. This cascade affects the cell wall integrity but the phenotype of Pkc1 mutants suggests additional targets which have not yet been identified. We show that a pkc1Delta mutant, as opposed to mutants in the MAP kinase cascade, displays two major defects in the control of carbon metabolism. It shows a delay in the initiation of fermentation upon addition of glucose and a defect in derepression of SUC2 gene after exhaustion of glucose from the medium. After addition of glucose the production of both ethanol and glycerol started very slowly. The V(max) of glucose transport dropped considerably and Northern blot analysis showed that induction of the HXT1, HXT2 and HXT4 genes was strongly reduced. Growth of the pkc1Delta mutant was absent on glycerol and poor on galactose and raffinose. Oxygen uptake was barely present. Derepression of invertase activity and SUC2 transcription upon transfer of cells from glucose to raffinose was deficient in the pkc1Delta mutant as opposed to the wild-type. Our results suggest an involvement of Pkc1p in the control of carbon metabolism which is not shared by the downstream MAP kinase cascade.
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PMID:Evidence for involvement of Saccharomyces cerevisiae protein kinase C in glucose induction of HXT genes and derepression of SUC2. 1270 97

Large amounts of globotriose (Galalpha-4Galbeta-4Glc) are shown to be produced by the high cell density culture of an Escherichia coli strain over-expressing the Neisseria meningitidis lgtC gene for alpha-1,4-Gal transferase. The strain which was devoid of both alpha and beta galactosidase activity was fed with glycerol as the energy and carbon source and with lactose as precursor for globotriose synthesis. After complete exhaustion of lactose, globotriose could serve as an alternative acceptor for LgtC and the formation of a series of polygalactosylated compounds was observed. The system was extended to the synthesis of globotetraose (GalNAcbeta-3Galalpha-4Galbeta-4Glc) by overexpressing two additional genes: lgtD from Haemophilus influenzae Rd which encodes a beta-1,3-GalNAc transferase and wbpP from Pseudomonas aeruginosa which encodes a UDP-GalNAc C4 epimerase. Globotetraose could also be produced from exogenous globotriose which was shown to be actively taken up by the cells.
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PMID:Large scale in vivo synthesis of globotriose and globotetraose by high cell density culture of metabolically engineered Escherichia coli. 1576 Jul 13

The impact of rehydration with glycerol on cardiovascular and thermoregulatory responses during exercise in the heat was studied in eight highly trained male cyclists. Each subject completed three dehydration-rehydration experimental trials that differed only in the rehydration treatment, each separated by 7 days. Before each experimental day, subjects dehydrated to -4% of their body weight by exercise and water restriction. The experimental treatments were as follows: no fluid (NF), glycerol bolus (1 g/kg body wt) followed by water (G), and water alone (W). Rehydration (3% body weight) was given over an 80-min period. After rehydration, subjects cycled (74% peak O2 uptake) to exhaustion in a hot and wet (37 degrees C and 48% relative humidity) environment. For G, plasma volume was expanded (P < 0.05) during rehydration and remained higher than W (P < 0.05) during exercise. Exercise time to exhaustion during G (33 +/- 4 min) was longer (P < 0.05) compared with both W (27 +/- 3 min) and NF (19 +/- 3 min). Cutaneous vascular conductance was significantly elevated (P < 0.05) during G, but G provided no other thermoregulatory or cardiovascular benefits compared with W and NF. Fluid-regulating hormones (vasopressin, aldosterone, atriopeptin, and plasma renin activity) decreased during rehydration and increased during exercise (except atriopeptin), but there were no differences between G and W. These data indicated that glycerol had little or no major effect on fluid-regulating factors during rehydration or exercise, and the improved exercise capacity in G was likely due to a greater plasma volume during exercise.
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PMID:Rehydration with glycerol: endocrine, cardiovascular, and thermoregulatory responses during exercise in the heat. 1621 Apr 41

The fermentation of desmethyl-asterriquinone B-1, a diabetes target, by a Pseudomonasarias species was conducted at the 600-l scale using a revised complex medium containing yeast extract and soy hydrolysate. Oat flour and tomato paste were removed from this medium due to difficulties in sterilization. An initial cerelose charge of 40 g/l improved titer and reduced product degradation in the broth at cultivation conditions. An initial mannitol concentration of 65 g/l effectively avoided mid-cycle mannitol additions necessary for the 40 g/l mannitol concentration without the reduction in productivity seen at 90 g/l mannitol. These additions diluted the broth because of the low aqueous solubility of mannitol. Titers reached 3.0 g/l after 158 h with an optimized process, increasing two-fold from the original medium and operating conditions. Reproducible foaming occurred at the point of glucose exhaustion when the culture switched to mannitol consumption. Use of alternative carbon sources (glycerol, soybean oil, sorbitol in conjunction with cerelose) was not effective in attaining similar productivity and did not reduce the extent of foaming. In the case of fructose, the extent of foaming was markedly reduced but product formation was negligible.
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PMID:Carbon and complex nitrogen source selection for secondary metabolite cultivation at the pilot scale. 1623 23

We compared the effect of glycerol-induced hyperhydration (GIH) to that of water-induced hyperhydration (WIH) on cardiovascular and thermoregulatory functions and endurance performance (EP) during prolonged cycling in a temperate climate in subjects consuming fluid during exercise. At weekly intervals, 6 trained male subjects ingested, in a randomized, double-blind, counterbalanced fashion, either a glycerol (1.2 g glycerol/kg bodyweight (BW) with 26 mL/kg BW of water-aspartame-flavored fluid) or placebo solution (water-aspartame-flavored fluid only) over a 2 h period. Subjects then performed 2 h of cycling at 66% of the maximal oxygen consumption (VO(2) max) and 25 degrees C while drinking 500 mL/h of sports drink, which was followed by a step-incremented cycling test to exhaustion. Levels of hyperhydration did not differ significantly between treatments before exercise. During exercise, GIH significantly reduced urine production by 246 mL. GIH did not increase sweat rate nor did it decrease heart rate, rectal temperature, or perceived exertion during exercise as compared with WIH. EP was not significantly different between treatments. Neither treatment induced undesirable side effects. It is concluded that, compared with WIH, GIH decreases urine production, but does not improve cardiovascular or thermoregulatory functions, nor does it improve EP during 2 h of cycling in a 25 degrees C environment in trained athletes consuming 500 mL/h of fluid during exercise.
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PMID:Effect of glycerol-induced hyperhydration on thermoregulatory and cardiovascular functions and endurance performance during prolonged cycling in a 25 degrees C environment. 1660 27


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