Search Results
Results 401 - 450 of 877
< 4 5 6 7 8 9 10 11 12 13 14 >
Harber V J - - 1997
Food restriction has been shown to result in an impairment of thyroid status, as the body attempts to conserve energy. In turn, hypothyroidism has been associated with impaired oxidative muscle metabolism, which could negatively affect one's ability to perform exercise. The purpose of this study was to examine the relationship ...
Monsieurs K - - 1997
Our aim was to develop an exercise protocol using 31P-magnetic resonance spectroscopy (31P-MRS), which can discriminate between malignant hyperthermia-susceptible (MHS) individuals and controls. MRS spectra of the forearm muscles were recorded at rest, during and after a standardized exercise protocol in 10 MHS patients and compared with spectra obtained in ...
Barnes P R - - 1997
We have used 31P magnetic resonance spectroscopy to investigate skeletal muscle bioenergetics in a total of 31 patients with myotonic dystrophy. Results from resting flexor digitorum superficialis and calf muscle showed a significant elevation in the concentration ratio of inorganic phosphate to ATP and a significant reduction in the phosphorylation ...
Kemp G J - - 1997
Relationships between pH and the concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), and lactate during ischemic exercise depend on passive buffering, proton consumption as a consequence of net PCr breakdown, the control of glycogenolysis, (particularly in relation to the concentration of Pi, a substrate of glycogen phosphorylase that is produced ...
Taylor D J - - 1997
31P magnetic resonance spectroscopy studies were carried out on calf muscle of 144 normal male and female subjects age 20-83 years in order to investigate age-related changes in muscle metabolism. Compared to the young adults (20-29 years), oxidative capacity was higher in the children (6-12 years) and was significantly decreased ...
Dulieu V - - 1997
OBJECTIVE: To determine by 31P nuclear magnetic resonance (NMR) spectroscopy the efficacy of training in improving aerobic metabolism of calf muscle in nonamputated limb after recent vascular amputation; to assess the possible associated microcirculatory changes; and to evaluate the need for noninvasive monitoring techniques during training in the nonamputated limb ...
Dawson B - - 1997
Phosphocreatine (PCr) repletion following either single (1x6 s, n=7) or repeated (5x6 s, departing every 30 s, n=8) maximal short sprint cycling efforts was measured in separate groups of trained subjects. Muscle biopsies (vastus lateralis) were taken pre-exercise before warming up, and then at 10 s, 30 s and 3 ...
Wasserman K - - 1997
A progressive hyperkalemia is observed as exercise intensity increases. The current most popular hypothesis for the hyperkalemia is that the Na+-K+ pump cannot keep pace with the K+ efflux from muscle during the depolarization-repolarization process of the sarcolemmal membrane during muscle contraction. In this report, we present data that suggest ...
Skyllouriotis M L - - 1997
We report a 20-year-old man with gigantism syndrome, hypertrophic cardiomyopathy, muscle weakness, exercise intolerance, and severe psychomotor retardation since childhood. Histochemical and biochemical analysis of skeletal muscle biopsy revealed myoadenylate deaminase deficiency; molecular genetic analysis confirmed the diagnosis of primary (inherited) myoadenylate deaminase deficiency. Plasma, urine, and muscle carnitine concentrations ...
Brillault-Salvat C - - 1997
Novel tools are presented that aim at more comprehensive NMR investigations of human skeletal muscle metabolism, in particular during exercise protocols. They integrate imaging (NMRI) and spectroscopy (NMRS) experiments in a single dynamic examination. The first sequence that we propose combine NMR-plethysmography, 1H-NMRS of deoxymyoglobin and 31P-NMRS. This allows simultaneous ...
Thompson C H - - 1997
The effect of propionyl L-carnitine on skeletal muscle metabolism in chronic renal failure. Carnitine deficiency, resulting in defective oxidative ATP synthesis, has been implicated in the myopathy of chronic renal failure. Using 31P magnetic resonance spectroscopy we examined calf muscle metabolism in 10 dialysed patients before and after 8 weeks ...
Lodi R - - 1997
The authors present an in vivo phosphorus magnetic resonance spectroscopy systematic study on the effects of cytosolic pH on skeletal muscle mitochondrial respiration in human calf muscle. In 49 normal subjects, the effect of cytosolic pH on kinetics of phosphocreatine and adenosine diphosphate recovery and on maximum rate of mitochondrial ...
Penrice J - - 1997
Studies of the brains of severely birth-asphyxiated infants using proton (1H) magnetic resonance spectroscopy (MRS) have shown changes indicating a rise in cerebral lactate (Lac) and a fall in N-acetylaspartate (Naa). The aim of this study was to test two hypotheses: 1) that these changes can be reproduced in the ...
Lodi R - - 1997
OBJECTIVE: To determine whether a multisystemic bioenergetic deficit is an underlying feature of familial hypobetalipoproteinaemia. METHODS: Brain and skeletal muscle bioenergetics were studied by in vivo phosphorus MR spectroscopy (31P-MRS) in two neurologically affected members (mother and son) and in one asymptomatic member (daughter) of a kindred with familial hypobetalipoproteinaemia. ...
Shoemaker J K - - 1997
It is unclear whether sympathetic tone opposes dilator influences in exercising skeletal muscle. We examined high levels of sympathetic tone, evoked by lower body negative pressure (LBNP, -60 mmHg) on intramuscular pH and phosphocreatine (PCr) levels (31P-nuclear magnetic resonance spectroscopy) during graded rhythmic handgrip (30 contractions/min; approximately 17, 34, 52 ...
Salerno C - - 1997
31P-nuclear magnetic resonance spectroscopy was used to investigate in vivo the energy metabolism of the calf muscle in a 10-year-old patient with adenylosuccinate lyase deficiency and severe psychomotor retardation. The patient showed a markedly reduced PCr/P(i) molar ratio, known to well represent the cytosolic phosphorylation potential, due to low PCr ...
Schornack P A - - 1997
Proper ion balance between intra- and extracellular compartments is necessary for normal physiological function. Conversely, alterations in membrane ion transport occur in numerous pathological states. As a noninvasive, nondestructive spectroscopic technique, nuclear magnetic resonance (NMR) offers a powerful approach to the study of ion balance in intact biological systems. Unfortunately, ...
Clarke C E - - 1997
The lentiform nucleus of five patients with idiopathic Parkinson's disease (IPD) was studied by quantitative magnetic resonance spectroscopy (MRS), both before and after administration of apomorphine, and the spectra were compared with those from a group of age-matched normal subjects. The concentrations of the three major metabolites, choline, creatine, and ...
Goudemant J F - - 1997
The creatine kinase reaction has been studied by 31P NMR in exercising human calf muscle. Quantitative analysis of high energy phosphates and saturation transfer study of the creatine kinase flux in the direction of ATP synthesis (Vfor) were performed at rest and during exercise. As expected, exercise induced a [PCr] ...
De Bisschop E - - 1997
The effect of a six-month peritoneal amino acid administration on muscle metabolism at rest and during exercise was examined in 12 patients (4 control and 8 amino acid treated) on continuous ambulatory peritoneal dialysis. 31P-magnetic resonance spectroscopy was used to measure several high-energy phosphates (PCr, Pi) in resting muscle and ...
El Alaoui-Talibi Z - - 1997
The objective of the present work was the assessment of metabolic events responsible for the improvement of hemodynamic function of volume-overloaded hearts from rats receiving propionyl-L-carnitine. A severe cardiac hypertrophy was induced in 2-mo-old rats by surgical opening of an aortocaval communication. Three months later, during in vitro perfusions with ...
Righetti P G - - 1997
The present review offers a new look at capillary isoelectric focusing (cIEF) by centering on the most troublesome aspects of the technique, namely: 1) how to modulate the slope of the pH gradient, for increasing resolution (equivalent to pH gradient engineering, as easily available in immobilized pH gradients); and 2) ...
Argov Z - - 1997
Twenty-four patients with exercise intolerance of undetermined origin were examined by muscle phosphorus magnetic resonance spectroscopy (31P-MRS) to test for a possible underlying defect in oxidative metabolism. Results were compared to those of 37 normal controls and 22 patients with well-defined mitochondrial disorders. In 17 (71%) patients with exercise intolerance, ...
Newcomer B R - - 1997
Measurements of adenosine triphosphate (ATP) production rates, metabolic economy, intracellular pH, phosphodiesters, and phosphomonoesters along with the force output were used to study 90-s maximum voluntary contractions and two new exercise protocols (20-10 and 30-16 exercises). The 20-10 exercise consisted of thirty-one 20-s maximal voluntary contractions separated by 10-s rest ...
Lodi R - - 1997
Phosphorus MR spectroscopy (31P-MRS) was used to quantify skeletal muscle bioenergetics and proton efflux in 63 patients with migraine (23 with migraine without aura, MwoA, 22 with migraine with aura, MwA, and 18 with prolonged aura or stroke, CM) and in 14 patients with cluster headache (CH), all in an ...
Odland L M - - 1997
Our purpose was to determine the effect of creatine supplementation on power output during a 30-s maximal cycling (Wingate) test. Nine males underwent 3 randomly ordered tests following ingestion of a creatine supplementation (CRE), placebo (PLA), and control (CON) CRE was ingested as creatine monohydrate (CrH2O) dissolved in a flavored ...
Walter G - - 1997
The rate at which phosphocreatine (PCr) is resynthesized after exercise is related to muscle oxidative capacity (Vmax). With the use of a one-dimensional image-guided, localized nuclear magnetic resonance spectroscopy technique, PCr kinetics were monitored in the medial gastrocnemius of eight healthy subjects after voluntary, short duration, maximal rate exercise. Localized ...
Harkema S J - - 1997
The relationships between oxygen consumption (Q(O2)) and calculated cytoplasmic ADP concentration ([ADP]) and the free energy of ATP hydrolysis (deltaG(ATP)) were examined in ex vivo arterially perfused cat soleus muscles during repetitive twitch stimulation under normocapnic (5% CO2) and hypercapnic (70% CO2) conditions. Hypercapnia decreased extra- and intracellular pH by ...
Evans A B - - 1997
Although lung transplantation improves exercise capacity by removal of a ventilatory limitation, recipients' postoperative maximum oxygen uptake (VO2max) remains markedly abnormal. To determine if abnormal skeletal muscle oxidative capacity contributes to this impaired aerobic capacity, nine lung transplant recipients and eight healthy volunteers performed incremental quadriceps exercise to exhaustion with ...
Kemp G J - - 1997
In recovery from exercise, phosphocreatine resynthesis results in the net generation of protons, while the net efflux of protons restores pH to resting values. Because proton efflux rate declines as pH increases, it appears to have an approximately linear pH-dependence. We set out to examine this in detail using recovery ...
Saugen E - - 1997
This study examines the temporal changes in high-energy phosphate and metabolic levels, and in force-generating capacity, during and after voluntary submaximal repetitive isometric exercise (RIE). Eight male subjects performed one-legged RIE with the knee extensors at 40% maximum voluntary contraction (MVC) target force (duty cycle: 6 s contraction, 4 s ...
Cooke S R - - 1997
Phosphorus magnetic resonance spectroscopy (31P-MRS) was used to investigate the influence of maximal aerobic power (VO2max) on the recovery of human calf muscle from high-intensity exercise. The (VO2max) of 21 males was measured during treadmill exercise and subjects were assigned to either a low-aerobic-power (LAP) group (n = 10) or ...
Yoshida T - - 1997
To assess muscle metabolism and inorganic phosphate (P(i)) peak splitting during exercise, 31-phosphorus nuclear magnetic resonance spectroscopy was performed during ramp incremental and submaximal step exercise with and without circulatory occlusion. Seven healthy men performed calf flexion in a superconducting magnet. There was no P(i) splitting during ramp incremental exercise ...
Fries R - - 1997
The purpose of this study was to determine the termination and acceleration rates for 1 to 6 attempts of antitachycardia pacing [ATP] delivered by ICD in order to terminate spontaneously occurring VTs. Twenty-four ICD recipients with active ATP programs, including a maximum of six ATP sequences and spontaneously occurring VTs ...
Clark J F - - 1997
OBJECTIVE: Creatine and phosphocreatine (PCr) are important compounds in the normal energy metabolism of muscle. Recently, it has been shown that dietary creatine (5 to 20 g/day) can increase muscle creatine and PCr, with enhancement in anaerobic exercise performance after two weeks of administration caused by an increase in anaerobic ...
Hu M S - - 1997
The mechanism of colonic phosphate absorption is not well defined. We measured unidirectional phosphate fluxes across rat distal colon epithelium in the absence of transepithelial electrochemical gradients. Steady-state mucosal-to-serosal flux (Jms) was not different from the serosal-to-mucosal flux (Jsm), generating no net flux (Jnet = Jms - Jsm, was not ...
Nevill A M - - 1997
A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is ...
Yazaki K - - 1996
We investigated the effect of alcohol on muscle energy metabolism by using 31P magnetic resonance spectroscopy in 12 chronic alcoholics [6 with neurological signs and symptoms (such as cerebellar ataxia or diplopia) and 6 without neurological signs or symptoms], compared with five healthy subjects who also received acute alcohol loading. ...
Sanderson A L - - 1996
1. To examine metabolic correlates of insulin resistance in skeletal muscle, we used 31P magnetic resonance spectroscopy to study glycogenolytic and oxidative ATP synthesis in leg muscle of lean and obese Zucker rats in vivo during 6 min sciatic nerve stimulation at 2 Hz. 2. The water content of resting ...
Sant'Ana Pereira J A - - 1996
1. The relationship between myosin heavy chain (MyHC) isoforms and high energy phosphate content was studied in human muscle fibres at rest and following maximal dynamic exercise lasting 25 s. 2. Single fibre fragments were characterized as type I, type IIA, type IIX or type IIAX. These latter fibres were ...
Kemp G J - - 1996
31P magnetic resonance spectroscopy measurements of pH and the concentrations of orthophosphate and phosphocreatine were used to estimate rates of glycogenolytic and oxidative ATP synthesis in rat leg muscle during 6 min sciatic nerve stimulation at different rates (1-4 Hz). To study the regulation of glycogenolysis during exercise, the apparent ...
Wackerhage H - - 1996
In an oxygen-depleted muscle, glycolytically produced ATP is inversely related to the ([ATP]+ creatine phosphate [PCr]) decrease because ATP, PCr, and glycolysis are virtually the only energy sources under these conditions. In particular, the onset of glycolysis or any appreciable increase in the rate of glycolytic ATP production will lead ...
Matsumoto H - - 1996
We studied cerebral oxygen metabolism during hypoxia to demonstrate whether the redox state of cytochrome aa3 (cyt.aa3), as measured by near infrared spectrophotometry (NIRS), reflects brain energy level. Rats (n = 6) subjected to hypoxia were simultaneously monitored by NIRS and 31P nuclear magnetic resonance spectroscopy (NMRS). Brain function was ...
Hamaoka T - - 1996
The purpose of this study was to determine whether the initial rate of hemoglobin and myoglobin deoxygenation during immediate postexercise ischemia, a reflection of muscle O2 consumption (VO2mus), can be a quantitative measure of muscle oxidative metabolism. The finger flexor muscles of five healthy men (aged 25-31 yr) were monitored ...
Iotti S - - 1996
We used 31-phosphorus magnetic resonance spectroscopy to study in vivo the transport of inorganic phosphate (Pi) from cytosol into mitochondria as assessed by the kinetics of Pi recovery during ischemia after aerobic exercise in human skeletal muscle. In all subjects during the first 30 s of ischemia inorganic phosphate showed ...
Guthrie B M - - 1996
Resting and submaximal isometric exercise 31P magnetic resonance spectroscopy (MRS) was carried out on 7 endurance-trained males (26.0 +/- 3 yrs) and 7 sedentary males (27.0 +/- 4 yrs). Spectral analysis provided peak areas of phosphocreatine (PCr), inorganic phosphate (Pi), adenosine triphosphate (ATP), and the chemical shift of Pi relative ...
Heinonen O J - - 1996
Carnitine plays a central role in fatty acid (FA) metabolism. It transports long-chain fatty acids into mitochondria for beta-oxidation. Carnitine also modulates the metabolism of coenzyme-A (CoA). It is not surprising that the use of supplementary carnitine to improve physical performance has become widespread in recent years, although there is ...
Horská A - - 1996
31P spin-lattice relaxation times (T1) of metabolites in rat calf muscle at 1.9 Tesla and the forward rate through the creatine kinase (CK) reaction have been measured using a new method based on modeling progressive saturation explicitly incorporating the effect of chemical exchange. In a separate series of experiments, we ...
Kemp G J - - 1996
OBJECTIVE: To distinguish between the effects of reduced oxidative capacity and reduced metabolic efficiency on skeletal muscle bioenergetics during exercise in patients with congestive heart failure. DESIGN AND PATIENTS: Patients were studied by 31P magnetic resonance spectroscopy during aerobic exercise and recovery, and results compared with controls. RESULTS: In flexor ...
Van Den Thillart G - - 1996
The most attractive feature of nuclear magnetic resonance spectroscopy (MRS) is the noninvasive and nondestructive measurement of chemical compounds in intact tissues. MRS already has many applications in comparative physiology, usually based on observation of 31P, since levels of phosphorus compounds indicate tissue energy status and are changed during exercise, ...
< 4 5 6 7 8 9 10 11 12 13 14 >