Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EXERTION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources
PubMed1993

[Exertion syncope disclosing supravalvular mitral stenosis in an infant].

An infant with frequent upper airways infections presented syncopes during meals and weeping since the age of eleven months. Cardiac examination was always normal. At 14 months of age, an echocardiogram with colour Doppler demonstrated a severely stenotic isolated supramitral membrane with severe pulmonary hypertension. The membrane was immediately excised curing the malformation and suppressing definitively the syncopes, probably due to decreased cerebral blood flow during exertion. An echocardiogram should always be performed when syncopes remain unexplained in small children. It allows early diagnosis and treatment of congenital heart defects which do not have auscultatory findings especially those resulting in severe pulmonary venous obstruction.

Echocardiography↗
PubMed1995

Effects of caffeine and tryptophan on rectal temperature, metabolism, total exercise time, rate of perceived exertion and heart rate.

Stimulant properties during exercise have been attributed to caffeine (CAF) and tryptophan (Trp). The purpose of the present study was to investigate the effects of CAF and Trp ingestion on rectal temperature (Tre), total exercise time (TET), oxygen consumption (VO2), carbon dioxide production (VCO2), pulmonary ventilation (VE), heart rate (HR) and rate of perceived exertion (RPE) during exercise on a cycle ergometer at 80% of maximal work load, in eight healthy male volunteers. Each subject abstained from caffeine for 48 h and from animal-derived foods for 36 h before each experiment. Aerobic capacity was determined on the first day. In consecutive trials, conducted in a double-blind, randomized, crossed-over manner, each subject received capsules containing CAF (10 mg/kg), Trp (1.2 g), a combination of the two (CAF+Trp), and lactose (PLA), 1 h before exercise. Plasma CAF concentration (PC) was measured by high performance liquid chromatography (HPLC), before (basal concentration) and 1 and 2 h after ingestion of the capsules. At both times after CAF or CAF+Trp ingestion, the PC was elevated compared with the basal concentration (P < 0.05). During exercise, significant increases occurred with time in Tre, TET, VO2, VCO2, VE, HR and RPE (P < 0.01) while no significant difference was observed when CAF or CAF+Trp were compared with control values. Under the conditions of this study, CAF and/or Trp did not affect the physiological parameters measured before, during or after exercise at 80% of maximal work load.

Adult↗
PubMed1996

Exertional collapse and sudden death associated with sickle cell trait.

Although rare, exertional collapse and sudden death are the most serious potential complications of sickle cell trait. Studies suggest that this condition may occur in susceptible persons when poor physical conditioning, dehydration, heat stress or hypoxic states precipitate sickling of the abnormal erythrocytes. Sickling leads to endothelial damage, which can cause vasoconstriction, disseminated intravascular coagulation and local tissue damage. Cardiac effects include acute ischemia and arrhythmias. Muscle damage results in acute compartment syndromes and release of myoglobin into the circulation. Acute renal failure is possible. Diagnosis is based on a high index of suspicion, and characteristic presentation and laboratory findings, including myoglobinuria, hyperkalemia, hypocalcemia, hyperphosphatemia and elevated creatine kinase levels. The differential diagnosis includes pulmonary embolism, acute cardiac events, anaphylaxis and heat stroke. Management is based on stabilization, rehydration, and the treatment and prevention of complications.

Death, Sudden↗
PubMed1977

Perceived exertion associated with breathing hyperoxic mixtures during submaximal work.

The effect of an enriched inspired oxygen concentration on perceived exertion (RPE) was investigated while running at two submaximal treadmill loads. Twelve males (VO2 max = 49.3 ml/kg-min) worked at 50% and 80% VO2 max, breathing either air or 80% O2-20% N2 in random order using a single blind technique. Subjects were evaluated while running for 10 min and during a 20 min recovery. Heart rate (HR), ventilation (VE), respiration rate (RR), tidal volume (VT) and RPE were measured before, during and after work. Blood lactate was measured 1 min after work. Oxygen concentration did not statistically affect HR, VE, RR or VT during exercise or recovery. At both loads, RPE at the end of exercise was significantly reduced breathing the hyperoxic mixture. At 50% VO2 max, mean RPE decreased from 11.2 breathing room air to 9.6 breathing 80% O2 and, 80% VO2 max, from 13.8 to 11.7 (P less than 0.01). Blood lactates were significantly reduced breathing 80% O2; from 23.4 mg to 13.3 at 50% VO2 max and from 55.5 to 36.5 at 80% VO2 max (P less than 0.01). The RPE correlated with lactate (r=0.64) at the end of work. Results indicate that during moderate and heavy work RPE is significantly affected by the inspired O2 concentration and there is a significant relationship between RPE and blood lactate.

Adult↗
PubMed1996

Demonstration of frontal hypoperfusion in benign exertional headache by Technetium-99m-HMPAO SPECT.

We present a case of benign exertional headache (BEH) in a 15-yr-old boy. The patient suffered from exclusively exercise-induced headaches with migraine-like accompanying symptoms. No pathology could be detected by routine cardiovascular or neurological examinations by CT. The postexercise 99mTc-HMPAO brain SPECT performed during the provoked headache attack showed asymmetric bifrontal hypoperfusion. A second 99mTc-HMPAO study during a symptom-free phase under resting conditions was normal. The detection of impaired regional cerebral blood flow (rCBF) by 99mTc-HMPAO brain SPECT indicates a perfusion-related pathology in this type of headache. Analysis of rCBF with 99mTc-HMPAO in larger studies could be helpful in the clarification of BEH pathogenesis.

Adolescent↗
PubMed1996

Heart rate response and perceived exertion during twenty consecutive karate sparring matches.

This study investigated the changes in heart rate (HR) and perceived exertion ratings (RPE) of 20 consecutive karate sparring matches each of 2 minutes duration. The resting and maximal HR (HRmax) responses to the maximal treadmill test were 69.8 +/- 2.9 beats.min-1 and 198.5 +/- 8.2 beats.min-1, respectively. The resting HR before the 20 sparring matches was 83.5 +/- 11.3 beats min-1. The mean HR during the 20 sparring matches was 191.8 +/- 9.4 beats.min-1 which was equal to 96.7 +/- 4.2% of HRmax. At the end of the 20 sparring matches, the mean RPE obtained was 19 +/- 2. The results of this study suggest that the subjects could continue the 20 sparring matches for about 40 minutes at the intensity close to the HRmax.

Adult↗
PubMed1977

The role of exertion as a determinant of carboxyhemoglobin accumulation in firefighters.

The firefighter's exposure to carbon monoxide represents a relatively contant occupational hazard. Unfortunately, attempts to predict the level of this exposure in work situations have failed to be of practical benefit. This study was designed to examine the several determinants of carbon monoxide uptake by firefighters in a controlled situation. Twenty firefighters were monitored for heart rate and carboxyhemoglobin (COHb) levels during a search-and rescue drill in a smokefilled building. Carbon monoxide levels were maintained at 200 to 1000 ppm. Heart rates increased to 90% of maximum for age within minutes, and COHb levels increased at more than 1% per minute. The use of breathing apparatus provided full protection from uptake of COHb but was associated with significantly increased heart rates. The results show that exertional levels and, therefore, ventilatory rates may be so great during firefighting that even in moderate or low levels of atmospheric carbon monoxide the COHb can rise to dangerous levels within minutes. These findings suggest that no firefighter should be allowed to work in a burning or smoke-filled structure without the protection of breathing apparatus.

Adult↗
PubMed1997

[Primary subclavian vein thrombosis after intensive physical exertion].

Subclavian vein thrombosis accounts for approximately 1-2% of recorded deep venous thromboses. It may be primary or secondary, and insertion of a central venous catheter is the most common cause of secondary subclavian vein thrombosis. Traumas, anatomic abnormalities and carcinoma are important additional risk factors for secondary thrombosis. Primary thrombosis of the subclavian veins is known as Paget-Schroetter syndrome. New criteria for its diagnosis include a history of increased upper extremity use prior to onset of symptoms, the presence of a venographically demonstrated thrombus and absence of any definable causes. We describe a 42-year-old woman with a history of intensive physical exertion admitted with swelling, pain and difficulty moving her arm. The diagnosis of primary subclavian vein thrombosis was established from the history of physical effort, results of Doppler ultrasound, and exclusion of other causes of subclavian vein thrombosis. This case suggests that primary subclavian vein thrombosis should be considered in young patients with subclavian vein thrombosis after exclusion of secondary disease.

Adult↗
PubMed1997

Wavelet analysis of electromyography for back muscle fatigue detection during dynamic constant-torque exertions.

The fatigue of the back muscles appears to be strongly implicated as a risk factor for acquisition of low back pain, which is one of the leading ills of our industrial society. Previously, researchers have successfully measured the level of muscular fatigue by using the Fourier transform to analyze the frequency content of the electromyogram (EMG). However, due to the requirement that the EMG signal be stationary, the Fourier transform is suitable only for the analysis of static muscle exertions in which the muscle is held at constant length and tension. Because the majority of industrial work tasks are not static in nature, new methods for quantifying fatigue during dynamic work are needed. The wavelet transform is a novel, although mathematically well developed, technique for analyzing non-stationary signals that has only recently been applied to the study of EMG. Consequently, the main objective of this project is to develop techniques, using the wavelet transform, for the quantification of back muscle fatigue during dynamic repetitive working conditions.

Back Pain↗
PubMed1990

The pressure exerted by mucoceles in the frontal sinus. An experimental study in the cat.

The pathophysiologic process that results in bone erosion from frontal sinus mucoceles has long been a mystery. Traditionally, bone erosion has been attributed to pressure. However, no scientific evidence has yet been presented to support this hypothesis. To answer this question, seven cats had a mucocele created in one frontal sinus, with the other sinus left as a control. A manometer was inserted into each frontal sinus. Pressure readings were taken over a 7-month period. Pressures on the mucocele side were higher than on the control side and were sufficient to erode bone. Bone was thicker on the mucocele side than on the control side. This study established that mucoceles exert sufficient pressure to erode bone, and that such erosion may be part of a two-stage process.

Animals↗
PubMed1999

Exertion of tractional force requires the coordinated up-regulation of cell contractility and adhesion.

Although it is understood that cells exert mechanical forces on the extracellular matrix to promote structural organization, the exact mechanism of force transduction is not clearly understood. Using an in vitro force measurement assay, we evaluated two opposing conditions that inhibit or promote matrix organization by fibroblasts: serum deprivation and lysophosphatidic acid stimulation. Under serum deprivation, in spite of significant cell spreading and pseudopodial motility, rabbit corneal fibroblasts generated little or no force on the matrix within 2 h of observation. Lysophosphatidic acid stimulation of serum-starved cells caused dramatic cell contraction (within 2 min), which correlated temporally with a rapid increase in the tractional force generation on the matrix (0.52 x 10(-7) - 1.9 x 10(-7) N; n = 7 experiments). No cell translocation was observed during the period of force generation in response to lysophosphatidic acid-stimulation. These findings, taken together with a concomitant up-regulation of stress fibers in lysophosphatidic acid stimulated fibroblasts, indicate that contractility of non-motile cells involved in forming stress fibers and strong cell-matrix adhesion is the principal force-generating mechanism involved in matrix organization.

Actins↗
PubMed1999

Selective pressure exerted by immunodominant HIV-1-specific cytotoxic T lymphocyte responses during primary infection drives genetic variation restricted to the cognate epitope.

HIV-specific cytotoxic T lymphocytes (CTL) play a central role in the control of HIV-1 replication during primary infection. It has been hypothesized that the appearance of CTL escape mutants represents an important mechanism by which HIV-1 escapes the host cell-mediated immune response. However, evidences for a direct relationship between CTL responses and emergence of CTL escape mutants are still limited. Here we report detailed longitudinal analysis of DNA sequence variation performed over the entire HIV-1 envelope in two subjects during primary HIV infection. Estimates of the frequencies of synonymous (ds) and non-synonymous (dN) nucleotide substitutions were used to identify regions of the HIV-1 envelope which were subjected to significant levels of selective pressure. These regions were shown to comprise defined epitopes recognized by CTL. Furthermore, dN mutation fixed within these epitopes effectively abolished recognition by the host CTL response. These results provide compelling evidence that the CTL epitope mutations directly resulted from the selective pressure exerted by the virus-specific cytotoxic response.

Cells, Cultured↗
PubMed2000

Mouse homolog of the Drosophila Pc-G gene esc exerts a dominant negative effect in Drosophila.

The Polycomb group genes are involved in maintaining long term transcriptional repression of the homeotic genes in both Drosophila and mammals. The mouse eed locus encodes the highly conserved ortholog of the Drosophila ESC protein. To test the functional conservation between the two genes, eed was introduced into the fly to determine whether it could rescue the esc mutant phenotype. eed exerted a dominant negative effect on the leg transformation phenotype associated with the esc mutation. This result is interpreted in light of in vitro protein-protein binding data and in vivo polytene chromosome staining indicating the lack of significant interaction between Eed and fly E(Z), a molecular partner of ESC. genesis 26:67-76, 2000

Animals↗
PubMed2000

Mannan-binding lectin and C1q bind to distinct structures and exert differential effects on macrophages.

While the interaction of complement component C1q with cellular proteins is extensively studied, much less is known about the binding of the structurally related molecule, mannan-binding lectin (MBL) to various cells. Here we show by cytofluorimetry that the interaction of MBL with immunocompetent cells is much more restricted than that of C1q. It is shown that under conditions of physiological ionic strength MBL binds to human monocyte-derived macrophages (Mphi) and monocytoid cell lines, but not to T and B lymphocytes, in contrast to C1q, which interacts with all these cells under the same conditions. As opposed to the binding of C1q, low ionic strength does not improve the interaction of MBL with Mphi. No competition for cellular binding sites was found when MBL and C1q were added simultaneously to the cells. Studying the functional consequences of the interaction, we found that the release of TNF-alpha from Mphi is induced by C1q but not by MBL. Production of complement C3 by Mphi is stimulated by C1q strongly, while the effect of MBL is much weaker. C3 produced upon C1q-mediated triggering is shown to opsonize RBC, resulting in enhanced phagocytosis. These results suggest that cell membrane molecules binding MBL and C1 q are not identical; moreover, biological functions exerted by these proteins are also markedly different.

Binding Sites↗
PubMed2001

Dichloroacetate exerts therapeutic effects in transgenic mouse models of Huntington's disease.

Dichloroacetate (DCA) stimulates pyruvate dehydrogenase complex (PDHC) activity and lowers cerebral lactate concentrations. In the R6/2 and N171-82Q transgenic mouse models of Huntington's disease (HD), DCA significantly increased survival, improved motor function, delayed loss of body weight, attenuated the development of striatal neuron atrophy, and prevented diabetes. The percentage of PDHC in the active form was significantly reduced in R6/2 mice at 12 weeks of age, and DCA ameliorated the deficit. These results provide further evidence for a role of energy dysfunction in HD pathogenesis and suggest that DCA may exert therapeutic benefits in HD.

Animals↗
PubMed2003

The biomolecule ubiquinone exerts a variety of biological functions.

The chemistry of ubiquinone allows reversible addition of single electrons and protons. This unique property is used in nature for aerobic energy gain, for unilateral proton accumulation, for the generation of reactive oxygen species involved in physiological signaling and a variety of pathophysiological events. Since several years ubiquinone is also considered to play a major role in the control of lipid peroxidation, since this lipophilic biomolecule was recognized to recycle alpha-tocopherol radicals back to the chain-breaking form, vitamin E. Ubiquinone is therefore a biomolecule which has increasingly focused the interest of many research groups due to its alternative pro- and antioxidant activity. We have intensively investigated the role of ubiquinone as prooxidant in mitochondria and will present experimental evidences on conditions required for this function, we will also show that lysosomal ubiquinone has a double function as proton translocator and radical source under certain metabolic conditions. Furthermore, we have addressed the antioxidant role of ubiquinone and found that the efficiency of this activity is widely dependent on the type of biomembrane where ubiquinone exerts its chain-breaking activity.

Animals↗
PubMed1993

Long-term double-blind evaluation of amlodipine and nadolol in patients with stable exertional angina pectoris. The Investigators of Study 152.

The efficacy and tolerability of amlodipine 2.5-10 mg once daily was compared with nadolol 40-160 mg once daily in a long-term double-blind parallel-group study in patients with stable exertional angina pectoris. A total of 80 patients were randomized to receive amlodipine or nadolol for 26 weeks after a 2-week single-blind placebo run-in period. The effects of amlodipine and nadolol on total exercise time were minimal and not significantly different. However, amlodipine produced a slightly but not significantly greater increase in time to onset of angina than nadolol (+21% amlodipine; +8% nadolol). No significant differences were noted between amlodipine and nadolol on ST-segment depression, angina attack rate, or nitroglycerin consumption. A slightly greater improvement was attained after amlodipine on patient and investigator assessments of treatments. A statistically significant difference (p < 0.0001) was found between treatments on the effects on myocardial oxygen requirements (as assessed by the rate pressure product). Nadolol produced a reduction of 29% compared with a slight reduction of 4% with amlodipine. Fewer side effects were reported with amlodipine (43%) than with nadolol (83%) (p < 0.0001), resulting in discontinuation of therapy in three amlodipine and four nadolol patients. Long-term treatment with amlodipine and nadolol produced comparable effects in patients with angina pectoris, with fewer side effects being reported after treatment with amlodipine.

Adolescent↗