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Biomedical subjects

E Toft

Publications and source records attributed to E Toft.

At least 19 recordsLinked to original sources
PubMed1991

Postoperative hypophosphataemia and muscle function.

Muscle function tests of the triceps brachii muscle were performed before operation and on the third postoperative day in ten patients undergoing elective cholecystectomy. Electromyograms (EMGs) were recorded by surface electrodes during sustained isotonic and isometric muscle contraction with a constant force of 20 per cent of the preoperative maximal voluntary contraction. Root-mean-square of the EMG was calculated together with the neuromuscular efficiency and measures of the fatiguability. These parameters were compared with changes in the simultaneously measured serum phosphate concentrations. Mean (s.e.m.) neuromuscular efficiency measured after 32-40 s of muscle contraction decreased 14(5) per cent after operation (P less than 0.01), whereas the mean fatiguability of the muscle was unchanged. Mean serum phosphate concentration was 0.87(0.06) mmol/l before operation and 0.79(0.06) mmol/l 3 days after the operation (P greater than 0.05). Two patients developed severe postoperative hypophosphataemia (serum phosphate concentration less than 0.50 mmol/l). Postoperative muscle function deterioration was not associated with changes in the serum phosphate level (P greater than 0.10; r = 0.03). We conclude that patients undergoing cholecystectomy develop postoperative deterioration in skeletal muscle function, which is not associated with serum phosphate concentration.

Adult↗
PubMed1991

Involvement of thin afferents in carpal tunnel syndrome: evaluated quantitatively by argon laser stimulation.

The thin afferent nerves were tested quantitatively by determining the thresholds of warmth and pricking pain to argon laser stimulation and by measuring the brain potentials related to pricking pain. In 27 patients with electrophysiologically verified carpal tunnel syndrome these parameters were measured from fingers 3 and 5 on both hands. All patients had had sensory symptoms ranging from 3 months to 25 years. Both the thresholds were elevated (P less than 0.05) at finger 3 compared to measurements from finger 5, and compared to finger 3 in a group of 39 controls. Four patients with symptoms for more than 7 years had thresholds below the control values. The power of the pain-evoked brain potentials elicited from finger 3 was lower (P less than 0.05) compared to finger 5, and compared to the control group (P less than 0.01). No correlations were found between the measured parameters and the clinical electrophysiological investigation. The findings support previous assumptions that chronic low-force compressions cause impairment of intraneural microcirculation, and hence can affect the function of the thin afferents.

Adolescent↗
PubMed1991

Stretch reflex variation in the relaxed and the pre-activated quadriceps muscle of normal humans.

The stretch reflex to patellar tendon taps was quantified by force measurements at the ankle in 7 normal subjects. In each experiment the stretch reflex was elicited from 14 consecutive stretches by two types of hammers (an ordinary hand-held hammer and a motorized hammer) in the relaxed and the pre-activated quadriceps muscle. The coefficient of variation for the 14 stretch reflexes fell from 54% in the relaxed muscle to 39% in the contracting muscle (p less than 0.05). The stretch reflex varied less between the different levels of active contraction than between the relaxed state and the contracted level (p less than 0.05). The experiment was repeated in all subjects and at all contraction levels. The coefficient of variation of the mean for the two experiments fell non-significantly from a mean value of 27% in the relaxed muscle to 14% in the contracting muscle. The coefficients of variation for the two hammers were almost identical. It is concluded that quantification of the stretch reflex can be made more precisely in the contracting muscle.

Adult↗
PubMed1991

Mechanical and electromyographic responses to stretch of the human ankle extensors.

1. During maintained ankle extension with background torques ranging from 0 to 70 N.m, the ankle extensors were stretched by a 5 degree rotation of the ankle joint. Maximal stretch velocity was 170 degrees/s. Regression analysis of simultaneous measurements of total torque and needle and surface electromyograms (EMG) from the soleus and gastrocnemius muscles showed that the soleus muscle generates about two-thirds of the maximal torque (approximately 120 Nm) with the subjects in sitting position. In addition, it was found that there is considerable cross talk between the soleus and gastrocnemius muscles when EMGs are recorded by surface electrodes. 2. The soleus EMG response to stretch began with a "phasic" response (latency 41 +/- 4 ms, mean +/- SD), consisting of two peaks, labeled M1 and M2. The phasic response ended 120-140 ms after stretch onset and was followed by a period of reduced EMG activity, ending at 170-210 ms. After this "silent period," a smaller "tonic" response was seen. The phasic responses of the soleus muscle were much larger than the corresponding responses in the anterior tibial muscle. In contrast, the tonic responses were comparable in the soleus and anterior tibial muscles. 3. The amplitudes of the phasic M1 and M2 responses were independent of the level of the background contraction. This disagrees with the "automatic gain principle," according to which the amplitudes of M1 and M2 should increase proportionally with the background EMG. In contrast to the phasic responses, the amplitude of the tonic EMG response, measured 200-400 ms after stretch onset, followed the automatic gain principle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Plasma atrial natriuretic peptide in elite runners.

Plasma atrial natriuretic peptide (ANP) was measured in relation to a 5-km race in 11 elite mid- and long-distance runners. Plasma ANP, measured in relation to the race, was compared with the relative changes in plasma volume and the physical fitness of the runners. Relative changes in plasma volume were estimated by changes in hemoglobin and hematocrit, and physical fitness was evaluated by a cycle ergometer test, running time, and resting heart-rate. In connection with the race, plasma ANP increased in all the runners. Median plasma ANP was 4.7 pmol.l-1 before the race and 12.9 pmol.l-1 immediately after the race. No correlation was found between the changes in ANP and the relative changes in plasma volume or the measurements of physical fitness. A volume expansion of the red blood cells was found immediately after the race. We conclude that well-conditioned subjects have a prominent rise in plasma ANP, in spite of a high maximal cardiac output.

Adult↗
PubMed1990

Effect of physical exercise on cytokines and lymphocyte subpopulations in human peripheral blood.

To examine the effect of intensive physical exercise on interleukin 2 (IL-2), tumor necrosis factor alpha (TNF alpha) and lymphocyte subsets, eleven elite and well-conditioned runners were tested in relation to a five-kilometer race. IL-2 was significantly decreased (p less than 0.01) immediately after the exercise and significantly increased after 24 hours (p less than 0.05), compared to the pre-exercise values taken at steady state. TNF alpha was significantly increased after 2 hours (p less than 0.05), and returned to habitual values after 24 hours. In the steady state at rest, elevation of HLA-DR+ cells was observed in all runners compared with control subjects (p less than 0.05), indicating a persistent activation of lymphoid cells. In connection with exercise a significant increase in NK cells (CD16+) was observed (p less than 0.01). The T-helper/T-suppressor (CD4+/CD8+) ratio was significantly reduced in connection with physical activity (p less than 0.01). In seven runners the ratio was reduced to a value of less than one. This decrease was observed immediately after the exercise, followed by increased ratios 2 hours later (p less than 0.01), due to oppositely directed quantitative changes of the CD4+ and CD8+ cell populations. After 24 hours the ratios returned to habitual levels. Furthermore, we confirmed an increase in the total number of granulocytes in connection with exercise (p less than 0.01), and observed a decrease in absolute numbers of lymphocytes two hours after exercise (p less than 0.01). We emphasize the importance of obtaining information about physical activity within the previous 24 hours before measuring white blood cell parameters.

Adult↗
PubMed1990

Rapid estimation of serum myoglobin concentration during rhabdomyolysis with a latex-agglutination test (Rapi-Tex).

A latex-agglutination test (Rapi-Tex) was used for semiquantitative estimation of myoglobin concentration in 89 serum samples obtained from ten patients undergoing lower-limb arterial embolectomy. Each serum sample was tested with Rapi-Tex both undiluted and after 1:50 dilution with saline. The myoglobin concentration was additionally measured with enzyme-immunoassay. In the undiluted samples there were five 'false negative' Rapi-Tex results--two in the myoglobin concentration interval 0-300 micrograms and three in the samples with myoglobin exceeding 25,000 micrograms/l--and four 'false positive' results. None of the diluted samples gave rise to false classification. Using 1:50 diluted serum, the negative predictive value of the Rapi-Tex test for identification of a myoglobin concentration greater than 5,000 micrograms/l was 0.99 (95% confidence limits 0.94-1.00), and the positive predictive value was 1.00 (0.61-1.00). Rapi-tex is concluded to be a useful emergency test for severe hypermyoglobinemia.

Acute Kidney Injury↗
PubMed1989

[Stretching in relation to sports and prevention of injuries].

Stretching is a regular item in training programmes and it is employed to increase flexibility, to prevent muscle tenderness, overuse injuries and strains. Stretching is carried out by stretching muscles and connective tissue to the extreme positions of joints. A review of stretching exercises based on the literature is presented in relation to prevention of injuries. The various techniques employed are reviewed.

Athletic Injuries↗
PubMed1989

Mechanical and electromyographic responses to stretch of the human anterior tibial muscle at different levels of contraction.

The EMG response and the mechanical response to 2 degree stretch of the human anterior tibial muscle was studied during contractions ranging from 0% to 80% of maximal voluntary contraction (MVC). The EMG response showed three distinct peaks M1, M2, and M3 with peak latencies of 59 ms, 86 ms, and 120 ms respectively. At low background torques M1 dominated while M2 and M3 were small or absent. M2 and M3 dominated above 40% of MVC and M2 in particular showed "automatic gain compensation", i.e. it constituted a - more or less - constant proportion of the background EMG for all contraction levels. The ratio between M1 amplitude and background EMG steadily decreased with contraction level. Even though the summed contributions of M1, M2, and M3 to some degree showed automatic gain compensation, this was not the case for the mechanical response to stretch. Between 0% and 30% of MVC the reflex mediated mechanical response increased approximately in proportion to the contraction level, but the reflex mediated mechanical response peaked at 40% of MVC and declined to zero at 80% of MVC. This discrepancy between EMG and mechanical response was explained by a simple model. The regression line between rectified and filtered tibialis anterior EMG and torque was used to predict the mechanical response from the EMG response. At increasing contraction levels the twitch elicited by supramaximal electrical stimulation decreases, and we reduced the predicted mechanical response by the same factor as the twitch.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Biomechanical properties of the human ankle in relation to passive stretch.

Viscous/plastic properties were investigated in the passive tissue opposing dorsiflexion of the human ankle. The foot was rotated (dorsiflexed) and fixed. Due to viscous/plastic properties, the passive torque declined with time. After 300 s, torque, relative to the initial torque at 0 s, had fallen by 22.7% +/- 2.6% (mean +/- 1S.D.), as an expression of the relative importance of the viscous/plastic tissue properties for the passive torque. By a peel-off technique the number of different tissue elements with viscous/plastic properties was found to be at least three. After 100 s, all but one of these elements had yielded completely. Viscous/plastic properties were unchanged by stretching when measured 90 min after a single stretching program and when measured 24 h after stretching procedures had been performed twice a day for three weeks.

Adult↗
PubMed1989

Serum and urinary phosphate during and after prolonged muscular ischaemia in non-exercising men and women.

Serum inorganic phosphate (Pi) concentrations and urinary Pi excretions were measured in nine patients undergoing abdominal aortic bypass grafting (group I) and in nine patients undergoing lower limb arterial embolectomy (group II). In group I, serum Pi concentrations were normal until 24 h after reperfusion, when they decreased, reaching their nadir at 48 h (median Pi 0.45 mmol 1(-1). The urinary phosphate clearance relative to the creatinine clearance (Cp/Cc) increased 5 min after reperfusion reaching a maximal median value (0.454) in the 2-24-h collection period. In group II, eight patients had a normal and one had a subnormal serum Pi before reperfusion. None developed hypo- or hyperphosphataemia and the Cp/Cc remained unchanged. Daily urinary Pi excretion was higher in group I than in group II (P less than 0.03). The authors concluded that the regional muscular ischaemia in non-exercising men and women was not associated with hyperphosphataemia. The possible influence of major surgery and anaesthesia on phosphate homeostasis should be considered.

Aorta, Abdominal↗
PubMed1989

Quantitation of the stretch reflex. Technical procedures and clinical applications.

The stretch reflex should ideally be quantitated for better clinical use by standardizing the muscle stretch and measuring the resulting muscle contraction. Quantitation of muscle contraction can be done by force measurements or electromyographic recordings. The electromyographic response to stretch consists of one component (short latency response) for short stretches (less than 15 ms) and of 2 or 3 components (short and long latency responses) for longer stretches (greater than 40-50 ms). The magnitude of the phasic stretch reflex is reflected by the short latency response, whereas the magnitude of the tonic stretch reflex is reflected by both the short and the long latency responses. In clinical studies of upper motor neuron syndromes, the knee jerk and the muscle tone correlated with the magnitude of the short latency response. In patients with paralysis agitans an increased long latency response, which correlated to the rigidity, was found.

Humans↗
PubMed1989

[Reflex examination. Neurophysiologic and biochemical status].

The neural network excites when a stretch reflex is elicited during a physical examination. It is important to be aware that the stretch reflex depends on the contraction level of the muscle before stretch, and on the amplitude and velocity of the muscle stretch. A changed resistance from passive tissue or muscle fibre them self has to be taken into account when evaluating the size of the stretch reflex. A weak contraction compared with no contraction in the stretched muscle decrease the variation in the size of the stretch reflex. Influence from other types of receptors and synergistic and antagonistic muscles can also contribute to the stretch reflex.

Animals↗
PubMed1988

Muscle stiffness in human ankle dorsiflexors: intrinsic and reflex components.

1. The purpose of this study was to evaluate the mechanical response to stretch in normal human ankle dorsiflexors at different levels of voluntary contraction. In an active muscle, the total mechanical response is the sum of the intrinsic response from the contractile apparatus, the response from passive tissues, and the reflex mediated response. Each of these components was investigated. 2. The total incremental stiffness was defined as the ratio between the torque increment and the amplitude of the stretch. In 14 subjects the total stiffness increased from approximately 0.6 N.m/deg to approximately 2.5 N.m/deg at 50% of MVC and remained constant (+/- 10%) from 30 to 80% of MVC. 3. The contribution to incremental stiffness from intrinsic muscle properties was measured during electrical stimulation of the deep peroneal nerve at 7-50 Hz. Intrinsic stiffness increased linearly with torque from approximately 0.5 N.m/deg to approximately 2.5 N.m/deg at 80% of MVC. 4. The reflex component (total minus intrinsic stiffness) had a maximum of 0.5-1.5 N.m/deg at 30-50% of MVC and was approximately zero at no and maximal contraction. For intermediate levels of contraction the reflex increased the stiffness with 40-100% of the intrinsic stiffness in this flexor muscle. 5. The reflex contribution to total stiffness began approximately 50 ms after onset of stretch and peaked 150-300 ms after onset of stretch. 6. Total, intrinsic, and reflex mediated stiffness were all nearly independent of the amplitude of stretch in the range from 2 to 7 degrees. The higher stiffness observed for 1 degree stretches could be due to "short range stiffness" of the cross bridges. 7. Stretching of a contracting muscle generates large force increments even for moderate amplitudes of stretch. Approximately half of this force increment is due to the stretch reflex, which makes the muscle stiffer than predicted from the intrinsic stiffness. These findings in human flexor muscles are surprisingly similar to previous findings in extensor muscles of the decerebrate cat.

Adult↗
PubMed1988

Effect of daunorubicin on subcellular pools of glutathione in cultured heart cells from neonatal rats.

Alterations in cellular GSH and its compartmentation were investigated as a possible mechanism of toxicity of the anthracycline derivative daunorubicin in neonatal heart cells. Cultured beating heart cells from neonatal rats were exposed to daunorubicin at therapeutically relevant concentrations and the resulting changes in cellular GSH as well as cytosolic and mitochondrial pools of GSH were determined. Toxicity was estimated as an increased permeability of the plasma membrane to cytosolic enzymes, e.g., lactate dehydrogenase. Control heart cells were found to contain 12.2 +/- 1.8 nmoles GSH/10(6) cells. Daunorubicin caused a rapid initial decrease followed by a transient increase in cellular GSH. The extent of the latter increase was dependent on the concentration of daunorubicin. High concentrations of daunorubicin gave only a slight increase followed by a pronounced decrease in cellular GSH. By applying a digitonin-based method the effect of daunorubicin on the cytosolic and mitochondrial pools of GSH were separated. The concentration of cytosolic and mitochondrial reduced GSH was estimated to be 8.9 +/- 1.5 nmoles/10(6) cells and 3.3 +/- 0.6 nmoles/10(6) cells, respectively. The results indicate that daunorubicin caused a decrease of cytosolic GSH and, after a short lag period, a release of alctate dehydrogenase. No decrease of mitochondrial GSH occurred under these conditions indicating that daunorubicin influences selectively cytosolic GSH. No lipid peroxidation products were detected in DRB-treated cells under conditions when lactate dehydrogenase was released. Likewise, addition of the iron-chelator desferrioxamin did not influence the release of lactate dehydrogenase, whereas dithiothreitol offered partial protection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗