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J Duchateau

Publications and source records attributed to J Duchateau.

At least 127 records · Page 7Linked to original sources
PubMed1988

Training effects of sub-maximal electrostimulation in a human muscle.

This paper compares the effects of 6 wk of sub-maximal training by electrostimulation (100 Hz) and voluntary contractions on the contractile properties of the adductor pollicis muscle in intact man. The daily training program consisted of ten series of twenty 1-s isotonic contractions (60 to 65% of maximum) separated by 1-s intervals. The observed increase in muscle force, tested in maximal voluntary and electrically evoked contractions, appears to be significantly smaller during electrostimulation than during a training session performed by voluntary contractions. The increase in force recorded during electrostimulation is not associated with changes in the tetanus rates of tension development and tension relaxation (dP0/dt). Conversely, the tetanus time course is found to be significantly accelerated in muscles trained by voluntary contractions. No change of the surface action potential total area was observed during both training procedures. Furthermore, electrostimulation does not improve muscle resistance to fatigue, which is observed to be significantly increased after training by voluntary contractions. This study indicates that electrostimulation augments the muscle force of contraction by changing peripheral processes associated with intra-cellular events, without modifying the nervous command of the contraction. The comparison of the peripheral changes recorded during sub-maximal training by electrostimulation and voluntary contractions suggests that electrostimulation is less efficient, but complementary to voluntary training because the number and the type of trained motor units are different in the two procedures.

Adult↗
PubMed1988

[The significance of C-reactive protein in the diagnosis of chorioamnionitis in cases of premature rupture of the membranes].

We have retrospectively studied the changes in the level of C-reactive protein (CRP) and of white blood cells in 82 patients who had premature rupture of the membranes between the 20th and the 36th week of pregnancy in order to estimate the possibility of prenatal screening for amnion infections in early rupture of the membranes. The level of CRP was shown to be quickly and significantly raised in cases of clinical or histological chorioamnionitis, whereas the change in maternal leucocytes alters little and later. The level of CRP can be worked out as an early biological marker which is sensitive and cheap in the clinical supervision of cases with early rupture of the membranes.

C-Reactive Protein↗
PubMed1988

Failure to demonstrate complement activation during bronchial challenge test.

In order to demonstrate a possible complement activation during early bronchospastic reaction in asthma, we have measured plasmatic C3d (a split product of C3) and the C3d/C3 index, both of which are sensitive indices of complement activation. Twenty-nine allergenic bronchial challenge tests were accomplished, with an absence of response in six cases, an early reaction in sixteen cases and a dual reaction in seven cases. Changes in plasmatic C3d or C3d/C3 five min after an early reaction, or five min after the last dose of allergen (in the six cases without bronchial response) were insignificant. However, complement activation in the lungs during asthmatic reaction cannot be completely excluded without studies using the bronchoalveolar technique.

Adolescent↗
PubMed1988

[Asthma and complement].

The complement system has an important place in the development of the inflammatory reaction. The complement may be activated by the classical pathway (itself activated by immune complexes, CRP etc.) or the alternative pathway (activated by bacterial endotoxins, different lung allergens etc.). This activation culminates in the release of opsonising, chemotactic, smooth muscle constrictor, and mast cell activating factors. The complement system is present locally at the level of the bronchi and could participate in the development of bronchial inflammation narrowly associated with asthma. Study of the complement system in the plasma in asthmatics has not shown a relation between its state of activation and bronchomotor tone. However, in view of recent studies of the complement in the bronchi, analysed on broncho-alveolar lavage, the potential role of complement in asthma should be re-evaluated.

Asthma↗
PubMed1988

IVth International Meeting of Clinical Biology CH Sainte-Ode, Baconfoy, Belgium May 23-24th, 1987 clinical biology in intensive care medicine. Leukocyte aggregation and complement activation in respiratory distress syndrome (ARDS).

A diffuse lesion in the alveolar-capillary membrane appears as an initial pathological event which preludes the emergence of an Acute Respiratory Distress (ARDS) with pulmonary oedema. The implication of polymorphous nuclear cells (PMN) as the cells initiating this lesion remains solidly established. The activation of the complement system has been established in numerous circumstances associated with the risk of the development of an ARDS. This activation can be exogenous and leads to the generation of inflammatory agents, stimulating different types of cells such as the PMN, the monocytes and mastocytes by intermediation of specific receptors, and activate important function of locomotion, adhesion, aggregation, degranulation, etc. Authors describe here the behaviour of C5a and the aggregability of PMN in such patients with a risk of ARDS.

Belgium↗
PubMed1987

Electro-mechanical failures and lactate production during fatigue.

The electrical and mechanical failures observed during sustained and intermittent electrically triggered (30 Hz) contractions of human flexor carpi ulnaris were compared with the blood lactate concentration. The changes recorded during contractions sustained for 60 s were compared with those observed during a series of sixty 1 s contractions separated by 1 s intervals, and also with the changes during the first 30 min of recovery. No significant (P less than 0.05) difference in force reduction or maximal venous lactate concentration was observed in either fatigue test, although electrical failure differed significantly (P less than 0.05). The recovery of electrical failure was poorly correlated with the reduction in lactate concentration following both sustained (r = -0.70) and intermittent contractions (r = 0.72). In contrast, the recovery in tetanic tension, rate of tension development and time to half relaxation correlated closely with the reduction in venous lactate concentration (r = -0.95, -0.93 and 0.96 respectively). It is suggested that, of the peripheral processes which appear to play a dominant role in peripheral fatigue, lactate production controls mechanical failure directly.

Action Potentials↗
PubMed1987

Biochemical investigations after burning injury: complement system, protease-antiprotease balance and acute-phase reactants.

Seventeen burned patients were investigated--Group I (n=10) with a mean burned area expressed as unit burn standard (UBS) of 69 +/- 24 and Group II (n = 7) with a mean UBS of 23 +/- 8. Blood samples were collected immediately after admission, 6-12 h after injury, during the morning and evening of day 1, and then daily for 2 weeks. This prospective study demonstrated complement activation in vivo in all burned patients, measured by C3d/C3 ratio index which was not related to the extent of the burned surface. A significant protease-antiprotease imbalance, correlated to the severity of burns, was found, leukocyte elastase was increased throughout the observation period, alpha 2-macroglobulin drastically decreased in severely burned patients, and alpha 1-proteinase inhibitor promptly decreased below the normal level in patients with more than 40 UBS. Finally, there was a delayed but then persistent acute-phase reactant protein response involving C-reactive protein, haptoglobin and alpha 1-acid glycoprotein, the concentrations of which reached a plateau on days 6 or 7.

Acute-Phase Proteins↗
PubMed1987

Chronic pain: illusion or pathology? A case report of a vascular leiomyoma in the leg.

Patients with chronic pain constitute a major problem for the surgeon as the cause of their pain is often difficult to diagnose and is only rarely a well circumscribed lesion which is amenable to surgical or other treatment. We report a case of chronic pain due to a vascular leiomyoma beneath the deep fascia of the leg. Angioleiomyomas are rare tumours that are usually found in the subcutaneous tissue.

Chronic Disease↗
PubMed1987

Difficulty in initiating and maintaining sleep associated with cow's milk allergy in infants.

To confirm that sleeplessness in infants can be related to an undiagnosed allergy to cow's milk proteins, 71 infants were studied. Group I consisted of 20 infants referred for chronic insomnia that had appeared in the early days of life. Group II was made up of 31 infants admitted for skin or digestive symptoms attributed to cow's milk intolerance; 13 of these infants were shown to sleep as poorly as the infants of group I. Group III consisted of 20 infants with no history of sleep disturbance or milk allergy. The three groups of infants were comparable for sex and age. Laboratory tests revealed immunologic reactions to milk in all the infants in groups I and II. The sleep of the insomniac infants (group I, and the 13 "poor sleepers" in group II) became normal after cow's milk was eliminated from the diet. Insomnia reappeared when the infants in group I were challenged with milk. We conclude that infants with clinically evident milk allergy may suffer from sleeplessness and that when no evident cause for a chronic insomnia can be found in an infant the possibility of milk allergy should be given serious consideration.

Animals↗
PubMed1987

Electrical and mechanical changes in immobilized human muscle.

After forearm fracture, the human thumb was unilaterally immobilized in eight subjects for 6 wk in a standard plaster cast. Changes of contraction properties were studied in the adductor pollicis muscle. The contralateral muscle remained unrestrained and served as control. After immobilization, the maximal voluntary contraction was reduced by 55% (P less than 0.05), and the electrically evoked maximal tetanic contraction (Po) was reduced by 33% (P less than 0.05). The decrease of Po was associated with increased maximal rate of tension development (10%) and decreased maximal rate of tension relaxation (22%). The twitch times to peak and to half relaxation were increased by 16 and 14%, respectively, but the twitch tension (Pt) was not significantly changed and the Pt/Po ratio was increased by 43% after immobilization. The muscle surface action potential presented an increase of its duration (19%) and a decrease of the amplitude and the total area (15 and 26%, respectively). The comparison of the electrical and mechanical alterations recorded during voluntary contractions, and in contractions evoked by electrical stimulation of the motor nerve, suggests that immobilization not only modifies the peripheral processes associated with contraction but also changes central and/or neural command of the contraction. At peripheral sites, it is proposed that the intracellular processes of contraction play the major role in the contractile impairment recorded during immobilization.

Electromyography↗
PubMed1987

A polymeric IgA response in serum can be produced by parenteral immunization.

The magnitude and the kinetics of the serum-specific polymeric (p-) and monomeric (m-) IgA antibody responses were analysed following parenteral stimulation with tetanus toxoid (TT) vaccine in 10 volunteers, 5-20 years after a previous boost. A rapid marked serum IgA antibody response involving both the monomeric and polymeric components of IgA was observed: m-IgA and p-IgA antibodies reached a peak of serum activity at about 11 days, around 6 days before the peak of IgG antibody activity. At the peak of the IgA response, p-IgA accounted for approximately half of the anti-TT activity (median 54%, 25-79%). However, p-IgA antibodies rapidly disappeared from serum over a few weeks, whereas the serum m-IgA antibody response was maintained over a prolonged period of time. For one subject out of five, anti-TT IgA were also detected in saliva with a peak of activity earlier than in serum. Calculation of the albumin relative coefficient of excretion for anti-TT IgA in this saliva suggested a local synthesis of these antibodies. The present study indicates that a polymeric IgA antibody response in serum can be produced by parenteral immunization in primed individuals, and it raises the question of the mechanisms that control polymeric versus monomeric IgA production.

Adult↗
PubMed1986

Contributions of slow and fast muscles of triceps surae to a cyclic movement.

The relative contribution of synergistic muscles has been studied during pedalling on a bicycle. The electromyographic (EMG) activity of the different components of triceps surae (namely soleus or SOL and medial gastrocnemius or MG) has been recorded and analyzed for increasing pedalling speed performed against increasing resistance. The results indicate that SOL IEMG (integrated EMG) increases linearly (y = 2x-12.1; r = 0.98) with increasing load (10-70 N) at constant speed (60 rpm), whereas no change is noted in MG IEMG below 40 N. In contrast, when the pedalling speed is increased (from 30 to 170 rpm) at constant load, MG IEMG shows the largest increase. Furthermore, although in both muscles EMG activity appears earlier in the movement with increases in load and/or speed, the delay between the onset of both EMGs remains unchanged at constant speed and synchronization of MG with SOL is only observed when speed is increased above 140 rpm. These results suggest that the different muscles of the triceps surae make specific contributions to the development of the mechanical tension required to maintain or increase the speed of movement.

Adult↗