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Biomedical subjects

J Duchateau

Publications and source records attributed to J Duchateau.

At least 163 records · Page 9Linked to original sources
PubMed1984

Training effects on muscle fatigue in man.

Effects of 3 months training, on electrical and mechanical failures during fatigue, were studied in human adductor pollicis muscle. Eight subjects carried out a daily training program of 10 series of 20 fast (0.5 s) voluntary contractions, against a load equivalent to 30-40% of the muscle maximal force. Contractile properties in control and trained muscles are tested by delivering supramaximal electrical pulses (30 Hz) to the motor nerve, thereby triggering series of 60 1-s contractions separated by 1-s intervals. Training produces significant increase in tension development during a 30 Hz isometric tetanus (+ 13%; P less than 0.001). Concimitant rates of tension development and of relaxation are respectively augmented by + 18% (P less than 0.001) and + 12% (P less than 0.001). No significant change of surface muscle action potential (SAP) is observed after training. The considerable loss of force recorded during fatigue in control muscles (-36%) is significantly smaller (P less than 0.001) after training (-17%). Slowing of tension development and of tension relaxation, observed during fatigue in control muscles (respectively -47% and -79%) is smaller after training (respectively -28% and -65%). Analysis of electrical failure indicates that training significantly (P less than 0.01) reduces augmentation of muscle SAP duration and area recorded during fatigue. Comparison of time courses of mechanical and electrical failures in control and trained muscles, supports the idea that intracellular processes play the major role in tension decay associated with fatigue in human adductor pollicis muscle.

Action Potentials↗
PubMed1984

Isometric or dynamic training: differential effects on mechanical properties of a human muscle.

This work compares the specific effects of 3 mo of moderate, isometric, or dynamic voluntary exercises on the contractile properties of human adductor pollicis muscle. Isometric training consisted of 10 daily contractions of 5-s duration at the frequency of one contraction per minute. Dynamic training consisted of 10 daily series of 10 fast contractions (less than 0.5-s duration) moving a load of one-third of the maximal muscle strength at a frequency of one series per minute. Both training programs produced a concomitant increase in maximal tetanic tension and in peak rate of tension development (Ro). A larger increase (P less than 0.05) was found after isometric training (20 vs. 11% after dynamic exercises), whereas Ro augmented more (P less than 0.05) after dynamic contractions (31 vs. 18% after isometric training). Enhancements of twitch force (Pt), rates of twitch tension development (Rt), and of relaxation (St) were, respectively, 20, 20, and 12% after isometric training. There was no modification of contraction time and time of half relaxation (T 1/2R). Conversely, dynamic training produced increases of Rt (25%) and St (16%), associated with an apparently paradoxical decrease of Pt (10%) and reductions of contraction time (11%) and T 1/2R (9%). Maximal shortening velocity was only increased after dynamic training (21%), whereas the maximal muscle power presented a large increase (P less than 0.05) after isometric exercises (51 vs. 19% after dynamic exercises) and a shift of its optimal peak toward heavier loads. This study suggests that human muscle adapts differently to isometric or to dynamic training programs and provides evidence that its contractile kinetics can be altered by exercises performed in physiological conditions.

Adolescent↗
PubMed1984

Complement activation in patients at risk of developing the adult respiratory distress syndrome.

In this prospective study of 50 patients, 36 of whom developed the adult respiratory distress syndrome (ARDS), early and intense complement activation was demonstrated. These patients were at risk of the ARDS because of multiple injuries, major abdominal surgery, acute pancreatitis, severe burns, or disseminated intravascular coagulation. Abnormal C3 consumption (as measured by the C3d/C3 ratio) and elevated plasma C5a-like activity (as measured by a leukocyte aggregation assay) were associated with, respectively, 84 and 86% of cases of ARDS. Both tests were more sensitive indicators of complement consumption than were assays of total hemolytic complement activity (CH50) or total C3. The C3d/C3 ratio showed a close, inverse correlation with CH50 in 47 healthy subjects, and was increased in 12 control patients after minor surgery. The C5a-like activity was found only in patients at risk of ARDS; it was highly associated with clinical conditions that predispose to the ARDS, but it cannot be considered as a real predictor of ARDS occurrence in these patients. Sequential samples from both sides of the pulmonary circulation showed initial pulmonary clearance followed by the release of C5a-like activity. No simultaneous changes in C3 levels were found, suggesting the possible presence of modulating factors. These observations suggest that other factors (e.g., hypoxia and metabolic cascades) may influence the development of ARDS.

Complement Activation↗
PubMed1984

Demonstration of auto-anti-idiotypic antibody cross-reacting with public idiotypic determinants in the serum of rye-sensitive allergic patients.

The present study documents the presence, in the serum of one allergic individual, of auto-anti-idiotypic antibodies cross-reacting with public idiotypic determinants expressed on human IgE and IgG anti-Rye I antibodies. Sera from rye-sensitive patients were tested for specific IgG and IgE antibodies to Rye I by double antibody. The IgG fraction, isolated from the serum of a patient with a history of previous hyposensitization therapy, was repeatedly absorbed on Rye-I-Sepharose as well as on IgM- and IgG-Sepharose to remove anti-Rye I antibodies as well as any possible anti-heavy or light chain activity. This IgG fraction, named anti-idiotypic fraction (a-IdF), blocked in a dose-dependent fashion the reaction of IgG and IgE anti-Rye I antibodies with Rye I antigen. The a-IdF also blocked the binding of anti-rye antibodies to Rye I antigen in the serum of 20 unrelated allergic patients, indicating that these anti-Rye I antibodies bore public idiotypic determinants.

Adolescent↗
PubMed1984

Immunomodulation with thymopentin in humans.

The effect of thymopentin administered i.v. or s.c. on the levels of circulating specific IgM and IgG KLH (key-hole limpet haemocyanine) antibodies and non-specific immunoglobulins were measured at weekly intervals in elderly volunteers for three subsequent weeks after vaccination with 500 micrograms KLH. As compared with the placebo group, specific IgM and IgG antibody responses significantly increased in the s.c. treated group, but remained at significantly lower levels in the i.v. treated groups. Increases in non-specific immunoglobulin levels were observed after vaccination in the placebo group; no such increases appeared in the groups treated with thymopentin. The results demonstrate the immunomodulatory effect of thymopentin in humans. It is assumed that, depending on the route of application (which indirectly represents different doses), thymopentin can either stimulate or inhibit immune processes. As an immunomodulator it may represent a new therapeutic tool for immunostimulation as well as for specific immunosuppression.

Adjuvants, Immunologic↗
PubMed1984

Preliminary results on clinical and immunological effects of thymopentin in AIDS.

In an open study, 10 African patients with AIDS were treated with thymopentin 50 mg i.v. 3 times a week for 2 consecutive months: 1 month by i.v. direct injections and 1 month by 30-min i.v. infusions. In group A there were 6 patients with AIDS-lymphadenopathy characterized by weight loss, chronic fever, generalized lymphadenopathy and OKT-4 to OKT-8 ratio below 0.2. Group B consisted of 4 patients with AIDS and opportunistic infections. Immunological studies performed before, during and after therapy included lymphocyte count, T-cell subsets assessment, study of blastogenic response of lymphocytes to PHA and delayed hypersensitivity skin testing to 5 antigens. In group A, results after thymopentin i.v. direct injections showed a significant increase in OKT-3 and OKT-8 cells. After thymopentin i.v. infusion, blastogenic response to PHA increased significantly as compared with pretherapy values and to the values after i.v. direct injections. At the end of infusion therapy, skin tests became positive for 3 antigens (range 2-4). Furthermore, all 6 patients noted subjective improvement associated with significant weight gain and disappearance of fever. In contrast, in group B the clinical and immunological status worsened during therapy and two patients died from opportunistic infections. This preliminary study suggests that i.v. infusion with thymopentin may be useful in the early phase of the acquired immune deficiency syndrome as it produces symptomatic and immunological improvement.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Effects of chronic aspirin ingestion in aspirin-intolerant asthmatic patients.

The effects of regular aspirin ingestion after aspirin-desensitization were evaluated in 10 aspirin-intolerant asthmatic patients. Chronic aspirin ingestion was not observed to be associated with either a significant improvement of mean FEV1 values or with a decrease in daily corticosteroid requirements. This study suggests that regular aspirin ingestion in aspirin-intolerant asthmatic patients does not induce a measurable improvement of the respiratory status.

Administration, Oral↗
PubMed1984

[Indications for the aspirin provocation test in the asthmatic].

Oral provocation tests using aspirin (n = 55), tartrazine (n = 37) and benzoate (n = 28) were performed in 55 asthmatic patients. A positive aspirin provocation test was observed in 15 patients (27%). These patients often had a past history of aspirin intolerance, 53% of them also had nasal polyposis and 5 out of 12 had associated tartrazine intolerance, while 2 out of 8 had associated benzoate intolerance. The authors consider that these features may help the clinician to detect the asthmatic patient at high risk of aspirin intolerance in whom a provocation test should be performed.

Adult↗
PubMed1984

Rapidly fatal bronchiolitis obliterans with circulating antinuclear and rheumatoid factors.

A 57-year-old woman developed severe bronchiolitis obliterans and presented circulating antinuclear and rheumatoid factors without any evidence of connective tissue disease. The evolution was rapidly fatal despite corticosteroid therapy and immunosuppressive treatment. The post-mortem study disclosed no connective tissue disease lesions. We suggest that the serologic abnormalities could be secondary to the inflammation of the bronchioles.

Antibodies, Antinuclear↗
PubMed1984

Decreased sensitivity to tartrazine after aspirin desensitization in an asthmatic patient intolerant to both aspirin and tartrazine.

An aspirin- and tartrazine-sensitive asthmatic patient underwent a desensitization to the adverse effects of aspirin by oral aspirin challenges. After a month of daily aspirin ingestion, the patient's reactivity to tartrazine, tested by oral challenge, was observed to the blunted. This report suggests that desensitization to the adverse effects of aspirin might protect the patient against the adverse effects of tartrazine.

Adult↗
PubMed1983

Genetic deficiency of C4 presenting with recurrent infections and a SLE-like disease. Genetic and immunologic studies.

A young girl presenting with recurrent pulmonary infections and atypical lupus erythematosus was totally deficient in C4. In one sister, also deficient in C4, the same symptoms developed. Results of family studies were consistent with an autosomal recessive mode of transmission and with linkage of the genes determining C4 deficiency to those of the major histocompatibility complex. The patient's serum and red cells were Chido- and Rodgers-negative. Humoral and cellular immunity were normal, except for a low lymphocyte response in mixed lymphocyte culture. The cellular function of the patient's polymorphonuclear leukocytes was normal, for both phagocytosis and bactericidal activity using Candida albicans. However, in the presence of C4-deficient serum, opsonin generation and bactericidal indexes were diminished. These defects were completely reversible upon addition of purified C4.

Child, Preschool↗
PubMed1983

Heterogeneity of immunoregulatory T cells in human thyroid autoimmunity: influence of thyroid status.

Monoclonal antibodies of the OKT series were used to identify circulating T lymphocytes (OKT3+), their helper-inducer (OKT4+) and suppressor-cytotoxic (OKT8+) subsets and cells bearing Ia antigen (OKIa+) in 75 patients with thyroid autoimmune disorders, including 14 Graves' disease, 21 myxoedema, 20 asymptomatic thyroiditis, 12 Hashimoto's thyroiditis and eight simple goitre with superimposed thyroiditis. In the whole population of patients, a negative correlation was observed between the percentage of OKT8+ cells and serum free thyroxine levels whatever the type of thyroiditis. The percentage of OKT8+ cells was decreased in Graves' disease and increased in myxoedema while it reversed after adequate treatment of the two diseases. However, a trend to a decrease in the proportion of OKT8+ cells was still observed in treated Graves' disease and in all the other groups of thyroiditis with euthyroidism. The minor modifications observed for OKT3+ and OKT4+ cells were in relation with those of OKT8+ cells. There was an increased percentage of Ia+ cells in Graves' disease and in Hashimoto's thyroiditis partly reflecting the presence of activated lymphocytes. In conclusion, these data suggest first of all a direct influence of serum T4 on the distribution of circulating OKT8+ cells in addition to documenting the heterogeneity of T cell immunoregulatory factors.

Adolescent↗