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Biomedical subjects

Y Rideau

Publications and source records attributed to Y Rideau.

At least 19 recordsLinked to original sources
PubMed1997

Clinical implications of maximal respiratory pressure determinations for individuals with Duchenne muscular dystrophy.

OBJECTIVE: To analyze the relationship between disease progression, pulmonary volumes, respiratory muscle strength (maximum inspiratory [MIP] and expiratory [MEP] pressure), and arterial blood gases for patients with Duchenne muscular dystrophy (DMD). DESIGN: An inception cohort study of pulmonary volumes, MIPs, and MEPs, correlated with age and PaCO2 levels and with each other using linear and nonlinear regression analyses. SETTING: Outpatient clinic. PATIENTS: Fifty-two consecutive DMD patients who presented for regular evaluations at a regional DMD center. RESULTS: Maximum expiratory pressures were 47.7% +/- 10.9% of normal in the 167- to 14-year-old patients and decreased linearly thereafter (MEP% = -2.7 x age +73.8; p < .001). Declines in MEP also correlated linearly with expiratory reserve volume (p < .001) and inversely with residual volume (p < .001). By contrast, MIP was 66.3% +/- 19.0% in the 357- to 14-year-old patients and then declined to 30.2% +/- 19.5% after age 14. No linear relationships were found with age but declines did correlate linearly with inspiratory reserve volume (p < .001) and total lung capacity (p < .001). PaCO2 elevations correlated best with decreases in MIP (p < .0001) and appeared when MIP was below 30cmH2O. CONCLUSIONS: Lung volume changes in DMD patients correlate with respiratory muscle weakness, and although inspiratory muscle dysfunction plays a key role in the development of chronic ventilatory insufficiency, reductions in expiratory muscle strength are the first signs of dysfunction and lead to the first episodes of respiratory failure.

Adolescent↗
PubMed1996

In-vitro biomechanical study of a dorso-lumbo-sacral posterior supple instrumentation with variable section.

This study is designed to analyse the behavior, in the sagittal plane, of a complete human dorso-lumbar rachis, made rigid by the posterior instrumentation used for the treatment of scoliosis, on subjects suffering from DMD (Duchenne Muscular Dystrophy). The object of this analysis is to demonstrate the reliability of early surgery made possible by new instrumentation. Close review of the literature shows that the currently used Harrington or Luque instrumentations lead to mechanical complications, especially rod breaking, at the thoraco-lumbar junction. 8 specimens were non-destructively tested in-vitro. Compression and flexion were applied. For each test, rachis movements with and then without instrumentation, and also rod restraints were noted. The results show a linear stiffness multiplied by 8.3 in flexion and 11.6 in extension. The maximum restraint recorded for physiological displacements is 77 MPa. This remains largely under the fatigue-breaking limit of the metal used (stainless steel hammer-hardened 316 L, Young's modulus = 200,000 MPa, Poisson's ratio = 0.21, endurance limit = 350 MPa at 5 x 10(6) cycles). The results of this study encourage us to continue and develop early surgery in children affected by myopathy, with fixation of the complete rachis, including a lumbo-sacral arthrodesis and a supple dorsal part of the mounting, in the sagittal plane.

Aged↗
PubMed1995

Treatment of respiratory insufficiency in Duchenne's muscular dystrophy: nasal ventilation in the initial stages.

Fourteen patients with Duchenne's muscular dystrophy (DMD) received nasal ventilation at the beginning of the declining phase of their vital capacity (VC). At that point, the mean value (SD) of their vital capacity was 1,756 (363) mL notably inferior to the predicted values. Nasal ventilation was performed according to a precise protocol, with an average nocturnal duration of 8 h. The annual decline of vital capacity was about 70 ml, showing a significant reduction compared with the value of 200 mL.yr-1 of untreated patients. Follow-up of treated patients (3.8 yrs; SD 1.9 yrs) has enabled us to distinguish different groups of results with useful practical consequences. In 29% of cases, the initial progression of decline of vital capacity was poorly modified by the treatment. In 71% of patients, the decline of VC was significantly decreased. In 35% of cases tracheal ventilation followed nasal ventilation. The normal mortality rate of DMD has greatly changed as a result of this method.

Adolescent↗
PubMed1993

Changes in cytosolic resting ionized calcium level and in calcium transients during in vitro development of normal and Duchenne muscular dystrophy cultured skeletal muscle measured by laser cytofluorimetry using indo-1.

Intracellular calcium activity was recorded during in vitro myogenesis of human normal and DMD muscle, using the calcium probe Indo-1 under laser illumination, at rest and during different kinds of stimulation (acetylcholine, high K+, caffeine). In myoblasts, the resting intracellular calcium level was significantly larger in DMD cells (89 +/- 9 nM; n = 40 vs 37 +/- 5 nM; n = 22) but there was no significant difference in myotubes, after fusion (44 +/- 4 nM; n = 34 vs 36 +/- 4 nM; n = 52). A similar evolution was observed in cells cultured from FSH biopsies. The amplitude of ACh- and high K(+)-induced calcium transients was significantly halved in DMD myotubes as compared to control ones and non-significantly decreased for caffeine responses. Some alterations in the kinetics of responses were observed in DMD muscle: the rising phases of ACh- and high K(+)-elicited transients and the decaying phase of the ACh-responses were significantly slowed down. It is concluded that: (i) in aneurally cultured human muscle, an increase in the basal level of internal calcium can occur at early stages of myogenesis before the expression of the dystrophin gene; and (ii) the changes in calcium transients induced by depolarization or direct stimulation of sarcoplasmic reticulum are not susceptible of inducing a calcium overload in DMD cells.

Acetylcholine↗
PubMed1992

A third type of calcium current in cultured human skeletal muscle cells.

A third type of calcium current could be recorded on a non-negligible number of human skeletal muscle cells (normal and Duchenne dystrophic (DMD)) in primary culture. This transient current exhibited a maximum at 0 mV, a time-to-peak around 30 ms, an inactivation time constant around 70 ms and was insensitive to nifedipine. On these basis, it differentiates from T- and L-type previously described and looks like the neuronal N-type. However, this third type of current was not sensitive to omega-Cgtx, a specific N-type blocker. The occurrence and the possible role of this current are briefly discussed.

Calcium Channel Blockers↗
PubMed1990

Calcium currents in normal and dystrophic human skeletal muscle cells in culture.

Human muscle cells obtained from biopsy specimens were grown in a primary culture system and electrophysiologically studied. Whole cell patch-clamp recordings revealed the presence of two types of calcium currents: (i) a low-threshold (-60 mV) one (ICa, T) with fast activation and inactivation kinetics (time-to-peak: 39 ms at -30 mV); and (ii) a high-threshold (-10 mV) one (ICa,L) with slower kinetics (time-to-peak: 550 ms at 20 mV). These two types of calcium currents could be also distinguished by their pharmacological characteristics since ICa,L was sensitive to the antagonist and agonist dihydropyridine derivatives contrary to ICa,T which was completely resistant to these compounds. These functional calcium channels existed both in normal and Duchenne dystrophic (DMD) human skeletal muscle cells in culture. We discuss a possible role of these two types of calcium channels in the myoplasmic calcium accumulation observed in the Duchenne muscular dystrophy.

Calcium↗
PubMed1985

[Treatment of Duchenne's myopathy with early physiotherapy. Critical analysis].

The efficiency of a therapeutic modality in Duchenne Muscular Dystrophy (DMD) is difficult to judge. The usual criterion used is the time period between the beginning of walking and its loss. Thirty-five patients treated with early intensive physiotherapy were compared with 28 untreated ones. On average, the prolongation of walking in the treated group was 8 months. However, average age of death was 18 years 8 months in treated patients and 20 years 2 months in untreated patients. In order to judge the benefits of a treatment it is absolutely essential to consider the whole of the evolution of the disease, without omitting the wheelchair bound stage when the most severe complications occur.

Adolescent↗
PubMed1984

The treatment of scoliosis in Duchenne muscular dystrophy.

There are not, as yet, clear indications for the surgical management of scoliosis in Duchenne muscular dystrophy (DMD), taking into account the varying severity of the clinical course. Monitoring the vital capacity can be most important for the indication and timing of surgery. In some cases, delaying surgical intervention with conservative management using spinal braces and wheelchair inserts can permit the restrictive lung syndrome to advance to the point that surgery will be contraindicated. Ten such patients conservatively treated for an average of 5 years exhibited perhaps a slower progression but ultimately an advanced deformity. From a second group of five carefully selected and surgically treated patients, indications for spinal surgery were reviewed. Surgical intervention should be prophylactically undertaken when there is high risk of a rapidly evolving curve with a severe restrictive lung syndrome.

Braces↗
PubMed1984

[Therapeutic indications in scoliosis of Duchenne muscular dystrophy. Apropos of 10 cases].

Ten patients suffering from Duchenne muscular dystrophy were followed up for more than 7 years. The diagnosis was determined by biopsy. Progress of the disease was severe and all patients died before the age of 18. The average angle of the scoliosis at the end of this development was 73 degrees. The maximum vital capacity was 1198 ml. The authors conclude that neither the use of a brace nor adaptation of a wheelchair are helpful. Surgical treatment is hazardous when the curve is greater than 23 degrees. The indications for such treatment are based on the importance of the degree of pulmonary restriction and on early signs of severe progress of the scoliosis.

Child, Preschool↗