Biomedical subjects
Publications and source records attributed to P Chauvin.
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Myotonic muscular dystrophy (MyD) is an inherited human disease involving skeletal muscle as well as many other organ systems. We have approached the study of this disorder by growing normal and diseased human muscle in a primary tissue culture system and investigating some of the electrical properties of the resulting myotubes. The most distinctive abnormality noted in MyD myotubes was an increased tendency to fire repetitive action potentials. A decreased action potential afterhyperpolarization amplitude and the presence of depolarizing afterpotentials were also noted, as were a decreased resting membrane potential, decreased action potential amplitude and overshoot, and decreased outward-going rectification. Although the ionic basis of these abnormal properties in vitro is not clearly defined, changes in the slow outward-going potassium current offer the best explanation. Furthermore, MyD cell culture offers a valuable model for critical analysis of the molecular mechanisms underlying MyD deficits.
Clinical and radiological results of an antirejection therapy based on the local action of a thyroid hormone, thyrocalcitonin, were studied. A double action was noted as it may stop the rhyzalase, and, more particularly, it reestablishes normal alveolodental relationships. Immunological factors are discussed. The therapeutic mode of action is emphasized as being a new method of local treatment.
A clinical experimental study involving human grafts (heterochronic and heterogenic homografts) was carried out after different techniques (isolation, preservation, decontamination, freezing-thawing cycles of grafts). Surgical application then the clinical and radiological course were followed up over a period of up to 4 years. Some pulp specimens were examined histologically. Clinical, radiological and histological correlation was envisaged in order to offer hypotheses, in particular immunological, with regard to the course of the process.
Postoperative analgesia by the use of acupuncture was attempted in 88 cases after stomatological operations, of which 60 were for impacted wisdom teeth. During the three years of clinical study of this method it has become simplified; from being applied before, during, and after operation, acupuncture is now used exclusively postoperatively without apparent effects on the analgesia obtained. The results appear to be extremely favourable in relation to those obtained under routine conditions after operation without acupuncture.
Myasthenia gravis is an autoimmune disease of man characterized by remitting and relapsing muscle fatigability. Although the etiology and pathogenesis are incompletely understood, the presence of circulating antibodies directed against the nicotinic acetylcholine (ACh) receptor in 80--90% of patients with myasthenia gravis and the identification of immune complexes at their neuromuscular junction have helped explain the altered neuromuscular transmission. The ACh receptor antibodies do not block access of ACh to the receptor, but do decrease the number of receptors by accelerating their degradation both in rat myotube cultures and in vivo models. In vitro these antibodies play a major role in myasthenia gravis. However, correlations of antibody titers with the clinical state following thymectomy or in neonatal myasthenia suggest that host factors may be equally important in determining whether the ACh receptor antibodies will result in clinical myasthenia.
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In France, the sentinel general practitioners of the French Communicable Diseases Network (FCDN) monitor the epidemiological surveillance of eight communicable diseases, including measles. For the last 10 years, this surveillance has shown a seasonality of the annual incidence of measles (with peaks in late spring) and a decrease in incidence since the last outbreaks in 1986 and 1987. This decrease, the increasing mean age of the cases and an increase in the percentage of appropriately vaccinated cases are due to the increasing vaccination coverage of children due to the national immunization programme was reinforced in 1989. However, with 75,000 cases in 1993, measles is far from being a rare disease in France; epidemiological surveillance and improved vaccination coverage are still necessary.
The seeds and roots of Heliotropium lasocarpium, contain a pyrrolizidine alkaloid which causes toxic liver injury and veno-occlusive disease (VOD), characterised by an occlusive lesion of the centrolobular veins of the liver, when consumed by humans. The Farkhar region of Southern Tadjikistan, was blockaded from May to November 1992. This led to a famine and a delay of two months in the wheat harvest. Heliotropium lasocarpium had time to grow in the fields and their seeds were therefore collected with the wheat. The contaminated wheat was distributed to the population, who milled it and made bread. The first case of liver toxicity was six weeks after the first consumption of the contaminated bread. By March 1993, 3,906 cases had been recorded (attack rate = 4%). The attack rate were 0.4%, 5.4%, 4.0%, 2.8% and 1.5% for the less than 1 year, 1-14 years, 15-30 years, 31-50 years and over 50 years age groups respectively. The overall case fatality ratio (CFR) was 1.3% and increased with age from 0 to 5.9% in the same age groups. Two of the ten collective farms represented 83.3% of the cases attack rate of 16.9% and 23.6%. Four stages of illness were defined. Stage I corresponds to abdominal pain, nausea or vomiting, and asthenia. All stage I patients (55.5%) recovered rapidly. Stage II is an association of Stage I and hepatomegalia (29.9%). Stage III includes ascites in addition to these symptoms (13.7%) and stage IV alteration of consciousness (0.9%). The last case was reported on March 4th 1993.(ABSTRACT TRUNCATED AT 250 WORDS)