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Biomedical subjects

G Duport

Publications and source records attributed to G Duport.

At least 37 records · Page 2Linked to original sources
PubMed1995

Abnormal calcium homeostasis in Duchenne muscular dystrophy myotubes contracting in vitro.

Resting intracellular calcium activity was recorded in three kinds of human muscle cells in culture: normal (control) and dystrophic (DMD and FSH), by means of a ratiometric fluorescence method using the calcium probe Indo-1 under laser illumination. DMD cells are characterized by a lack of dystrophin whereas FSH cells express normal dystrophin. The aim of this study was to determine whether, in dystrophin-deficient muscle cells (DMD), contraction destabilized internal calcium homeostasis. Muscle cells were cocultured with rat spinal cord explants to improve the maturation of human myotubes up to the stage where contraction appears. The resting intracellular calcium level was significantly higher in contracting DMD cells (107 +/- 8 nM; n = 44) compared to control cells (66 +/- 6 nM; n = 43) or in FSH cells (56 +/- 6 nM; n = 35). DMD myotubes cocultured in the presence of TTX which inhibited contractile activity, did not develop an increase in free cytosolic Ca2+ concentration. The amplitudes of calcium transients elicited by exposure to acetylcholine (ACh) or high K+ medium (100K) were significantly higher in contracting DMD myotubes than in control ones. The extra-responses were not observed in DMD myotubes cocultured with TTX. This study strongly suggest that: (i) contraction is a dominant factor contributing to Ca2+ abnormalities in DMD cells; and (ii) contracting dystrophin-deficient cells have defective calcium handling mechanisms during electrical events which involve sarcolemma.

Acetylcholine↗
PubMed1995

[Metacarpal aneurysmal cysts. Report of two cases and review of the literature].

The authors present two cases of aneurysmal cyst, one primary and one secondary. The first case was treated surgically by resection and bone graft. The second case, associated with a giant cell tumors, was initially treated surgically by resection and bone graft, but, because of a rapid recurrence of the giant cell tumor, the middle finger had to be amputated. The clinical, radiological and histopathological features of aneurysmal cyst are recalled. The various therapeutic modalities recalled and their value in this particular site are discussed.

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↗
PubMed1992

[Place of the right gastro-epiploic artery in coronary revascularization by exclusive arterial grafts].

From March 1990 to July 1991, 35 patients underwent coronary artery bypass grafts using the right gastro-epiploic artery (GEA). Twenty-nine patients had exclusively arterial grafts using a combination of GEA and internal mammary artery (IMA) in situ. The selection criteria for this group of 29 patients included a life expectancy exceeding ten years to avoid the need for reoperation due to deterioration of the grafts. This group consisted of 27 men and two women under the age of 70 years (mean age: 58 years, range: 36 to 70), 11 patients (38%) were under the age of 50 years and 15 (52%) were under the age of 60 years. Cardiac status was relatively well preserved. The mean ejection fraction was 58% (range: 25-70%). Fourteen patients (48%) had had a preoperative myocardial infarction. Fifty-five p. cent were smokers, 41% suffered from HT and 31% had a dyslipidaemia. Six patients (20%) had respiratory failure, 6 others (20%) were severely overweight and 2 patients were diabetic. According to the NYHA classification, 14 patients (48%) were stage IV, 9 patients (31%) were stage III and 6 patients (20%) were stage II. The mean number of bypass grafts per patient was 2.8 and 8 sequential bypass grafts (27%) were performed. The GEA was used in 29 cases, the left IMA was used in 28 cases, the right IMA was used in 13 cases and the epigastric artery was used as a free graft in 3 cases. Associated lesions included a resected left ventricular aneurysm. No associated valve procedures were performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Distal ischemia of the upper limb due to obliteration of the ulnar artery at the wrist: surgical treatment].

So-called "Raynaud's distal ischaemic phenomena of the upper limb may be responsible for disabling functional impairement and even lesions requiring amputation of one or several fingers. The ulnar artery is usually involved in these phenomena because of its anatomical position and its importance in the blood supply of the hand and the fingers. The authors present three clinical cases of distal ischaemia of the upper limb due to obliteration of the ulnar artery at the wrist, treated by microsurgical vein graft. A review of the literature revealed only 23 well documented cases of this type of treatment, i.e. 10% of all treatment options, which gave 95 to 100% of favourable results. The three patients in our series, reviewed after 2, 3 and 5 years, were considered to be cured. Although the severity of the disease can be evaluated by the clinical course, arteriography appears to be the key examination for diagnosis, prognosis and choice of treatment. However, two practical attitudes are recommended to avoid the risk of progression towards digital necrosis: when the symptoms are chronic, arteriography is indicated in the case of resistance to medical treatment or immediately in the case of unstable symptoms. The diagnosis of occlusion of the ulnar artery at the wrist then justifies treatment by microsurgical vein graft; when the symptoms are acute, treatment should preserve as much as possible the palmar and digital ulnar arterial blood supply.

Adult↗
PubMed1991

[Early angiographic assessment of coronary revascularizations using the internal mammary artery. Apropos of a consecutive and prospective series of 180 bypass grafts].

This report describes a consecutive and prospective series of 136 patients, who underwent coronary bypass using the internal mammary arteries. Coronary angiography was routinely performed on all patients 8 days after surgery. A total of 137 operations (1 reoperation) were performed on 180 coronary arteries using 132 left internal mammary arteries and 25 right internal mammary arteries. Direct bypass was performed 133 times (73.8%), sequential bypass 23 times (25.5%) and free graft once. Bypass involved 1 coronary artery 89 times (65.4%), 2 coronary arteries 46 times (33.8%) and 3 coronary arteries in 1 case. The overall early success rate of internal mammary bypass in this series was 94.8% including 2 bypasses which were patent but non-functional. Of the 23 sequential bypasses, only 1 anastomosis out of 46 was not patent for a success rate of 97.3%. These good results are attributed to the large diameter of the mammary artery. Early postsurgical imaging is valuable for several reasons. It allows detection of surgical errors and improvement of the procedure. It enables distinction between residual primary surgical stenosis and secondary stenosis or genuine restenosis. It allows analysis of perioperative complications allows. No correlations between myocardial infarction and bypass obstruction were found. Finally, it permits endoluminal therapies such as thrombolysis (1 case in this series) and dilatation (2 cases). In conclusion, although we do not perform angiography routinely, our policy is to perform imaging in all cases of postoperative complications and after certain procedures such as sequential bypass.

Anastomosis, Surgical↗
PubMed1991

[Primary results of laser recanalization in the endovascular treatment of arterial stenosis and occlusion of the lower limbs. Apropos of 45 treated cases].

Forty-five lower limb arterial lesions were treated by Nd Yag laser angioplasty using 1.4 and 2 mm hybrid catheters in 31 patients. This population comprised 28 men and 3 women (average age 63.8 +/- 3 years) 20 were in Stage II, 5 in Stage III and 6 in Stage IV of Fontaine's classification. The arteriographic lesions were 22 occlusions with an average length of 12.3 cm and 23 stenoses averaging 87% luminal reduction a few millimeters long to a maximum of a string of stenoses. Seventeen of these lesions were very calcified. The stenoses were situated on the iliac artery (7 cases), superficial femoral artery (28 cases), popliteal artery (9 cases) and the tibio-peroneal artery (1 case). There were no fatalities or recourse to emergency surgery. All patients underwent complementary balloon dilatation. The immediate patency rate was 91% in stenotic and 72% in occlusive lesions. At one week, the patency rate for stenotic lesions was unchanged but it had fallen to 59% for occlusive lesions (arteriographic evaluation). Angioscopy was used 22 times: it was indissociable to laser angioplasty as it enabled diagnosis and controlled the result. The use of thermal laser with hybrid catheters (metallic window tip) in endovascular procedures is a safe and effective method of treating stenosis and occlusion of lower limb arteries.

Adult↗
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↗
PubMed1988

Sino-atrial dissociation: evidence by intracardiac recordings in man and by microelectrode studies on isolated rabbit atrium.

The electrophysiologic mechanisms of sinus dysfunction have recently been determined by direct recordings of the sinus node electrogram. The association of various degrees of abnormalities in the formation of the impulse within the sinus node and of sinoatrial conduction block, represents the pathophysiological substrate of the mechanism of sinus node dysfunction. The purpose of this work is to present clinical and experimental data supporting the concept of sinus node isolation. In our clinical case, the sinus node was probably intact despite aspects of sinus node dysfunction on the surface ECG. Sinus node electrograms were recorded with a sinoatrial conduction time of 100 ms (normal values in our laboratory: 83 ms +/- 38 ms). Atrial mapping demonstrated that the area depolarized by the sinus node involved a 2 cm2 zone surrounding it. This perisinusal activity could not be recorded on the surface ECG. Both exit and entry blocks in the sinus node were demonstrated. Our experimental data showed a total desynchronization between the electrical activity of the sinus node and that of the atrium under hypoxic conditions. Both types of cases demonstrated that an atrial dysrhythmia was coexisting with regular sinus activity. From these data we concluded that a sinus node free from any pathological involvement could be associated with severe symptoms of sinus node dysfunction on the surface ECG.

Animals↗
PubMed1986

[Intra-sinus echo: demonstration using direct intracavitary recording of the sinus potential].

The authors searched for intra-sinusal echos during electrophysiological investigation of 53 patients (41 men, 12 women, average age: 61 +/- 12 years). Cycles of sinus echos were recorded in 8 patients (15 per cent). The period during which sinus echos could be recorded was 125 ms (average 40.6 +/- 34 ms). Indirect assessment of sinus node function in patients with sinus echos was normal (corrected sinus node recovery time, estimated atrio-sino atrial conduction times using Narula's technique). A valid and reproducible direct recording of the sinus node potential was only possible in one patient. In this case the echo cycles were provoked by stimulation periods of between 440 and 320 ms (echo zone of 120 ms). All the echos obtained were preceded by a sinus node potential with a different duration and morphology to that observed during basal sinus cycles (respective sino-atrial conduction times 105 and 115 ms). In this patient we were also able to induce sinus echos after a single extrastimulus during the spontaneous rhythm. the echo zone was 130 ms and with a shorter coupling interval (310 ms) two successive sinus echos were recorded. The demonstration of intrasinusal echos by direct recording of the sinus node potential supports the experimental data of Allessie and Bonke on isolated right atrial tissues of the rabbit. Improvements in the technique of endocavitary direct recording of the sinus node potential in man should complete this data by showing the possibility of sinoatrial tachycardias due to reentry.

Action Potentials↗
PubMed1982

Curative and aesthetic results of surgical treatment of 138 basal-cell carcinomas.

We herewith present a review of 138 basal-cell carcinomas, mostly on the face, that were treated by surgical excision and immediate repair. In a few cases, frozen sections were taken to ensure complete excision of the neoplasm. Local flaps were favored; distant flaps and full-thickness skin grafts were required in selected case. The recurrence rate with a minimum of 3 years of follow-up is 2.1%. Cosmetic results, evaluated by the patients themselves and by one of the authors (G.D.) who did not participate in the surgery, were judged "excellent," that is, without visible scars or deformities, in 61.4% of the cases, and "good" in 31.4%. The results are discussed.

Aged↗
PubMed1981

[Calculation of the ejection fraction from simultaneously recorded systolic intervals and angiography. Comparative study].

Garrard, Weissler and Dodge have reported a close correlation (r = -0,90) between angiographic ejection fractions (EF) and the ratio of left ventricular preejection and ejection periods (PEP/LVET) in patients with left ventricular disease without simultaneous recording equation Y" = 1,25 - 1,25 x where x is the PEP/LVET ratio and Y" the ejection fraction. Using this formula a theoretical EF may be calculated when the PEP/LVET ratio is known. A number of precautions must be taken in measuring systolic time intervals (synchronous recordings, rapid and constant recording speeds of at least 100 mm/s, good quality tracings). Respecting these conditions, close correlations between the theoretical and angiographic EF were obtained. However, discrepancies were observed in some cases and so the relationship was examined with and without simultaneous recordings in 28 patients (19 with coronary artery disease). The equations obtained were Y = 1,2 - 1,51 x and Y = 1,04 - 1,04 x respectively. The correlations in the whole group and in the coronary subgroup were not as good when the recording was not simultaneous (r = -0,78, compared to r = -0,85). The theoretic EF appeared to be "optimised" under these conditions. The "optimisation" increased with increasing values of the PEP/LVET ratio. A downward correction had to be made for abnormally high values (for example for a PEP/LVET of 0,38, the EF had to be corrected by -3,1% and for a value of 0,50 by -10,5%). This was also applicable in the patients with coronary artery disease. Curiously, the equation relating simultaneous EF and PEP/LVET was very close to that obtained by Garrard (Ya = 1, 12 - 1,27 x, ra = -0,80). The theoretical EF calculated from this equation was very close to the angiographic value. However, it was slightly higher or lower in coronary patients with or without myocardial infarction. Garrard's equation would appear to be useful for repeated studies of the ejection fraction in these patients.

Adult↗