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Biomedical subjects

P Chevalier

Publications and source records attributed to P Chevalier.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Thrombosis on the mitral valve prosthesis and disseminated cancer: treatment by fibrinolysis].

The authors report the case of a 63-year-old woman with occlusive thrombosis of a mitral valve prosthesis and cardiogenic shock successfully treated by systemic thrombolytic therapy. This treatment was given despite metastatic hepatic and bone breast cancer. This, and other recently reported cases, argues in favour of widening the indication of thrombolysis as treatment of first intention in cases of obstruction of atrioventricular valve prostheses. Nevertheless, the relative safety of surgical treatment and the risk of systemic thromboembolism of thrombolysis, incites caution and reservation of medical therapy for carefully selected patients.

Breast Neoplasms↗
PubMed1995

[Muromonab CD3 (Orthoclone OKT3) for the prophylaxis of heart allograft rejection. Hemodynamics and respiratory tolerance].

OBJECTIVE: Treatment of transplant rejection with muromonab CD3 (Orthoclone OKT3) may result in haemodynamic instability and pulmonary oedema, which would question its prophylactic use. The aim of this study was to the evaluate haemodynamic and respiratory tolerance of prophylactic treatment of cardiac rejection with OKT3. STUDY DESIGN: Prospective clinical study. PATIENTS: Twelve patients, whose pulmonary arterial resistances before transplantation were less than 400 dyn.s.cm-5, with haemodynamic and respiratory stability during the 4 hours before OKT3 administration. METHOD: Patients under preventive haemodynamic support with isoprenaline 0.05 micrograms.kg-1.min-1 and dopamine 3 micrograms.kg-1.min-1. Immunosuppressive treatment with azathioprine 5 mg.kg-1 at d0 and 3 mg.kg-1 at d1 and d2 and with methylprednisolone 720 mg at d0 and 240 mg at d1 and d2. OKT3, 5 mg administered i.v. at d0, d1, d2. Respiratory and haemodynamic variables were recorded prior to (T0), 30 min (T1) and 360 min (T2) after injection of OKT3. RESULT: Neither clinical nor radiological changes were observed after the OKT3 injections. At d0, T2, the heart rate increased and PaO2 and SaO2 decreased. At d1 and d2, T1, PaO2 decreased, and QS2QT at T1 d2 increased by nearly 3%. CONCLUSION: OKT3 does not result in major circulatory and haematosis changes, provided patients are selected, especially free of pretransplantation pulmonary hypertension. Prior to the treatment with OKT3, they should be in a satisfactory haemodynamic and respiratory status and receive high doses of corticosteroids.

Adult↗
PubMed1995

[The in-vitro inactivation of HBsAg by extracts of plants in the genus Phyllanthus].

Three species from the Phyllanthus genus coming from the Cuban eastern zone were studied to determine the inactivation capacity of the surface antigen (Ags HB) of in vitro hepatitis B virus. Alcoholic extracts were prepared from each species and from different parts of such plants, and sera from patients positive to Ags HB were treated with them. Results demonstrate that the analysed species own the capacity of inactivating that antigen between the 93 and the 97% of the sera assayed. The inactivation capacity analysis of the three parts of Phyllanthus chamaecristoides revealed a greater activity in extracts from the stems (97%) with a behavior resembling the two incubation temperatures used. The presence of flavonoids in the extract of this species is observed.

Chi-Square Distribution↗
PubMed1994

Aprikalim: radioimmunoassay and pharmacokinetic studies in mouse, monkey, and dog.

A stereoselective and specific radioimmunoassay (RIA) was developed for aprikalim (RP 52891), a novel potassium channel opener. Antibodies were produced in rabbits immunized with the pure levorotatory enantiomer (1R,2R) of the hapten derivative bearing an acid function at the end of the lateral chain and conjugated to bovine serum albumin. In displacement studies with the enantiomerically pure radioligand (radioiodinated tyrosine methyl ester conjugate of the hapten derivative), the opposite enantiomer showed only 0.1% cross-reaction. Negligible binding occurred when analogues or metabolites of aprikalim were tested for cross-reactivity. The detection limit was 0.25 ng/mL (9.31 x 10(-10) M) in a 20-microL plasma sample. The assay was used successfully to determine aprikalim pharmacokinetics in mice, monkeys, and dogs. Beagle dogs were given a 10 micrograms/kg intravenous (iv) bolus dose or 10 micrograms/kg iv bolus followed by 0.1 microgram/kg/min infused over 30 min (nonhypotensive doses which reduce myocardial infarct size significantly). The plasma concentrations declined monoexponentially with a mean overall elimination half-life of 1.53 h and a mean plasma clearance of 52 mL/min (5.1 mL/min/kg). A slow-release oral formulation produced a significant delay in the rate of absorption, a 4-fold decrease in the peak plasma level, and a 2-fold decrease in apparent oral bioavailability relative to that observed for an oral solution. A comparison of aprikalim pharmacokinetic parameters in mouse, monkey, and dog revealed great similarity in disposition characteristics in these species.

Animals↗
PubMed1994

In vitro lymphocyte-differentiating effects of thymulin (Zn-FTS) on lymphocyte subpopulations of severely malnourished children.

This work investigates how thymic dysfunction contributes to the depression of cell-mediated immunity in protein-energy malnutrition (PEM). In Bolivian children hospitalized for severe PEM, the size of the thymus was measured by echography, and the lymphocyte subpopulations were detected by using monoclonal antibodies. These data were compared with those obtained from healthy control subjects. Regardless of the clinical form of PEM, our results show a high degree of T lymphocyte immaturity in severely malnourished children, which correlates with a severe involution of the thymus. Before in vitro incubation with thymulin, this significant increase in the percentage of circulating immature T lymphocytes was concomitant with a decrease in mature T lymphocytes and a slight increase in cytotoxic T subpopulations. After in vitro incubation with thymulin, immature T lymphocytes decreased and mature T lymphocytes increased.

Anthropometry↗
PubMed1994

Vagal release of vasoactive intestinal peptide can promote vagotonic tachycardia in the isolated innervated rat heart.

OBJECTIVE: The aim was to determine the extent to which endogenous release of vasoactive intestinal polypeptide (VIP) might be implicated in the modulation of sinoatrial rate in the presence and absence of muscarinic blockade or beta blockade. METHODS: Langendorff perfused rat hearts were studied with the right vagus intact. The hearts were maintained in sinus rhythm and subjected to right vagal stimuli of 5, 10, 20, and 30 Hz. RESULTS: Administration of exogenous VIP, 10(-8) M, increased sinus rate by 20% (p < 0.05). This increase in heart rate was reduced significantly to 8% by the VIP antagonist [D-p-Cl-Phe6, Leu17]VIP, 10(-7) M, which alone had no effect on sinus rate. Vagal stimulation reduced sinus rate from a control of 254(SEM 2) to 164(17) beats.min-1 (p < 0.05) at 20 Hz. VIP, 10(-8) M, increased these rates to 284(6) and 220(21) beats.min-1 (p < 0.05). In another eight vagally stimulated hearts, frequencies of 5-20 Hz reduced sinus rate. At 30 Hz heart rate increased in five, and the resultant rate was significantly faster in these [154(10) beats.min-1] than in the remainder [98(12) beats.min-1, p < 0.05]. Vagal stimulation also increased sinus rate (p < 0.05) in four of seven additional hearts perfused with atropine, 2 x 10(-6) M. This increase was completely abolished by [D-p-Cl-Phe6, Leu17]VIP. That the effect was not beta adrenergic was demonstrated in eight experiments using atropine plus propranolol, 1 x 10(-7) M. A vagally induced increment in rate still occurred (p < 0.05) and was abolished by [D-p-CL-Phe6, Leu17]VIP. The ability to ascribe a rate change to VIP release was maximal in the presence of propranolol and atropine, intermediate in the presence of atropine alone, and minimal in the absence of muscarinic or beta blockade. CONCLUSIONS: Vagally released VIP is capable of limiting the decrement in sinus rate that occurs at high frequencies of vagal stimulation, and in some circumstances can actually increment sinus rate. Its role as an endogenous modulator of vagal effects on heart rate and as a possible cause of vagal and postvagal tachycardias should be further explored.

Animals↗
PubMed1994

Tubulin binding agent CI-980 has positive inotropic and local anesthetic actions.

Tubulin binding agents inhibit tubulin polymerization by actions at specific binding sites. CI-980 acts at the colchicine-binding site, which is distinct from the vinca-alkaloid binding site. We studied the actions of CI-980 in two models: neonatal rat myocytes in tissue culture and adult canine Purkinje fibers. In the first model, experiments on cell shortening and calcium signaling (using fluo3) showed that CI-980 increased the amplitude of both cell shortening and the Ca signal. The comparison drug, vinblastine, shared the effect on Ca signaling, but not that on cell shortening. In addition, high concentrations of CI-980 decreased the beating rate of spontaneously firing cell cultures. In canine Purkinje fibers, CI-980 decreased action potential amplitude (APA), Vmax, and conduction velocity and prolonged repolarization. It also decreased automaticity and suppressed delayed afterdepolarizations (DAD). These studies suggest that CI-980 is a novel compound in that it exerts antiarrhythmic effects on the AP but is positively inotropic. Whether all these actions derive from a primary effect on tubulin or whether they reflect action on both tubulin and transsarcolemmal ion channels remains to be determined.

Action Potentials↗
PubMed1994

Pharmacokinetic and pharmacodynamic study of suriclone imipramine interaction in man.

Suriclone is a novel cyclopyrrolone exhibiting anxiolytic activity. Twelve healthy Caucasian male volunteers participated in the study. A single dose of suriclone 0.4 mg, imipramine 75 mg, suriclone 0.4 mg + imipramine 75 mg, or placebo was given according to a 4 x 4 Latin-square design in order to assess the effect of drug association on pharmacokinetics and psychomotor performances. Visual analogue scale ratings, critical flicker frequency, choice visual reaction time, and Pauli, picture memory and Sternberg tests were performed before and 1.5, 6 and 9 h after drug administration. Suriclone, with the exception of the Pauli test, had no effect on psychomotor performances. The imipramine-suriclone association appeared to disturb some performances (no statistical significance), probably due to the effect of imipramine. Blood samples were collected for determination of imipramine and suriclone plasma levels respectively by high-performance liquid chromatography and radioimmunoassays. Suriclone AUC, Cmax and Tmax were not affected by imipramine, and reciprocally.

Adult↗
PubMed1994

Radiofrequency ablation of atrial flutter. Efficacy of an anatomically guided approach.

BACKGROUND: Previous reports have shown that radiofrequency ablation can terminate atrial flutter and prevent recurrences. However, different methods have been used, and the current experience remains limited. The objective of the present study was to determine the efficacy of radiofrequency ablation of atrial tissue in patients with atrial flutter using an anatomically guided approach. METHODS AND RESULTS: We treated 22 patients aged 30 to 73 years. Atrial flutter was recurrent for a mean of 5 years despite the administration of multiple antiarrhythmic drugs. Radiofrequency current was directed to the atrial isthmus between the inferior vena cava and the tricuspid ring, regardless of the morphology of local electrograms. Radiofrequency energy was applied during typical atrial flutter in 12 patients, atypical atrial flutter in 2 patients, and successively both forms in 8 patients. In 19 patients, atrial flutter abruptly terminated. In 3 patients, atrial flutter persisted despite 37, 48, and 25 applications, respectively. Atrial recordings demonstrated that atrial flutter termination occurred as a consequence of conduction block at the site of radiofrequency energy application, regardless of the type of atrial flutter. The number of applications before termination ranged from 1 to 82 (mean, 32). Atrial flutter could no longer be induced in every case. There were no complications. During a 13-month mean follow-up, atrial flutter recurred in only 2 of the 19 patients who had a successful ablation. Four patients experienced chronic atrial fibrillation, and 2 of them returned to sinus rhythm with antiarrhythmic therapy. CONCLUSIONS: Radiofrequency ablation of atrial flutter using anatomic guidance is feasible and effective. Further experience is needed to delineate its role as an alternative approach to the management of refractory atrial flutter.

Adult↗
PubMed1994

[Electron beam scanner and thoracic transplantation].

To follow an heart transplantation, EBCT is more precise than ultrasonography and scintigraphy to calculate a stroke volume. In lung transplantation, it is important before surgery to know the value of right ventricule stroke volume in order to choice the surgical protocol. After lung transplantation SFE helps to follow the patient to look after complications, to drain a collection or to guide a biopsy. SFE contribution is discussed in rejection, infectious diseases, detection of immuno-induced carcinomas, in bronchiolitis obliterans and recurrence of the primitive disease.

Graft Rejection↗
PubMed1994

[Aspergillosis and renal, heart and lung transplantation].

The increase of organ transplantations during the last decades conjointly with the prescription of heavy immunosuppressive drugs, has led to an increased incidence of new invasive aspergillosis (IA). This study is a report of the Broussais Hospital experience from 1968 to 1993 on kidney, heart and heart and lungs transplantations. It concerns 21 IA cases. Incidence was 0.5% for kidney, 4.5% for heart and 18% for heart and lungs transplantations. The most important risk factors were the increase of immunosuppressive therapy (66% of the cases), neutropenia (19%), and renovation of the hospital wards (36%). Lung was the most frequent site of infection (95% of the cases), clinical symptoms were no significant. Diagnosis procedures were realised on biopsy (23%) and on bronchoalveolar lavage (66%). Usual amphotericin B treatment was disappointing: mortality rate of 77%, the liposomal preparation of the drug seemed to be more efficient: mortality rate of 50%. Itraconazole appeared to be used in succession with a careful adaptation of posology. Prophylactic amphotericin B in a local way (sprays and aerosols) led to a good efficiency jointly with the patient isolation during constructions in the hospital area.

Adolescent↗
PubMed1993

Primary cardiogenic shock during acute myocardial infarction: results of emergency cardiac transplantation.

Fifteen patients with acute myocardial infarction and cardiogenic shock underwent emergency cardiac transplantation after medical treatment failed to improve their haemodynamic status. Their mean age was 49 +/- 7 years. The infarction was anterior in 12 cases, inferoposterior in two cases, and septal in one. Shock occurred within 3 days after the onset of chest pain in nine patients, and during the first day in six of them. Mechanical circulatory assistance was used in six patients as a bridge to transplantation when their haemodynamic status could not be stabilized pharmacologically. Orthotopic cardiac transplantation was performed an average of 15.6 +/- 14 days after onset of infarction. Three patients died during the early post-operative period. Another died 7 months after transplantation. During the mean follow-up period of 30.6 +/- 20.3 months, there were three acute rejections, all successfully treated, and one chronic rejection. The survival rate for this series is 70%. Thus, emergency cardiac transplantation may be the best option for selected patients with acute myocardial infarction and cardiogenic shock refractory to conventional therapy.

Adult↗