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S Lafitte

Publications and source records attributed to S Lafitte.

At least 37 records · Page 2Linked to original sources
PubMed2001

Accuracy and reproducibility of coronary flow rate assessment by real-time contrast echocardiography: in vitro and in vivo studies.

Real-time myocardial contrast echo (MCE) provides the potential to assess myocardial blood flow from time-intensity refilling curves after high-energy bubble destruction. This study validated the accuracy of this approach and the effect of specific examination variables and instrument settings on results. The effects of examination depth and angle as well as dynamic range, pulse repetition frequency, and line density were assessed with the use of in vitro incremental flow rates produced in an in vitro tissue phantom. In vivo recordings of real-time imaging with an infusion of a contrast agent (Optison) were obtained in 7 open-chest dogs with graded left anterior descending artery stenosis at baseline and during adenosine hyperemia, and were compared with flow probe measurements. After bubble destruction, time-intensity data were fitted to an exponential function, and the rate of intensity increase (b) and peak plateau intensity (A) were derived from refilling curves. In vivo real-time values for b, but not A, correlated closely with flow probe measures (r = 0.93). A similar correlation for b was observed in vitro (r = 0.98). The correlation between flow rate and b was influenced by several examination variables, including depth, angle, and instrument settings. Real-time MCE provides accurate quantification of coronary flow by assessing the rate of microbubble refilling. However, this parameter may be affected by several examination and instrument variables. Therefore, real-time MCE refilling measures are best applied by comparing baseline values with those of stress studies.

Animals↗
PubMed2001

[Fibrinolysis in myocardial infarction with EKG elevation. Optimization of myocardial reperfusion by treatment with antithrombotic agents].

In the case of acute coronary syndrome with prolonged ST elevation on ECG showing an acute coronary obstruction, the urgent institution of fibrinolysis is a widely validated treatment. Since the first placebo controlled studies with streptokinase until the development of bolus administration rt-PA varieties, fibrinolytic agents have lowered mortality. Associated anti-thrombotic drugs are multiplying in parallel. Their association is recognised as necessary in order to avoid early reocclusions which worsen the prognosis of infarction, the fibrinolysis triggering a harmful prothrombotic effect, notably due to the clot thrombin re-exposed during thrombolysis. Aspirin has an essential place formally demonstrated in ISIS 2. Non-fractionated heparin has more complex effects and its administration protocol in association with fibrinolysis has recently been reviewed with a reduction in dosage because prolonged clotting times during fibrinolysis have provoked a distinct increase in the risk of intracranial haemorrhage. The low molecular weight heparins seem to have become the adjuvant treatment of choice following publication of the ASSENT-3 trial. Pentasaccharide seems attractive. The place of hirudine and its derivatives in the acute phase of MI appear limited after the results of the HERO-2 trial, associating hirulog and streptokinase, with the earlier studies also having been disappointing. The GPIIbIIIa blockers in association with a half dose of fibrinolysis do not aggravate the intracerebral haemorrhagic risk before 75 years old and clearly reduce hospital morbidity in infarction, at the price however of an increase in transfusions.

Aspirin↗
PubMed2001

[Anticoagulation in mechanical valve prostheses. A difficult situation].

Although long-term anticoagulant therapy in patients with mechanical valve prostheses is well codified, a number of difficult situations persists because of the high thromboembolic risk. The protocols of anticoagulation suggested in these situations are controversial as there are no large scale prospective therapeutic trials. However, modern protocols take more and more into account the thromboembolic risk in each individual case. The authors review the most common situations: the early postoperative period for which no precise consensus exists in the literature; anticoagulation in extra-cardiac surgery, a common situation for which the protocols remain very debatable; anticoagulation in pregnancy, a special situation because of the risk of embryopathy with oral anticoagulant therapy and the risk of thromboembolism with heparin; anticoagulation in cases of thromboembolic complications; anticoagulation during infectious endocarditis; anticoagulation during serious haemorrhage.

Anticoagulants↗
PubMed2000

Improved reliability for echocardiographic measurement of left ventricular volume using harmonic power imaging mode combined with contrast agent.

Harmonic power imaging (HPI) is a new echocardiographic modality that enhances the detection of contrast agents in the left ventricle. The endocardium can be delineated by conventional echocardiography using ultrasound contrast agents, although the images tend to be faint. The present study was designed to assess left ventricular volume using HPI after intravenous injection of the contrast agent Levovist (Schering SA, Berlin, Germany) in 25 unselected patients. End-diastolic volume, end-systolic volume, and ejection fraction were determined for each patient with angiography and with 4 different ultrasound modalities: (1) conventional mode without contrast, (2) contrast conventional mode, (3) contrast harmonic intermittent imaging mode, and (4) contrast triggered HPI. The use of HPI improved correlations between the echographic and angiographic measurements for all parameters as well as precision and bias determined by Bland and Altman analysis. The relative errors for interobserver variability were also lower with HPI. This study demonstrates that echocardiographic determination of left ventricular volumes and ejection fraction is more accurate and reproducible using HPI combined with Levovist.

Angiography↗
PubMed2000

Early and long-term (one-year) effects of the association of aspirin and oral anticoagulant on thrombi and morbidity after replacement of the mitral valve with the St. Jude medical prosthesis: a clinical and transesophageal echocardiographic study.

OBJECTIVES: The aim of the study was to test the value of low dose aspirin associated with standard oral anticoagulants (OAC) after mechanical mitral valve replacement (MMRV) to reduce strands, thrombi and thromboembolic events. BACKGROUND: Strands and thrombi are thought to increase the risk of embolic events after MMVR, particularly in the immediate postoperative period. METHODS: Two hundred twenty-nine patients were prospectively recruited: 109 patients (group A+) were randomly assigned to aspirin (200 mg per day) with OAC and 120 patients (group A-) to OAC alone (international normalized ratio 2.5 to 3.5). All patients were subjected to multiplane transesophageal echocardiography at nine days and five months and were followed up for one year. RESULTS: At nine days and five months, there was a high and comparable incidence of strands in the two groups (group A+: 44%, 58%; group A-: 49%, 63%). However, the incidence of nonobstructive periprosthetic valve thrombi was significantly lower in group A+ at 9 days: 5% versus 13%, p = 0.03. Total thromboembolic events were reduced in group A+ (9% vs. 25%, p = 0.004) although there was an increased incidence of gastrointestinal hemorrhage (7% vs. 0%). Overall mortality was 9% in group A+ and 4% in group A-. Valve-related events were similar in both groups. Early thrombi, but not strands, were associated with higher morbidity, especially thromboembolic events (30% vs. 13%, p = 0.003). CONCLUSIONS: One year after MMVR, the association of aspirin with OAC reduced thrombi and thromboembolic events, but not morbidity, due to an increase in hemorrhagic complications.

Administration, Oral↗
PubMed2000

[Hematoma of the aortic wall: from diagnosis to treatment].

Haematoma of the thoracic aortic wall is a relatively new concept, the physiopathology of which remains controversial. It results from an haemorrhage of the aortic wall due to rupture of the vasa-vasorum without communication with the arterial lumen. This is a diagnosis of elimination of dissection of the aorta which has been made possible by modern techniques of imaging, such as transoesophageal echocardiography, helicoidal scanner and magnetic nuclear resonance imaging. The prognosis of haematoma of the aortic wall is not as bad as that of dissection of the aorta. Recent studies have shown that the condition may stabilise, regress or progress towards complications of two types: early, dissection or fissuration of the aorta, and late, aortic aneurysm. This is a medico-surgical emergency, the treatment of which is not well codified. However, schematically, haematoma of the aortic wall should be managed in the same way as dissection of the aorta: surgery when the ascending aorta is affected, medical treatment in other cases in the absence of complications.

Aortic Dissection↗
PubMed2000

[Treatment of left atrial thrombosis by low-molecular-weight heparin. A preliminary study of 6 cases].

Left atrial thrombosis is a serious complication of atrial fibrillation because of its embolic potential, especially for the cerebral circulation. These thrombi are usually treated by oral anticoagulation. The authors studied the efficacy and tolerance of a low molecular weight heparin. Enoxaparin, in the treatment of this condition. This was a prospective study carried out over a 1 year period. Patient recruitment came from the transoesophageal echocardiography laboratory: of 15 thrombi detected, 6 were treated by ambulatory Enoxaparin therapy. Five of the 6 patients had no signs of left atrial thrombosis after 3 weeks of Enoxaparin therapy. The left atrial thrombus of the 6th patient remained hyperechogenic and had decreased in length from 27 to 24 mm. No cases of bleeding, haematoma, embolism or thrombopenia were observed with this treatment. This preliminary study shows that low molecular weight heparin may be used as an alternative to classical oral anticoagulation for the treatment of left atrial thrombosis.

Aged↗
PubMed1999

Can power motion imaging mode combined with contrast agent assess myocardial contraction and perfusion? In vitro and in vivo studies.

Power motion imaging (PMI) is a new Doppler imaging technology that can enhance contrast agent visualization. We hypothesized that PMI combined with Albunex injection (CPMI) could provide new insights into myocardial contractility and perfusion. In a first step, PMI signal was studied with an in vitro phantom. In a second step, PMI signal was studied in 10 rabbits at different workloads. In a third step, 10 rabbits were studied before and after ischemia produced by coronary ligation and finally during reperfusion. During the latter protocol, epicardial echocardiography analyzed by PMI and fundamental mode was performed before and after Albunex injection. PMI signal was well correlated with phantom velocity. PMI signal and myocardial wall thickening were well correlated, particularly in the septal area. On the coronary occlusion model, ischemia was associated with a significant decrease in PMI and CPMI signals, whereas reperfusion was associated with a significant decrease in PMI signals only, indicating stunning. We conclude that PMI combined with CPMI is a powerful tool to assess myocardial contractility and perfusion.

Albumins↗
PubMed1999

Definition and mapping of epitopes recognized by specific monoclonal antibodies to Schistosoma bovis 28 kDa glutathione S-transferase: relation with anti-egg viability immunity.

Monoclonal antibodies to the 28kDa glutathione S-transferase of Schistosoma bovis have been constructed in mice and used to characterize the epitope(s) potentially implied in the induction of anti-fecundity and anti-egg viability immune responses. Among the MoAbs produced three were particularly studied: Sb4-50 (IgG2a) and Sb4-56 (IgG1) which inhibited Sb28GST activity and Sb4-10 (IgG1) which did not. The use of overlapping peptides covering the entire amino acid sequence of Sb28GST, allowed us to define the linear epitopes recognized by these anti-Sb28GST MoAbs. Amino acid residues 202-211 were recognized by both MoAbs Sb4-50 and Sb4-56 and MoAb Sb4-10 recognized amino acid residues 58-67. Their capacity to inhibit GST activity suggested binding to the active site or to neighbouring regions, which include the C-terminal domain (a.a. 190-211) of the protein. When passively transferred into BALB/c mice MoAbs induced a significant reduction in egg hatching and an increase in immature eggs. Effects on worm burdens were, however, variable and no clear-cut association between the inhibition of enzyme activity and anti-fecundity or anti-viability activities was recorded. Our data indicate that beside the anti-fecundity and anti-viability immunity related to the impairment of GST activity, immune response to epitopes located in other regions of the molecule also contribute to the reduction of egg viability.

Amino Acid Sequence↗
PubMed1999

X-linked immunodeficiency affects the outcome of Schistosoma mansoni infection in the murine model.

The incidence of the X-linked immunodeficiency (Xid) on the outcome of Schistosoma mansoni infection has been evaluated through a comparative analysis of parasitological and immune parameters in two different mouse strains: control BALB/c and BALB. Xid mice which carry the Xid mutation and lack B1 (CD5+ B) cells. This study clearly demonstrates that infected B1 cell-deficient animals display a higher susceptibility to S. mansoni infection as revealed by an increase in the tissue egg loads and a significantly elevated mortality, as well as an increase in the granuloma densities. The analysis of the humoral and the cellular responses, conducted in the same experimental conditions, indicates differences in terms of cytokine production after specific antigenic stimulation of splenocytes. Larger amounts of IFN-gamma and IL-4 are observed in BALB. Xid mice while IL-10 production is reduced. In parallel, the study of the specific antibody isotype profiles shows higher amounts of specific IgE and IgG1 antibodies and lower amounts of IgM and IgA in BALB. Xid mice. Taken together, these observations support the idea that B cells are playing a role in the ability of mice to tolerate infection with Schistosoma mansoni.

Animals↗
PubMed1999

Egg-hatching inhibition in mice immunized with recombinant Schistosoma bovis 28 kDa glutathione S-transferase.

The capacity of a recombinant glutathione S-transferase from Schistosoma bovis (rSb 28GST) to protect BALB/c mice against homologous and heterologous infections with, respectively, S. bovis or Schistosoma mansoni has been studied. Two injections of the rSb 28GST and an intravenous boost resulted in a marked specific IgG response on the day of experimental challenge with S. bovis or S. mansoni cercariae. Immunization of BALB/c mice led to a reduction in egg maturation and egg viability after infection with S. bovis or S. mansoni. Adult worm recoveries after an S. bovis challenge infection and tissue egg densities (intestine and liver) in S. mansoni challenge infection were also reduced in the immunized groups, but these differences were not statistically significant. No association between in vitro inhibition of GST enzymatic activity induced by immunized mouse sera and worm burden reduction was recorded. The analysis of the immune response, on the day of perfusion, showed the production of immunoglobulin (Ig)G1, IgG2a and IgG2b specific antibodies and the production of interleukin (IL)-4 and IL-5 by spleen cells after rSb 28GST stimulation. These data suggest that rSb 28GST immunization induces a moderate effect upon egg maturation and egg hatching, suggesting the involvement of similar mechanisms of action and common, but not exclusive, targets during S. bovis and S. mansoni infections. As a consequence, immunization with rSb 28GST may prove useful in affecting the pathology and transmission of African schistosomes.

Animals↗
PubMed1999

Cytokine mRNA expression in lymphoid organs associated with the expression of IgA response in the rat.

The T-helper dependency of the IgA antibody response has been investigated in rats injected intravenously with Schistosoma mansoni eggs. This method, allowing the trapping of parasite eggs in the lung tissue, led to a strong anti-egg IgA antibody response in the bronchoalveolar lavage but not in the serum. To characterize the cytokine pattern associated with the IgA response, kinetic analysis of the cytokine mRNA expression in the lungs, periaortic nodes (PN) and spleen was undertaken. Under such conditions, significant levels of mRNA encoding IL-5 and IL-10 were recorded in spleen during the early period following egg injection, as well as a more prolonged expression of TGF-beta and IL-6 mRNAs. However, neither IFN-gamma nor IL-4 mRNA could be detected in these samples. Finally, in lungs and in PN, RT-PCR analysis revealed delayed production of cytokine mRNA. Taken together our data suggest that the rat mucosal IgA antibody response is predominantly linked to a Th2 response.

Animals↗
PubMed1999

Profiles of Th1 and Th2 cytokines after primary and secondary infection by Schistosoma mansoni in the semipermissive rat host.

In contrast to most mouse strains, rats eliminate the primary schistosome burden around 4 weeks postinfection and subsequently develop protective immunity to reinfection. In rat schistosomiasis, we have shown predominant expression of a Th2-type cytokine response at the mRNA level after primary infection. In the present study, we showed a significant increase in interleukin-4 (IL-4) mRNA expression in inguinal lymph nodes early after a secondary infection. IL-5 mRNA expression showed a significant increase at days 2 and 4 postreinfection in the spleen and lymph nodes, respectively. We did not detect any gamma interferon (IFN-gamma) mRNA after a challenge infection. Analysis of cytokine secretion by stimulated spleen cells after a primary infection showed predominant expression of IL-4 with maximum production on day 21, accompanied by production of IL-5 from day 11 to day 67. A significant increase in IFN-gamma secretion was detected at day 21. Analysis of immunoglobulin G2b (IgG2b) and IgG2c (Th1-related isotypes) showed undetectable levels of IgG2b, but detectable levels of specific IgG2c antibodies were observed from day 42. The analysis of Th2-related isotypes showed high specific IgG1 and IgG2a antibody titers from day 29. After a secondary infection, only IL-4 and IL-5 secretion was sustained. This is supported by the increased production of Th2-related isotypes. These findings showed that S. mansoni infection can drive Th2 responses in rats in the absence of egg production which is required to induce a Th2 response in mice and are in favor of the role of Th2-type cytokines in protective immunity against reinfection.

Animals↗
PubMed1999

[Superiority of second harmonic imaging for echocardiographic measurement of lef ventricular volumes. Comparison with angiocardiography].

Analysis of left ventricular volumes is a prognostic factor in cardiovascular disease. Echocardiography is a means of obtaining these parameters but is limited by poor reproducibility. Recently, a new echocardiographic technique, second harmonic imaging (SHI), developed through contrast agent methods, significantly improved the quality of imaging. The aim of this study was to demonstrate the value of SHI for assessing left ventricular volumes. Thirty patients admitted for cardiovascular evaluation and requiring angiocardiography underwent echocardiography with calculation of end diastolic (EDV) and end systolic volumes (ESV) of the left ventricle in fundamental (FI) and second harmonic (SHI) imaging. These measurements were compared with those of angiocardiography. The reproducibility of SHI was calculated after repetition of the measurements by two independent observers for both echocardiographic modes. There was a significant improvement of the parameters of linear regression in SHI compared with FI both for EDV (r = 0.93 versus 0.76) and for ESV (r = 0.94 versus 0.83), the reproducibility was also significantly improved in SHI (relative error of 5% versus 12% for intra-observer error and 6% versus 13% for inter-observer error). The authors conclude that SHI significantly improves two-dimensional imaging and provides a reliable and reproducible measurement of left ventricular volumes.

Adult↗
PubMed1998

Expression of rat interleukin-5 and generation of neutralizing antiserum: a comparative study of rat IL-5 produced in Escherichia coli and insect cells.

A cDNA coding for rat IL-5 was obtained by RT-PCR from total spleen RNA. With the exception of a single a.a. replacement at position 85 (L-P), it is identical to the published sequence obtained by retroviral gene transfer. This cDNA was used to express biologically active recombinant IL-5 in E. coli and in insect cells using a baculovirus system. Rat IL-5 is more active on B13, an IL-5 dependent cell line, when produced in insect cells (specific activity 1.47 x 10(11)UI/mg compared to 4.28 x 10(6)UI/mg). This increased activity seems to be associated with the presence of IL-5 homodimers in recombinant protein preparations. A rabbit antiserum raised against recombinant bacterial IL-5 specifically inhibited B13 proliferation induced by bacterial and baculoviral IL-5. The availability of such reagents should facilitate studying the role of IL-5 in different infectious diseases, experimental allergic encephalomyelitis and in transplantation biology where the rat represents a more suitable model than mice.

Animals↗
PubMed1998

Successful irrigated-tip catheter ablation of atrial flutter resistant to conventional radiofrequency ablation.

BACKGROUND: Catheter ablation of typical right atrial flutter is now widely performed. The best end point has been demonstrated to be bidirectional isthmus block. We investigated the use of irrigated-tip catheters in a small subset of patients who failed isthmus ablation with conventional radiofrequency (RF) ablation. METHODS AND RESULTS: Of 170 patients referred for ablation of common atrial flutter, conventional ablation of the cavotricuspid isthmus with >21 applications failed to create a bidirectional block in 13 (7.6%). An irrigated-tip catheter ablation was performed on identified gaps in the ablation line according to a protocol found to be safe in animals: a moderate flow rate of 17 mL/min and temperature-controlled (target, 50 degrees C) RF delivery with a power limit of 50 W. Bidirectional isthmus block was achieved in 12 patients by use of a mean delivered power of 40+/-6 W with a single application in 6 patients and 2 to 6 applications in the other 6. No side effects occurred during or after the procedure. CONCLUSIONS: Irrigated-tip catheter ablation is safe and effective for achieving cavotricuspid isthmus block when conventional RF energy has failed.

Adult↗
PubMed1998

Murine Schistosoma bovis infection: analysis of parasitic and immune parameters.

Humoral and cellular responses to Schistosoma bovis antigens have been evaluated over a period of 11 weeks in mice exposed to S. bovis cercariae and data analysed in the context of the parasitic parameters (worm and egg loads) recorded at days 30, 60 and 80 of the ongoing infection. Results revealed a decrease of worm burden, particularly marked for female worms, between day 60 and day 80 of infection suggesting a higher susceptibility of female schistosomes to attrition mechanisms. The B-cell response, studied by measuring the production of different isotypes, was directed against different stage specific antigens, with a predominance of IgG1 antibodies associated with a significant increase of IgA and IgE antibodies after egg deposition. The T-cell response, assessed after in vitro stimulation of splenocytes, showed a predominant production of Th-2 cytokines (IL-4, IL-5 and IL-10) occurring after egg laying. Interestingly in contrast to S. mansoni infection the Th-2 polarization did not seem to be exclusively triggered by egg-associated antigens since significant amounts of IL-10 were produced after stimulation with adult worm antigen preparation (SWAP) before the beginning of egg deposition.

Animals↗