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Biomedical subjects

M Bertrand

Publications and source records attributed to M Bertrand.

At least 19 recordsLinked to original sources
PubMed1996

ACE polymorphism, a genetic predictor of occlusion after coronary angioplasty.

In this study, restenosis after coronary angioplasty is evaluated in a series of 291 consecutive patients according to ACE genotypes. The authors conclude that the ACE 2ID polymorphism has no effect on progressive restenosis after balloon angioplasty, but it is implicated in a distinct mechanism of restenosis (thrombosis and occlusion) that could explain discrepancies among previously published studies.

Angioplasty, Balloon, Coronary↗
PubMed1996

Fundamental limitations on the contrast-transfer efficiency in elastography: an analytic study.

Elastography is a new ultrasonic imaging technique introduced to produce images of the Young's modulus distribution of compliant tissue. This Young's modulus distribution is derived from the ultrasonically estimated longitudinal internal strains induced by an external compression of the tissue. The displayed two-dimensional images are called elastograms. Recently, contrast-transfer efficiency, defined as the ratio of elasticity contrast as measured from elastogram to the true contrast, was used to illustrate by simulation the fundamental limitation of elastography in displaying the elastic modulus contrast of soft inclusion in a hard background and vice versa. In this paper, using a classical analytic solution of the elasticity equations derived for an infinite medium subjected to a uniaxial compression, we confirm such earlier simulations results. For this purpose we derive an analytic expression predicting the observed contrast in elastograms.

Animals↗
PubMed1996

Effects of pentoxifylline on circulating cytokine concentrations and hemodynamics in patients with septic shock: results from a double-blind, randomized, placebo-controlled study.

OBJECTIVE: To determine whether a continuous intravenous infusion of pentoxifylline, a methylxanthine derivative, alters the serum cytokine concentrations and/or hemodynamic measurements in patients with septic shock. DESIGN: A prospective, randomized, double-blind, placebo-controlled study. SETTING: Medical intensive care unit in a university hospital. PATIENTS: Sixteen patients with septic shock. INTERVENTIONS: Patients were randomly assigned to receive either pentoxifylline (1 mg/kg) followed by an infusion of 1.5 mg/kg/hr for 24 hrs (n = 8), or placebo (n = 8). MEASUREMENTS AND MAIN RESULTS: Tumor necrosis factor (TNF) and interleukin (IL)-6 concentrations were measured by radioimmunoassays; IL-8 concentrations by an enzyme-linked immunosorbent assay (ELISA) and pentoxifylline concentrations by high-performance liquid chromatography at 0, 3, 6, 12, 18, 24 and 48 hrs after study entry. Pulmonary artery catheter-derived hemodynamics were measured at 0, 0.75, 3, 6, 12, 18, and 24 hrs. In pentoxifylline-treated patients, at 24 hrs, serum concentrations of TNF were significantly lower compared with controls (12 +/- 2 vs. 42 +/- 12 pg/mL, respectively, p = .04). Serum concentrations of IL-6 and IL-8 did not differ between the two treatment groups. There were also no significant differences in any hemodynamic and oxygenation measurements comparing the two treatment groups. Pentoxifylline concentrations were 1,544 +/- 241 ng/mL after the initial dose, and 5,776 +/- 1,781 ng/mL at the end of the 24-hr infusion. Five patients in the pentoxifylline group and four patients in the placebo group died. CONCLUSIONS: Pentoxifylline is able to decrease serum TNF but not IL-6 or IL-8 serum concentrations during septic shock. Pentoxifylline was well tolerated by all eight patients with no adverse effect. Further studies are needed to determine if pentoxifylline's ability to lower circulating TNF concentration without altering hemodynamics will improve outcome in septic shock.

Adult↗
PubMed1995

Detection of autoantibodies against oxidized low-density lipoproteins and of IgG-bound low density lipoproteins in patients with coronary artery disease.

The role of oxidized low-density lipoprotein (ox-LDL) in the pathogenesis of atherosclerosis has been the object of intense investigation. It has been proposed that, due to the antigenic properties of ox-LDL, the anti-ox-LDL antibody titre could represent a useful index of in vivo LDL oxidation. On the other hand, LDL immune complexes (LDL-IC) have been demonstrated in patients with coronary disease and could play an atherogenic role. The goal of our study was to investigate anti-malondialdehyde (MDA)-LDL autoantibodies and LDL-IC in a cohort of patients with coronary artery disease. Seventy control subjects and 70 coronary angiographically documented patients were compared; in addition 32 healthy male non-smokers were compared with 32 healthy male smokers (> 10 cigarettes/day). All patients were matched for age and cholesterolemia. Enzyme-linked immunosorbent assay was used to measure anti-MDA-LDL autoantibodies and LDL-IC. Titres of anti-MDA-LDL autoantibodies were not larger in patients with documented coronary artery stenosis and in smokers than they were in controls and non-smokers. The titre of LDL-IC was not higher in patients with coronary artery stenosis than in controls. The results thus indicate that in populations matched for age and cholesterolemia the titres of anti-MDA-LDL autoantibodies and the titre of LDL-IC are not increased in patients suffering from coronary artery stenosis. Furthermore, cigarette smoking does not induce higher titres of anti-MDA-LDL autoantibodies in healthy patients.

Aged↗
PubMed1995

Hemolysis in primary lipoprotein lipase deficiency.

A slight to moderate hemolysis is often present in plasma from patients with primary lipoprotein lipase (LPL) deficiency. To determine the nature of this hemolysis, we measured erythrocyte hypo-osmotic fragility, plasma free hemoglobin, and phospholipid composition in 26 patients with primary LPL deficiency and 21 unrelated controls. In some patients, these investigations were completed by erythrocyte cytoskeletal protein determinations and abdominal echography. Osmotic fragility was similar between control subjects and patients. However, there was a significantly increased concentration of plasma free hemoglobin in primary LPL deficiency (0.282 +/- 0.331 v 0.048 +/- 0.038 g/L in controls, P < .005). In LPL-deficient patients, an increase of plasma lysophosphatidylcholine concentration (12.6% +/- 5.8% v 6.4% +/- 1.9% in controls, P < .0001) was also found. The protein composition of the erythrocyte membrane skeleton was abnormal in some LPL-deficient patients and splenomegaly was present in 12, but these abnormalities did not correlate with plasma free hemoglobin levels. Bilirubin and haptoglobin levels were also within physiologic ranges in these patients, suggesting that the observed hemolysis did not result from hypersplenism. It appears likely that the accumulation of lysophosphatidylcholine was due to an impairment in the reverse metabolic pathway converting lysophosphatidylcholine back to phosphatidylcholine. Collectively, these data, along with a positive correlation between plasma free hemoglobin and lysophosphatidylcholine levels (r = .58, P = .0001), suggest that the hemolysis observed in primary LPL deficiency is mediated to some extent by the abnormally elevated concentration of lysophosphatidylcholine.

Adult↗
PubMed1995

Echographic image mean gray level changes with tissue dynamics: a system-based model study.

In echography, several groups have reported a systematic decrease in the total backscattering intensity or image mean gray level during myocardial contraction with a minimum at end-systole and maximum at end-diastole. In order to investigate this phenomenon, we use a three-dimensional inhomogeneous continuum model to mimic the tissue as a collection of cells that scatter the acoustic wave due to their individual impedance. The mathematical analysis clearly shows the relationship between the mean gray level changes and the size, orientation, and deformation of the cells that compose the tissue, as well as the frequency of the transducer. Using a myocardial model example, the mean gray level changes reported in the literature during contraction are described in terms of changes in orientation and deformation of cardiac fibers. The model is simple and should set the ground for further study and analysis of speckle pattern changes during tissue motion.

Echocardiography↗
PubMed1994

Dipyridamole-thallium scintigraphy and gated radionuclide angiography to assess cardiac risk before abdominal aortic surgery.

BACKGROUND: Because many patients with atherosclerotic disease of the abdominal aorta also have coronary artery disease, assessment of cardiac risk before abdominal aortic surgery has received much attention. Our prospective study was designed to identify predictors of cardiac risk in consecutive patients evaluated preoperatively with dipyridamole-thallium single-photon-emission computed tomography (SPECT) to assess myocardial perfusion and radionuclide angiography to measure left ventricular ejection fraction. METHODS: Clinical and scintigraphic data were collected prospectively during hospitalization in 457 consecutive patients undergoing elective abdominal aortic surgery. Adverse cardiac outcomes were predicted with multivariate analyses. RESULTS: Eighty-six patients (19 percent) had one or more of the following postoperative complications: prolonged myocardial ischemia (61 patients), myocardial infarction (22), congestive heart failure (20), and severe ventricular tachyarrhythmia (2). Twenty patients died postoperatively (4.4 percent), half of them from cardiac causes. Information about myocardial perfusion obtained from dipyridamole-thallium SPECT did not accurately predict adverse cardiac outcomes. The best correlates of cardiac complications were definite clinical evidence of coronary artery disease (odds ratio, 2.6; 95 percent confidence interval, 1.6 to 4.3) and age greater than 65 years (odds ratio, 2.3; 95 percent confidence interval, 1.4 to 3.6). Measurement of the ejection fraction was useful only in the prediction of left ventricular failure. Age greater than 65 years was the only predictor of death (odds ratio, 26.4; 95 percent confidence interval, 3.5 to 200.0). CONCLUSIONS: The presence of definite clinical evidence of coronary artery disease and older age were the most important preoperative predictors of an adverse cardiac outcome after abdominal aortic surgery. These results suggest that the routine use of dipyridamole-thallium SPECT and radionuclide angiography for screening before abdominal aortic surgery may not be justified.

Aged↗
PubMed1994

Recoil following Wiktor stent implantation for restenotic lesions of coronary arteries.

The purpose of this study was to determine acute recoil of the vessel wall immediately after Wiktor stent implantation in native coronary arteries of 77 consecutive patients and to assess whether there was compression or "late recoil" of the stent itself at long-term follow-up. Furthermore, the relationship between recoil and a number of clinical, angiographic, and procedural variables was studied in addition to the relation between acute recoil renarrowing or restenosis was assessed. All angiograms were analyzed with the Cardiovascular Angiography Analysis System using automated edge detection. Acute recoil was defined by the difference between the mean diameter of the fully expanded balloon on which the stent was mounted and the mean diameter of the stented segment. Late recoil was calculated by comparing the mean diameter of the stent itself immediately after implantation and at follow-up without opacification of the vessel. Acute recoil amounted to 0.25 +/- 0.32 mm or 8.2%. Multivariate analysis identified sex (coefficient = -0.20, p = 0.04) and stent/artery ratio (coefficient = 0.99, p = 0.0001) as the only independent predictors of acute recoil. "Late recoil" of the stent itself was not observed. The overall difference between the mean diameter of the stent itself immediately after implantation and at follow-up was -0.15 +/- 0.33 mm, suggesting an overall increase in diameter of 5.0%. There was no relation between acute recoil and late restenosis. On the contrary, there was a trend towards a greater degree of recoil in patients without restenosis. Moreover, linear regression analysis disclosed a weak but negative correlation between acute recoil and a loss in minimal luminal diameter (coefficient: -0.55, p = 0.04). The Wiktor stent effectively scaffolds the instrumented vessel. Only a minimal amount of acute recoil was noted, which did not contribute to late luminal renarrowing or restenosis. In addition, no late compression of the stent itself was observed. These data suggest that tissue ingrowth into the lumen of the stented segment is the main cause of late luminal renarrowing after stent implantation.

Aged↗
PubMed1994

The application of electrospray and neutral-loss mass spectrometry to the identification of the metabolites of S12813 in rat liver slices.

The metabolism of S12813, (3-(2-[4-phenyl piperazin-1-yl] ethyl)-2-oxo-2,3-dihydro oxazolo [4,5-b] pyridine chlorohydrate), in rat liver slice incubates was examined by high performance liquid chromatography combined with mass spectrometry. Electrospray ionization was used together with tandem mass spectrometric techniques of analysis (MS/MS). Polar phase I and phase II metabolites were identified as C-oxidation products, which were then conjugated to form either sulphate or glucuronide metabolites. On the basis of the identifications made, a metabolic pathway of S12813 in rat liver slices has been proposed.

Analgesics↗
PubMed1994

A pilot study of intra-arterial carboplatin in patients with recurrent carcinoma of the cervix, postradiation.

Twelve patients with recurrent squamous cell carcinoma of the cervix restricted to the pelvis were treated with intra-arterial infusion of carboplatin. The initial carboplatin dose was 300 mg/m2, every 4 weeks, and the dose was escalated to 450 mg/m2. Myelosuppression was the dose-limiting toxicity at the 450 mg/m2 dose. One patient died of treatment-related febrile neutropenia at that dose level. Two patients having received one cycle at 300 mg/m2 suffered grade 3 peripheral paresthesia. There were no objective responses but five patients had a subjective improvement of pain and performance status.

Adult↗
PubMed1994

Recombinant protein expression in a Drosophila cell line: comparison with the baculovirus system.

In this report, we compare two different expression systems: baculovirus/Sf9 and stable recombinant Drosophila Schneider 2 (S2) cell lines. The construction of a recombinant S2 cell line is simple and quick, and in batch fermentations the cells have a doubling time of 20 hours until reaching a plateau density of 20 million cells/ml. Protein expression is driven by the Drosophila Metallothionein promoter which is tightly regulated. When expressed in S2 cells, the extracellular domain of human VCAM, an adhesion molecule, is indistinguishable from the same protein produced by baculovirus-infected Sf9 cells. Additionally, we present data on the expression of a seven trans-membrane protein, the dopamine D4 receptor, which has been successfully expressed in both systems. The receptor integrates correctly in the S2 membrane, binds [3H]spiperone with high affinity and exhibits pharmacological characteristics identical to that of the receptor expressed in Sf9 and mammalian cells. The general implications for large scale production of recombinant proteins are discussed.

Animals↗
PubMed1994

Aprotinin to decrease bleeding and intraoperative blood transfusion requirements during descending thoracic and thoracoabdominal aortic aneurysmectomy using cardiopulmonary bypass.

The purpose of this retrospective study was to assess the efficacy of aprotinin, an antifibrinolytic agent, in reducing bleeding and blood transfusion requirements in patients undergoing descending thoracic or thoracoabdominal aortic aneurysmectomy using cardiopulmonary bypass (CPB). Sixty-nine consecutive patients underwent thoracic or thoracoabdominal aneurysmectomy using CPB in a 2-year period. None of the 29 patients operated on in 1990 (group 1) received aprotinin, whereas all 40 patients operated on in 1991 (group 2) were placed on a high-dose regimen of aprotinin. There were no significant differences between the two groups. Administration of aprotinin was associated with a decrease in CPB time (p = 0.02), surgical duration (p = 0.05) and intraoperative blood loss (p = 0.008) as well as a reduction in intraoperative packed red cells (p = 0.01), Cell-Saver units (p = 0.05), fresh-frozen plasma units (p = 0.002), and platelet concentrate (p = 0.01) requirements. These data suggest that aprotinin is effective in reducing bleeding and blood transfusion requirements during descending thoracic or thoracoabdominal aortic aneurysmectomy using CPB.

Adult↗
PubMed1994

Autologous blood donation before myocardial revascularization: a Holter-electrocardiographic analysis.

The influence of preoperative autologous blood donation on myocardial ischemia and arrhythmias was evaluated in 24 patients scheduled for coronary artery bypass grafting (CABG). All had a Holter recorder placed 24 hours before predonation (day 1), the cassette was changed prior to donation, and the recording continued for 24 hours thereafter (day 2). Each patient served as his or her own control, and observations made on day 2 were compared with those of day 1. Ischemia was quantitated by calculating the duration (C.Dur.) and the area (C. Area) of ischemic ST segment depressions, and ventricular premature beats (VPB) were classified according to the Lown grading system. Twenty-one men and 3 women were monitored. On day 1, 9 patients had 20 ischemic events, 3 being symptomatic. Nine patients demonstrated ischemia on day 2, representing a total of 3 symptomatic and 26 silent events. When comparing the two monitoring periods, 7 patients had longer or more severe ST segment depression whereas 6 other patients presented with more severe VPBs on day 2. Three patients had less ischemia on day 2, one remained stable, and 13 had no ischemia throughout the study. Silent ischemia was significantly more prolonged (C.Dur.Sil 316 v 152 sec, P < 0.05) and more intense (C. Area Sil 8 v 3.8 mm.min, P < 0.05) on day 2. Moreover, on top of a normal circadian distribution of ischemic events in the morning and in the evening, 40% of events were related to the donation or to a trip to the hospital. No preoperative characteristic helped to detect patients at risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Silent ischemia].

Silent myocardial ischaemia is a very common phenomenon in patients with coronary artery disease. It may occur in patients with clinical manifestations of angina, be detected during the post-myocardial infarction period or in patients totally asymptomatic. Whatsoever, it is well demonstrated that silent myocardial ischaemia has a very potent prognostic value. Therapeutic implications are similar to those in symptomatic ischaemia. Indications for myocardial revascularization by mean of angioplasty or bypass grafting may be discussed and depend on ventricular function and extension of coronary lesions.

Angina Pectoris↗
PubMed1994

Hypothermic circulatory arrest for thoracic aneurysmectomy through left-sided thoracotomy.

PURPOSE: In an attempt to clarify the role of hypothermic circulatory arrest (HCA) in the management of complex aortic aneurysms operated on through the left thoracotomy, our technique of HCA and outcome were reviewed. METHODS: During a 21-month period, 15 (17%) of 87 aneurysms of the descending thoracic or thoracoabdominal aorta were operated on by HCA. Eleven patients had chronic aortic dissections (four type A and seven type B), two patients had atherosclerotic aneurysms, and one each had congenital or infected postoperative aneurysms. The use of HCA was planned before surgery in 14 patients. Indications included proximal aortic disease in 12 patients, making either clamping of the transverse aortic arch unsafe (eight patients) or necessitating replacement of the arch with a graft (four patients). Preoperative decision to use HCA was made in two additional patients, one with a ruptured aneurysm and another patient for spinal cord and visceral protection because of anticipated prolonged ischemia as a result of reoperation. Intraoperative technical difficulties prompted the use of HCA in only one patient. Deep hypothermia (15 degrees to 24 degrees C) was induced through partial cardiopulmonary bypass. Left-sided heart venting was necessary in five patients. Aortic replacement was limited to the descending thoracic aorta in five patients, whereas it involved the thoracoabdominal aorta in 10 patients. Four patients had associated replacement of the aortic arch. RESULTS: Three patients died (one of a ruptured aneurysm) during surgery or early after surgery (two of bleeding and one of left ventricular failure). All other patients awoke neurologically intact, but one patient had delayed onset of paraplegia. Another patient died 4 days after surgery of rupture of the ascending aorta. Eleven patients were perioperative survivors without significant morbidity. CONCLUSIONS: Hypothermic circulatory arrest is a valuable adjunct in the management of complex aortic aneurysms through left-sided thoracotomy. Its results warrant consideration of its selective use for spinal cord/visceral protection.

Adult↗
PubMed1994

High-frequency jet ventilation vs continuous positive airway pressure for differential lung ventilation in patients undergoing resection of thoracoabdominal aortic aneurysm.

Twenty patients, scheduled for surgical resection of thoracoabdominal aortic aneurysm were divided into two groups according to the type of differential lung ventilation used during graft replacement of the descending thoracic aorta. In the high-frequency jet ventilation (HFJV) group of ten patients, HFJV was applied to the left lung once collapsed and retracted by the surgeon, the patient lying in the right lateral decubitus and being intubated by a Carlens' tube. In the continuous positive airway pressure (CPAP) group of ten patients, CPAP was applied to the left lung at the same mean airway pressure as HFJV (1 kPa). Before anaesthetic induction, an arterial and a Swan-Ganz catheter were inserted for cardiovascular monitoring. The same anaesthetic technique using fentanyl 6 micrograms.kg-1, flunitrazepam 0.02 mg.kg-1 and pancuronium 0.1 mg.kg-1 was used for each patient. Haemodynamic and respiratory measurements were made; 15 min after positioning the patients in the right lateral decubitus using two-lung ventilation; 15 min after collapse and retraction of the left lung using one-lung ventilation and 15 min after using differential lung ventilation with CPAP or HFJV. Left lung collapse with conventional one-lung ventilation induced a dramatic decrease in arterial oxygenation: PaO2/FIO2 ratio decreased from 43 +/- 6 kPa to 20 +/- 8 kPa, alveolo-arterial oxygen difference increased from 24 +/- 7 kPa to 72 +/- 11 kPa and pulmonary shunt increased from 17 +/- 2% to 37 +/- 3%. Whereas differential lung ventilation with CPAP did not improve any of the respiratory parameters measured, differential lung ventilation with HFJV, significantly increased PaO2/FIO2 ratio to 41 +/- 14 kPa.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗