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Biomedical subjects

Laurent Chiche

Publications and source records attributed to Laurent Chiche.

26 records · Page 2Linked to original sources
PubMed2003

Renal autotransplantation for vascular disease: late outcome according to etiology.

PURPOSE: The purpose of this study was to evaluate the early and late outcomes of renal autotransplantation (RAT) according to the etiology of the underlying renal artery disease. MATERIAL AND METHODS: Between January 1985 and April 2001, we performed 68 RAT procedures in 57 patients. The surgical indications were fibromuscular dysplasia (FMD) for 34 RAT procedures in 30 patients (11 men, 19 women; mean age, 41.3 +/- 14.6 years), Takayasu's disease (TD) for 26 RAT procedures in 19 patients (five men, 14 women; mean age, 33.0 +/- 12.3 years), and atherosclerosis for eight RAT procedures in eight patients (seven men, one woman; mean age, 66.5 +/- 7.9 years). The incidence rate of hypertension was 87% in patients with FMD and 100% in patients with TD and atherosclerosis. The incidence rate of renal dysfunction was 75% in patients with atherosclerosis, 27% in patients with FMD, and 16% in patients with TD. Autotransplantation was isolated in 31 cases and was associated with another vascular procedure in 37 cases, including 22 thoracoabdominal aorta repairs and 11 abdominal aorta or iliac artery repairs. The technique used to achieve renal revascularization was direct reimplantation in 17 cases and indirect reimplantation in 51 cases. The conduit used for indirect reimplantation was an arterial autograft in 42 cases, a vein autograft in seven cases, and a prosthetic graft in two cases. Simultaneous revascularization of the contralateral kidney was performed in 21 patients and included nine RAT procedures. Contralateral nephrectomy was performed in five patients. RESULTS: In the FMD group, early segmental infarction was observed in four cases. Secondary nephrectomy was necessary in one case (at 88 months). Actuarial survival rates were 96.2% +/- 0.03% at 5 years and 84.1% +/- 0.11% at 10 years. Secondary patency rates were 100% at 5 years and 92% +/- 0.07% at 10 years. Hypertension normalized or improved in 96% of patients. Renal function improved in 50% of patients. In the TD group, one patient died of multiple organ failure 4 days after the procedure. Nephrectomy was necessary in one case. The actuarial survival rate was 94.7% +/- 0.05% and the secondary patency rate was 91.3% +/- 0.05% at both 5 and 10 years. Hypertension normalized or improved in 89% of the cases, and kidney function improved in all cases. In the atherosclerosis group, nephrectomy was necessary during the early postoperative period in three cases and during late follow-up in two cases (at 9 months and at 68 months, respectively). Actuarial survival rates were 54.7% +/- 0.2% at 5 years and 18.2% +/- 0.16% at 10 years. The secondary patency rates were 50.0% +/- 0.17% at 5 years and 33.3% +/- 0.18% at 10 years. Hypertension normalized or improved in 50% of cases, and kidney function improved in 33% of cases. CONCLUSION: RAT is highly effective for treatment of complex renovascular lesions related to FMD and TD. Although RAT is less effective for atherosclerosis, it may be the only alternative in cases involving extensive renovascular disease.

Adult↗
PubMed2003

Aortoesophageal fistula: value of in situ aortic allograft replacement.

PURPOSE: The purpose of this report is to describe our experience in management of aortoesophageal fistulas (AEF) with special emphasis on the value of in situ aortic allograft replacement. PATIENTS: Nine patients presenting with AEF were observed between May 1988 and April 2002. There were 4 men and 5 women with a mean age of 54.3 years (range, 32-77 years). Six patients presented secondary AEF after aortic repair. Two patients presented primary AEF after rupture of an atherosclerotic aneurysm into the esophagus. In the remaining patient, AEF was caused by swallowing a fishbone. In 6 cases involving true AEF with a direct communication between the aorta and esophagus, massive exsanguinating hematemesis occurred. It was usually preceded by minor sentinel bleeding. Two patients presented esophagoparaprosthetic fistula (EPPF). One patient presented primary AEF that was contained by a large thrombus in the communication. The clinical picture in these 3 patients involved severe sepsis without hemorrhage. RESULTS: Two patients died as a result of massive hemorrhage before assessment and surgical treatment could be undertaken. One 77-year-old woman presenting EPPF refused to undergo surgery and died because of infection. The remaining 6 patients underwent surgical treatment with various outcomes. One man died during thoracotomy caused by exsanguinating hemorrhage. One woman presenting EPPF was treated by exclusion followed by ascending aorta to abdominal aorta bypass grafting, removal of the prosthesis, esophageal exclusion, and directed esophageal fistula. She died of infection. The other 4 patients were treated by in situ aortic allograft replacement. The damaged esophagus was repaired by using the Thal technique in 1 patient. In the remaining 3 cases subtotal esophagectomy was performed in association with cervical esophagostomy, ligation of the abdominal esophagus, gastrostomy, and jejunostomy. One patient died of sepsis during the first 24 hours after the operation. The other 3 patients underwent secondary esophagoplasty and survived with no further sign of infection. Mean duration of follow-up in the survivor group was 53 months (range, 15-95 months). Overall 6 patients, including 3 that did not undergo surgical treatment, died and 3 patients survived. CONCLUSION: Our experience confirms that AEF is a rare but catastrophic disorder. In situ allograft replacement usually in association with subtotal esophagectomy appears to be an excellent salvage modality whenever emergency surgery is feasible.

Adult↗
PubMed2002

Coronary and carotid artery disease in patients with degenerative aneurysm of the descending thoracic or thoracoabdominal aorta: prevalence and impact on operative mortality.

From January 1, 1995 to July 31, 2000, a total of 133 patients underwent elective surgical treatment for degenerative aneurysm of the descending thoracic (n = 45) or thoracoabdominal (n = 88) aorta. There were 116 men (87%) and 17 women (13%) with a mean age of 66.4 +/- 8.7 years (range, 39 to 84 years). Sixteen patients (12%) died in the immediate postoperative period. Thirteen patients (10%) had already undergone myocardial revascularizaton. Thirty-five patients (26%) presented clinical symptoms of coronary artery disease. Preoperative coronary arteriography was performed in 84 (63%) patients, demonstrating normal findings or clinically insignificant lesions in 48 patients (57%), single-vessel lesions (>70% reduction in diameter) in 19 patients, two-vessel lesions in 12 patients, and three-vessel lesions in 5 patients. On the basis of these findings, myocardial revascularization was performed before aortic repair in 11 patients. The total number of myocardial revascularization procedures in this series was 24 (18%). Four patients had previously undergone a total of 6 carotid endarterectomy procedures. Routine duplex ultrasound demonstrated significant carotid artery lesions in 12 patients (9%). Ten of these patients (8%) underwent carotid endarterectomy. The total number of carotid endarterectomy procedures in this series was 16 in 14 patients. The prevalence of coronary and carotid lesions in patients indicated for elective treatment for degenerative aneurysm of the descending thoracic or thoracoabdominal aorta was similar to that observed in patients presenting degenerative aneurysm of the infrarenal abdominal aorta. Univariate analysis demonstrated that coronary and carotid lesions with or without treatment are a significant risk factor for mortality following surgical repair of degenerative aneurysm of the descending thoracic or thoracoabdominal aorta. This finding suggests that routine preoperative coronary arteriography and duplex ultrasound are warranted.

Adult↗
PubMed2002

The [Lys(-2)-Arg(-1)-des(17-21)]-endothelin-1 peptide retains the specific Arg(-1)-Asp8 salt bridge but reveals discrepancies between NMR data and molecular dynamics simulations.

The [des(17-21)]-endothelin-1 (CSH-ET) and [Lys(-)(2)-Arg(-)(1)-des(17-21)]-endothelin-1 (KR-CSH-ET) peptides, designed by removing the five-residue hydrophobic tail from the endothelin-1 (ET-1) and [Lys(-)(2)-Arg(-)(1)]-endothelin-1 (KR-ET-1) peptides, respectively, were synthesized. Previous studies on KR-ET-1 showed that, in contrast to ET-1, this engineered compound displays a pH-dependent conformational change related to the formation of a stabilizing salt bridge between the Arg(-)(1) and Asp(8) side chains. CD and NMR spectra indicate that CSH-ET and KR-CSH-ET display conformational behavior similar to those of ET-1 and KR-ET-1, respectively. The short salt bridge-stabilized KR-CSH-ET peptide therefore appears to be an attractive elementary scaffold for drug design. The solution structure of the salt-bridged form of KR-CSH-ET was determined by NMR at pH 4.5 and is very similar to the corresponding form of the parent KR-ET-1 peptide. Molecular dynamics simulations of the salt-bridged form of KR-CSH-ET were performed using both the GB/SA implicit solvation scheme or an explicit solvation and the particle-mesh Ewald method for long-range electrostatic calculation. Unexpectedly, the Arg(-)(1)-Asp(8) salt bridge does not display in the simulation the stability that could be expected from the experimental data. The cooperative involvement of a cation-pi interaction in formation of the salt bridge has been hypothesized. Difficulties in accurately simulating cation-pi interactions might be responsible for the lack of stability in the simulation. At this time, however, no definitive explanation for the observed discrepancy between experiments and simulations is available, and further experimental studies appear to be necessary to fully understand in atomic detail the pH-dependent conformational change observed in the KR-ET-1 series.

Amino Acid Motifs↗
PubMed2002

Combined infrarenal aorta and carotid artery reconstruction: early and late outcome in 152 patients.

Between January 1, 1985 and December 31, 1998, we performed combined infrarenal aorta and carotid artery reconstruction in 152 consecutive patients. The mean age of these patients was 65.4 +/- 8.6 years (range, 43-88 years). Infrarenal aortic disease involved abdominal aortic aneurysm in 78 patients (44.7%) and occlusive aortoiliac lesions in 84 (55.3%). Carotid artery disease was detected by performing routine Doppler ultrasonography prior to aortic reconstruction. A total of 121 carotid lesions were asymptomatic (79.6%). A total of 32 patients (21%) had a history of contralateral carotid repair. Eighty-one patients (53.2%) presented with coronary artery disease diagnosed on the basis of clinical and/or laboratory testing. Concurrent lesions were diagnosed in the renal arteries of 43 patients (28.3%) and in the visceral arteries of 16 (10.5%). Based on the results of cardiac evaluation, eight patients underwent coronary revascularization before combined reconstruction. Renal or visceral artery reconstruction was carried out during the same procedure in 30 (19.7%) and 10 (6.6%) patients, respectively. Univariate analysis demonstrated six factors that were significantly associated with perioperative mortality and morbidity: age, coronary artery disease, chronic obstructive pulmonary disease, procedure time, intraoperative blood loss, and creatinemia over 140 micromol/L. Multivariate analysis showed that only the first four of these factors were independent. Actuarial survival in the overall population, including the patients who died during the perioperative period, was 73.9 +/- 7.1% at 5 years and 50.9 +/- 10% at 10 years. From our experience, we conclude that combined infrarenal aorta and carotid artery reconstruction can be performed with no additional operative risks and consequently is the strategy of choice. In our series neither procedure had any effect on the early or late outcome of the other. Our experience suggests that combined surgery is a safe alternative to staged surgery in patients with concurrent lesions involving the infrarenal aorta and carotid artery bifurcation.

Adult↗
PubMed2002

Helix motion in protein C12A-p8(MTCP1): comparison of molecular dynamics simulations and multifield NMR relaxation data.

The human p8(MTCP1) protein is constituted by an original disulfide bridged alpha-hairpin motif, and a third hydrophilic helix that appeared mobile and independent in NMR analysis. To get atomic scale description of the possible motions involved, a 12-ns molecular dynamics simulation of the C12A-p8(MTCP1) mutated protein and 10 400-ps simulations were performed in explicit water at 298 K. Analyses of the essential dynamics subspace and of the time-evolution of secondary structures indicate large displacements and internal motions of the third helix. Simulated order parameters, S,(2) are consistent to those obtained from (15)N-NMR relaxation data recorded at five different magnetic fields (proton resonance frequencies: 400, 500, 600, 700, and 800 MHz). The simulations show a fairly rigid alpha-hairpin motif with only very small local conformational changes, although the loop between helices undergoes significant correlated motions. The displacements and internal motions of the third helix can be essentially accounted for by alpha-helical to 3(10)-helical transitions near its N-terminus and by a hinge-bending motion near glycine 52. The loss of the alpha-helical conformation for a large part of the third helix during about 25% of the simulation time supports the possible occurrence of a slow motion as suggested by previous analyses of the (3)J(NH-H(alpha)) coupling constant values and of the proton-deuterium NH exchange kinetics.

Computer Simulation↗
PubMed2002

Distal vertebral artery reconstruction: long-term outcome.

PURPOSE: The purpose of this article was to report our long-term results of distal vertebral artery (DVA) reconstruction. METHOD: From 1978 to 2001 we performed 352 DVA reconstructions on 323 patients (177 men, 148 women; mean age, 60.0 +/- 12.1 years). Symptoms of vertebrobasilar insufficiency were present in 332 cases (94.3%). Bypass grafting using mostly saphenous vein graft was performed in 240 cases (68.2%). In 102 cases (29.0%) the DVA was transposed into the internal carotid artery (ICA). Other techniques were used in 10 cases. RESULTS: Stroke caused all 7 deaths (2.0%) in the early postoperative period. There were 5 nonfatal strokes (1.4%). Strokes were hemispheric in 7 cases (6 ipsilateral, 1 contralateral) and vertebrobasilar in 5 cases. There were 6 strokes (2.3%) in the subgroup of 264 isolated DVA reconstruction and 6 strokes (6.8%) in the subgroup of 88 procedures involving combined ICA and DVA reconstruction (P <.04). Temporary paralysis of the spinal accessory nerve occurred in 26 cases (7.4%). Intraoperative or early postoperative angiography findings were available in 341 of 345 cases (98.8%). Early postoperative occlusion occurred after 25 procedures (7.1%). Complete clinical follow-up was available for 313 (99.1%) of the postoperative survivors. Mean duration of follow-up was 99.5 +/- 62.5 months. Assessment of late patency was performed in 343 (99.4%) of 345 cases by angiography (21.2%) or duplex scanning (78.8%). A total of 65 (23.7%) patients died during follow-up. No deaths resulted from vertebrobasilar or hemispheric stroke. Cumulative Kaplan-Meier survival rate was 89.0% +/- 3.9% at 5 years and 75.4% +/- 7.1% at 10 years. Significant vertebrobasilar symptom-free rate was 94.0% +/- 3.5% at 5 years and 92.8% +/- 3.8% at 10 years. Primary patency rate was 89.3% +/- 3.6% at 5 years and 88.1% +/- 4.0% at 10 years. CONCLUSIONS: This study clearly establishes the excellent long-term results of DVA reconstruction for the treatment of extracranial lesions of the vertebral artery. However, every effort should be made to reduce the rate of early postoperative occlusions. The subgroup of patients involving combined ICA and DVA reconstruction remains at high risk of postoperative stroke.

Adolescent↗