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Philippe Cluzel

Publications and source records attributed to Philippe Cluzel.

31 records · Page 2Linked to original sources
PubMed2004

Cardiovascular involvement, an overlooked feature of Erdheim-Chester disease: report of 6 new cases and a literature review.

Erdheim-Chester disease (ECD) is a rare, non-Langerhans form of histiocytosis of unknown origin. It is characterized by xanthomatous or xanthogranulomatous infiltration of tissues by spumous ("foamy") histiocytes. As of this writing, 178 cases have been reported. ECD is characterized by heterogeneous systemic manifestations. Bone pain is the most frequent symptom. About half of all patients have extraskeletal manifestations. Cardiovascular manifestations of ECD remain underestimated. We report 6 new cases of ECD associated with periaortic fibrosis. In 4 of these cases, the whole aorta had a "coated" aspect. A literature review revealed 66 cases of ECD with cardiovascular involvement. We therefore analyzed 72 ECD patients with cardiovascular involvement: 40 (55.6%) had periaortic "fibrosis," 32 (44.4%) had pericardial involvement, and 22 (30.6%) had myocardial involvement. Six had a right atrial tumor. Symptomatic valvular heart disease (3 aortic and 3 mitral regurgitations) was found in 6 patients. Nineteen patients (26.4%) had heart failure, leading to death in 8 cases. Six patients had renovascular hypertension related to perirenal artery stenosis. Data concerning follow-up were available for 58 (80.6%) patients. Of these, 35 (60.3%) patients died, confirming the severe prognosis of ECD. Cardiovascular complications were responsible for the death of 11 of the 35 patients (31.4%).

Adult↗
PubMed2003

A natural class of robust networks.

As biological studies shift from molecular description to system analysis we need to identify the design principles of large intracellular networks. In particular, without knowing the molecular details, we want to determine how cells reliably perform essential intracellular tasks. Recent analyses of signaling pathways and regulatory transcription networks have revealed a common network architecture, termed scale-free topology. Although the structural properties of such networks have been thoroughly studied, their dynamical properties remain largely unexplored. We present a prototype for the study of dynamical systems to predict the functional robustness of intracellular networks against variations of their internal parameters. We demonstrate that the dynamical robustness of these complex networks is a direct consequence of their scale-free topology. By contrast, networks with homogeneous random topologies require fine-tuning of their internal parameters to sustain stable dynamical activity. Considering the ubiquity of scale-free networks in nature, we hypothesize that this topology is not only the result of aggregation processes such as preferential attachment; it may also be the result of evolutionary selective processes.

Biophysical Phenomena↗
PubMed2003

A high-throughput capillary assay for bacterial chemotaxis.

We present a high-throughput capillary assay in order to characterize the chemotactic response of the E. coli bacterium. We measure the number of organisms attracted into an array of 96 capillary tubes containing the attractant L-aspartate. The effect of bacterial concentration on the chemotactic response is reported. Such high-throughput assay can be used to characterize bacterial chemotaxis function of a wide range of biochemical parameters.

Chemotaxis↗
PubMed2003

Mesenteric ischaemia in haemodialysis patients: a case/control study.

BACKGROUND: Mesenteric ischaemia is not uncommon in dialysis patients and seems to have been increasing in the last decade. However, the risk factors for mesenteric ischaemia are unclear and prognosis of patients after this type of ischaemic accident is not well defined. METHODS: From January 1988 to June 1999, 15 haemodialysis patients (0.3% per patient-year) from a single institution presented with mesenteric ischaemia and the clinical, biological and radiological aspects of the ischaemia were described. To identify risk factors for mesenteric ischaemia, each ischaemic patient (case) was matched with two other haemodialysis patients not having ischaemia (controls). Survival curves were then established for the two groups. RESULTS: A marked hypotensive episode was present in seven out of 15 case patients (47%) during dialysis sessions that preceded mesenteric ischaemia. Abdominal pain, guarding, fever and hyperleucocytosis were all present in 13 out of 15 patients (87%). An abdominal computerized tomography scan with opaque enema enabled a rapid diagnosis for six patients. The caecum was the most frequently (47%) affected segment. Twelve patients were surgically treated and the remaining three were given medical support. The two groups (case and control) were not different in cardiovascular risk factors, comorbidity, administered drugs or main haemodialysis characteristics. The median survival of the case group was 600 days, whereas 80% of the control group survived beyond this period (P=0.0132). Eleven case patients survived >3 months after mesenteric ischaemia and had a median survival of 1500 days, which was identical to their matched control patients. CONCLUSIONS: Mesenteric ischaemia should be systematically suspected in patients experiencing abdominal pain during or after dialysis sessions. Prompt diagnosis and treatment usually allow for a favourable prognosis.

Aged↗
PubMed2003

Potential exposure to hepatitis C virus through accidental blood contact in interventional radiology.

PURPOSE: To quantify the prevalence of accidental blood exposure (ABE) among interventional radiologists and contrast that with the prevalence of patients with hepatitis C virus (HCV) undergoing interventional radiology procedures. MATERIALS AND METHODS: A multicenter epidemiologic study was conducted in radiology wards in France. The risk of ABE to radiologists was assessed based on personal interviews that determined the frequency and type of ABE and the use of standard protective barriers. Patients who underwent invasive procedures underwent prospective sampling for HCV serologic analysis. HCV viremia was measured in patients who tested positive for HCV. RESULTS: Of the 77 radiologists who participated in 11 interventional radiology wards, 44% reported at least one incident of mucous membrane blood exposure and 52% reported at least one percutaneous injury since the beginning of their occupational activity. Compliance with standard precautions was poor, especially for the use of protective clothes and safety material. Overall, 91 of 944 treated patients (9.7%) tested positive for HCV during the study period, of whom 90.1% had positive viremia results, demonstrating a high potential for contamination through blood contacts. CONCLUSIONS: The probability of HCV transmission from contact with contaminated blood after percutaneous injury ranged from 0.013 to 0.030; the high frequency of accidental blood exposure and high percentage of patients with HCV could generate a risk of exposure to HCV for radiologists who perform invasive procedures with frequent blood contact. The need to reinforce compliance with standard hygiene precautions is becoming crucial for medical and technical personnel working in these wards.

Blood-Borne Pathogens↗
PubMed2003

[Value of preserved saphenous vein graft for the creation of access ports in hemodialyzed patients: report of 309 cases].

INTRODUCTION: Biological grafts are rarely used for the creation of vascular access, despite their many advantages. Our group prefers to use distal vascular accesses with interposition of a biological graft when direct access cannot be achieved. The objective of this study was to determine the long-term patency and the complication rate of a series of 309 vascular access procedures using a preserved saphenous (PS) vein homograft. MATERIALS AND METHODS: 410 (27%) of the 1,500 vascular access procedures performed by our group required the use of a graft, including 376 PS vein homografts (25%). This retrospective study comprised complete data collection for 309 arteriovenous fistulas (AVF) using preserved saphenous (PS) vein graft in the forearm performed in 267 patients between 1985 and 2000. Primary patency was defined as the interval between creation of the vascular access and the first complication requiring surgical or radiological correction; secondary patency was defined as the interval between creation and loss of the graft, with or without revision of the fistula. Survival rates were calculated according to the Kaplan-Meier method. Inter-group comparison was performed by the Logrank test and analysis of variance was performed by logistic regression. RESULTS: Primary patency rates were 77%, 40% and 27% at 1,2 and 5 years, respectively. Secondary patency rates were 79% and 47% at 1 year and 5 years, respectively. The thrombosis rate was 42%. Two episodes of thrombosis occurred in 25% of grafts and 3 episodes were observed in 10% of cases. Infection rates were 1.9% postoperatively and 5% after dialysis, respectively. An aneurysm occurred on 10% of grafts. The operator's experience (RR = 1.58; p < 0.05) and diabetic nephropathy (RR = 1.89; p = 0.059) significantly influenced graft patency. In contrast, the position of the graft, the fact that it crossed the elbow joint, and the site of the arterial anastomosis did not have any negative impact on graft patency. DISCUSSION: Preservation of the patient's vascular capital is an essential objective in patients with chronic renal insufficiency, which is sometimes difficult to reconcile with the need to create vascular accesses with a long life span. The strategic choice between a distal access requiring a graft and a direct proximal access depends on the clinical context: cardiac function, waiting list for renal transplantation. Our preferred material in the case of bypass graft is the PS graft, as it presents the same resistance and the same patency rates as synthetic grafts, without the associated septic complications. CONCLUSION: The PS vein graft is a good material for the creation of vascular accesses with similar patency rates to those of prosthetic grafts. Vein grafts present a number of advantages, particularly a greater ease of use facilitating distal implantation of the graft and a low infection rate.

Adolescent↗
PubMed2002

Effects of contrast material on computed tomographic measurements of lung volumes in patients with acute lung injury.

BACKGROUND: Intravenous injection of contrast material is routinely performed in order to differentiate nonaerated lung parenchyma from pleural effusion in critically ill patients undergoing thoracic computed tomography (CT). The aim of the present study was to evaluate the effects of contrast material on CT measurement of lung volumes in 14 patients with acute lung injury. METHOD: A spiral thoracic CT scan, consisting of contiguous axial sections of 10 mm thickness, was performed from the apex to the diaphragm at end-expiration both before and 30 s (group 1; n = 7) or 15 min (group 2; n = 7) after injection of 80 ml contrast material. Volumes of gas and tissue, and volumic distribution of CT attenuations were measured before and after injection using specially designed software (Lungview; Institut National des Télécommunications, Evry, France). The maximal artifactual increase in lung tissue resulting from a hypothetical leakage within the lung of the 80 ml contrast material was calculated. RESULTS: Injection of contrast material significantly increased the apparent volume of lung tissue by 83 +/- 57 ml in group 1 and 102 +/- 80 ml in group 2, whereas the corresponding maximal artifactual increases in lung tissue were 42 +/- 52 ml and 31 +/- 18 ml. CONCLUSION: Because systematic injection of contrast material increases the amount of extravascular lung water in patients with acute lung injury, it seems prudent to avoid this procedure in critically ill patients undergoing a thoracic CT scan and to reserve its use for specific indications.

Adult↗
PubMed2002

Mechanical model of the inspiratory pump.

The inspiratory pump (inspiratory muscles and the rib cage) translates inspiratory commands in alveolar ventilation by applying expanding forces to the lungs. Its functioning is of paramount importance to the physiology of breathing and of many pathological situations. Major difficulties in studying its function in relationship with its structure arise from the extremely complex geometrical disposition of its active and passive elements. We herein describe a two-compartment model of the inspiratory pump, with model parameters identification derived from actual measurements obtained by magnetic resonance imaging in normal humans. The equations governing the model are presented. Numerical simulations validate the model by showing a behaviour similar to physiological observations. This opens the possibility of predicting the behaviour of the respiratory system during diseases involving changes in its mechanical or geometrical characteristics.

Biomechanical Phenomena↗
PubMed2002

Renal function after aortic stent-grafting including coverage of renal arterial ostia.

Considerable experience has been gained with endoluminal stent-graft techniques for the treatment of infrarenal aortic aneurysms. The inclusion of uncovered suprarenal stents eases the treatment of cases with a short, angulated, or bottlenecked proximal neck. However, few data have been published on the effect of a stent-graft crossing renal artery ostia on long-term renal function. We therefore retrospectively analyzed the influence of intra-aortic stent-grafts, including suprarenal fixation on long-term renal function. Thirty-nine patients who received a Gianturco Z stent across renal artery ostia as part of a made-to-measure stent-graft treating an infrarenal aortic aneurysm were evaluated at 6 (all patients) and 30 months (15 patients) after surgery. Renal function evaluation included serum creatinine level, creatinine clearance using the Cockcroft-Gault formula, and renal tomography. Initial technical success was achieved in all patients. There were no minor or major complications. Mean serum creatinine levels were 1.16 +/- 0.25, 1.12 +/- 0.28, and 1.24 +/- 0.25 mg/dL before and 6 and 30 months after endoluminal stent-graft performance, respectively (P = not significant [NS]). Mean creatinine clearances were 60.3 +/- 19.7, 63 +/- 23, and 60.6 +/- 17.5 mL/min before and 6 and 30 months after endoluminal stent-graft performance, respectively (P = NS). Only two patients (5%) had a decrease in glomerular filtration rate greater than 20% at 6 months. Both patients had renal insufficiency before endovascular grafting. Renal function was stable in all patients at 30 months' follow-up. We suggest that renal function is unaffected by coverage of renal arterial ostia with Gianturco Z stents.

Aged↗
PubMed2002

Detection of vascular access stenosis by measurement of access blood flow from ionic dialysance.

BACKGROUND/AIM: The measurement of the vascular access blood flow rate (Q(a)) in chronic hemodialyzed patients was proposed to predict access thrombosis. We have recently presented a new method based on the measurements of ionic dialysance at normal and reversed positions of the blood lines. We evaluate the reliability of the measurement of Q(a) by this method in detecting significant access stenoses. METHODS: Twenty-five patients on chronic hemodialysis and having a vascular access cannulated with two needles were studied. The Q(a) was evaluated by the Diascan ionic dialysance (Q(a-id)) method and by the ultrasound dilution technique (Q(a-us); Transonic) during the same dialysis session. The measurements were available for 23 patients. In addition, the patients had ultrasonography of their fistula followed by angiography, if a stenosis was detected. RESULTS: Q(a-id) and Q(a-us) were not significantly different, showing a difference in Q(a) at 32 +/- 469 ml/min. Q(a-id) was significantly different between patients with or without stenosis (508 +/- 241 vs. 1,125 +/- 652 ml/min, p < 0.05). Among patients with a Q(a) <500 ml/min by Q(a-id), 5 had a stenosis detected by ultrasonography (sensitivity 83%), and 3 had no stenosis (false-positive rate 18%). Of these 3 patients, 2 had a thrombotic event at 1 and 3 months, suggesting that a more sensitive detection of stenosis for this range of Q(a) is needed and that a Q(a) <500 ml/min has a higher power to predict thromboses than a stenosis by ultrasonography. CONCLUSIONS: The measurement of the access flow rate by the Q(a-id) method has a clinical relevance to the detection of vascular access stenosis. An intervention program based on the Q(a-id) has to be evaluated.

Arterio-Arterial Fistula↗
PubMed2002

[Tailored endoprostheses for the endovascular treatment of aorto-iliac aneurysms: current features and perspectives].

We describe here our preliminary experience with the almost exclusive use of a range of made to measure stent-grafts home-made from commercially available components. From January 1996 to December 1999, 188 aortoiliac aneurysms (AIA) were treated with stent-grafts that were home-made to measure using Z autoexpandable stainless steel stents connected with polyester sutures and covered with commercially available polyester vascular prostheses. These stent-grafts were implanted through 18 to 24 (typically 20) Fr. commercially available introducers via a surgical remote access. Made to measure tubular, bifurcated, tapered, and/or blind stents combined with extra-anatomic bypass designs increased the rate of endovascular treatment (ET) of AIA in this series. This rate was further increased through the use of uncovered proximal or distal stents when dealing with short or tortuous necks near major side branches and through use of hybrid, partly surgical designs, one with stented and the other with stentless ends, the latter allowing for a surgically made anastomosis. The results of our experience with these techniques show that use of home-made to measure stent-grafts greatly increases the feasibility of the ET of AIA among unselected patients while offering enough efficiency and safety to deserve further investigation. Future perspectives are discussed.

Angioscopy↗
PubMedDate not supplied

Custom-made stent-grafts for aortic aneurysm repair using gianturco Z stents and woven polyester: healing in an animal model.

The purpose of this study was to evaluate the healing at 6 months of aortic stent-grafts custom-made by using Z stents and woven polyester in an animal model. Stent-grafts were built by a published method using autoexpandable stainless steel stents continuously compiled with polyester sutures and covered with a woven polyester membrane. Fourteen stent-grafts of 3 different designs were deployed under fluoroscopic control into the thoracic and the abdominal aorta of 7 adult sheep. At 6 months, all the implants of the sheep that survived the implantation were angiographed and harvested for macroscopy and microscopy. All stent-grafts were implanted successfully and remained patent from then to the explantation procedure. All stent-grafts implanted among the 6 of 7 (86%) animals that survived after the implantation remained patent, stayed free from local complications, and did not migrate during more than 6 months. In all these cases during this period, the implant functioned as a satisfactory aortic substitute while the aortic segment containing the graft kept a normal structure. There was no adverse effects of the presence of the implant upon the aorta or the animal. Stent-grafts home-made according to the described methods gave results at 6 months in this animal model compatible with a safe clinical application among humans.

Animals↗