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Biomedical subjects

A Ravel

Publications and source records attributed to A Ravel.

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

Origin and initial course of the renal arteries: a radiological study.

The aim of this study was to determine the topography of the origin, implantation angle and initial course of the renal arteries in the transverse and frontal planes, from a prospective analysis of angiograms and helical CT-scans of 40 patients. In the frontal plane, the implantation angles of the right and left renal arteries were 73.8 +/- 17 degrees and 65.6 +/- 16 degrees respectively; 17.9% of the right renal arteries were straight compared with only 5% of the left ones. The first sinuosity was observed to be at a distance greater than the aortic diameter for 43.6% of right renal arteries and at a distance less than the aortic diameter for 62.5% for the left renal a. In the transverse plane, the right renal a. had an implantation angle of 65.6 +/- 15.7 degrees compared with 95.7 +/- 16.85% for the left renal a. The artery was rectilinear in 2.6% of the cases on the right side, and in 2.5% of the cases on the left. The first sinuosity occurred before the lateral margin of the spine was reached in 60.5% of right renal arteries and after the margin of psoas major muscle for 55% of left renal arteries. A knowledge of the anatomy of the origin and initial course of the renal arteries is important when considering vessel dilatation and the implantation of stents in the renal arteries. No correlation was observed between the origin, sinuosity or angulation of the renal arteries which could aid interventional procedures.

Adult↗
PubMed2001

[Treatment with aorto-iliac stents of acute lower limb ischemia in a patient complicating acute type B aortic dissection].

Treatment with aorto iliac endoprothesis of lower limb ischemia occuring in a patient with acute type B dissection. The mechanism was dynamic ischemia. The dissecting flap prolapsed into the iliac artery origin and narrowed the aortic true lumen above it, but without extension of the flap into the iliac artery lumen. After right iliac artery stenting, a relative left iliac artery ischemia by the shift of the dissection flap required stent implantation. Eight months later, the walking perimeter without pain was 1500m. The interest of endovascular techniques to treat visceral or lower limb ischemic complications in dissected aorta is discussed.

Aortic Dissection↗
PubMed2001

[Cross-sectional imaging of post endocarditis paravalvular myocardial abscesses of native mitral valves: 4 cases].

Four cases of submitral myocardial abscess imaged by CT or MRI following endocarditis are described. All cases occurred in fragile patients (diabetes mellitus, dialysis, severe cardiovascular diseases). An iatrogenic source was noted in one patient. Staphylococcus aureus was responsible in 2 patients. If subvalvular aortic abscesses are usually described, submitral myocardial abscesses are infrequent. In addition to transesophageal echocardiography, a technique superior to transthoracic echocardiography, CT and MRI may incidentally suggest the correct diagnosis. Both techniques provide useful morphological evaluation, information that can be used to optimize the timing for surgical repair.

Abscess↗
PubMed2000

Column efficiency and separation of DNA fragments using slalom chromatography: hydrodynamic study and fractal considerations.

Novel equations (Guillaume Y. C.; et al. Anal. Chem. 2000, 72, 853) were developed to describe the large double-stranded DNA molecule retention in slalom chromatography (SC). These equations were applied for the first time to model both the "apparent selectivity" and the resolution between two eluted DNA fragments on a chromatogram. A study of the column efficiency corroborated the fact that slalom chromatography is not based on an adsorption or equilibrium phenomenon, but can be attributed to a hydrodynamic phenomenon. Using a combination of the dynamics of DNA fragment progression in the column and fractal considerations, it was shown that the apparent selectivity depends both on the DNA fragment sizes and mobile-phase flow rate and therefore a balance between two hydrodynamic regimes. A chromatographic response function was also used to obtain the most efficient separation conditions for a mixture of DNA fragments in a minimum analysis time. The chromatographic data confirmed that in SC the flow rate can increase or maintain the separation efficiency with an associated decrease in the analysis time. This constitutes an attractive outcome in relation to the classical chromatographic separation.

Chromatography↗
PubMed2000

Mobile-phase-viscosity dependence on DNA separation in slalom chromatography.

Slalom chromatography (SC) is an alternative chromatographic procedure for the separation of relatively large double-stranded DNA molecules and is based on a new principle. The retardation of the DNA fragments from the cleavage of the Lambda DNA by the KpnI restriction enzyme was studied using an acetonitrile-phosphate buffer as a mobile phase with various concentrations of viscosity modifier (i.e. glycerol) and a C1 column as a stationary phase. The DNA molecule retention was accurately described over the glycerol concentration range using a model previously established. It was shown that the eluent viscosity increase enhanced the slalom chromatographic capacity to separate the DNA fragments. A connection between SC and 'hydrodynamic chromatography' processes was predicted to link the two processes in a global separation mechanism based on a non-equilibrium principle.

Chromatography, Liquid↗
PubMed2000

[Aneurysm of the duodeno-pancreatic arcades. Diagnostic imagery and therapeutic indications].

BACKGROUND: Aneurysms of the duodenopancreatic arcades account for 2 to 3% of all aneurysms of the digestive arteries. Mortality is high due to the risk of rupture and the difficult diagnostic situation. CASE REPORTS: The first case involved a short wide collar aneurysm implanted on the first centimeter of the superior mesenteric artery, associated with tight stenosis of the celiac trunk. The patient complained of diffuse abdominal pain and was treated surgically. In the second case, there was a false aneurysm of the gastroduodenal artery which developed a few months after acute biliary pancreatitis. The aneurysm was treated by exclusion using a transcutaneously delivered endovascular coil prosthesis. CONCLUSION: These cases illustrate the importance of imaging (magnetic resonance angiography) both for diagnosis and treatment monitoring, allowing early care with very limited morbidity and mortality.

Abdominal Pain↗
PubMed2000

Degree of solute inclusion in native beta-cyclodextrin: chromatographic approach

The reversed-phase liquid chromatography retention and separation of a series of D,L dansyl amino acids were investigated over a wide range of salting-out agent (sucrose) concentrations using native beta-cyclodextrin as a chiral stationary phase. An original treatment was developed to determine the number of sucrose molecules (n) excluded from the solute-beta-cyclodextrin cavity interface when the analyte transfer occurred. Using the n values, the relative degrees of compound inclusion were calculated and correlated to the steric bulkiness of the solute. Thermodynamic parameter variations are discussed in relation to the inclusion degree of the dansyl amino acids. This numerical approach is a valuable tool to explore the steric effects implied in the host-guest complex formation.

Journal Article↗
PubMed2000

Coil embolization of a false aneurysm with aorto-cutaneous fistula after prosthetic graft replacement of the ascending aorta.

AIM: To report palliative embolization of a false aneurysm over the distal suture line of an ascending aorta graft replacement. MATERIAL AND METHOD: A 78-year-old male patient was admitted for increasing bleeding of a chronic Manubrium ulceration, 20 months after coronary artery bypass complicated by perioperative ascending aorta dissection requiring prosthetic graft replacement. One month later, he underwent epiploplasty for a mediastinitis followed by long-term antibiotic therapy. Five months later, he presented with a Manubrium ulceration of the sternotomy. Spiral computerized tomography (CT) and aortography revealed a 20 mm anterior peri-prosthetic false aneurysm with a wide neck. Advanced age, active mediastinitis and patient's objection led us to perform percutaneous occlusion according to the Moret remodeling technique while protecting the coils release with balloon catheter inflation. RESULTS: No post-operative complication was observed and at 1-year follow-up the patient was doing well with no recurrent bleeding. Magnetic resonance imaging (MRI) and spiral CT controls confirmed coils stability without any internal flow. CONCLUSION: Percutaneous coils embolization of a large false aneurysm in the ascending aorta can be a palliative treatment in a surgically unsuited patient.

Aged↗
PubMed2000

Infrapopliteal percutaneous transluminal angioplasty for limb salvage.

PURPOSE: To evaluate long-term results of infrapopliteal percutaneous transluminal angioplasty (PTA) for limb salvage. MATERIAL AND METHODS: A retrospective study of 71 consecutive infrapopliteal PTAs in 49 patients with rest pain (n = 20) or ulceration (n = 29) was conducted. In 18 patients, surgical minor amputation or debridment was also performed. RESULTS: Technical success was achieved in 45 patients. Four failures necessitated 2 amputations. One patient died in the postoperative course. Global morbidity rate was 16%, including minor complications in 5 patients and major vascular complications in 3 patients. After technical success during the follow-up (median duration 21 months), restenoses occurred in 4 patients, of whom 3 had a successful re-PTA (clinical success rate 72%). Survival, primary patency, secondary patency and limb salvage rates were, respectively, 75%, 81%, 88% and 87% after 3 years. The only positive predictive factor for primary patency was the presence of diabetes mellitus. CONCLUSION: Infrapopliteal PTA is a safe and effective procedure, allowing good patency and limb salvage rates with low mortality and morbidity.

Adult↗
PubMed2000

[Pituitary gland MRI and Cushing disease: report of 14 operated patients].

PURPOSE: Evaluate the MR sensibility for detection and localisation of ACTH-secreting microadenomas of the pituitary gland. PATIENTS: and method. The MRI studies of the pituitary gland, performed before transsphenoidal surgical exploration, about 14 patients who present clinical and biological signs of Cushing disease, were reviewed retrospectively. We have always used unenhanced sagittal and coronal spin-echo T1 sequences, and coronal T1 after injection of gadolinium (1 Tesla). RESULTS: The global sensibility for detection of an adenoma was 100% (84 to 92% when the lesional localisation was considered). The injection of gadolinium increased the sensibility of 38 to 42% according the readers. 7 to 14% of the lesions were isointense after injection. The estimation of lesional size after injection was the nearer to the surgical results. The indirect sign most frequently seen (35.7 to 64.3%) was focal bulging of the sellar diaphragm. The only differences between the different radiologists, statistically significant, concerned the lesional size before injection and location of the lesion in the sagittal plane. CONCLUSION: This study confirmed the good sensibility of contrast-enhanced MRI in detection of ACTH-secreting microadenomas. The anatomo-radiological correlations are nevertheless incomplete.

Adult↗
PubMed2000

[Chronic hematic cyst of the orbit (orbital subperiosteal hematoma)].

A case of chronic hematic cyst of the orbit which caused unilateral globe displacement with painful diplopia is described in a 72-year-old man. CT scans showed an extraconal soft tissue mass located between the orbital roof and the superior rectus muscle with a bone lysis. Characteristic appearance on MRI (benign signs, subperiosteal localization of the hematoma) has been confirmed by removal surgery. Chronic hematic cyst of the orbit is uncommon and MRI is helpful to establish this diagnostic.

Aged↗
PubMed2000

[Comparative assessment of helical CT-angiography, 2D TOF MR-angiography and 3D gadolinium enhanced MRA in aorto-iliac occlusive disease].

PURPOSE: To compare helical CT-angiography (CTA) and two techniques of MR angiography (MRA) to conventional angiography in aorto-iliac occlusive disease. MATERIALS AND METHODS: The abdominal aorta and iliac arteries in 22 patients (4 for preoperative assessment of abdominal aortic aneurysm and 18 for peripheral vascular disease) were imaged using four techniques: digital subtraction angiography ("gold standard"), 2D TOF MR angiography, 3D Gd-enhanced MR angiography and helical CT angiography. Source (CTA and 2D TOF MRA) and MIPed images (after subtraction measures before and after gadolinium injection for 3D Gd-MRA) were reviewed. RESULTS: Sensitivity, specificity and accuracy for the detection of significant (>50%) stenosis and occlusion of aorto-iliac arteries were respectively: 38%, 89%, 77% for 2D TOF MRA; 75%, 71%, 72% for 3D Gd-MRA and 95%, 90%, 92% for CTA. Excluding the internal iliac arteries, results were 54%, 96%, 88% for 2D TOF MRA; 96%, 80%, 83% for 3D Gd-MRA and 92%, 93%, 95% for CTA. CONCLUSION: 3D Gd-MRA, a technique with potential for further improvement, is superior to 2D TOF MRA for detecting significant stenosis and occlusion of aorto-iliac arteries. Results at Gd-MRA are nearly similar to those at CTA (after excluding internal iliac arteries). Results at Gd-MRA are not affected by calcified plaque.

Adult↗
PubMed2000

[Percutaneous recanalization of occluded renal arteries].

Acute embolic renal artery occlusion is usually clinically typical. In case of early diagnosis, an in situ thrombolysis may be effective. As thrombosis often progressively completes a severe renal artery stenosis, the classical clinical description of renal infarction (lumbar pain, hematuria) is frequently not present. The kidney parenchyma downstream from the renal arterial occlusion is not always irreparably lost: collateral circulation may preserve nephron viability, which requires a lower perfusion pressure than glomerular filtration. An iodine, isotopic, or MR gadolinium nephrogram may prove this viability. Over the last 10 years, we attempted 21 percutaneous recanalizations of renal artery occlusion. Mean patient age was 62 years (44-85). All were hypertensive. Serum creatinin level of 17 patients was above 130 micromoles/ml. Three patients were previously hemodialysed. We observed 8 failures, without any complication. Thirteen immediate technical successes occurred, but one rethrombosis occurred at Day 1. Immediate complications were seen in 2 patients: 1 acute pulmonary edema, 1 puncture site false aneurysm. The mean follow up of the 12 technical successes was 26 months (18-60). One rethrombosis occurred at 6 months. Hypertension was unchanged in 4 patients and improved in 8. In all patients with renal insufficiency, a significative improvement of serum creatinine level was observed. It was possible to discontinue hemodialysis in the 3 patients previously hemodialysed. One predictive factor of success was recognized: a short delay (shorter than 90 days) between occlusion and recanalization. Percutaneous recanalization must be proposed in case of renal artery occlusion, especially to avoid vascular azotemia and dialysis, even if the kidney fed by the occluded artery is small.

Acute Disease↗
PubMed1999

Blood cholesterol and walnut consumption: a cross-sectional survey in France.

BACKGROUND: The preventive role of polyunsaturated fatty acids in cardiovascular disease has been recognized. We conducted a cross-sectional study to assess the association between walnut consumption (oil and kernel) as a source of polyunsaturated fatty acids and blood lipid levels. METHODS: Seven hundred ninety-three persons, males and females, ages 18-65 years, living in a walnut production area (Dauphiné, France) attended health screening visits organized by the Agriculture Social Security. Past diet (1-year recall, including walnut and animal fat consumption) and cardiovascular risk factors were ascertained using food frequency questionnaires. For each participant a blood sample was taken to measure HDL, LDL, and total cholesterol; apo A1; and apo B. RESULTS: A high level of HDL cholesterol and apo A1 was associated with a high amount of walnut consumption (oil and kernel) in the regular diet, with a positive trend with increasing degree of walnut consumption. This association did not appear to be confounded by dietary animal fat and alcohol as measured in this study. Other blood lipids did not show significant associations with walnut consumption. CONCLUSION: The positive effect of walnut consumption on blood HDL cholesterol and apo A1 is of special interest since these lipid parameters have been shown to be negatively correlated with cardiovascular morbidity.

Adult↗
PubMed1999

Dynamic magnetic resonance imaging of the female pelvis: radio-anatomy and pathologic applications. Preliminary results.

Dynamic MRI of the pelvis was performed in 16 young nulliparous, normally continent women. The examinations were performed in the dorsal decubitus position. Using Turbo-Flash scans (acquisition time: 2.1 sec), sagittal images were obtained at rest and with maximal pelvic straining. The sacral promontory-subpubic (PSP) and the subpubic-subsacral axes (SPSS) measured respectively 80.5 degrees and 30 degrees in relation to the horizontal plane, without a statistically significant difference between rest and straining. A marked deformation of the posterior wall of the bladder was observed in 13 cases and the bladder neck was frontally deformed in 10 cases. With straining, the base of the bladder did not descend beyond 15 mm below the SPSS, and the cervix stayed at least 14 mm above the SPSS. These were established as the normal criteria for pelvic assessment. 20 multiparous patients (mean age 65 years), referred for urinary stress incontinence and/or prolapse, were investigated using the criteria previously established. The PSP, SPSS, and vaginal angle measured 80.95 degrees, 30.57 degrees, and 69.69 degrees respectively in relation to the horizontal. No statistically significant difference was detected between straining and rest conditions. The angle of the uterus in relation to the horizontal was 57.36 degrees at rest and 65.90 degrees in straining with a difference that was statistically significant. In six patients, the base of the bladder descended more than 1.5 cm while straining and in seven patients the cervix descended at least 1.4 cm below the SPSS while straining, both statistically significant differences. Overall, between our control and study populations, there were no significant differences between PSP and SPSS measured on straining and at rest. However, differences were detected in the vaginal angle, bladder-base position, and cervical position. These results suggest the potential substitution of MRI for colpocystography.

Aged↗
PubMed1999

[Air imaging].

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Abdomen↗