PubMed Health⌕ Search

Biomedical subjects

J Y Gauvrit

Publications and source records attributed to J Y Gauvrit.

At least 19 recordsLinked to original sources
PubMed2006

New separation method for organic and inorganic selenium compounds based on anion exchange chromatography followed by inductively coupled plasma mass spectrometry.

We describe a new method for separating the organic and inorganic selenocompounds methaneseleninic acid, selenite, selenate, methylselenocysteine, selenocystine as well as both selenomethionine and its oxidized form. The separation is performed on a Hamilton PRP-X100 column. According to the literature, the oxidized form of selenomethionine-which is easily formed-is eluted close to the dead volume when this column is used. The choice of parahydroxybenzoic acid as mobile phase enabled us to elute all of these species after this oxidized form, resulting in better identification and quantification. The factors determining separation (eluent concentration, pH, gradient) were optimized via an experimental design. Application of the method to yeast and commercial tablets showed that the principal Se compound present was selenomethionine, which was also present in its oxidized form.

Anions↗
PubMed2006

The role of spiral CT for the assessment of the intracranial circulation in suspected brain-death.

BACKGROUND AND PURPOSE: The aim of this study was to assess the role of spiral CT for the diagnosis of brain death. METHODS: Over a 12-month period, 15 patients that fulfilled the clinical criteria of brain death were referred from the intensive care unit to evaluate remaining intracranial blood flow by spiral CT. The clinical diagnosis was confirmed by an apnea test in all cases. Two phases of spiral CT were performed at 20 and 60 seconds after the start of contrast media injection. Qualitative analysis included the evaluation of vessel opacification (arteries and veins) by two radiologists in consensus. RESULTS: The cortical segments of the middle cerebral artery (MCA) were assessable in all patients, whereas the internal cerebral veins could not be evaluated in five patients due to artifacts or intracranial hemorrhage. Opacification of the major branches of the circle of Willis was observed in seven cases. Unilateral opacification of cortical branches of the MCA occurred in one. We did not observe bilateral enhancement of cortical MCA branches. The internal cerebral veins did not enhance in brain death. CONCLUSION: The absence of internal cerebral vein opacification and the absence of bilateral enhancement of cortical MCA branches constituted the best criteria of brain death by contrast enhanced spiral CT.

Adolescent↗
PubMed2006

[Midline tumors of the central nervous system].

The anatomy of the supratentoriel midline structures of the brain is complex: corpus callosum, third ventricle, trigone, choroid plexus, pineal gland, falx cerebri. Different types of tumors can arise from these structures including tumors of the trigone and septum, tumors of the falx, third ventricular tumors and pinal region tumors. These tumors share similar features: minimal clinical symptoms despite their occasional large size, mild non-specific intracranial hypertension syndrome, value of MRI for depiction of tumor location, stereotactic biopsy, relative difficulty of surgical management.

Adult↗
PubMed2005

Optimization of the coupling of high-temperature liquid chromatography and flame ionization detection application to the separations of alcohols.

The feasibility of coupling high-temperature liquid chromatography (HTLC) to flame ionization detection (FID) has been studied. FID parameter values (hydrogen flow-rate, air flow-rate and FID temperature), typically set in gas chromatography are rarely suitable for liquid chromatography. Best values depend obviously on the water flow rate which is defined depending on both column temperature and column internal diameter. The FID parameters were optimized according to the water flow-rate by means of an experimental design. The potential of the method is shown with some alcohol separations and the value of increasing column temperature while reducing the column diameter is highlighted.

Alcohols↗
PubMed2005

[Neuroimaging characteristics of intracerebral haematoma].

The objective of brain imaging is to identify the hematoma according to its different stages and to find a potential underlying cause because of the risk of recurrence and the possibilities of treatment. In emergency, the diagnosis of hematoma is often obtained by CT scan, however today MRI has proved to be more accurate than CT to detect hemorrhage and to identify an underlying etiology. In some cases, according to the patient age, the medical history and the location of the hematoma, it may be necessary to perform a conventional angiography in order to exclude an intracranial vascular malformation. The aim of this review is to detail the different aspects of intracerebral hemorrhages according to the sequences and the temporal evolution, and to describe special findings which can help to identify an underlying etiology.

Cerebral Hemorrhage↗
PubMed2005

[Dynamic MRA in the evaluation of intracranial vascular diseases].

Conventional catheter angiography (CCA) remains the gold standard for the evaluation of most intracranial vascular malformations. MRA techniques such as Time of Flight, Phase Contrast or 3D contrast-enhanced MRA, provide anatomic evaluation but without hemodynamic information. Recently developed, dynamic MRA is based on dynamic acquisition of images and image subtraction; these two principal characteristics produce images comparable to those obtained by CCA. The purpose of this review is to explain the principles, advantages and drawbacks of this technique in the evaluation of arteriovenous malformations, arteriovenous fistulas, aneurysms and venous thrombosis.

Adult↗
PubMed2005

[Diagnosis and follow-up of cervical arterial dissections--results of the SFNV-SFNR study].

INTRODUCTION: the objective of this study was to determine the role of radiological techniques in the diagnosis, assessment of severity and follow-up of cervical arterial dissections. MATERIAL AND METHODS: from 1995 to 2001 a multicentre retrospective study was conducted in 24 hospital centers. A multiple-choice questionnaire was sent to each center in order to collect clinical information and imaging details regarding the diagnosis and follow-up of cervical arterial dissections. RESULTS: information was gathered on 459 patients, comprising a total of 384 carotid artery dissections and 170 vertebral artery dissections. A mean of 4.85 diagnostic examinations per patient were conducted. Morphological imaging of the brain by CT or by MRI was performed on all except 3 patients. Cervical Doppler ultrasound examination was the most frequently performed test throughout the entire study period (performed in 87% of patients). Conventional arteriography was a routinely employed test in 1995 whereas by 2001 it comprised only 31.2% of requested examinations, having been progressively replaced by MRI and MRA scanning, which comprised 60% of all examinations performed by 2001. A combination of cervical Doppler ultrasonography, axial MRI and MRA of the neck vessels were performed in 39.6% of patients in 2001. Examination of the intracranial vessels was performed by transcranial Doppler ultrasound in 40% of cases and by MRA in 30% of cases. For the follow-up of arterial dissections, an average of 1.4 examinations was performed per patient. The majority of such follow-up examinations comprised Doppler ultrasound and/or MRA of the neck arteries. CONCLUSION: The imaging diagnosis and follow-up of cervical arterial dissections will increasingly rely on non-invasive imaging techniques.

Carotid Artery, Internal, Dissection↗
PubMed2005

[Value of MRI in the etiologic diagnosis of cerebral infarction].

The causes of ischaemic brain damage are numerous. Four main groups are described: atherosclerotic disease of the cervical and intracranial arteries represents 50% of the causes, small vessel disease with lacunar infarcts 25%, cardio-embolic disease 20% and non-atheromatous arterial disease and blood dyscrasias 10%. In 10% of cases, no etiology is identified. MRI has a dominating place in the etiologic assessment of cerebral infarction, by distinguishing the various types of infarction, detecting associated abnormalities like leukoencephalopathy and haemorrhage and by analyzing the lumen and wall of vessels.

Atherosclerosis↗
PubMed2005

Brain MRI in late-onset multiple sclerosis.

Multiple sclerosis (MS) with clinical onset after 50 years of age is unusual (between 1 and 6%) and is frequently misdiagnosed. Furthermore, brain magnetic resonance imaging (MRI) abnormalities are frequently observed in subjects over 50 years of age. The aim of this study was to describe brain MRI in late-onset MS to evaluate the sensitivity and specificity of radiological MS criteria in patients aged over 50 years. We evaluated the brain MRI of 20 patients with onset of MS after 50 years of age. We compared these MRI with 26 controls matched for age, sex and vascular risk factors. MRI were blindly analysed by two neuroradiologists according to Paty et al.'s [Neurology38 (1988) 180] criteria, Fazekas et al.'s [Neurology38 (1988) 1822] criteria and Barkhof et al.'s [Brain120 (1997) 2059] criteria. The mean age at MRI scanning was 58 years. Sensitivity was 90% for Paty et al.'s criteria, 80% for Fazekas et al.'s criteria and 85% for Barkhof et al.'s criteria. Specificity was 54% for Paty et al.'s criteria, 69% for Fazekas et al.'s criteria and 65% for Barkhof et al.'s criteria. Barkhof et al.'s criteria are less specific in older patients than in young patients. We suggest that spinal cord MRI and cerebrospinal fluid analysis should be systematically performed in suspected late-onset MS in order to increase the specificity of the diagnosis.

Aged↗
PubMed2004

Endovascular treatment of remnants of intracranial aneurysms following incomplete clipping.

We report clinical and angiographic findings in eight patients treated by the endovascular approach for an intracranial aneurysm remnant after incomplete surgical clipping. They were seven women and one man, mean age 38 years (range 14-50 years). In three, the remnant was responsible for a recurrent subarachnoid haemorrhage. All were treated by embolisation of the remnant using Guglielmi detachable coils. In two, a nondetachable balloon was inflated in front of the remnant during coil detachment because of a wide neck. Mean clinical and imaging follow-up was 19 months (range 12-24 months). Immediate angiography showed complete occlusion of the remnant and follow-up clinical examination showed good or excellent recovery in all patients. Imaging follow-up confirmed persistent occlusion of the remnant in all cases.

Adolescent↗
PubMed2004

[A critical appraisal of diagnostic imaging techniques in asymptomatic carotid stenosis].

Asymptomatic stenosis of the internal carotid artery requires a non-invasive imaging work-up. The objectives include the quantification of the degree of stenosis, the analysis of the atherosclerotic plaque and the consequences of this stenosis on the brain tissue. Previous studies showed the reliability of MR angiography and spiral CT for the assessment of the arterial lumen. However, the consensus is based on the association of ultrasonography and MRA because of the non-invasive approach of these examinations that allow a complete evaluation of both the extracranial and the intracranial vessels. Recent advances in MRI will probably allow to simultaneously analyze the arterial wall in order to detect the plaques at risk and to optimize the therapeutic approach.

Carotid Stenosis↗
PubMed2004

[Cerebral arteriovenous malformations: value of the non invasive vascular imaging techniques].

Imaging evaluation of cerebral arteriovenous malformations (AVM) requires selective visualization of the different compartments of the malformation in order to select the therapeutic management. Conventional angiography remains the reference to analyze intracranial vessel conspicuity but non-invasive methods constitute an excellent alternative. Among these techniques, CT angiography is rarely used because of the need to inject iodinated contrast material and because of irradiation. MR angiography provides useful information and can be performed using several techniques: time of flight with or without contrast material injection, phase contrast, three-dimensional (3D) gradient echo acquisition after contrast material injection and, more recently, MR digital subtraction angiography. The purpose of this review article is to summarize the different non-invasive techniques for vascular imaging and to analyze the usefulness of these techniques for the assessment of brain AVMs.

Angiography, Digital Subtraction↗
PubMed2003

Angioplasty and stenting for high-grade internal carotid artery stenosis: safety study in 39 selected patients.

BACKGROUND: Carotid angioplasty and stenting (CAS) is sometimes used as an alternative to surgery, despite the lack of evidence for its safety and efficacy. METHOD: Over a 33-month period, 39 consecutive patients with a stenosis >/=70% underwent CAS (4 in a randomized trial and 35 because of contra-indications for surgery). RESULTS: In 5 patients (13%; 95% CI: 3-23), a major complication occurred (3 disabling ischaemic strokes, 1 myocardial infarction, 1 acute interstitial nephropathy). In 7 patients (18%; 95% CI: 6-30), a minor complication occurred (5 transient ischaemic attacks, 1 transient confusional state, 1 non-disabling ischaemic stroke). CONCLUSION: CAS cannot be considered as a routine procedure and should be restricted to high-risk patients unfit for surgery.

Adult↗
PubMed2003

Giant aneurysms of the internal carotid artery: endovascular treatment and long-term follow-up.

We report the long-term follow-up of 18 patients with giant aneurysms of the internal carotid artery (ICA) referred for endovascular occlusion of the parent vessel. There were 10 aneurysms involving the infra- and/or supraclinoid cavernous segment, six the ophthalmic segment, one the petrous segment and one the bifurcation. One patient who did not tolerate test occlusion was treated medically. Clinical and imaging follow-up were obtained in 16 patients for a mean of 30 months, range 6-80 months. Endovascular treatment led to excellent clinical outcome in 16 patients. One 34-year-old woman, who presented with subarachnoid haemorrhage (SAH), died from bilateral middle cerebral artery infarcts due to severe vasospasm 4 days after treatment. The patient treated medically died from SAH. Long-term imaging follow-up in 16 patients revealed a markedly smaller aneurysm sac in all cases.

Adult↗
PubMed2003

[Sub-acute phase of cerebral ischemia: value of MRI].

MRI is the examination of choice for the evaluation of ischemic brain injury. At the acute phase, this examination may differentiate infarcted tissue from hypoperfused tissue. At the subacute phase, MRI allows to confirm the diagnosis of ischemia, exclude other diagnoses, recognize the rare appearances of cerebral ischemia, distinguish the different aspects of infarct and detect some rare diseases at the origin of the ischemic event.

Acute Disease↗