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Biomedical subjects

P Pernot

Publications and source records attributed to P Pernot.

At least 19 recordsLinked to original sources
PubMed2006

High-throughput sample handling and data collection at synchrotrons: embedding the ESRF into the high-throughput gene-to-structure pipeline.

An automatic data-collection system has been implemented and installed on seven insertion-device beamlines and a bending-magnet beamline at the ESRF (European Synchrotron Radiation Facility) as part of the SPINE (Structural Proteomics In Europe) development of an automated structure-determination pipeline. The system allows remote interaction with beamline-control systems and automatic sample mounting, alignment, characterization, data collection and processing. Reports of all actions taken are available for inspection via database modules and web services.

Data Collection↗
PubMed2006

Solvation dynamics of the electron produced by two-photon ionization of liquid polyols. 1. Ethylene glycol.

Solvated electrons have been produced in ethylene glycol by two-photon ionization of the solvent with 263 nm femtosecond laser pulses. The two-photon absorption coefficient of ethylene glycol at 263 nm is determined to be beta = (2.1 +/- 0.2) x 10(-11) m W(-1). The dynamics of electron solvation in ethylene glycol has been studied by pump-probe transient absorption spectroscopy. So, time-resolved absorption spectra ranging from 430 to 710 nm have been measured. A blue shift of the spectra is observed for the first tens of picoseconds. Using the Bayesian data analysis method, the observed solvation dynamics are reconstructed with different models: stepwise mechanisms, continuous relaxation models, or combinations of stepwise and continuous relaxation. Comparison between models is in favor of continuous relaxation, which is mainly governed by solvent molecular motions.

Journal Article↗
PubMed2006

[Spinal cord compression by arachnoid cysts].

Spinal arachnoid cysts are considered to be rare entities, intradural locations are even less common. We report two cases of patients (two women aged 77- and 21-year-old) who presented spinal cord compression by intradural arachnoid cysts. For the second patient, repeated surgical procedures were necessary to improve the neurological status. After presenting the case reports, we expose the pathophysiological mechanisms and clinical features, and the surgical difficulties of treating this rare cause of spinal cord compression.

Adult↗
PubMed2000

Phase imaging using highly coherent X-rays: radiography, tomography, diffraction topography.

Several hard X-rays imaging techniques greatly benefit from the coherence of the beams delivered by the modern synchrotron radiation sources. This is illustrated with examples recorded on the 'long' (145 m) ID19 'imaging' beamline of the ESRF. Phase imaging is directly related to the small angular size of the source as seen from one point of the sample ('effective divergence' approximately microradians). When using the ;propagation' technique, phase radiography and tomography are instrumentally very simple. They are often used in the 'edge detection' regime, where the jumps of density are clearly observed. The in situ damage assessment of micro-heterogeneous materials is one example of the many applications. Recently a more quantitative approach has been developed, which provides a three-dimensional density mapping of the sample ('holotomography'). The combination of diffraction topography and phase-contrast imaging constitutes a powerful tool. The observation of holes of discrete sizes in quasicrystals, and the investigation of poled ferroelectric materials, result from this combination.

Journal Article↗
PubMed2000

[Neuronavigation in third ventricle tumors].

The authors present the results of neuronavigation as a help to open neurosurgery for the tumors of the third ventricle. From January, 1995 to August, 1999, six image-guided surgical procedures were performed to remove third ventricle lesions : 4 colloïd cysts, 1 ependymoma, and 1 craniopharyngioma. The operative approach was transcortical in 5 cases, and transcallosal in 1 case. The use of neuronavigation allows a decrease of the surgical trauma during the surgical approach. The procedure secures the neurosurgeon in the choice and execution of his pathway to the target. It becomes however less accurate after opening the ventricle, because of the brainshift induced by the loss of cerebrospinal fluid becomes important. Nevertheless, neuronavigation is useful in the surgery of the third ventricle, especially if it is used with neuroendoscopy.

Adult↗
PubMed1995

[Simultaneous hepatic cholangiocarcinoma and bone fibrosarcoma 45 years after ingestion of Thorotrast].

This case of a 63 year old man reports the simultaneous development of hepatic cholangiocarcinoma and fibrosarcoma of the sacrum 45 years after the systemic injection of Thorotrast. The characteristic radiologic aspect was an important criteria for diagnosis. Biopsies have confirmed the histology of both tumors. We describe the way to thorotrastosis diagnosis and characteristic malignant tumors, especially cholangiocarcinoma, induced by Thorotrast.

Bone Neoplasms↗
PubMed1992

[Laser microsurgery of meningioma. An analysis of a consecutive series of 164 cases treated surgically by using different lasers].

Over a six years period, 224 laser procedures were performed in our clinic, of these 164 (72%) involved meningiomas of various intracranial and spinal locations; 82 (50%) tumors were located in the posterior fossa, 36 (32%) were suprasellar or parasellar meningiomas: a carbon dioxide laser was used in 56 cases, a double wave length YAG laser in 101 cases, and recently a simultaneous Nd YAG and CO2 combolaser in 7 cases. Complete tumor removal was accomplished in 83% of cases and overall mortality was 3%. We think that microscope guided laser techniques represents a significant advancement in the ability to remove deep situated meningiomas that might prove difficult to extirpate by conventional microsurgery. The advantages of these methods include: 1. reduced brain retraction; 2. the ability to operate with smaller and different exposures; 3. a reduced amount of mechanical manipulation by vaporizing in first the dural attachment; 4. improved operative precision and 5. decreased intra operative blood loss.

Adult↗
PubMed1990

[Preservation of auditory function in the excision of acoustic neuroma].

Selection criteria for the preservation of auditory function during excision of acoustic neurinoma have been defined for a long time, and the means for a successful achievement of such a goal are widely known. Recruitment of special patients, for whom maintenance of an even deeply altered hearing capacity constitutes a requisite for continuation of professional work has lead us to extend indications for the pre- and retrosigmoid approaches recommended by J.M. Sterkers. The authors present a series of 16 patients, in which a single case of cophosis was deplored.

Audiometry↗
PubMed1989

[hCG and its subunits as tumor markers].

hCG is known to be produced by trophoblastic cells as well as by many normal tissues and malignancies. hCG is considered as a reliable marker for gonadal and extra gonadal choriocarcinomas; moreover it has been evidenced by immunohistochemical techniques in other malignancies. In this study, hCG and/or its alpha and beta subunits were detected in 73 males. Intact hCG was detected in 48 patients with gonadal tumors (n = 37) or extragonadal malignancies (n = 11), with or without free alpha or beta subunits. In the other 25 patients, native hCG was not detected but there were significant amounts of free beta subunit in 8 germ cells tumors and 17 extragonadal tumors. The production of free beta chains is correlated with a severe evolution in extragonadal tumors. hCG should be considered as a good marker for many tumors, but it is absolutely necessary to evaluate intact hCG as well as free beta chains.

Biomarkers, Tumor↗
PubMed1987

[Combination of traumatic vascular and neural lesions of the limbs. Surgical approach. Apropos of 10 cases].

Ten cases of limb injuries including vascular and nervous lesions are reported. After pointing out the modalities of diagnosis, the authors describe the surgical technic: vascular management first, and then nervous repair. After a six months to three years follow-up, among eight cases, the vascular repair is successful every time, and the nervous repair five times. Although each technic is usually easy, the association of both lesions needs the collaboration of multidisciplinary surgical teams.

Adult↗
PubMed1987

[Inter-apophyseal articular synovial cyst of the lumbar spine. X-ray computed tomographic and magnetic resonance imaging correlation. Apropos of 2 cases].

Two patients presenting with L5 radiculagia were investigated by CT scan imaging. The origin of the pain was determined with certitude as arising from intraspinal development of an interapophyseal synovial cyst. Examination of the two cases by MR imaging provided conflicting results: in one patient images obtained by MR were not contributive and the synovial cyst would probably have been missed while in the other patient images were specific and very sensitive for diagnosis of interapophyseal synovial lesions. Treatment was surgical in both cases.

Female↗
PubMed1984

X-ray analysis of the kinetics of Escherichia coli lipid and membrane structural transitions.

Synchrotron radiation was used to follow the time course of the transitions, induced by temperature jump, in Escherichia coli membranes and their lipid extracts isolated from a fatty acid auxotroph grown with different fatty acids. We measured the relaxation times associated with the phase transitions as well as with the conformational transition of the hydrocarbon chains and observed different behavior as a function of chemical composition. Relaxation times of about 1-2 s were found at a hexagonal to lamellar phase transition and within a lamellar phase whose parameters display important variations with temperature when the conformational transition takes place. On the other hand, no delay was observed for a phase transition where large lipid or water diffusion was not needed. We have shown that phase transitions and conformational transitions are, to a large extent, uncoupled and that the relaxation times corresponding to the latter transition could be related to the size of the ordered domains. In all cases, the order to disorder conformational transition is more rapid than the disorder to order transition. Finally, the relaxation times of the disorder to order transition observed with the membranes and with their lipid extracts were found to be strongly correlated, indicating that the proteins do not play a role in this transition.

Cell Membrane↗
PubMed1984

[Treatment of spondylolisthesis (stage I-II) by neurosurgical decompression without either osteosynthesis or reduction].

Between 1978 and 1982, 45 patients (44 adults, 1 child) with lumbar isthmic spondylolisthesis (SPL) were operated upon, through a classical posterior approach without setting or fixing. 46 SPL were at the L5-S1 level, 9 at the L4-L5, with 31 class I and 14 class II SPL, according to Meyerding. All the patients had experienced backache with radicular pain. A bilateral interlaminar way with preserving the posterior arch, allowed a large dural and radicular decompression. At the slipping level the wedge-shaped bone was removed while stripping off the disc together with its cartilaginous layer. Every possibility of root compression was cleared up: fibrosis, soft discs, osteophytic spurs, roof of the intervertebral foramina, with exploration of the adjacent levels. Neither bone graft or metallic devices were used. Apophyseal joints and their synovial membrane were denervated by coagulation. The postoperative course was uneventful. Bracing was needed for 2 months. X-ray postoperative follow-up demonstrated an important narrowing of the intervertebral space with constitution of a solid intersomatic fibrous joint without increase of slipping. Good and excellent results were obtained in 68% of cases, fair result in 20% with A 1 to 4 years follow-up. 80% of patients returned to their pre-operative occupation. After reviewing the data of the literature the authors ascertain that more complicated and sophisticated procedures do not bring out better results. They conclude that their safe and simple technique should be widely advocated for lumbar class I and II spondylolisthesis.

Adult↗
PubMed1982

[Venous graft bypass between the subclavian artery and a cortical artery, prior to carotid ligation for giant cervical carotid aneurysm].

Three cases of giant aneurysm of the cervical internal carotid artery are reported. In 2 cases the aneurysm was on the left side, with a symptomatology of repeated TI A's. In 1 case the aneurysm was on the right side, with a pharyngeal symptomatology. All 3 cases were an indication of cervical internal carotid artery ligation. Prior to the carotid ligation it was thought preferable to perform an extra-intracranial arterial By-pass. The superficial temporal artery not being available, a long By-pass was performed, between the subclavian artery and a cortical artery, by means of a saphenous vein graft. In 2 cases the By-pass was angiographically patent, 11 months and 1 year postoperatively. In one case, the postoperative angiogram (3 weeks) failed to show the By-pass. The advantages and disadvantages of the procedure are discussed.

Carotid Artery Diseases↗