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Biomedical subjects

F Marin

Publications and source records attributed to F Marin.

At least 37 records · Page 2Linked to original sources
PubMed2003

[CD-ROM burning of CT scan images: initial experience].

OBJECTIVES: To evaluate the cost, the functionment and the impact of the installation of a CD-ROM burning system of CT scan images. MATERIALS AND METHODS: An automated CD-ROM burning system (e-patient*, TSI, Paris, France) allows to burn CDs for CT scan examinations containing more than 4 films. During a 3 month period, we have delivered for each examination a CD-ROM including images with a Dicom viewer and a selection of interesting images printed on one film. The system has been evaluated by the technologists, the radiologists and the referring physicians by means of a questionnaire. The costs and the technical problems have also been studied. RESULTS: The benefits of our system are the increase of the diagnostic performances of the referring physicians who use the DICOM format and a reduction of the printing costs. All referring physicians pointed out major changes in their daily work including difficulties to visualize images in relation with a lack of computer infrastructure and the impossibility of simultaneous analysis of several examinations. Technologists encountered technical problems to bum examinations and radiologists had to do extra work to related to image selection. CONCLUSION: The installation of an automated burning system requires the creation of a dedicated team to train all the users and adapt the presentation of results to the clinical constraints (i.e. performing and printing an image selection). This system will not replace the hospital network but will be complementary.

CD-ROM↗
PubMed2002

Experimental measurement of the dynamic photothermal effect in Fabry-Perot cavities for gravitational wave detectors.

We report the experimental observation of the frequency dependence of the photothermal effect. The measurements are performed by modulating the laser power absorbed by the mirrors of two high-finesse Fabry-Perot cavities. The results are very well described by a recently proposed theoretical model [M. Cerdonio, L. Conti, A. Heidmann, and M. Pinard, Phys. Rev. D 63, 082003 (2001)]], confirming the correctness of such calculations. Our observations and quantitative characterization of the dynamic photothermal effect demonstrate its critical importance for interferometric displacement measurements towards the quantum limit, as those necessary for gravitational wave detection.

Journal Article↗
PubMed2002

[Efficacy of C1-C2 block with posterior parasagittal approach in the treatment of Arnold neuralgia in 24 patients].

UNLABELLED: The purpose of the study is to evaluate the efficacy of C1-C2 block from a posterior parasagittal approach to treat Arnold neuralgia. MATERIALS AND METHODS: 24 patients have been interviewed after 33 blocks were performed. The mean delay was 22 months. The posterior approach had always been performed using fluoroscopy. 27 blocks were performed with Hydrocortancyl((R)), 6 with Altim((R)). RESULTS: 71% of patients were symptomatically improved after one month, 62% after 3 months and more than 50% after one year. Using a visual analogue scale, pain was reduced of 5.8, i.e. 70% of patients were improved. An important reduction of pain killer requirements was noted for improved patients, patients with pain recurrence asked for a new infiltration. No significant side effect was noted. CONCLUSION: Our method seems to be an efficient alternative to blocks performed on the origin of the nerve and to surgical treatment.

Adult↗
PubMed2002

[Pain management with nerve root block under ct and neurostimulator guidance].

PURPOSE: To evaluate the efficacy of nerve roots block under CT and neurostimulator guidance for the management of pain. MATERIAL: and method. Nerve root blocks were performed in 27 patients (pudendal nerve, intercostal nerve, ilio-hypogastric nerve, thoracic and lumbar sympatholysis). These were performed with corticosteroids (Altim((R))) (20 patients) or phenol (7 patients). RESULTS: Seventeen patients (63%) had pain reduction during at least 15 days. The pain relief was longer with phenol. Complications appeared in the 3 lumbar sympatholysis (inguinal pain) and one of the thoracic sympatholysis (Claude Bernard Horner syndrome). CONCLUSION: The nerve root blocks seem to have some efficacy and a further evaluation is necessary to assess their impact on the ability of patients to return to work and their need for pain medication. When performing these procedures, one must be careful to avoid potential complications and verify that the procedure is needed.

Adult↗
PubMed2002

[Influence of the height of the joint space on the three-dimensional kinetics of total knee prostheses and behavior of the lateral ligaments: an in vitro study].

PURPOSE OF THE STUDY: The level of the joint space can be modified after implantation of a total knee prosthesis. Likewise, ligament balance is a cardinal point of the surgical technique. The purpose of this in vitro work was to study the influence of the position of the distal tibiofemoral joint space after implantation of a total knee prosthesis on the three-dimensional kinetics of the knee joint and on the behavior of the lateral ligaments. MATERIAL AND METHOD: Total knee arthroplasty (TKA) with a posterior stabilized prosthesis was performed on seven fresh-frozen cadaver specimens. A specially-designed experimental device was used to achieve continuous knee motion simulating hip flexion from a vertical position. The Vicon optoelectronic system was used to record the femorotibial and femoropatellar kinematics in three dimensions. Two electronic goniometers were positioned on the insertions of the lateral ligaments to measure ligament displacements during knee movements. Five configurations were recorded on each knee: healthy knee, same knee after TKA, and 2-mm and 4-mm upward displacement of the prosthetic distal tibiofemoral joint space. Ligament balance at extension was preserved in all configurations. The kinematic curves obtained were compared with the coefficient of multiple correlation. RESULTS: Changing the position of the joint space had a significant effect on the kinematics of the patella (rotation and abduction-rotation) but did not have a significant effect on the femorotibial kinematics. Variations in the length of the lateral ligaments were of small amplitude. Lowering the joint space led to laxity at flexion. Raising the joint space tightened the ligaments at flexion. DISCUSSION: These results confirm our clinical impression when the level of the distal femur cut is set to achieve tension on the ligaments at knee extension. If the joint space is lowered, i.e. with a more sparing distal femur cut, the prosthesis takes up less space during flexion, leading to laxity at flexion. If the joint space is raised, i.e. with an excessive distal femur cut, the prosthesis takes up more space during flexion, tightening the lateral ligaments. CONCLUSION: The position of the joint space must be rigorously reproduced during TKA not only to maintain correct femorotibial kinematics, but most importantly to preserve patellar kinematics and proper behavior of the lateral ligaments. Ideally, the height of the joint space should be restored first, followed by control of the ligament balance. An over- or undercut of the femur can lead to defective femoropatellar kinematics and ligament tension at flexion despite good ligament balance at extension. In addition, ligament balance should not be achieved by displacing the tibial cut or by modifying the thickness of the tibial component, which would have an effect not only at extension but also at flexion.

Anthropometry↗
PubMed2001

Noise-assisted transmission of binary information: theory and experiment.

We study the response of a bistable vertical cavity surface emitting laser to an aperiodic binary signal, by adding a variable amount of noise. The resulting behavior is an example of aperiodic stochastic resonance, and in this work we give a detailed comparison between analytical and numerical results and accurate experimental measurements. We characterize the phenomenon by using different appropriate indicators, which also allow us to quantify the binary information transmission. We show that the quality of the transmission is enhanced by a suitable amount of noise, and we give a physical picture of the phenomenon.

Journal Article↗
PubMed2001

Large-scale fractionation of molluscan shell matrix.

The numerous proteins occluded within the molluscan shell play a key role in the control of the mineralization process. Although extensively studied, these proteins are still poorly known, mainly because they are difficult to fractionate. In the present paper, we present, for the first time, a simple combined strategy for separating successfully large amounts of molluscan shell proteins. Since shell proteins do not absorb at 280 nm, our approach is based on the "blind" separation of these proteins by a preparative denaturing electrophoresis. They are subsequently detected on dot-blot with polyclonal antibodies raised against the unfractionated soluble matrix. In the present case, this approach allows one to collect enough purified proteins to obtain amino-acid composition as well as N-terminal sequences, and to perform in vitro tests and glycosylation studies. Furthermore, this method permits one to raise polyclonal antibodies against the isolated proteins.

Animals↗
PubMed2001

Soluble proteins of the nacre of the giant oyster Pinctada maxima and of the abalone Haliotis tuberculata: extraction and partial analysis of nacre proteins.

Several proteins from nacre of the oyster Pinctada maxima and the abalone Haliotis tuberculata were extracted and partly characterized. Proteins dispersed in aragonite were solubilized during demineralization with acetic acid whereas proteins adsorbed on conchiolin were extracted with sodium dodecyl sulfate and beta-mercaptoethanol. The matrix of Pinctada maxima nacre is composed of one main protein with an apparent molecular weight of 20 kDa (p20). This protein was found in the acetic acid soluble fraction of nacre, as well as in the Laemmli-solubilized extract of conchiolin. In addition, the p20 solubilized with acetic acid can form oligomers made of 6 monomers linked together by disulfide bridges. The first N-terminal 21 amino acids of p20 were determined and no homology with known proteins was found. In Haliotis tuberculata nacre, 5 main proteins were solubilized during demineralization and 3 glycoproteins were detected. Stains-all and Alcian blue staining revealed polyanionic proteins in the extracts isolated from Pinctada maxima and Haliotis tuberculata nacre.

Amino Acid Sequence↗
PubMed2000

Experimental evidence of binary aperiodic stochastic resonance

A novel kind of aperiodic stochastic resonance is experimentally studied in a vertical cavity surface emitting laser. We characterize the response of the system to a random, binary signal as a function of an applied external noise. A maximum in the input-output correlation is found for a nonzero added noise. We present analytic results with a good agreement with the measurements. We also discuss the physical meaning of the phenomenon using simple arguments, and we compare it to stochastic resonance.

Journal Article↗
PubMed2000

Life-supporting human complement regulator decay accelerating factor transgenic pig liver xenograft maintains the metabolic function and coagulation in the nonhuman primate for up to 8 days.

BACKGROUND: It is not known whether the pig liver is capable of functioning efficiently when transplanted into a primate, neither is there experience in transplanting a liver from a transgenic pigs expressing the human complement regulator human complement regulator decay accelerating factor (h-DAF) into a baboon. The objective of this study was to determine whether the porcine liver would support the metabolic functions of non-human primates and to establish the effect of hDAF expression in the prevention of hyperacute rejection of porcine livers transplanted into primates. METHODS: Five orthotopic liver xenotransplants from pig to baboon were carried out: three from unmodified pigs and two using livers from h-DAF transgenic pigs. FINDINGS: The three control animals transplanted with livers from unmodified pigs survived for less than 12 hr. Baboons transplanted with livers from h-DAF transgenic pigs survived for 4 and 8 days. Hyperacute rejection was not detected in the baboons transplanted with hDAF transgenic pig livers; however, it was demonstrated in the three transplants from unmodified pigs. Baboons transplanted with livers from h-DAF transgenic pigs were extubated at postoperative day 1 and were awake and able to eat and drink. In the recipients of hDAF transgenic pig livers the clotting parameters reached nearly normal levels at day 2 after transplantation and remained normal up to the end of the experiments. In these hDAF liver recipients, porcine fibrinogen was first detected in the baboon plasma 2 hr postreperfusion, and was present up to the end of the experiments. One animal was euthanized at day 8 after development of sepsis and coagulopathy, the other animal arrested at day 4, after an episode of vomiting and aspiration. The postmortem examination of the hDAF transgenic liver xenografts did not demonstrate rejection. INTERPRETATION: The livers from h-DAF transgenic pigs did not undergo hyperacute rejection after orthotopic xenotransplantation in baboons. When HAR is abrogated, the porcine liver maintains sufficient coagulation and protein levels in the baboon up to 8 days after OLT.

Acute Disease↗
PubMed2000

Mucins and molluscan calcification. Molecular characterization of mucoperlin, a novel mucin-like protein from the nacreous shell layer of the fan mussel Pinna nobilis (Bivalvia, pteriomorphia).

A cDNA expression library constructed from mantle tissue mRNA of the Mediterranean fan mussel Pinna nobilis was screened with antibodies raised against the acetic acid-soluble shell matrix of the same species. This resulted in the isolation of a 2138-base pair cDNA, containing 13 tandem repeats of 93 base pairs. The deduced protein has a molecular mass of 66.7 kDa and a isoelectric point of 4.8. This protein, which is enriched in serine and proline residues, was overexpressed, purified, and used for producing polyclonal antibodies. Immunological in situ and in vitro tests showed that the protein is localized in the nacreous aragonitic layer of P. nobilis, but not in the calcitic prisms. Because this protein of the nacre of P. nobilis exhibits some mucin-like characteristics, we propose the name mucoperlin. This is the first paper reporting the cloning of a molluscan mucin and the first molecular evidence for the involvement of a mucin in molluscan calcification. This finding corroborates our previous hypothesis that some of the proteinaceous constituents of the molluscan shell matrix would derive from mucins, common to many metazoan lineages of the late Precambrian (Marin, F., Smith, M., Isa, Y., Muyzer, G. and Westbroek, P. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 1554-1559). The adaptation of an ancestral mucin to a new function, the regulation of the mineralization process, may be one of the molecular events, among others, that would explain the simultaneous emergence of organized calcification in many metazoan lineages during the Cambrian explosion.

Amino Acid Sequence↗
PubMed2000

Stochastic resonance in vertical cavity surface emitting lasers

We report a detailed experimental investigation of stochastic resonance (SR) in the polarized emission of a pump-modulated vertical cavity surface emitting laser. We characterize SR in the time and frequency domains, with a quantitative agreement with existing theories. We further report a statistical analysis of SR in terms of residence-time probability distributions exhibiting alternative features which are fully explained here. By using an accurate choice of the indicator, we are also able to give clear evidence of bona fide resonance.

Journal Article↗
PubMed1999

Acute cardiac rupture complicating pre-discharge exercise testing. A case report with complete echocardiographic follow-up.

The case of a 76 year-old male who suffered acute free wall rupture and sudden hemodynamic deterioration during the recovery phase of a pre-discharge exercise testing (performed 7 days after a noncomplicated myocardial infarction) is presented. Usefulness of echocardiography in early diagnosis, management (guiding pericardiocentesis) and follow-up is remarked and, on the other hand, medical treatment after a successful resuscitation is confirmed as an alternative option in these cases.

Acute Disease↗