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Biomedical subjects

J Simonet

Publications and source records attributed to J Simonet.

18 recordsLinked to original sources
PubMed2006

[Diagnosis and treatment of soft-tissue tumors].

The diagnostic and therapeutic management of patients with soft-tissue tumors would be similar to the approach used for bone tumors if it were not for one crucial factor: the absolute necessity to recognize a sarcoma. The predominant features are the size of the tumor and its superficial or deep localization. If the tumor is small and superficial, biopsy can be associated with immediate resection without risk of dissemination to the deep tissues: this is the biopsy-resection approach. If the tumor is deep or superficial but large sized, search for locoregional spread with MRI is necessary before undertaking any surgical procedure. MRI can help guide the biopsy and plan resection if the tumor is a sarcoma. A first biopsy is necessary to establish the histological diagnosis and elaborate the therapeutic strategy. Samples should be sent immediately to the pathology lab which should examine sterile fresh tissue. Experience has demonstrated that proper rules for diagnosis and treatment are not necessarily applied initially in approximately one-fourth of all subjects with a malignant soft-tissue tumor. Besides the medical problems caused by this situation, the patient loses a chance for cure. When the tumor is a sarcoma, surgery is the basis of treatment. Complementary radiation therapy may be necessary, particularly for high-grade tumors or if the surgical margin was insufficient. Systemic or locoregional chemotherapy can also be used for high-grade or non-resectable tumors.

Biopsy↗
PubMed2006

Degradation of the Poliovirus 1 genome by chlorine dioxide.

AIMS: This study was undertaken to gain an understanding of the factors that influence viral RNA degradation in the presence of chlorine dioxide (ClO(2)), which will be very useful in helping to define the significance of the presence of the viral genome in disinfected water. METHODS AND RESULTS: We focused our investigation on the influence of ClO(2) on extracted RNA on the one hand, and on the infectious virus on the other. Our first results show that RNA degradation, like viral inactivation, is dose dependent. The influence of the spatial organization of the targeted genomic sequence, as well as that of its size and location (and/or sequence) on degradation of the Poliovirus 1 genome by ClO(2), was studied using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The results show that the preferential sites of action of ClO(2) appear to be located in the untranslated regions, 5'- and 3'-UTR, a phenomenon influenced by both the presence of secondary structures and the genomic sequence in these regions. Our results also reveal a rapid decrease of infectious particles quantified by the cell culture for the applied dose. Comparison between cell culture and real-time PCR for viral detection reveals disagreement following disinfection treatment, even for the largest targeted fragment (a 6,989-base fragment representing the quasi-whole viral genome). CONCLUSIONS: The detection of genome fragments is insufficient to confirm the presence of the infectious virus, as each targeted fragment shows a different sensitivity. Hence, the smallest targeted fragment (76 bp) persisted throughout the analysis period, while the longest targeted fragment (6,989 bp) disappeared very rapidly. Highly sensitive regions (i.e. 5'- and 3'-UTR) should be targeted to avoid an overestimation of the risk of viral infection using molecular biology methods in water following disinfection. Further studies in this area are needed. SIGNIFICANCE AND IMPACT OF THE STUDY: To date, it has not been possible to routinely apply virological controls to drinking water because of the time-consuming nature of the gold standard technique (cell culture) and its inability to detect all serotypes (e.g. Norovirus). Molecular techniques (e.g. real-time RT-PCR) constitute a solution to the rapid and specific detection of all the serotypes. However, ignorance of the mechanisms of viral degradation prevents the validation of PCR for the measurement of the risk of infection to humans following disinfection treatment.

Chlorine Compounds↗
PubMed2005

Cathodic modifications of platinum surfaces in organic solvent: reversibility and cation type effects.

Cathodic modification of platinum surfaces leads to the formation of iono-platinic phases ([Pt(n-), M+, MX]), which involves the insertion of cations and salts into the platinum electrode. This process was investigated at the local scale by in situ observation of surface electrochemical processes by atomic force microscopy (EC-AFM) techniques as a function of the salt and the injected charge, with special attention about the process reversibility. AFM images recorded in solution after the cathodic modifications of well-defined platinum surfaces [epitaxial platinum deposit on (100) MgO substrate] show drastic modification on the morphology of the surface, confirming previous ex situ studies. The amplitude of the modifications directly depends on both the nature of supporting electrolyte and the quantity of charge injected into the platinum. As long as the injected charge remains small enough to maintain the adhesion of the Pt deposit onto the MgO substrate, the process was found to be fully reversible. Indeed, impressive morphology changes occur under the cathodic treatment (formation of [Pt(n-), M+, MX]) but the initial geometry is totally recovered after reoxidation of the iono-platinic phase. This cycle of reduction-reoxidation can be performed several times without any significant alteration of the recovered surface and of its structural characteristics. It is suggested that the modification starts at the interface solution platinum surface and then its insertion into the platinum surface.

Journal Article↗
PubMed2003

Intermittent dislocation of the flexor hallucis longus tendon.

Dislocation of the flexor hallucis longus tendon is an exceptional occurrence. To our knowledge, this is the first case ever reported of an intermittent dislocation in a 17-year-old woman; she was a synchronised swimmer. She consulted for a right internal retro-malleolar syndrome. Voluntary "snap" was triggered by a mechanism which combined maximal ankle dorsiflexion and interphalangeal plantar flexion of the toes. Non-enhanced dynamic helical CT and axial MRI were performed, which revealed the dislocation of the right flexor hallucis longus tendon outside the posterior intertubercular talar groove. Static and dynamic imaging would appear to be required to make this uncommon diagnosis.

Adolescent↗
PubMed2001

[Experimental study of compression by Herbert screw in carpal scaphoid fracture].

PURPOSE OF THE STUDY: The purpose of this experimental work was to obtain a radiographical assessment of the effect of the compression achieved with the Herbert screw due to its different thread diameters by comparing the real and expected reduction of interfragment gap (IFG) on cadaver bones. To better understand and define the limits of this "self-compressing" effect and to study the usefulness of screw sizes smaller than the scaphoid, we measured the maximal and mean reduction of IFG without using the instrumentation. MATERIAL AND METHODS: Twelve scaphoids were obtained from fresh cadavers. The scaphoid holes were drilled and tapped in the largest axis of the scaphoid, in a central position parallel to an anti-rotation wire. A transverse osteotomy was made in the mid third of the scaphoid to simulate a Schernberg grade III fracture. The real IFG reduction was defined as the difference between the gap measured before and after screwing. The expected IFG reduction was defined by multiplying the number of screw turns by the pitch height per turn. RESULTS: On the reduction average, a Herbert screw produced a 1.1 mm IFG reduction. The maximal reduction IFG measured was 1.5 mm. For 7 cases, the real IFG reduction was larger than expected, for 4 cases it was smaller than expected and for 1 case the difference was considered negligible. The Fisher test did not demonstrate any significant statistical difference between the real and expected IFG reduction for all scaphoids. The operator perceived a subjective sensation of compression after one screw turn that continued up through the last turn. DISCUSSION: The Herbert screw develops maximal compression force when all the screw threads are totally anchored in the bone. The interfragment gap closes linearly, bringing the two bone fragments together. However, failure can result if the gap is too wide (>2 mm), the screw is poorly positioned, or there is an inappropriate correspondence between screw length and diameter and scaphoid size. Unlike spongy bone screws, the Herbert screw has a round non-conical tip thread and a shallow thread that do not bring the bone fragments together. The perception of compression corresponds to the passage of the screw through the spongy bone and not to real narrowing of the gap between the fragments. In clinical practice, because of the use of instrumentation for open surgery in carpal scaphoid fracture, it is not necessary to rely on these data, but they can be useful for percutaneous screw insertion without a guidewire and without prior compression or for another localization. Peroperative radiographs should be obtained to assess the quality of the screw position and check reduction and the reality of the compression.

Aged↗
PubMed2000

Giant cervical epidural veins after lumbar puncture in a case of intracranial hypotension.

A 29-year-old woman presented with dilated epidural veins and incapacitating headache after undergoing a lumbar puncture. Two months later, the results of follow-up MR imaging were normal. These findings suggest that temporary dilation of the epidural vein may occur in association with post-lumbar puncture intracranial hypotension syndrome. In these cases, it seems useful to confirm whether the patient has recently undergone a lumbar puncture.

Adult↗
PubMed1997

Anatomical basis of the variable aspects of injuries of the axillary nerve (excluding the terminal branches in the deltoid muscle).

The course of the axillary n. is complex with three points of angulation that may be used to delineate four segments and a fifth segment that corresponds to the intramuscular ending of the nerve in the deltoid m. The purpose of this study was to determine the precise anatomy of the nerve and of its branches, and some morphologic features for each segment. Thirty-two shoulders from embalmed adult cadavers have been studied. The axillary n. was divided in five segments: 1) from its origin to the inferior border of the subscapularis m., 2) from the subscapularis m. to the anterolateral border of the tendon of the long head of the triceps brachii m., 3) from the triceps to the posteromedial part of the surgical neck of the humerus, 4) from the humerus to the entry into the deltoid m., 5) the intramuscular distribution of the nerve in the deltoid m. In each segment from 1 to 4 were noted the origins of the branches to the subscapularis and teres minor mm. and to the scapulohumeral joint, and the origins of the lateral cutaneous branchial n. and of the terminal motor branches to the deltoid m. The length and the diameter of the nerve in the segments and the distance from the segment S1 to the musculotendinous junction of the subscapularis m. were measured. The results showed that the mean diameters were about 4.1 mm in segment 1, 4.1 mm in segment 2 and 3.4 mm in segment 3. The mean distance to the musculotendinous junction was 7.7 mm. Many variations in the levels of origin of the different muscular, articular or cutaneous branches were found without symmetry between the right and left sides. The lateral cutaneous brachial n. was absent in four cases. The results are compared with those in the literature. The division into five segments is proposed to radiologists and surgeons for evaluation or operative procedures on the axillary n., and to provide a hypothesis about the variable aspects of injuries of the nerve.

Adult↗
PubMed1996

[Lumbar interapophyseal septic arthritis. Apropos of 3 cases].

Septic arthritis of spinal apophyseal joint, seldom described, mainly concern the lumbar spine. We report three cases. Inflammatory lesions of the paravertebral soft tissues were associated in each case; an epidural abscess was present twice. Our three cases were due to Staphylococcus aureus. The initial clinical features were consistent with a spondylodiscitis. Imaging led to the correct diagnosis in all cases. According to our observations and several others of the literature: facet joint lesions are visible too late on plain films. Bone scintigraphy is sensitive, but not specific. CT scan and MRI are the most contributive investigations. A pathologic aspect of the paravertebral soft tissues is visible less than one week after the beginning of the symptoms on CT scan and MRI. Lesions of the facet joint are detectable as soon as the first week on MRI, and after 15 days of clinical course on CT scan. Epidural abscess, when present, is best shown by MRI as early as the first week. CT scan can guide percutaneous needle biopsies of the paravertebral abscesses or of the concerned facet joint.

Abscess↗
PubMed1993

[Fatigue fractures].

Stress fractures are extremely common microtraumatic lesions which occur in specific areas of healthy bones. Since clinical findings are often misleading and radiological signs are known to be delayed, diagnosis can be uneasy. In some instances, infectious or tumoral diseases have to be ruled out. Such difficult cases are shown to stress on the potential interest of CT scanner and magnetic resonance imaging.

Fractures, Stress↗
PubMed1992

[Femoral and tibial bone torsions associated with internal femoro-tibial osteoarthritis. Index of cumulative torsions].

Among the hypothesis about pathogenesis of medial knee osteoarthritis, the participation of modifications of the alignment of the limb in the frontal plane is known. The participation of the femoral and tibial torsions had been assessed by a few authors. In this study, the torsions have been measured by computerized tomodensitometry. The global torsional morphology of the limb has been defined by the measure of the Index of Cumulated Torsions. The values of torsions have been compared with the angle deformities measured in the frontal plane. The effects of the bone torsions on the position of the lower limb during the weight-bearing phase of the gait and the consequences about the knee have been studied.

Aged↗
PubMed1978

[Diagnosis of a nonparasitic splenic cyst].

It is reported on a case of the infrequent non-parasitic cyst of the spleen. Here the difficulties of the diagnostics due to the poorness of clinical and laboratory-chemical symptoms are emphasized. After the radiological exclusion of the belonging of the spacial demand to the gastrointestinal canal and to the uropoietic system it is recommended to strive for the angiographical clarification and, when a cyst of the spleen is to be proven, for the splenectomy.

Adult↗