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Biomedical subjects

F Hor

Publications and source records attributed to F Hor.

At least 19 recordsLinked to original sources
PubMed2000

7beta-hydroxysterol is cytotoxic to neonatal rat astrocytes in primary culture when cAMP levels are increased.

We have shown previously that 7beta-hydroxycholesterol (7betaOHCH) and 7beta-hydroxycholesteryl-3-oleate (7betaOHCH- 3-OL) are potent inhibitors of lesion-induced astrogliosis in the rat cortex or spinal cord; these substances reduce reactive astrocyte proliferation and hypertrophy. In this study, we employed cultured newborn rat astrocytes with increased cAMP levels as an in vitro model of reactive astrocytes. Treatment with either dibutyryl-cAMP (dbcAMP) or isoproterenol resulted in morphologic differentiation of astrocytes which became fibrous. Concomitant incubation with 30 microM 7betaOHCH and dbcAMP (or isoproterenol) provoked the cells to retract and was cytotoxic. When the beta-adrenergic receptor-mediated cAMP increase was abolished by propranolol, the 7betaOHCH cytotoxicity was inhibited. Immunocytochemical labelling for glial fibrillary acidic protein (GFAP) and beta-tubulin and electron microscopy suggested that intermediate filament and microtubular organizations were modified by 7betaOHCH. Analysis of the activity of cAMP-dependent protein kinase (PKA) in astrocytes treated with dbcAMP and 7betaOHCH showed a rapid and marked inhibition of the phosphotransferase activity which lasted for 24 hr. We suggest that this culture system provides an experimental system to study the molecular mechanisms involved in the effect of oxysterols on astrocytic hypertrophy. The cytotoxicity of 7betaOHCH seems to be mediated by inhibition of PKA, which phosphorylates intermediate filaments and the transcription factor cyclic AMP responsive element binding.

Adrenergic beta-Agonists↗
PubMed1999

CT and MRI findings in primitive pituitary abscess: a case report and review of literature.

Pituitary abscess is not rare. Clinical and radiological features in a primitive pituitary abscess are reported. Transphenoidal surgery revealed an abscess. Preoperative diagnosis of pituitary abscess remains difficult. Sellar round cystic mass isointense to grey matter on T1, high intensity signal on T2, with a peripheral rim enhancement following gadolinium injection associated with thickened stalk and diabetes insipidus may be suggestive of pituitary abscess.

Abscess↗
PubMed1997

[Imaging networks, surgical simulation, computer-assisted neurosurgery].

OBJECTIVE: In 1988, the neurosurgeons and neuroradiologists at the Val-de-Grâce hospital decided to create a stereotaxis site using advanced medical imaging date (CT-scan or MRI). METHODS: Two MRI machines and on CT unit were linked to a network (ETHERNET) available for radiologists in 1989. Neurosurgeons adapted stereotaxis sites using Leksell, Fisher and CRW software for MRI. A data processing program recognizing these sites was developed for stereotaxic biopsies based on MRI data. The network was extended in 1992 to the radiotherapy unit for multiple beam stereotaxic irradiations. Finally from 1994, when a computer-guided microscope (Zeiss MKM) was installed, nearly all neurosurgical procedures were conducted under stereotaxic conditions. RESULTS: Since 1989, approximately 900 computer-guided stereotaxic biopsies have been performed with precision in the millimeter range. Since 1994, the Zeiss MKM microscope has been used for 120 computer-guided procedures with the frameless stereotaxic technique guided from landmarks on the outer cranium or attached to the scalp. Mean precision obtained with landmarks was 1.2 mm and 2.8 mm with scalp markers. CONCLUSION: These techniques of computer-assisted neurosurgery based on advanced medical imaging techniques has been revolutionary for surgical approach to intracranial and intracerebral diseases. Smaller assess routes and precise pathways allow an approach to formerly inoperable lesions with minimal risk.

Biopsy↗
PubMed1997

[Pituitary abscess. A rare complication of sinusitis].

This report is of a pituitary abscess arising from chronic sinusitis. The MRI suggested a pituitary tumor with suprasellar extension and diagnosis was made operatively. Pituitary abscesses are rare entities. Despite the advent of MRI, diagnosis is often only made operatively.

Abscess↗
PubMed1996

Presence of MHC-I and B-7 molecules in rat and human glioma cells expressing antisense IGF-I mRNA.

Tumor cells frequently express the insulin-like growth factor I (IGF-I). Recently we demonstrated that rat glioma cells when transfected with a vector encoding antisense IGF-I cDNA lost tumorigenicity and induced a tumor specific immune response involving CD8+ lymphocytes. Here we show that the cultured transfected cell lines, rat C-6 glioma, human primary glioma and mouse teratocarcinoma, expressed an increased level of MHC-I and of co-signaling B-7 molecules. This increased expression of MHC-I and B-7, demonstrated by 51Cr release complement dependent cytoxicity assay and by immunostaining flow cytometry analysis, could contribute to the final immune recognition of glioma immunogenicity.

Animals↗
PubMed1996

[Immunotherapy of tumors expressing IGF-I].

Recently we demonstrated that rat glioma cells when transfected with a vector encoding antisense IGF-I c-DNA lost tumorigenicity and induced a tumor specific immune response involving CD8+ lymphocytes. Here we showed, using immunostaining flow cytometry analysis, that the transfected cell lines, rat C-6 glioma and rat LF hepatoma, expressed an increase level of MHC-class I, and even the amount of MHC-I was found to be higher in the transfected hepatoma, than in the transfected glioma cells. This increased expression of MHC-I could contribute to the final immune recognition of tumour immunogenicity.

Animals↗
PubMed1996

[Toxic aluminum encephalopathy. Predominant involvement of the limbic system on MRI].

Two patients underwent acoustic schwannoma surgery by transmastoid approach. Petrous bone defect was filled in with aluminium-containing bone cement (Ionocem). A pseudomeningocele by CSF accumulation in subcutaneous temporoparietal area appeared after the procedure and, in subsequent weeks, encephalopathy with confusion and seizures. MRI showed cerebral involvement with herpes-like disposition. Temporal stereotactic biopsy in a case did not confirm viral encephalitis but disclosed cellular accumulation of lipofucsin and particles highly suggestive of aluminum-inclusions. Aluminium's levels in blood and CSF of both patients were very high and confirm the brain's toxic involvement. Aluminium's toxicity would be advocated in patients with neurologic disorders who have undergone maxillofacial or skull bone-cementoplasty by an aluminum-containing biomaterial, if this cement is in contact with CSF.

Aged↗
PubMed1994

A cytogenetic study of 19 recurrent gliomas.

A cytogenetic analysis was performed on 19 recurrent gliomas all of which had been treated by radiotherapy. All cases exhibited clonal chromosomal anomalies, the tumors were classified into four categories in relation to their mono- or polyclonality and to the presence or absence of a clonal evolution. Polyclonal tumors without clonal evolution had a delay of recurrence significantly longer than monoclonal or polyclonal tumors with clonal evolution. This difference could be related to the presence of clones with different malignant potential, which could be differentiated by their pattern of chromosomal aberrations. The malignant potential of "highly malignant" clones resulted from the juxtaposition of imbalances, such as monosomy 10, as in high-grade primary gliomas, and presumably radiation-induced structural rearrangements. That of clones of low malignancy was almost limited to the presence of multiple balanced structural rearrangements, probably induced by radiation.

Adolescent↗
PubMed1994

[Stereotaxic biopsies of pineal tumors. Comments on their risk and implication apropos of 370 cases].

370 stereotactic biopsies of pineal region tumors, from 15 neurosurgical centers in France have been reviewed with the goal to evaluate the mortality/morbidity rates and diagnostic yield of this procedure. The impact of neuroradiological means of localisation, the probe trajectory, the type of biopsy instrument, the time of shunting are discussed in order to maximize the diagnostic yield and minimize the mortality/morbidity rates. Stereotactic biopsy contribution, as compared to other diagnostic methods, in pineal region tumors was evaluated. The mortality rate was 1.3 % (5 patients of 370), 3 patients suffered severe neurological complication. In relation to the large number of patients in this study, we can assess that the mortality rate of stereotactic biopsy in this region doesn't significantly exceed that of stereotactic brain tumor biopsies in general.

Adolescent↗
PubMed1992

Tumour resection by stereotactic laser endoscopy.

Recent advances in neuro-imaging have led to the early diagnosis of increasingly smaller and more deeply-seated tumours. Conventional neurosurgical techniques are often not satisfactory to deal with these lesions. The authors describe their preliminary experience with a prototype neuro-endoscope. The technical characteristics of the instrument and description of its use in performing stereotactic laser tumour resection are provided.

Brain 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↗
PubMed1992

[Stereotaxy, MRI and independent computer. 85 punctures].

After 150 stereotactic biopsy with CT, the team of Val-de-Grâce has made these ones with MRI and simulation of the complete procedure with an independent computer. The result of 85 biopsies is reported. This one imply the acquisition of 3DFT millimetrics slices, the transfer by Ethernet network on a computer where a specific software treat the data and allow to establish the better course for the needle biopsy. The constraints of quality are very important and some test must be executed. The diagnosis are established, avoiding an unless trepanation.

Adult↗
PubMed1985

Treatment of cerebrospinal fluid rhinorrhea by percutaneous lumboperitoneal shunting: review of 15 cases.

Fifteen patients with recalcitrant cerebrospinal fluid (CSF) fistula underwent the insertion of a lumboperitoneal shunt. The shunt consists of a two-piece Silastic tube and has been used in a population of 150 patients with communicating hydrocephalus, persistent postoperative meningocele, and benign intracranial hypertension. The spinal catheter is introduced subcutaneously and no flushing device is used. We studied three groups: 9 patients had a history of head trauma, and 7 of these had undergone one or several ineffective direct approaches to the dural leak. Four patients presented with a presumably congenital fistula. Two patients had persistent rhinorrhea due to previous intracranial procedures. Indium-111 cisternography was performed in 10 patients before lumboperitonel (LP) shunting and failed in 2 of those to document the site of leakage. Twelve patients showed cessation of rhinorrhea after LP shunting. In 4 of these, shunt-related complications responded to shunt removal with no further recurrence of rhinorrhea. Two patients underwent revision of the shunt. In 3 patients, the LP shunt failed to control the CSF leak and further intracranial procedures were indicated. The LP shunt provides an attractive and technically simple solution when direct methods of treatment have failed. Additionally, LP shunting should be considered as a primary mode of treatment in elderly patients or when impairment of CSF dynamics is documented by radionuclide cisternography and computed tomographic scanning. When an LP shunt is ineffective, shunt function should be checked by isotopic studies before additional surgery is performed.

Adult↗