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Biomedical subjects

A Thierry

Publications and source records attributed to A Thierry.

At least 19 recordsLinked to original sources
PubMed1992

Nested chromosomal fragmentation in yeast using the meganuclease I-Sce I: a new method for physical mapping of eukaryotic genomes.

We have developed a new method for the physical mapping of genomes and the rapid sorting of genomic libraries which is based on chromosome fragmentation by the meganuclease I-Sce I, the first available member of a new class of endonucleases with very long recognition sequences. I-Sce I allows complete cleavage at a single artificially inserted site in an entire genome. Sites can be inserted by homologous recombination using specific cassettes containing selectable markers or, at random, using transposons. This method has been applied to the physical mapping of chromosome XI (620 kb) of Saccharomyces cerevisi and to the sorting of a cosmid library. Our strategy has potential applications to various genome mapping projects. A set of transgenic yeast strains carrying the I-Sce I sites at various locations along a chromosome defines physical intervals against which new genes, DNA fragments or clones can be mapped directly by simple hybridizations.

Chromosome Mapping↗
PubMed1992

Sequence of a segment of yeast chromosome XI identifies a new mitochondrial carrier, a new member of the G protein family, and a protein with the PAAKK motif of the H1 histones.

We have entirely sequenced an 8.3 kb segment localized on the left arm of chromosome XI of Saccharomyces cerevisiae. Five new open reading frames have been uncovered. One of them encodes a new mitochondrial carrier protein which is dispensable for growth on glycerol medium. Another could be a new member of the G protein family. A third possesses the PAAKK motif common to H1 histones.

Amino Acid Sequence↗
PubMed1992

The sequence of a 9.3 kb segment located on the left arm of the yeast chromosome XI reveals five open reading frames including the CCE1 gene and putative products related to MYO2 and to the ribosomal protein L10.

We report here the sequence of a 9.3 kb DNA segment of chromosome XI of Saccharomyces cerevisiae, located between the MAK11 locus and the centromere. This sequence contains four long open reading frames (ORFs), YKL160, YKL162, YKL164, YKL165 and part of another ORF, YKL166, covering altogether 90% of the entire sequence. One of these ORFs, YKL164, corresponds to CCE1. Translation products of two other ORFs, YKL160 and YKL165, exhibit homology with previously known S. cerevisiae proteins: the ribosomal protein L10, and the MYO2 gene product, respectively.

Amino Acid Sequence↗
PubMed1992

MRI assessment of anterior callosotomy in the treatment of pharmacoresistant epilepsy.

Section of the anterior two-thirds of the corpus callosum is a well-known treatment of some forms of epilepsy of long duration resistant to anti-epileptic drugs and dangerous for the patient (tonic and atonic seizures). The aim of this functional surgery is to obtain the most complete rostral and caudal section of the corpus callosum without risk of disconnection syndrome. Callosotomy is seldom performed in Europe. We present our experience of magnetic resonance imaging (MRI) in the pre- and postoperative assessment of 6 patients who underwent anterior callosotomy and were followed up for more than six months. Our results were encouraging with considerable improvement of the patients' social life.

Adolescent↗
PubMed1991

Sensitization of multidrug-resistant colon cancer cells to doxorubicin encapsulated in liposomes.

The effectiveness of liposome-encapsulated doxorubicin in overcoming multidrug resistance was studied in various human colon cancer cells. Colon-cancer cell lines SW403, HT29, SW620, and SW620/R overexpressed P-glycoprotein as determined by immunoflow cytometry, thereby confirming the presence of the multidrug-resistant phenotype. Important differences were observed in the cytotoxicity of free doxorubicin as represented by IC50 values of 0.168, 0.058, 0.023, and 9.83 microM for SW403, HT29, SW620, and SW620/R, respectively. Liposomally encapsulated doxorubicin provided an IC50 that was 1.4 times lower than that of the free drug in the doxorubicin-resistant SW 620/R cell line, whereas no difference was evident in the sensitive parental SW620 cells. In addition, liposome-encapsulated doxorubicin exhibited 1.31- and 2.33-fold cytotoxicity to HT-29 and SW403 cells, respectively. The intracellular drug accumulation in SW620/R cells was enhanced by liposomally encapsulated doxorubicin, whereas it was reduced in all other cell lines as compared with that of free drug. The colon-cancer cell lines demonstrated different degrees of doxorubicin-induced DNA strand breakage that correlated with their sensitivities to drug-induced cytotoxicity. However, no difference was observed between DNA breakage caused by the free drug and that induced by liposome-encapsulated doxorubicin in any of the cell lines. The results suggest that the enhanced cytotoxicity of liposomal doxorubicin to colon cancer cells was due to some secondary non-DNA target. However, liposomally encapsulated doxorubicin appears to be effective in diminishing the multidrug-resistant phenotype and may have clinical applications.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

[Aneurysm rupture and cocaine addiction].

We describe a new case in which cocaine use was related to stroke and review the literature. Cocaine is increasingly used by drug addicts. The neurological complications are unpredictable. They include generalized or partial epileptic seizures, ischaemic or haemorrhagic cerebral vascular accident. In this case, stroke after intravenous drug injection is associated with rupture of an intra-cranial aneurysm. We put the accent on the difficulties to diagnose the cerebral stroke in cocaine abusers.

Adult↗
PubMed1990

DNA damage induced by a new 2-chloroethyl nitrosourea on malignant melanoma cells.

Different biological aspects of a novel 2-chloroethyl nitrosourea derived from cysteamine, N'-(2-chloroethyl)-N-[2-(methylsulfinyl)ethyl]-N'- nitrosourea (CMSOEN2), were studied. Drug-induced cytotoxic effects, uptake kinetics, DNA damage, and O6-alkylguanine-DNA alkyltransferase activity were determined in 3 melanoma cell lines: the murine B16 and 2 human metastatic-derived cell lines (M4 Beu and M3 Dau). We found that radioactivity uptake and incorporation in acido-precipitable material was inversely proportional to cell drug viability. The highly CMSOEN2-sensitive B16 line showed the lowest total radioactivity uptake. In fact, among the melanoma cell parameters studied, 3 of them were well correlated: (a) cytotoxicity as reflected by the colony-forming assay; (b) DNA cross-link frequency estimated by the alkaline elution technique; and (c) O6-alkylguanine-DNA alkyltransferase activity (Mer phenotype), defined as the ability of cell extracts to remove O6-methylguanine from N-methyl-N-nitrosourea-alkylated DNA. The 2 human cell lines (M4 Beu and M3 Dau), the most resistant to the cytostatic drug effects, showed little or no ability to form DNA lethal cross-links. These results correspond to the higher O6-alkylguanine-DNA alkyltransferase activity found in human-derived cell lines compared with that present in murine B16 cell lines. This study confirms that the cell content in this repair DNA protein is certainly one of the important factors implicated in the variability of response to 2-chloroethyl nitrosourea treatment observed in a number of established malignant cell lines. It has been shown that pretreatment of derived cell lines with methylating agents (N-methyl-N-nitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine) or O6-methylguanine used as a free base, increased cytotoxic effects of this class of anticancer agents, likely by saturating receptor sites (sulfhydryl groups) of this specific DNA repair enzyme. Nevertheless, in preliminary Phase I and II clinical trials, 2 patients who had been treated with multiple chemotherapies including alkylating agents [1-(2-chloroethyl)-3- cyclohexyl-1-nitrosourea, 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide, platinum derivatives], presented complete or partial remission after CMSOEN2 treatment. Our results raise the question of the exact relation between the Mer phenotype determined in derived murine or human cultured cells and that directly observed on surgically excised tumors in cancer patients. The original Mer phenotype could be modified by cell culture conditions since it has been shown that O6-alkylguanine-DNA alkyltransferase activity is widely distributed between normal and tumoral tissues without any real difference.

Antineoplastic Agents↗
PubMed1990

Purification and characterization of the in vitro activity of I-Sce I, a novel and highly specific endonuclease encoded by a group I intron.

Group I intron encoded proteins represent a novel class of site specific double strand endonucleases. The endonuclease activity of this class of proteins has been first demonstrated in vivo for I-Sce I which is encoded by a mitochondrial intron of Saccharomyces cerevisiae. Assays using crude cell extracts have shown that I-Sce I can be used in vitro as a restriction endonuclease potentially useful for recombinant DNA technology owing to its large recognition sequence (18 nucleotides). We report here the purification and the first detailed analysis of the in vitro activity and properties of I-Sce I.

Base Sequence↗
PubMed1990

[Epidural hematoma of the posterior cranial fossa].

The use of CT scans has entirely modified the prognosis of epidural hematomas of the posterior cranial fossa. The analysis of a personal series of 20 cases diagnosed and treated over a 10 year period, that is 6.5% of E.D.H. cases seen in this hospital, has enabled us: to propose an anatomical study regrouping the different topographic forms observed in the literature as well as in the present series. to check the deceptive radiological appearance of these hematomas. The main sign remains the existence of a cranial fracture at the level of the occipital bone. Repeated CT scans should attempt to localize this lesion. In 15% of our cases, the lesion was only detected on the second CT scan. to recommend a simple and rapid surgical procedure in the ventral decubitus position, which does not involve the foramen magnum approach. This is performed away from the occipital junction of the venous sinus. to underline the progressive decrease in the mortality rate (10%) and the good subsequent prognosis of these apparently serious forms which have left no sequelae.

Adolescent↗
PubMed1989

Presence of specific platelet-activating factor binding sites in the rat retina.

The specificity of the effects of platelet-activating factor (PAF) on the electrophysiology of the retina suggests the existence of specific sites for PAF in this tissue. In this study, we report the presence of tritiated PAF ([3H]PAF) specific binding sites in membrane preparations of the retina of albino rats. The binding of [3H]PAF was saturable, specific, time-dependent and reversible. Scatchard analysis of the data revealed that the high-affinity retinal binding site possessed a Kd of 2.9 +/- 0.4 nM and Bmax of 0.85 +/- 0.16 pmol/mg protein. These values are comparable with those found for the membranous PAF receptor sites in platelets, neutrophils, lung tissue and brain. We have recently reported that PAF dose dependently modulates the b-wave of the electroretinogram (ERG) obtained from the isolated rat retina. The results of the present study suggest that such PAF-induced disturbances of the ERG may be mediated via specific receptors located in the retina.

Animals↗
PubMed1989

[Multiple and recurrent extradural hematomas].

Among 130 patients with post traumatic extradural haematomas treated during the 1979-1984 period, there were 11 patients with multiple extradural haematomas, generally visualized at the first C.T. examination and 5 patients with recurring haematomas. The patients who have just been operated upon must be clinically watched and a new C.T. examination must be made if a deterioration of the patient's condition appeared or if the post operative condition is not that expected after the first C.T.

Hematoma, Epidural, Cranial↗
PubMed1988

Diencephalic epilepsy with congenital suprasellar arachnoid cyst in an infant.

The authors report the case of a 2-year-old infant who presented with paroxysm and short changes characterized by acute drowsiness, cold sweats, ocular reversion, facial cyanosis, and bradycardia. Between these attacks, the condition was normal, suggesting diencephalic seizures. Over 2 months five fits were observed by the parents when some to-and-fro bobbing of the head onto the trunk appeared during drowsiness. One electroencephalogram was normal without a slow background or spikes discharges. As the skull radiographs showed erosion of the jugum and chronic intracranial hypertension features, a CT scan was performed and showed hydrocephalus associated with a congenital suprasellar cyst. The cyst was opened into basal cisterns with cystoperitoneal shunt. The histological examination revealed that it was an arachnoid cyst. Six months later, the infant was free of diencephalic seizures and head bobbing. Thus, we can assert that there was a direct relationship between this cyst and the diencephalic seizures. From this case, the authors make a review of the clinical features of diencephalic epilepsy, and their different causes and show that both diencephalic epilepsy and suprasellar arachnoid cysts are not common.

Child, Preschool↗
PubMed1988

[Parkinsonian syndrome caused by traumatic hematomas in the basal ganglia].

A 61 year old man, without neurological history, has a coma after a facial concussion. While the consciousness is improving, parkinsonism feature is observed with tremor at rest, rigidity and bradykinesia. From the radiological point of view, hematoma of right and left basal ganglia is observed on C.T. Scan performed 6 hours after cranial trauma. The authors study the role of these 2 hematomas in genesis of parkinsonism through literature data and they bring a mean piece in pathophysiology of parkinsonism reported in boxers.

Basal Ganglia Diseases↗
PubMed1987

[Complications observed in the surgery of aneurysms of the circle of Willis in a perspective of early operation].

This report concern a series of 100 consecutive patients operated by direct attack for intracranial ruptured aneurysms (mortality: 14%, complete removal: 70%). 35% of this patients have been early operated before the 96e hour. In this series, only one case of spasm was observed. But we have observed other neurosurgical complications, analysed and compared to the postoperative course of the patients who had delayed operations.

Circle of Willis↗
PubMed1986

[3H]thienyl-phencyclidine ([3H]TCP) binds to two different sites in rat brain. Localization by autoradiographic and biochemical techniques.

A high affinity [3H]thienyl-phencyclidine ([3H]TCP) binding and its similarity to that of [3H]phencyclidine ([3H]PCP) have been demonstrated on whole rat brain homogenates. We now describe the regional distribution of the [3H]TCP binding sites in the rat brain with fixed sections and frozen slide-mounted sections visualized by autoradiography and with homogenates of 12 regions by direct binding experiments. The 3 techniques give a similar pattern for the [3H]TCP binding distribution and the biochemical study reveals that two distinct binding sites for [3H]TCP exist: one of high affinity (5-10 nM) in the forebrain, which should be responsible for the psychotropic effects and a second one of lower affinity (50-80 nM) in the hindbrain and the spinal cord, which should be involved in the extrapyramidal behavior induced by PCP and congeneers. Competition experiments have shown that muscarinic compounds interact only with the hindbrain receptor possibly in two different sites, although morphine interacts with a very low affinity with the forebrain's high affinity receptor. Results obtained with SKF-10,047 (N-allylnormetazocine) seem to indicate that TCP and sigma-receptors are different.

Animals↗