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Biomedical subjects

D Fournier

Publications and source records attributed to D Fournier.

At least 73 records · Page 4Linked to original sources
PubMed1995

Acute apatite arthritis of the shoulder in a young woman.

We describe the case of a 40-year-old-woman with an acute arthritis of the left shoulder. Synovial fluid aspirated from the joint cavity appeared purulent but contained few leucocytes and no birefringent crystals. It was, however, rich in apatite crystals. A communication between the subacromial bursa and the gleno-humeral cavity through the rotator cuff could be demonstrated by sonography. The acute arthritis was secondary to the intra-articular rupture of a peri-articular calcification.

Acute Disease↗
PubMed1995

Zolpidem displays heterogeneity in its binding to the nonhuman primate benzodiazepine receptor in vivo.

The distinctive pharmacological activity of zolpidem in rats compared with classical benzodiazepines has been related to its differential affinity for benzodiazepine receptor (BZR) subtypes. By contrast, in nonhuman primates the pharmacological activity of zolpidem was found to be quite similar to that of classical BZR agonists. In an attempt to explain this discrepancy, we examined the ability of zolpidem to differentiate BZR subtypes in vivo in primate brain using positron emission tomography. The BZRs were specifically labeled with [11C]flumazenil. Radiotracer displacement by zolpidem was monophasic in cerebellum and neocortex, with in vivo Hill coefficients close to 1. Conversely, displacement of [11C]flumazenil was biphasic in hippocampus, amygdala, septum, insula, striatum, and pons, with Hill coefficients significantly smaller than 1, suggesting two different binding sites for zolpidem. In these cerebral regions, the half-maximal inhibitory doses for the high-affinity binding site were similar to those found in cerebellum and neocortex and approximately 100-fold higher for the low-affinity binding site. The low-affinity binding site accounted for < 32% of the specific [11C]-flumazenil binding. Such zolpidem binding characteristics contrast with those reported for rodents, where three different binding sites were found. Species differences in binding characteristics may explain why zolpidem has a distinctive pharmacological activity in rodents, whereas its pharmacological activity in primates is quite similar to that of classical BZR agonists, except for the absence of severe effects on memory functions, which may be due to the lack of substantial zolpidem affinity for a distinct BZR subtype in cerebral structures belonging to the limbic system.

Animals↗
PubMed1995

Isolation of Porphyromonas gingivalis strain from tubal-ovarian abscess.

An unusual case of involvement of Porphyromonas gingivalis is described. Two anaerobic isolates, identified as Fusobacterium nucleatum and P. gingivalis, were recovered from the pus of a tubal-ovarian abscess in a 35-year-old woman. Identification of the P. gingivalis isolate was confirmed by randomly amplified polymorphic DNA fingerprinting.

Abscess↗
PubMed1995

[Value of duplex ultrasound in diagnosis of ergotism of the legs].

Ergot's derivatives are widely used in the treatment of migraine and in the prophylaxy of deep venous thrombosis in association with heparin. Clinical ergotism is rarely observed and can affect all the arteries, especially of the inferior limbs. Vasospasm of the peripheral arteries and collateral formation are specific findings on angiography. We report the illustrative case of a 38 years old woman hospitalized for a small bowel occlusion. She suffers from chronic migraine treated by ergotamine tartrate. During her hospitalization, she develops an acute ischemia of the lower limbs. An ergotism was clinically suspected and confirmed by Duplex sonography which demonstrate multiple vasospasm. Under iv sodium nitroprusside and peridural analgesia the spasm resolved in 24 hours. The control Duplex sonography confirm the normality of the lower limb arteries. This examination modality allow a non-invasive diagnosis and evolution control of arteriospasm.

Adult↗
PubMed1995

Cytological events during the initiation of meristematic nodules in calli derived from eggplant protoplasts.

Histological and ultrastructural studies have been undertaken in order to identify the particularities and, if possible, some mechanisms involved in regeneration from protoplasts in the eggplant Solanum melongena. The most important result consists of a peculiar and concomitant association of meristematic and differentiated features only in cells from which regenerative processes originate.

Microscopy, Electron↗
PubMed1994

Biochemical characterization of Drosophila melanogaster acetylcholinesterase expressed by recombinant baculoviruses.

Recombinant baculoviruses expressing full length and 3' truncated forms of c-DNA encoding the Drosophila melanogaster acetylcholinesterase (AChE) were constructed. Biochemical analyses showed that full length recombinant protein was enzymatically active and anchored to the cell membrane via a glycolipidic residue. DTT treatment dissociated the native form into monomers migrating as did the corresponding form of AChE extracted from drosophila heads. Finally, DFP labelling demonstrated that the specific proteolytic cleavage leading to the formation of 55 and 16 kDa subunits occurred in Sf9 cells. In contrast with the full-length enzyme, C-terminal-truncated forms were highly secreted, confirming the prominent role of the C-terminal hydrophobic peptide for the addition of the glycolipidic residue. Accumulation of inactive precursor was observed when recombinant proteins were overproduced using an improved baculovirus, suggesting a saturation of insect cell machineries.

Acetylcholinesterase↗
PubMed1994

Resistance-associated point mutations in insecticide-insensitive acetylcholinesterase.

Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a strong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organophosphates and carbamates. Here, we report the sequence analysis of the Ace gene in several resistant field strains of Drosophila melanogaster. This analysis resulted in the identification of five point mutations associated with reduced sensitivities to insecticides. In some cases, several of these mutations were found to be combined in the same protein, leading to different resistance patterns. Our results suggest that recombination between resistant alleles preexisting in natural populations is a mechanism by which insects rapidly adapt to new selective pressures.

Acetylcholinesterase↗
PubMed1994

Drosophila melanogaster acetylcholinesterase: identification and expression of two mutations responsible for cold- and heat-sensitive phenotypes.

AceIJ29 and AceIJ40 are cold- and heat-sensitive variants of the gene coding for acetylcholinesterase in Drosophila melanogaster. In the homozygous condition, these mutations are lethal when animals are raised at restrictive temperatures, i.e., below 23 degrees C for AceIJ29 or above 25 degrees C for AceIJ40. The coding regions of the gene in these mutants were sequenced and mutations changing Ser374 to Phe in AceIJ29 and Pro75 to Leu in AceIJ40 were found. Acetylcholinesterases bearing these mutations were expressed in Xenopus oocytes and we found that these mutations decrease the secretion rate of the protein most probably by affecting its folding. This phenomenon is exacerbated at restrictive temperatures decreasing the amount of secreted acetylcholinesterase below the lethality threshold. In parallel, the substitution of the conserved Asp248 by an Asn residue completely inhibits the activity of the enzyme and its secretion, preventing the correct folding of the protein in a non-conditional manner.

Acetylcholinesterase↗
PubMed1994

cDNA sequence, gene structure, and in vitro expression of ace-1, the gene encoding acetylcholinesterase of class A in the nematode Caenorhabditis elegans.

Three genes, ace-1, ace-2, and ace-3, encode three acetylcholinesterase classes (A, B, and C) in the nematode Caenorhabditis elegans. A fragment of genomic DNA was amplified by a polymerase chain reaction (PCR) using degenerate oligonucleotides based on sequences conserved in the cholinesterase family. This fragment mapped to chromosome X at a position that perfectly matched the location of ace-1 previously determined by genetic methods. Comparison of genomic and cDNA sequences showed that the open reading frame was interrupted by eight introns. The product of ace-1 (ACE-1, 620 amino acids) presented 42% identity with Torpedo and human acetylcholinesterases, 41% with human butyrylcholinesterase, and 35% with Drosophila acetylcholinesterase. The overall structure of cholinesterases was conserved in ACE-1 as indicated by the conserved sequence positions of Ser-216, His-468, and Glu-346 (S200, H440, E327 in Torpedo (AChE) as components of the catalytic triad, of the six cysteines which form three intrachain disulfide bonds, and of Trp-99(84), a critical side chain in the choline binding site. Spodoptera Sf9 cells were infected by a recombinant baculovirus containing ace-1 cDNA. The secreted enzyme was active and existed as hydrophilic 5 and 11.5 S molecular forms. It hydrolyzed both acetylthiocholine and butyrylthiocholine and was inhibited by acetylthiocholine above 10 mM.

Acetylcholinesterase↗
PubMed1994

Mitochondrial DNA from a spider mite: isolation, restriction map and partial sequence of the cytochrome oxidase subunit I gene.

Mitochondrial (mt) DNA of the phytophagous mite Tetranychus urticae was purified and a restriction map was constructed. The 12.5 kb long genome is the shortest animal mtDNA known. A 564 bp clone comprising part of the gene for cytochrome oxidase subunit I was sequenced. As has been found in insects, the mitochondrial sequences of mites are extremely A+T rich (75% on average, 96.5% at the third codon position).

Animals↗
PubMed1994

[Value of transcranial Doppler ultrasonography in the management of severe head injuries].

Transcranial doppler ultrasonography (TCD) is a non invasive technique for the assessment of cerebral blood flow (CBF). The aim of this prospective study was to evaluate the benefit of TCD for the monitoring of major head trauma patients. Therefore 10 of such patients, aged 17 to 37 years, had a TCD at admission and subsequently at least twice a day. Following data were measured simultaneously at the site of the right and the left middle cerebral arteries: the systolic (SV), diastolic (DV) and mean (MV) blood velocity, the resistance index (RI) of Pourcelot (RI = SV-DV/SV) and the pulsatility index (PI) of Gosling (PI = SV-DV/MV). Simultaneously, the mean intracranial pressure (ICP) obtained with a subarachnoid probe, the PaCO2 and the mean arterial pressure (Pa) were measured. The cerebral perfusion pressure (CPP) was calculated with the formula: CPP = Pa-ICP. A total of 132 measures were analysed. There was a linear relation between RI and CPP (r = 0.566; p < 0.001), between RI and ICP (r = 0.822; p < 0.001), as well as between PI and CPP (r = 0.563; p < 0.001) and between PI and ICP (r = 0.837; p < 0.001). In the opposite there was no statistically significant relation between ICP and MV (r = 0.18) nor between CPP and MV (r = 0.23). However, a MV over 100 cm.s-1 was regularly associated with a ICP over 60 mmHg. The close correlation between RI, PI and ICP allows to use RI or PI to estimate ICP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Drug targeting into the central nervous system by stereotactic implantation of biodegradable microspheres.

Controlled drug release in the central nervous system through an implantable polymeric vector has been developed in recent years. For this purpose, different polymeric devices composed primarily of synthetic biocompatible and biodegradable polymers have been investigated. The first polymeric devices developed were macroscopic implants (monolithic devices), which required open surgery for implantation. Microencapsulation methods, however, allow the production of microparticles or nanoparticles loaded with neuroactive drugs. Because of their size, these micro- or nanoparticles may be easily implanted by stereotaxy in discrete, precise, and functional areas of the brain without causing damage to the surrounding tissue. Presently, this method is most frequently applied in the fields of neuro-oncology and neurodegenerative diseases, but neurologically, the potential applications of drug targeting by stereotactic implantation of drug-loaded particles are legion.

Biodegradation, Environmental↗
PubMed1994

[Malignant astrocytoma of the cerebellum. Apropos of 10 cases. Review of the literature].

While reviewing a series of 138 cerebellar tumors operated upon between 1978 and 1991, the authors could only find 2 glioblastomas and 8 anaplastic astrocytomas, occurring in 4 children (3 to 14 years old) and 6 adults (23 to 48 years old). These 10 cases represent 2% of the all malignant gliomas population observed during the same period of time. Clinically speaking, nothing makes these tumors different from other cerebellar ones. However, with an heterogenous image and an irregular contrast enhancement, the CT (scan) appearance can lead to the diagnosis. 7 lesions develop within the cerebellar vermis (vermis cerebelli) and 3 develop within the cerebellar hemisphere. Total surgical resection is performed in 9 cases and subtotal resection in 1 case (because of the extension to the floor of the fourth ventricle). Adjunctive radiotherapy on their posterior cranial fossa is achieved in 8 cases. The 2 patients with a glioblastoma present with a recurrence of their tumor at 15 months and 6 years respectively, and eventually died. Out of the patients with an anaplastic astrocytoma, 4 are still alive without recurrence and with a median follow-up of 7 years. The pathogenesis of such lesions is discussed. An aggressive therapeutic management is suggested because of the possible prolonged survival rate.

Adolescent↗
PubMed1994

Are the calcium antagonists really useful in cerebral aneurysmal surgery? A retrospective study.

From 1983 to 1990, 234 patients with one or several cerebral arterial aneurysms were surgically treated in our department. Since 1983, we have been performing surgery as early as possible. As soon as the subarachnoid hemorrhage diagnosis is confirmed by computed tomography (or if unconfirmed, by lumbar puncture), we assume that each patient may have an aneurysm. Between 1987 and 1990, 111 patients were treated by vascular volume expansion (maintenance of central venous pressure above 5 cm H2O with 4% albumin or Ringer-lactate or, if necessary, with 20% albumin), which we supplemented with calcium antagonists (nimodipine in 60 patients and nicardipine in 51 patients). Two months after being discharged, each patient is examined by a neurosurgeon and, on the same day, is subjected to a neuropsychological evaluation and a computed tomographic scan of the brain. A few months after this consultation, a working-position/family-activities questionnaire is issued to the patient. All of the results studied on the basis of postoperative mortality, second-month computed tomographic scan ischemia, neuropsychological evaluation, and return to work show no significant difference between the groups with or without calcium antagonists or between the nimodipine and nicardipine subgroups.

Activities of Daily Living↗