Biomedical subjects

L Lacoste

Publications and source records attributed to L Lacoste.

54 records · Page 3Linked to original sources

PubMed1990

[Allergy to ketamine].

A case is reported of allergy to ketamine substantiated 2 years after the accident. The female patient had ketamine for the removal of a mole. During this procedure, she developed a generalized rash and laryngospasm; the use of adrenaline was required. Since that time, although no confirmatory investigations had been carried out, she had been given a paper identifying Ketalar as being the involved drug. Investigations were carried out after she had been given a further anaesthetic (without using ketamine) 2 years after the accident. These confirmed an allergic reaction to ketamine, and not to the solvent, chlorobutanol.

Adult↗

PubMed1988

Effect of nutritional constraints on the biosynthesis of the components of the phosphoenolpyruvate: sugar phosphotransferase system in a fresh isolate of Streptococcus mutans.

A procedure for the purification of enzyme I (EI) and the protein HPr, the general components of the phosphoenolpyruvate:sugar phosphotransferase system, from Streptococcus mutans serotype c is presented. The method was also applied successfully to the purification of EI and HPr from Streptococcus salivarius, Streptococcus sobrinus, and Streptococcus sanguis. Using specific antibodies obtained against the proteins purified from S. mutans DR0001, we determined quantitatively by rocket electrophoresis the cellular levels of EI and HPr in a freshly isolated strain of S. mutans grown under various conditions in continuous culture. The activity of a few specific EIIs was also determined by an in vitro phosphorylation test. Results indicated that maximum EII activities for glucose, mannose, and 2-deoxyglucose were obtained under conditions of glucose limitation, at pH 7.0 and low dilution rate (D = 0.057/h). Increasing the amount of glucose or the dilution rate (D = 0.40/h) or decreasing the pH from 7.0 to 5.5 resulted in a 1.4- to 24-fold decrease in these activities. The EII activity for fructose was not influenced by the growth conditions in the same way as the other EIIs. The fructose EII was highest at pH 5.5 and at high dilution rate under conditions of glucose or nitrogen limitation and was always repressed at pH 7.0 and at low dilution rates. The intracellular levels of EI were also dependent on the growth conditions. The highest concentration (0.65 nmol/mg of protein) was observed in cells grown under glucose limitation at pH 7.0 and high dilution rate, and the lowest concentration (0.12 nmol/mg of protein) was found in cells grown under glucose excess at pH 7.0 and high dilution rate. The other general component of the phosphoenolpyruvate:sugar phosphotransferase system, the protein HPr, was not influenced significantly by varying growth conditions.

Bacterial Proteins↗

PubMed1988

Pentylenetetrazole inhibits glutamate dehydrogenase and aspartate aminotransferase, and stimulates GABA aminotransferase in homogenates from rat cerebral cortex.

The mechanism by which pentylenetetrazole provokes convulsions in animals has been investigated by measuring its influence in vitro on the activities of several enzymes of glutamate metabolism in rat brain homogenates. Pentylenetetrazole does not affect the specific activities of glutamine synthetase, glutaminase, or glutamate decarboxylase; it inhibits those of glutamate dehydrogenase and aspartate aminotransferase, and stimulates that of gamma-aminobutyric acid (GABA) aminotransferase. The overall consequence of the action of pentylenetetrazole on the activities of these enzymes should be an increase in the concentration of glutamate and a decrease in that of GABA. This modulation of glutamate and GABA metabolism by pentylenetetrazole could contribute to the triggering of convulsions.

4-Aminobutyrate Transaminase↗

PubMed1987

[Recovery following anesthesia with diazepam-ketamine and fentanyl-methohexital].

The quality of recovery from general anaesthesia for day-case surgery is assessed by the Trailmaking test in a randomized study of 100 women scheduled for termination of pregnancy on an outpatients basis. All patients are in ASA group I or II. Recovery following diazepam-ketamine based anaesthesia is compared to that following fentanyl-methohexital based anaesthesia. In group A, 5 min after intravenous injection of diazepam (0,2 mg.kg-1), anaesthesia is induced with ketamine (1 mg.kg-1). If necessary, in response to spontaneous movement, for maintenance of anaesthesia, 1 or 2 supplementary doses of ketamine (0,5 mg.kg-1) are administered. In group B, 5 min after intravenous injection of fentanyl (1 microgram.kg-1), anaesthesia is induced with methohexital (2 mg.kg-1). If necessary, in response to spontaneous movement, for maintenance of anaesthesia, 1 or 2 supplementary doses of methohexital (0,7 mg.kg-1) are administered. The quality of recovery is assessed by Trailmaking test 1/2 h and 1 h after surgery and compared with pre-anaesthetic score. The two groups are comparable with regard to age, weight, educational level and average duration of anaesthesia. In group A, the mean score for the two parts of the test is not significantly different 1 h after surgery from the pre-anaesthetic score. In group B, the mean score for the two parts of the test is not significantly different 1/2 h after surgery than the pre-anaesthetic score. This better post-anesthetic score is explained by a learning effect of the test when used several times.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Legal↗

PubMed1986

Non-linear kinetics of glutamyl-tRNA synthesis catalyzed by high molecular weight complexes from rat brain neuronal cells but not from glial cells.

High molecular weight complexes of aminoacyl-tRNA synthetases isolated from rat brain catalyze the formation of glutamyl-tRNA with an initial lag time of the order of 1 min, as previously reported for the formation of glutamyl-tRNA and glutaminyl-tRNA catalyzed by similar complexes from bovine brain (Vadeboncoeur and Lapointe, Eur. J. Biochem., 109 (1980) 581-587). To determine the type(s) of brain cell(s) where this phenomenon occurs, we have studied the kinetics of glutamyl-tRNA formation catalyzed by high molecular weight complexes of aminoacyl-tRNA synthetases isolated from neuronal and from glial cells, either transformed (Neuro-2A and C6), or from primary cultures, or isolated from rat brain. The delay in the formation of glutamyl-tRNA was observed only in the case of neuronal cells isolated from rat brain, whereas a delay in the formation of glutaminyl-tRNA was also seen in these cells, as well as in neuronal cells in primary culture and in synaptosomes. The kinetics of formation of aspartyl-tRNA and valyl-tRNA catalyzed by high molecular weight complexes from all these cells was linear.

Acylation↗

PubMed1983

The monomeric glutamyl-tRNA synthetase from Bacillus subtilis 168 and its regulatory factor. Their purification, characterization, and the study of their interaction.

The glutamyl-tRNA synthetase from Bacillus subtilis has been purified to homogeneity. It is a monomer of Mr = 65,500 whose NH2-terminal sequence is Met-Asn-Glu-Val-Arg-Val-Arg-Tyr-Ser-Pro-Ser-Pro-Thr-Gly-His-Leu. The number of tryptic peptides indicates the absence of a significant amount of sequence duplication. Under certain conditions, this monomeric enzyme is co-purified with a polypeptide beta of Mr = 46,000, which increases the affinity of the enzyme about 10-fold for glutamate and for ATP, and stabilizes it against heat inactivation. gamma-Globulins prepared against the monomeric enzyme can inhibit completely the glutamyl-tRNA synthetase activity of a B. subtilis extract and precipitate from this extract both the monomeric enzyme and the regulatory factor beta. These anti-alpha immunoglobulins do nt precipitate pure beta. These results show that the glutamyl-tRNA synthetase of B. subtilis has a structure similar to that of the Escherichia coli enzyme (Lapointe, J., and Söll, D. (1972) J. Biol. Chem. 247, 4966-4974) and indicate that the beta factor has a function in the regulation of glutamyl-tRNA biosynthesis in vivo.

Amino Acid Sequence↗

PubMed1982

[Leptosphaeria (?) senegalensis, Segrétain, Baylet, Darasse et Camain. Perithecia and asci. II. Asci and ascospores].

The ascal wall of Leptosphaeria senegalensis typically belongs to the bitunicate type; in its fin al state it comprises an exoascus separated from the endoascus by a clear space. The three-layered endoascus is formed of fibrillae whose most internal are accordion-like folded. The ascospores have a complex wall; from the interior to the exterior it comprises: an endospore, an irregularity thickened epispore, a perispore, and an ectospore thickened in a cap at the posterior end of the spore. The comparison of ascospores of two "real" Leptosphaeria (L. acuta et L. maculans) with those of L. senegalensis shows that the latter species must no longer be included in the genus Leptosphaeria.

Ascomycota↗

PubMed1982

Derepression of the glutamine synthetase in neuroblastoma cells at low concentrations of glutamine.

Regulation of the biosynthesis of glutamine synthetase was studied in neuroblastoma cells (Neuro-2A) by use of a recently developed, sensitive radioisotopic assay. The removal of glutamine from the culture medium of these cells for 24 h resulted in a 10-fold increase in glutamine synthetase specific activity (15-fold after 2 weeks) compared with the basal level found in cells grown in the presence of 2 mM glutamine. Following the growth of these cells for 2 weeks in the presence of various concentrations of glutamine, a negative linear correlation was observed between the specific activity of glutamine synthetase (from 1.7 to 0.14 unit/mg) and the concentration of glutamine in the growth medium (from 0.5 to 2 mM). Cycloheximide or actinomycin D blocked the increase in glutamine synthetase activity observed in the absence of glutamine. These results suggest that the removal of glutamine led to the induction of glutamine synthetase by stimulating new enzyme synthesis. The enzyme was not degraded, but only diluted, by growth upon readdition of glutamine to the medium. The influence of glutamine depletion is also reported for C-6 glioma cells and glial cells in primary cultures.

Animals↗

PubMed1981

[Leptosphaeria (?) senegalensis Segretain, Baylet, Darasse et Camain. Perithecia and asci. I. Perithecial ontogeny and structure (author's transl)].

Perithecia of L, snegalensis develop from stromato-glomerular type primordia. One or several female cells (=ascogones), each of them topped by a trichogyne, appear in the carpocentral mass; each ascogone directly produces dicaryotic cells without any intervening pro-sporophytic vesicle. The development of the sterile elements is typical of an ascolocular Pryremomycete with a Pleospora type carpocentrum: formation of a perilocular layer composed of a non persistent subhymenial meniscus and a bell-shaped suprahymenial meniscus generating pseudo-paraphyses but no periphyses.

Ascomycota↗

PubMed1977

The role of misrepair processes in the isolation of new types of streptomycin-resistant mutants in Escherichia coli.

Treatment of Escherichia coli cells with ethylmethanesulfonate followed by a prolonged delay for phenotypic expression allows to select new types of streptomycin-resistant mutants, which are double mutants with one change resulting from base mispairing and the second one from misrepair. The error-prone recA-dependent pathway is involved in this misrepair, as evidenced by the fact that recA strains do not provide double mutants.

DNA Repair↗

PubMed1977

[Photoinhibition of chlamydosporulation of Candida albicans].

Candida albicans produced chlamydospores after 24 h in the dark at 27 degrees C, but the process was inhibited under adequate irradiation of light. The in vivo absorption spectra showed a main peak at 414 nm, and less important peaks at 430, 446, 477, 519, 549 and 560 nm. No bands were detected beyond 600 nm. A total inhibition of chlamydosporulation occurred at 414 nm (monochromatic light) for an initial energy of 2,000 ergs cm-2 s-1. A 4,000 ergs cm-2 s-1 irradiation energy was necessary to observe a marked inhibition at 460, 500 and 530 nm (les chlamydospores and/or immaturity); this energy must be raised to 300,000 ergs cm-2 s-1 to observe a similar effect at 575 and 630 nm. Biological activity spectra were in full concordance with absorption spectra at 414 nm; no interpretation of absorption band at 460 nm is given, but total or partial inhibition could be explained by modulation of protoporphyrin activity.

Candida albicans↗

PubMed1976

New types of streptomycin-resistant mutants of Escherichia coli.

Mutagenesis of Escherichia coli K12 cells with ethyl methanesulfonate and selection of streptomycin-resistant mutants after a long delay for phenotypic expression allowed us to isolate new types of streptomycin-resistant ribosomes. Misreading patterns of the ribosomes in the presence of streptomycin revealed that most of the streptomycin-resistant mutants isolated under these conditions differed from the four classical types of streptomycin-resistant mutants studied and characterized by Strigini, P. and Gorini, L. (1970) J. Mol. Biol. 47, 517-530.

Coliphages↗

PubMed1975

[Growth and sexual reproduction of the dermatophyte Arthroderma vanbreuseghemii Takashio (Trichophyton mentagrophytes (Robin blanchard) on a synthetic medium].

A synthetic medium without agar is proposed for the growth and the sexual reprpduction of the dermatophyte Arthroderma vanbreuseghemii (Trichophyton mentagrophytes). The determinations of mycelium dry weight showed that this species grew poorly with only one amino-acid as nitrogen source. A. vanbreuseghemii grew weakly on a mixture of glutamic and aspartic acid and serin. A small amount of aromatic amino-acids added to this mixture, increased the growth rate comparable to that obtained on peptone. The sexual reproduction was induced on synthetic medium with a propicious balance between carbon and nitrogen sources. Addition of 0.5 or 1g/1 of glucose to 50 mg N/1 supplied by the amino-acids mixture (including the aromatics) gave the optimal ratio. Using these conditions, many cleistothecia was produced by crossing two semi-compatible strains.

Amino Acids↗

PubMed1974