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Biomedical subjects

L Gauthier

Publications and source records attributed to L Gauthier.

At least 37 records · Page 2Linked to original sources
PubMed1997

[The rehabilitation of the psychiatric hospital. A question of audacity and synergy].

Using a mode of psychodynamic analysis, this article exposes some similarities between the factors that hinder the social reintegration of the "patient" and the social and political forces opposing the "rehabilitation" of the social institution represented by the psychiatric hospital. In support to this analogy, the article outlines the transformations realized over the last few years at the Centre hospitalier psychiatrique Sainte-Thérèse of Shawinigan and suggests that, in order to make such changes, the development of rehabilitation services can serve as a catalyst. The authors also propose a perceptual analysis of human, political and social reactions created by the metamorphosis of the traditional role attributed to the psychiatric hospital.

Attitude to Health↗
PubMed1996

Recall of childhood neglect and physical abuse as differential predictors of current psychological functioning.

The differential effects of neglect and physical abuse on psychological functioning are not well understood. The present study examined the relationship between reported neglect and physical abuse and symptomatology and attachment styles in a sample of 236 male and 276 female undergraduates. In contrast to physical abuse, which must involve some parental involvement in a child's life, neglect is characterized by a lack of parent-child interaction. As such, it was hypothesized that childhood neglect would be more predictive of symptomatology and dysfunctional attachment styles than would physical abuse. Results confirmed the expected relationship between neglect and more severe psychological problems and anxious attachment styles. Implications of these results point to the need to focus both empirically and theoretically on neglect and physical abuse as potentially separate moderators of psychosocial functioning.

Adult↗
PubMed1995

Fetal versus adult PreB or B cells: the human VH repertoire.

At the preB stage, when only the IGH locus has rearranged, mu chains become expressed in association with the psi L chains, lambda-like and VpreB, thus forming the preB receptor. By the use of a monoclonal anti VpreB antibody, preB cells were isolated from two adult bone marrow samples, and the VH repertoire was analyzed and compared to fetal, XLA (X-linked agammaglobulinemia), and adult B repertoires. Most VH genes identified were also expressed in fetal liver, XLA bone marrow, and adult PBLs, with similar predominant usage of certain germline genes. Multiple D/D fusions, limited N diversity, and preferential use of JH4 with a low level of DQ52 usage were also identified. Few mutations could be observed, not specifically localized in CDR regions, that could be interpreted as not positively selected. Conversely, a shorter length of CDR3 appeared to be the hallmark of the preB step. Thus, the association of psi L chains with mu does not bring about a bias in the VH gene usage, but a first selection on the CDR3 region could be the result of recognition by given autoantigens or ligands different for preB cells and B cells.

Adult↗
PubMed1995

The Melolontha melolontha entomopoxvirus (MmEPV) fusolin is related to the fusolins of lepidopteran EPVs and to the 37K baculovirus glycoprotein.

We have cloned and sequenced a 1.7-kbp DNA fragment of the MmEPV genome encompassing the major polypeptide of the spindle-shaped inclusions gene termed fusolin. The sequence contained a single open reading frame of 1203 nt capable of coding for a polypeptide of 45.8 kDa. The 13 N-terminal amino acid (aa) residues were hydrophobic and could act as a signal peptide. The aa sequence also contained 13 cysteine residues very likely involved in paracrystal formation. This sequence showed significant homologies with the fusolins of two lepidopteran EPVs, the Choristoneura biennis EPV (CbEPV) and the Heliothis armigera EPV, and also with the 37K glycoproteins of Autographa californica and Orgyia pseudotsugata baculoviruses. No homology was found between the MmEPV fusolin and the 100K MmEPV spherulin, nor with the 110K polypeptide of the CbEPV and Amsacta moorei EPV spheroidins. These data were confirmed by Western blot analysis. Transfection of vaccinia-infected mammalian cells with a plasmid encompassing the fusolin sequence plus the upstream regulatory region resulted in transient expression of the gene. This indicated that the vaccinia transcription machinery is able to transcribe the fusolin gene. The fusolin was also expressed in insect cells via a recombinant baculovirus.

Amino Acid Sequence↗
PubMed1995

Study of the genotoxic activity of six halogenated acetonitriles, using the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test.

Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of six halogenated acetonitriles identified in chlorinated waters (monochloro-, dichloro-, trichloro-, monobromo-, dibromo- and bromochloroacetonitrile). With the SOS chromotest, three of the chemicals studied (dichloro-, dibromo- and bromochloroacetonitrile) were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, all the compounds except dibromoacetonitrile showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for all the six haloacetonitriles studied. Moreover, two structure-activity relationships were noted: (1) the genotoxic activity of haloacetonitriles containing bromine substituents appeared higher than the corresponding chlorinated acetonitriles and (2) the clastogenic activity of the chlorinated acetonitriles increased with the number of chlorine substituents.

Acetonitriles↗
PubMed1995

Genotoxicity assay of chloral hydrate and chloropicrine.

The chlorination by-products chloral hydrate and chloropicrine were assayed for genotoxicity in three short-term tests. Chloropicrine was 100-fold more potent than chloral in inducing mutations in strain TA100 of S. typhimurium (fluctuation test) and, at variance with chloral, was positive in the SOS chromotest using strain PQ37 of E. coli. On the other hand, only chloral caused a significant increase in the frequency of micronucleated erythrocytes following in vivo exposure of the amphibian Pleurodeles waltl newt larvae.

Animals↗
PubMed1995

Amphibian micronucleus test in vivo: evaluation of the genotoxicity of some major polycyclic aromatic hydrocarbons found in a crude oil.

The micronucleus test using erythrocytes of Pleurodeles waltl larvae (Amphibia, Salamandridae) was used to detect the possible genotoxicity of four polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene and benzo[a]pyrene), which represent a major fraction of crude oil. Larvae were reared in water containing the test compound and the levels of micronucleated red blood cells were compared with those found in larvae reared in control water. The results are compared with published data from other tests used to evaluate the clastogenic or mutagenic properties of compounds. The results obtained confirm that benzo[a]pyrene has a strong genotoxic potential, whereas the genotoxicity of naphthalene is weak; in contrast, anthracene and phenanthrene gave a negative response.

Animals↗
PubMed1995

Use of the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test to study the genotoxicity of four trihalomethanes.

Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of four trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane and bromoform). With the SOS chromotest, all the chemicals studied except chloroform were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, only bromoform showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for bromodichloromethane and bromoform. It appeared that the presence of bromine substituent(s) generally led to significant genotoxic activity. Moreover, the use of the metabolic system significantly increased the genotoxicity of the brominated trihalomethanes in the SOS chromotest. Unlike previous investigations in which the SOS chromotest was always the least interesting assay, this study exhibited the good efficiency of this in vitro test on E.coli for the detection of trihalomethanes with bromine substituents.

Animals↗
PubMed1995

Regulation of ptsH and ptsI gene expression in Streptococcus salivarius ATCC 25975.

The transcriptional regulation of the Streptococcus salivarius ptsH and ptsI genes coding for the general energy-coupling proteins HPr and enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system were investigated. These genes form an operon with the gene order ptsH-ptsI. Three distinct mRNA species were detected: a 0.5 kb transcript specific for ptsH, and two long transcripts (2.2 and 2.4 kb) covering the whole pts operon. Transcription of all these mRNAs initiated at the same nucleotide located 9 bp downstream from a promoter located immediately upstream from the ptsH gene. The presence of a high-energy stem-loop structure (T0) located at the beginning of ptsI was responsible for the premature transcription termination generating the 0.5 kb ptsH-specific transcript. The long transcripts ended in the poly(U) region of two rho-independent-like terminators (T1 and T2) at the 3' end of ptsI. Studies with a 2-deoxyglucose-resistant spontaneous mutant of S. salivarius (L26) that produces an HPr-EI fusion protein suggest that the regulation of HPr and EI expression involves transcriptional as well as translational mechanisms.

Amino Acid Sequence↗
PubMed1994

Positive selection for resistance to 2-deoxyglucose gives rise, in Streptococcus salivarius, to seven classes of pleiotropic mutants, including ptsH and ptsI missense mutants.

We have used the toxic non-metabolizable glucose/mannose analogue 2-deoxyglucose to isolate a comprehensive collection of mutants of the phosphoenolpyruvate:sugar phosphotransferase system from Streptococcus salivarius. To increase the range of possible mutations, we isolated spontaneous mutants on different media containing 2-deoxyglucose and various metabolizable sugars, either lactose, melibiose, galactose or fructose. We found that the frequency at which 2-deoxyglucose-resistant mutants were isolated varied according to the growth substrate. The highest frequency was obtained with the combination galactose and 2-deoxyglucose and was 15-fold higher than the rate observed with the mixture melibiose and 2-deoxyglucose, the combination that gave the lowest frequency. By combining results from: (i) Western blot analysis of IIIMan, a specific component of the phosphoenolpyruvate:mannose phosphotransferase system in S. salivarius; (ii) rocket immunoelectrophoresis of HPr and EI, the two general energy-coupling proteins of the phosphotransferase system; and (iii) from gene sequencing, mutants could be assigned to seven classes.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗
PubMed1994

Properties of a Streptococcus salivarius spontaneous mutant in which the methionine at position 48 in the protein HPr has been replaced by a valine.

HPr is a protein of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) that participates in the concomitant transport and phosphorylation of sugars in bacteria. In gram-positive bacteria, HPr is also reversibly phosphorylated at a seryl residue at position 46 (Ser-46) by a metabolite-activated ATP-dependent kinase and a Pi-dependent HPr(Ser-P) phosphatase. We report in this article the isolation of a spontaneous mutant (mutant A66) from a streptococcus (Streptococcus salivarius) in which the methionine at position 48 (Met-48) in the protein HPr has been replaced by a valine (Val). The mutation inhibited the phosphorylation of HPr on Ser-46 by the ATP-dependent kinase but did not prevent phosphorylation of HPr by enzyme I or the phosphorylation of enzyme II complexes by HPr(His-P). The results, however, suggested that replacement of Met-48 by Val decreased the affinity of enzyme I for HPr or the affinity of enzyme II proteins for HPr(His-P) or both. Characterization of mutant A66 demonstrated that it has pleiotropic properties, including the lack of IIILman, a specific protein of the mannose PTS; decreased levels of HPr; derepression of some cytoplasmic proteins; reduced growth on PTS as well as on non-PTS sugars; and aberrant growth in medium containing a mixture of sugars.

Bacterial Proteins↗
PubMed1994

Use of desmopressin acetate to reduce blood transfusion requirements during cardiac surgery in patients with acetylsalicylic-acid-induced platelet dysfunction.

OBJECTIVE: To determine whether desmopressin acetate (DDAVP) has the ability to reduce blood loss in patients with a known bleeding tendency. DESIGN: A randomized, double-blind, placebo controlled study. SETTING: A university teaching hospital. PATIENTS: Men under the age of 70 years who had taken acetylsalicylic acid within 7 days of scheduled coronary artery bypass surgery. Patients with an abnormal hematologic profile or a history of bleeding or who were receiving heparin or undergoing repeat coronary bypass surgery were excluded. Forty-four patients were randomized with restriction in blocks of 10; 20 received DDAVP and 24 received a placebo. MAIN OUTCOME MEASURES: Blood loss and blood transfusion requirements. RESULTS: Patients treated with DDAVP lost significantly (p < 0.01) less blood than those receiving a placebo (1543 mL versus 2376 mL respectively). Nineteen patients had a blood loss of more than 2000 mL; 15 of these were in the placebo group. Significantly (p < 0.02) fewer patients receiving DDAVP required blood transfusion (9 versus 18). CONCLUSIONS: DDAVP reduces blood loss during cardiac bypass surgery in patients who have taken acetylsalicylic acid within 7 days before operation.

Aspirin↗
PubMed1993

In vivo detection of waste water and industrial effluent genotoxicity: use of the Newt Micronucleus Test (Jaylet Test).

The genotoxic potential of various waste waters has been evaluated in a micronucleus test using amphibian larvae. Genotoxicity was detected after dilution, in waste water from tanneries and from various petrochemical industries. Further studies have shown that sample treatment used for in vitro testing may affect the genotoxic response. Sterilization by gamma irradiation lowered genotoxic activity. Furthermore, microfiltration of effluent and extraction of organic micropollutants on XAD-4 resins, lead to the preparation of extracts which are not fully representative of the initial water sample. Testing of concentrates, as required for in vitro studies, will limit the scope of a survey to that part of the organic matter that can be recovered by concentration techniques. Many of the problems encountered in in vitro genotoxicity studies of waters, may be circumvented with direct testing on aquatic organisms. Thus, there is no need to concentrate or sterilise a sample. The tests can be carried out with intact animals, thus taking into account uptake and elimination, internal transport and metabolism. Finally, in vivo test-systems, such as the Newt Micronucleus Test, are more relevant to eukaryotes than bacterial assays and are suitable to assess the real impact of genotoxins discharged in the aquatic environment.

Animals↗
PubMed1993

Mechanisms that generate human immunoglobulin diversity operate from the 8th week of gestation in fetal liver.

The repertoire of immunoglobulin expressed very early in human development was approached by cloning and sequencing 55 rearranged and 11 germ-line VH transcripts, after amplification by polymerase chain reaction of cDNA libraries derived from two fetal livers at 8 and 13 weeks of gestation. All families with the exception of VH2, were expressed as soon as 8 weeks, with preferential usage of certain germ-line genes. Very few somatic mutations, randomly localized, were identified. By contrast, in a series of clones derived from the same VDJ rearrangement using the VH6 family, extensive mutations had taken place, mostly accumulated in the third complementarity-determining region (CDR3) suggesting that the specialized enzymatic machinery was at hand very early during human development. Some other characteristics of the fetal repertoire also emerged, namely increased usage of JH3 and JH2, as compared to the adult pattern, where JH4 is dominant and reduced length of the D/CDR3 regions. All D gene families were identified, and their usage frequently involved D-D fusions. N diversity was present very early, and increased with age. Identification of germ-line transcripts pertaining to all six VH families including pseudogenes, in the E55 library, revealed a population very different as compared to rearranged gene transcripts. This suggests that a large portion of VH locus is accessible for transcription, bringing no evidence of correlation between preferential rearrangement of a given VH gene and its localization in the locus.

Antibody Diversity↗
PubMed1993

Amphibian micronucleus test(s): a simple and reliable method for evaluating in vivo genotoxic effects of freshwater pollutants and radiations. Initial assessment.

A micronucleus test was developed using larvae from two urodele amphibians (Pleurodeles waltl and Ambystoma mexicanum) and an anuran (Xenopus laevis). The methods for maintenance of adults, egg laying, and rearing the larvae are described, and the conditions required for optimal response are given for each of these species. The tests are carried out during a period of intense erythropoiesis when red blood cells are actively dividing in circulating blood. The micronuclei are observed on blood smears. The genotoxic effects of X-rays were evaluated at 12 different doses over a range of 6-1200 rad. All doses, even the very low dose of 6 rad, gave positive results. The test substances were added to the water in which the larvae were reared, and the results obtained after treatment for 12 days and/or 8 days with 47 different chemical compounds are listed. Detailed results are given as the lowest concentration producing a positive response or the highest concentration producing a negative response. The reliability of the test system using the newt is now well established, while the tests using the other two amphibian species are still under evaluation. Integration of this test in a test battery for quality control of water would aid the evaluation of risks to human health, as well as the protection of aquatic ecosystems.

Ambystoma mexicanum↗
PubMed1993

Rapid transfusion of packed red blood cells: effects of dilution, pressure, and catheter size.

STUDY OBJECTIVE: To examine flow rates and quantify red blood cell (RBC) destruction using various catheter sizes, pressures, and dilutions in the transfusion of packed RBCs. DESIGN: Study equipment was identical to that used in clinical practice. Laboratory tests consisting of plasma free hemoglobin, hematocrit, RBC count, and plasma potassium were used to assess RBC destruction. Statistical analysis was performed using the two-tailed Student's t-test. Statistical significance was considered to be .05. INTERVENTION: Packed RBCs were transfused in vitro through 16-, 18-, 20-, and 22-gauge catheters using no pressure, 150 mm Hg, and 300 mm Hg pressure as well as dilutions of 0, 100, and 250 mL normal saline. OUTCOME MEASURES: Flow rates in milliliters per minute were recorded for all combinations. The extent of RBC destruction was estimated using RBC count, hematocrit, plasma free hemoglobin, and serum potassium. RESULTS: Increases in flow rates of tenfold simply by diluting the units with 250 mL normal saline and sevenfold with the application of a pressure device were seen at all catheter sizes. The combination of both dilution and pressure increased flow rates 33-fold, varying between 70 and 300 mL/min for 22- and 16-gauge catheters, respectively. No significant difference in RBC destruction was seen among the four catheter sizes. CONCLUSION: Flow rates of packed RBCs sufficient for volume resuscitation can be achieved using 20- and 22-gauge catheters without evidence of increased RBC destruction. When it is impossible to obtain large-bore venous access or when such access would necessitate a delay of five to ten minutes, smaller catheters used in conjunction with dilution, pressure, or both should be considered.

Catheterization↗