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Biomedical subjects

M Chartier

Publications and source records attributed to M Chartier.

At least 19 recordsLinked to original sources
PubMed2006

Childhood leukaemia incidence around French nuclear installations using geographic zoning based on gaseous discharge dose estimates.

The present study investigated for the first time the incidence of childhood leukaemia (1990-2001) around French nuclear installations using a geographic zoning based on estimated doses to the red bone marrow due to gaseous radioactive discharges. The observed number of cases of acute leukaemia (O=750) in 40 km2 centred on 23 French nuclear installations between 1990 and 2001 was lower than expected (E=795.01), although not significantly so (standardised incidence ratio SIR=0.94, 95% confidence interval=(0.88-1.01)). In none of the five zones defined on the basis of the estimated doses was the SIR significantly >1. There was no evidence of a trend in SIR with the estimated doses for all the children or for any of the three age groups studied. This study confirmed that there was no evidence of an increased incidence of childhood leukaemia around the 23 French nuclear sites.

Acute Disease↗
PubMed2002

Two-proton radioactivity of 45Fe.

In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip line nucleus 45Fe has been studied. Fragment-implantation events have been correlated with radioactive decay events in a 16x16 pixel silicon-strip detector. The decay-energy spectrum of 45Fe implants shows a distinct peak at (1.14+/-0.04) MeV with a half-life of T(1/2)=(4.7(+3.4)(-1.4)) ms. None of the events in this peak is in coincidence with beta particles. For a longer correlation interval, daughter decays of the two-proton daughter 43Cr can be observed after 45Fe implantation. The decay energy for 45Fe agrees nicely with several theoretical predictions for two-proton radioactivity.

Journal Article↗
PubMed2001

Partitioning of trace metals before and after biological removal of metals from sediments.

Metal removal by biological solubilization in three strongly contaminated sediments was carried out in a two-liter stirred bioreactor. Biological treatment yielded metal removal efficiencies in the range of 11-30%, 43-57%, 60-79%, 61-90%, 18-21%, 0-10% for Pb, Cu, Zn, Cd, Ni and Cr, respectively. The treated sediments were then rinsed with a NaCl solution (0.5 M), resulting in an increase by nearly 47% in Pb removal for the three sediments, while for other metals (Cu, Zn, Cd, Ni, Cr), the NaCl rinse did not seem to allow any significant increase in metal solubilization. A standard procedure of sequential selective extraction (SSE) was applied to the sediments before and after each treatment. With regard to Pb, Zn and Cd, the carbonate bound fractions (2/3 sediments) represented 18-42% of metals prior to treatment, while the iron and manganese oxides bound fraction constituted 39-60% of metals for the three sediments. Between 90 and 100% of Pb, Zn and Cd removed by the process came from the fractions bound to carbonates and from those bound to Fe and Mn oxides. The organic matter and sulfide bound fractions contained 65-72% of total Cu present before treatment and the process removed, on average, 63% Cu present in this fraction. In contrast, Ni and Cr were found mainly in the residual fractions (50-80%). Finally, this biological treatment did not solubilize Cr appreciably, while removal of Ni mostly originated from the carbonate and Fe/Mn oxides fractions (70-80%).

Carbonates↗
PubMed2001

Comorbidity of phobic disorders with alcoholism in a Canadian community sample.

OBJECTIVES: To examine the relation between phobic disorders and alcoholism in a Canadian community sample. METHOD: Data came from the Mental Health Supplement of the Ontario Health Survey. The University of Michigan revision of the Composite International Diagnostic Interview (UM-CIDI) was used to diagnose DSM-III-R psychiatric disorders in 8116 Canadian respondents between ages 15 and 64 years. Since the cross-system agreement (ICD-10 and DSM-III-R or DSM-IV) on the diagnosis of alcohol abuse is much lower than that for alcohol dependence, we also examined a WHO category, "hazardous alcohol use." Logistic regression controlling for age and sex was used to determine odds ratios (ORs) for phobic disorders and alcohol-use diagnoses. RESULTS: Individuals with lifetime alcohol abuse or dependence had two- to threefold increased odds of having a phobic disorder. Simple phobia and social phobia with multiple fears were significantly associated (ORs 1.5 to 2) with hazardous alcohol use (which had a prevalence of approximately 10%). CONCLUSIONS: Given the early onset of most phobic disorders, the findings suggest that these are a risk factor for hazardous patterns of alcohol use.

Adolescent↗
PubMed2000

Discovery of doubly magic 48Ni

In an experiment at the SISSI/LISE3 facility of GANIL, we used the projectile fragmentation of a primary 58Ni26+ beam at 74.5 MeV/nucleon with an average current of 3 &mgr;A on a natural nickel target to produce very neutron-deficient isotopes. In a 10-day experiment, 287 42Cr isotopes, 53 45Fe isotopes, 106 49Ni isotopes, and 4 48Ni isotopes were unambiguously identified. The doubly magic nucleus 48Ni, observed for the first time, is the most proton-rich isotope ever identified with an isospin projection T(z) = -4. It is probably the last doubly magic nucleus with "classical" shell closures accessible for present-day facilities. Its observation allows us to deduce a lower limit for the half-life of 48Ni of 0.5 &mgr;s.

Journal Article↗
PubMed1999

Decontamination of Fly Ash and Used Lime from Municipal Waste Incinerator Using Thiobacillus ferrooxidans.

/ The purification of incinerator gases produces large quantities of fly ash and used lime [a combination referred to as air pollution control residues (APCR)], both of which contain elevated levels of metals. This paper describes biological solubilization assays utilizing Thiobacillus ferrooxidans to leach metals from APCR to render them nonhazardous. The multistage solubilization process involves an alkaline aqueous phase that removes some Pb. In the second phase, the APCR are acidified to pH 4 with H(2)SO(4), then inoculated with a bacterial culture that has been acclimated in the presence of 2% Fe (FeCl(3)). Several rinses and decantings achieve removal of the leachable metals. The final step involves the addition of Ca(H(2)PO(4))(2) and an increase in the treatment pH prior to the final filtration. Viability of thiobacilli in APCR was poor. Despite this problem, the removal of Pb was 35.9%, 46.0%, and 68.7% (for APCR containing 1594, 3026, and 5038 mg Pb/kg, respectively), which demonstrates greater metal removal with increased APCR contamination. Zn removal varied from 68.2% (8273 mg Zn/kg APCR) to 79.5% (16,873 mg Zn/kg APCR), which was positively correlated to the level of residue contamination, whereas Cu was removed in the proportions of 26.9% (495 mg Cu/kg APCR) to 68.2% (465 mg Cu/kg APCR). Cadmium removal appeared to be independent of the level of Cd in the APCR; Cd was removed to the greatest degree, with a variation of 92.0% (129 mg Cd/kg APCR) to 94.7% (267 mg Cd/kg APCR). The treated APCR were tested using four different leachate tests. The APCR released 43 mg Pb/liter during contact with water, and 7.40 mg Cd/liter during TCLP [the toxicity characterization leaching procedure of the United States Environmental Protection Agency (US EPA)]. After biological treatment, the leachate from TCLP was within the acceptance criteria of the US EPA, if the pH of the APCR was increased to pH 5 after the biological treatment. In the case of the Transport Canada leaching test, a betterment of the process is required in order to satisfy the stringent regulatory level of 0.5 mg Cd/liter (0.68 and 0.57 mg/liter).KEY WORDS: Thiobacilli; Metals removal; Fly ash; Incinerator; Hazardous waste.http://link.springer-ny.com/link/service/journals/00267/bibs/24n4p517.html</HEA

Journal Article↗
PubMed1996

Membrane topology of the colicin A pore-forming domain analyzed by disulfide bond engineering.

Four colicin A double-cysteine mutants possessing a disulfide bond in their pore-forming domain were constructed to study the translocation and the pore formation of colicin A. The disulfide bonds connected alpha-helices 1 and 2, 2 and 10, 3 and 9, or 3 and 10 of the pore-forming domain. The disulfide bonds did not prevent the colicin A translocation through the Escherichia coli envelope. However, the mutated colicins were able to exert their in vivo channel activity only after reduction of their disulfide bonds. In vitro studies with brominated phospholipid vesicles and planar lipid bilayers revealed that the disulfide bond that connects the alpha-helices 2 and 10 prevented the colicin A membrane insertion, whereas the other double-cysteine mutants inserted into lipid vesicles. The disulfide bonds that connect either the alpha-helices 1 and 2 or 3 and 10 were unable to prevent the formation of a conducting channel in presence of membrane potential. These results indicate that alpha-helices 1, 2, 3, and 10 remain at the membrane surface after application of a membrane potential.

Colicins↗
PubMed1996

Polymerase chain reaction-based site-directed mutagenesis using magnetic beads.

Thyroglobulin double mutants with various substitutions were obtained with a new polymerase chain reaction-based mutagenesis technique. Maximum length of megaprimer and efficiency of mutagenesis were improved by purification of single-stranded DNA, using the avidin-biotin interaction. This method might allow the construction of large libraries of DNA, mutated at different sites.

Avidin↗
PubMed1995

Biofeedback for the treatment of fecal incontinence. Long-term clinical results.

UNLABELLED: Biofeedback therapy has been proposed as a treatment for fecal incontinence with good, short-term results. PURPOSE: This study was designed to assess long-term clinical results of biofeedback therapy compared with medical therapy alone and to assess manometric results in patients treated with biofeedback. METHODS: Two groups of incontinent patients were studied. Group 1 consisted of 16 patients (3 males and 13 females; mean age, 59.9 years). Etiologies treated by biofeedback included descending perineum syndrome (7), postfistula or hemorroidectomy (4), and miscellaneous (5). Group 2 consisted of eight patients (two males, six females; mean age, 62.2 years). Etiologies treated with medical treatment alone (including enema and antidiarrheal therapy) included descending perineum syndrome (3), postfistula or hemorroidectomy (2), and miscellaneous (3). The incontinence score was initially 17.81 +/- 3.27 (standard deviation) in Group 1 and 17.0 +/- 2.77 in Group 2. Resting pressure of the upper and lower anal sphincter, maximum squeezing pressure, and duration of contraction were not initially different in Groups 1 and 2 but were significantly lower than in the control group of patients without incontinence (n = 12; 8 males, 4 females; mean age, 66.4 years) (P < 0.05). Follow-up duration was 30 months, with intermediate clinical score at 6 months for Group 1. RESULTS: After biofeedback therapy, the incontinence score at 30 months was lower in Group 1 (14.43 +/- 6.35 vs. 17.81 +/- 3.27; P < 0.035) and unchanged in Group 2 (18.0 +/- 2.72 vs. 17.0 +/- 2.77). However, in Group 1 the score at 6 months was much lower than at 30 months (6.31 +/- 7.81 vs. 14.43 +/- 6.35; P < 0.001). Only the amplitude of voluntary contraction and upper anal pressure (51.1 (range, 27-90) vs 36.7 (range, 20-80) mmHg) were significantly increased (81.5 (range, 55-120) vs. 62.1 (range, 30-90) mmHg; P < 0.05). CONCLUSION: Biofeedback improved continence at 6 months and at 30 months. However, the score at 6 months was much better, suggesting that the initial good results may deteriorate over a long time. These data suggest that it could be useful to reinitiate biofeedback therapy in some patients.

Adult↗
PubMed1994

Unfolding of colicin A during its translocation through the Escherichia coli envelope as demonstrated by disulfide bond engineering.

Three double cysteine mutants, each possessing a disulfide bond in its pore-forming domain, were used to study the translocation of colicin A through the Escherichia coli envelope. These mutated colicins were able to exert their in vivo channel activity only after their disulfide bonds had been reduced by dithiothreitol. In solution, the reduction of the disulfide bonds by dithiothreitol was a slow process whose kinetics depended on the position of the disulfide bond (t1/2 varying between 35 and 100 s). This t1/2 was strongly decreased (t1/2 = 8-9 s) upon predenaturation of the mutated colicins with urea. The t1/2 values of reduction of the mutants bound to E. coli-sensitive cells were similar to those of predenatured colicins. This suggested that the interaction of the oxidized double cysteine mutants with the E. coli envelope triggered their unfolding. The disulfide bonds did not prevent but delayed the translocation of the colicins. The amplitude of the delay and the time at which it occurred during translocation depended on the position of the disulfide bond. We could discriminate between the delays accumulated during binding to the receptor and those during the translocation via OmpF and the Tol proteins.

Bacterial Outer Membrane Proteins↗
PubMed1994

Autonomic responsivity in generalized social phobia.

To determine whether patients with generalized social phobia exhibit evidence of abnormal autonomic nervous system (ANS) functioning, 15 non-depressed, medication-free subjects with DSM-IV social phobia (generalized type) and 15 healthy control subjects participated in a series of autonomic function tests. Generalized social phobics exhibited increased blood pressure responsivity to Valsalva and exaggerated vagal withdrawal in response to isometric exercise, but normal cardiovascular responsivity to all other tasks. Plasma norepinephrine and epinephrine levels were also normal. Studies with larger sample sizes and the use of specific neuropharmacologic probes seem warranted to further delineate a role for autonomic dysfunction in the pathophysiology of this disorder.

Adult↗
PubMed1994

Major factors influencing bacterial leaching of heavy metals (Cu and Zn) from anaerobic sludge.

Anaerobically digested sewage sludges were treated for heavy metal removal through a biological solubilization process called bacterial leaching (bioleaching). The solubilization of copper and zinc from these sludges is described in this study: using continuously stirred tank reactors with and without sludge recycling at different mean hydraulic residence times (1, 2, 3 and 4 days). Significant linear equations were established for the solubilization of zinc and copper according to relevant parameters: oxygen reduction potential (ORP), pH and residence time (t). Zinc solubilization was related to the residence time with a r2 (explained variance) of 0.82. Considering only t=2 and 3 days explained variance of 0.31 and 0.24 were found between zinc solubilization as a function of ORP and pH indicating a minor importance of those two factors for this metal in the range of pH and ORP experimented. Cu solubilization was weakly correlated to mean hydraulic residence time (r2=0.48), while it was highly correlated to ORP (r2=0.80) and pH (r2=0.62) considering only t of 2 and 3 days in the case of pH and ORP. The ORP dependence of Cu solubilization has been clearly demonstrated in this study. In addition to this, the importance of the substrate concentration for Cu solubilization has been confirmed. The hypothesis of a biological solubilization of Cu by the indirect mechanism has been supported. The results permit, under optimum conditions, the drawing of linear equations which will allow prediction of metal solubilization efficiencies from the parameters pH (Cu), ORP (Cu) and residence time (Cu and Zn), during the treatment. The linear regressions will be a useful tool for routine operation of the process.

Journal Article↗
PubMed1994

A single amino acid substitution can restore the solubility of aggregated colicin A mutants in Escherichia coli.

Mutants of colicin A have been prepared in which the three tryptophan residues (Trp86, Trp130 and Trp140), localized in the C-terminal domain of the soluble wild-type protein, have been substituted by phenylalanine. The Trp140Phe single mutation had the effect of decreasing the percentage of protein that is expressed as insoluble aggregates. The created hydrophobic cavity decreased the stability of the protein during its folding, resulting in partial aggregation in the cytoplasm of the Escherichia coli-producing cells. Aggregation was increased when Trp140 was substituted by Lys, Leu or Cys, or if the Trp140 mutation was combined with the Trp86Phe and/or Trp130Phe mutations. A single mutation, Lys113Phe, however, was able to restore the solubility of the aggregated mutants in vivo. Detailed analysis of the 3-D structure of the C-terminal domain of colicin A suggests that filling of the hydrophobic cavity is responsible for this effect.

Amino Acid Sequence↗
PubMed1993

Sleep in nondepressed patients with panic disorder: I. Systematic assessment of subjective sleep quality and sleep disturbance.

To systematically assess sleep complaints in panic disorder (PD), the Pittsburgh Sleep Quality Index (PSQI) was administered to 34 untreated patients with DSM-III-R PD and 34 age-matched healthy controls (HC). PD patients reported significantly more impaired sleep than HC as indicated by higher global index scores on the PSQI (6.9 +/- 2.9 versus 3.1 +/- 2.0; p < 0.0001) and on four of seven of its subscales; sleep was worst among those PD patients with a prior history of major depression. Sixty-eight percent of patients with PD reported moderately or severely impaired sleep compared to only 15% of HC (chi 2 = 17.5, p < 0.0005). Twenty-six percent of PD patients--but none of the HC--complained of frequent awakenings in the preceding month because they "could not breathe comfortably" (Fisher's exact test, p < 0.00625). One-month prevalence of sleep panic in the patients was 18%; lifetime prevalence was 68%. Whereas these findings confirm previous reports of frequent sleep complaints in patients with PD, they also raise the possibility that some of the findings might be trait phenomena attributable to a history of mood disorder.

Adult↗
PubMed1992

Structure of DNA-RecA complexes studied by residue differential linear dichroism and fluorescence spectroscopy for a genetically engineered RecA protein.

The structure of complexes of RecA with double-stranded and single-stranded DNA was studied by linear dichroism spectroscopy, fluorescence quenching and fluorescence anisotropy measurements. One of the two tryptophan residues (Trp291) of RecA was replaced by genetic engineering for an ultraviolet light-transparent threonine. This modified RecA protein shows, within experimental errors, the same DNA-binding kinetics and stoichiometry as the wild-type protein and no significant variation with respect to in vivo repair function was observed between cells with the two protein forms. By comparing the dichroic and fluorescence properties of the wild-type versus the modified protein, when bound to DNA, information about orientation and environment of the Trp291 chromophore in the complex could be obtained. The indole chromophore of Trp291Z was found to be oriented with its pseudo-long axis tilted 61 degrees and the aromatic plane is tilted 27 degrees relative to the fibre axis. Trp291 shows low mobility within the protein and therefore the deduced orientation may be used as a "handle" on the protein at the construction of three-dimensional models of RecA-DNA complexes. Comparison with the orientation for this residue in the crystal structure of the RecA homopolymer fibre indicates no measurable reorientation of the C-terminal subdomain of RecA upon DNA binding. Whereas the accuracy of the orientation determination of tryptophan, in absolute terms, is rather poor, changes of its orientation can be detected with high precision. Thus, similar Trp291 orientations are obtained in the complexes with single-stranded and double-stranded DNA, indicating similar structures of the protein fibres. The fluorescence quenching results indicate that the protein region of Trp291 is not involved in the binding of DNA.

DNA↗