Mass Measurement of 100Sn.
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Journal Article↗
Biomedical subjects
M Chartier
Publications and source records attributed to M Chartier.
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↗
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↗
Phase coexistence in multifragmentation?
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Journal Article↗
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↗
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↗
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↗
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↗
Energy dependence of multifragmentation in 84Kr+197Au collisions.
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Journal Article↗
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↗
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↗
[Autologous transfusion in heart surgery (apropos of 74 patients)].
The present study uses three techniques of autotransfusion in heart surgery under ECC: peroperative and post-ECC transfusion of blood removed after induction of anaesthesia (group I: 25 patients); postoperative transfusion of extravasated thoracic blood (group II: 24 patients) and a combination of the two (group III: 25 patients). Postoperative bleeding was comparable in all groups; A subset likely to haemorrhage made up of patients who had lost more than one litre of blood was isolated and demonstrated a reduction in the number of homologous red cell concentrates needed for the autotransfused population in comparison with the controls (2.4 +/- 2.6 vs 5.7 +/- 3.5 red cell concentrates, p less than 0.05) and was particularly marked in Group II patients who received 1.9 +/- 2.2 homologous red cell concentrates. None of the techniques caused any side-effects. Combination of the two autotransfusion techniques in heart surgery does not secure any additional advantages compared with postoperative autotransfusion alone.
Blood Transfusion, Autologous↗
Amoxycillin/clavulanic acid ('Augmentin') compared with a combination of aminopenicillin, aminoglycoside and metronidazole in the treatment of pelvic inflammatory disease.
A randomized, multi-centre trial was carried out in 152 hospitalized women with pelvic inflammatory disease to evaluate the efficacy and tolerability of amoxycillin/clavulanic acid compared with that of a standard regimen using three antimicrobial agents (aminopenicillin, an aminoglycoside and metronidazole). Seventy patients initially received 3 to 4 intravenous doses per day of 1 g amoxycillin/200 mg clavulanic acid (mean 7.7 days) and then 4 to 6 tablets per day of 500 mg amoxycillin/125 mg clavulanic acid (mean 11.2 days). The other group of 82 patients initially received parenteral therapy daily (mean 7.7 days) with a combination of 3 to 4 g amoxycillin or ampicillin, 160 mg gentamicin (or 150 mg dibekacin or tobramycin) and 1.5 g metronidazole, and then oral therapy with 2 to 3 g amoxycillin or ampicillin and 1 to 1.5 g metronidazole daily (11.1 days). Clinical results, assessed at discharge from hospital (mean 10 days in both groups), were comparable in both groups, with 96% complete or partial response and no failures in the amoxycillin/clavulanic acid group, and 90% complete or partial successes and 5 failures with the triple therapy regimen. Both treatments were well tolerated and very few side-effects were reported.
Adult↗
The membrane channel-forming colicin A: synthesis, secretion, structure, action and immunity.
The study of colicin release from producing cells has revealed a novel mechanism of secretion. Instead of a built-in 'tag', such as a signal peptide containing information for secretion, the mechanism employs coordinate expression of a small protein which causes an increase in the envelope permeability, resulting in the release of the colicin as well as other proteins. On the other hand, the mechanism of entry of colicins into sensitive cells involves the same three stages of protein translocation that have been demonstrated for various cellular organelles. They first interact with receptors located at the surface of the outer membrane and are then transferred across the cell envelope in a process that requires energy and depends upon accessory proteins (TolA, TolB, TolC, TolQ, TolR) which might play a role similar to that of the secretory apparatus of eukaryotic and prokaryotic cells. At this point, the type of colicin described in this review interacts specifically with the inner membrane to form an ion channel. The pore-forming colicins are isolated as soluble proteins and yet insert spontaneously into lipid bilayers. The three-dimensional structures of some of these colicins should soon become available and site-directed mutagenesis studies have now provided a large number of modified polypeptides. Their use in model systems, particularly those in which the role of transmembrane potential can be tested for polypeptide insertion and ionic channel gating, constitutes a powerful handle with which to improve our understanding of the dynamics of protein insertion into and across membranes and the molecular basis of membrane excitability. In addition, their immunity proteins, which exist only in one state (membrane-inserted) will also contribute to such an understanding.
Amino Acid Sequence↗
The complete nucleotide sequence of the colicinogenic plasmid ColA. High extent of homology with ColE1.
The complete nucleotide sequence of the colicinogenic plasmid ColA has been determined. The plasmid DNA consists of 6720 bp (molecular weight 4.48 X 10(6]. Fifteen putative biological functions have been identified using the functional map previously determined. These include 11 genes and 3 DNA sites. Nine genes encode proteins of which 3 have been fully characterized. The replication region of ColA coding for RNAI and RNAII is highly homologous to that of ColE1 and Clo DF13. The same holds true for the site-specific recombination region containing palindromic symmetry and involved in stable maintenance of the plasmids. A high percentage of homology has been detected for putative mobility proteins encoded by ColA and ColE1. The exclusion proteins are also highly homologous.
Amino Acid Sequence↗
Plasma corticosteroid patterns in the fetus.
In umbilical vein blood samples collected in 137 fetuses between 19 and 31 weeks of gestation, cortisol (F), cortisone (E), 17-hydroxyprogesterone (17-OHP) and 11-deoxycortisol (S) were radioimmunoassayed after column chromatography on Sephadex LH-20 of plasma extracts. While F levels plateaued throughout the period considered those of E displayed an increasing pattern which appeared to be comparable with that of unbound F in pregnant women. The declining pattern of S and more particularly of 17-OHP would suggest an increasing utilization and metabolization of these F precursors by the maturing fetus. E was not correlated with either 17-OHP or S but showed a significant correlation with F. S and 17-OHP were correlated with each other and with F. The significance of these correlations was discussed according to the different origin of these steroids and to their metabolic relationships. The application of this method for the prenatal diagnosis of inborn errors of steroid biogenesis is suggested.
17-alpha-Hydroxyprogesterone↗
Serum growth-promoting activity in normal and hypotrophic fetuses at midpregnancy.
Blood from 24 human fetuses aged 19-24 wk was collected by ultrasound-guided puncture of the umbilical cord in utero, performed for prenatal diagnosis of mother to fetus transmissible infections. Fetal serum growth-promoting activity (thymidine activity) was measured by its effect on 3H-thymidine incorporation into human lectin-activated lymphocytes. Ten blood samples were obtained at 19-22 wk of pregnancy and 14 at 23-24 wk. The pregnancies were maintained and the fetuses delivered, free of infection, at 38-40 wk, nine of them being small for date and 15 having a normal weight for gestation age. The bioassayable thymidine activity was significantly lower in the hypotrophic (0.84 +/- 0.04 U/ml) than in the normal fetuses (1.28 +/- 0.09 U/ml) whatever the time of sampling. Thymidine activity was significantly negatively correlated with gestational age in the normal for date fetuses, not in the small for date. It is suggested that early measurement of thymidine activity in fetal blood might be of value in the assessment of fetal growth despite the fact that the tissue growth factors may be more important in fetus than are the serum factors.
Adult↗
Prenatal diagnosis of congenital toxoplasmosis.
Prenatal diagnosis of congenital toxoplasmosis was attempted by means of fetal blood sampling at 20-24 weeks' gestation. It was possible to detect in fetal blood samples non-specific laboratory signs of fetal infection, specific antibodies of fetal origin (IgM), and parasitaemia by inoculation of the sample into mice. Amniotic-fluid samples were also inoculated into mice and parasites were often present when the fetus was infected. Ultrasound examination of the fetus was done repeatedly, mainly to detect any enlargement of the cerebral ventricles. Together the results of these examinations allowed a reliable diagnosis, which was confirmed by the presence of necrotic foci of toxoplasmic encephalitis in the fetus in every case. Only 1 case of congenital toxoplasmosis occurred among 209 cases with negative prenatal diagnoses.
Antibodies↗