PubMed Health⌕ Search

Biomedical subjects

A Leduc

Publications and source records attributed to A Leduc.

At least 19 recordsLinked to original sources
PubMed2006

Detection of Legionella spp. by fluorescent in situ hybridization in dental unit waterlines.

AIMS: To confirm the presence of viable Legionella spp. in dental unit waterlines (DUWL) using fluorescent in situ hybridization (FISH) and compare this method with culture approach and also to validate the utility of an enrichment to increase FISH sensitivity. METHODS AND RESULTS: Water samples from 40 dental units were analysed. Three different techniques for detecting Legionella spp. were compared: (i) culture approach, (ii) direct FISH and (iii) FISH with a previous R2A medium enrichment (R2A/FISH). The FISH detection was confirmed by PCR. The use of the direct FISH does not improve significantly the detection of legionellae when compared with the culture. On the contrary, when R2A/FISH was performed, sensitivity was, respectively, two- and threefold higher than that with the direct FISH and culture approach. Using R2A/FISH, 63% of water samples analysed showed a contamination by legionellae. CONCLUSIONS: Legionellae detection by direct FISH and R2A/FISH in dental unit water is possible but is more rapid and more sensitive (R2A/FISH) than the culture approach. SIGNIFICANCE AND IMPACT OF THE STUDY: R2A/FISH showed that several pathogens present in DUWL are viable but may not be culturable. Unlike PCR, R2A/FISH is designed to detect only metabolically active cells and therefore provides more pertinent information on infectious risk.

Bacteriological Techniques↗
PubMed2003

Disruption of the Saccharomyces cerevisiae cell-wall pathway gene SLG1 causes hypersensitivity to the antitumor drug bleomycin.

Bleomycin is an antitumor drug that damages DNA via a free radical-dependent mechanism, and yeast mutants defective in DNA repair are hypersensitive to the drug. To identify possible pathways that may contribute to bleomycin resistance in yeast, we characterized a panel of bleomycin-sensitive mutants that were previously isolated by insertion mutagenesis using the transposon miniTn3::Leu2::LacZ::AMP( R). One of these mutants harbored a single insertion in the SLG1 gene, which encodes a cell membrane protein that senses cell wall stress, and functions to maintain cell wall function by activating the protein kinase C signaling pathway. Deletion of the SLG1 gene in parental strains caused hypersensitivity to bleomycin, and this correlated with an accumulation of damaged DNA. A plasmid that expresses the native SLG1 gene or that increases PKC1 gene dosage restored bleomycin resistance to the slg1Delta mutant. Two-dimensional gel electrophoresis revealed that exposure to bleomycin triggered the expression of certain proteins, presumably to maintain cell wall function, in a Slg1-dependent manner. In addition, mutants lacking cell wall function were found to be hypersensitive to bleomycin. We conclude that mutants deficient in proteins that maintain cell wall function are severely compromised in their ability to limit bleomycin entry into the cell. Therefore, these mutants are burdened with increased genotoxicity upon exposure to bleomycin in the medium. Our results show that major mechanisms other than DNA repair are operating in yeast to mediate bleomycin resistance.

Antibiotics, Antineoplastic↗
PubMed2003

[Limb edema and lymphoscintigraphy].

Lymphoscintigraphic investigations represent techniques of nuclear medicine very contributive for the management and treatment of the limb edemas, either primary or secundary. Their principle is presented and methodologies proposed in the literature are reviewed. Their diagnostic contributions are detailed. The sensitivities and specificities of several protocols of investigation are reported. Some limitations of these examinations are analyzed and discussed. Clinical indications for their use are proposed and their interest with regard to the various treatments that can be applied to these limb edemas is discussed.

Adult↗
PubMed1998

Imaging techniques in the management and prevention of posttherapeutic upper limb edemas.

BACKGROUND: Upper limb edema remains the most frequent complication after treatments for breast carcinoma. Various imaging techniques can be used to prevent these complications, to manage them, and to diagnose the possible lymphonodal evolution that may underlie these events. In the present paper, these techniques are reviewed. METHODS: Based on clinical experience as well as on the data from the literature, these imaging techniques are presented, and their contributions are analyzed. RESULTS: The pre- and post-operative imaging and research techniques of the so-called sentinel nodes (using blue dye, and/or lymphoscintigraphy, and/or gamma probe) appear to be very promising for defining patients in whom axillary node clearance either might be avoided or is indicated. Lymphoscintigraphic investigations also can be used after surgery and/or radiation therapy to define patients who either are at risk to develop upper limb edema or present with latent edema. In patients with clinically obvious edema, even if it is limited, lymphoscintigraphic techniques can provide a morphologic and functional definition of the condition. Venous echo Doppler can be used when abnormalities of the venous return are suspected. In diagnosing the lymphonodal evolution of the disease, techniques like immunoscintigraphy, positron emission tomography (using 18-fluoro-2-deoxy-D-glucose), X-ray computed tomography, and nuclear magnetic resonance imaging can contribute. CONCLUSIONS: Various imaging techniques can be used to prevent and/or to manage the upper limb edema that may complicate the treatment(s) of the patients with breast carcinoma.

Arm↗
PubMed1998

The physical treatment of upper limb edema.

BACKGROUND: Edema of the upper limb, without any doubt, constitutes the most invalidating complication of breast carcinoma treatment. The swelling of the limb results from decreased liquid evacuation by surgical intervention at the axillary level and also by the eventual treatment by cobaltotherapy. METHOD: The physical treatment for edema of the limb consists of a combination of therapies that were tested for their effectiveness in laboratories on healthy students and also on patients who underwent surgery for breast carcinoma. The treatment consists of the application of manual lymphatic drainage (type Leduc), the use of multilayered bandages, and the use of intermittent pneumatic compression. The population studied was represented by 220 patients who underwent breast surgery. The authors followed their evolution during the first 2 weeks of treatment. Patients were not hospitalized. The edema was measured by using marks tattooed on the skin. RESULTS: The limb that developed edema was compared with the healthy limb. The most important reduction was obtained in the first week. The decrease was equivalent to 50% of the average of the difference between both upper limbs. During the second week, the results obtained stabilized; however, there was a slight decrease at the end of the second week. CONCLUSIONS: The physical treatment of edema represents the preferred therapeutic approach. However, it must answer to well-defined criteria to be efficient and for long-lasting effects. The physical treatment is used to treat outpatients, allowing them to follow a normal lifestyle.

Adult↗
PubMed1997

Interaction between Actinobacillus actinomycetemcomitans lipopolysaccharides and human hemoglobin.

Actinobacillus actinomycetemcomitans, a bacterium associated with juvenile periodontitis, was found to use human hemoglobin as a source of iron for cell growth. Cultivation in the presence of hemoglobin had only a slight effect on the cellular protein pattern, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Lipopolysaccharides obtained from A. actinomycetemcomitans were found to have a strong capacity to bind hemoglobin. This interaction appears not to involve the lipid A portion of the molecule as no inhibition was obtained when lipopolysaccharides were pre-treated with polymyxin B. This interaction between hemoglobin and lipopolysaccharides of A. actinomycetemcomitans may facilitate iron acquisition by this bacterium.

Aggregatibacter actinomycetemcomitans↗
PubMed1996

Comparative growth of Porphyromonas gingivalis strains in a defined basal medium.

Porphyromonas gingivalis is an asaccharolytic bacterium whose metabolism is dependent on the uptake of small peptides and amino acids. The aim of this work was to study the growth of P. gingivalis in a defined basal medium (DBM) supplemented with various sources of proteins. The strain 49417 as well as other virulent isolates could grow in DBM containing 1% bovine serum albumin (BSA). Cells cultivated under this condition showed a slightly modified protein profile, and expressed hemagglutinating as well as proteolytic activities. Other natural proteins under investigation could not support the growth in the DBM. On the other hand, the strain 33277 as well as other avirulent strains of P. gingivalis could not use BSA as a substrate. The ability of P. gingivalis to grow in DBM-BSA is not entirely dependent on its ability to degrade the protein substrate as strain 33277 was able to extensively hydrolyse the molecule. Differences in either metabolic enzymes or peptide transport mechanisms may explain the distinctive behavior between virulent and avirulent strains. Data from this work suggest a relationship between nutritional requirements and virulence of P. gingivalis in an animal model. The DBM-BSA may represent a more appropriate medium for studies on the physiology of P. gingivalis.

Journal Article↗
PubMed1995

Outer membrane-associated deoxyribonuclease activity of Porphyromonas gingivalis.

Extracellular outer membrane vesicles which are produced by Gram-negative bacteria may enclose deoxyribonucleic acid (DNA). While characterizing vesicles of Porphyromonas gingivalis, it was found that they do not contain detectable amount of DNA. It was also shown that the presence of deoxyribonuclease activity on whole cells and vesicles can degrade plasmidic and linear DNA. Deoxyribonuclease activity was also demonstrated in several other Gram-negative oral bacterial species. The nuclease activity of P. gingivalis was further characterized. When deoxyribonuclease activity was analyzed by zymography, only one active band was detected under the conditions tested. This nuclease enzyme showed a molecular weight of approximately 50 kDa. The activity was inhibited by 5 mM ZnCl2 or 100 mM EDTA whereas Mg2+ or Ca2+ ions were not required for activity. Activity was totally destroyed by treatment at 70 degrees C for 15 min. Although the enzyme may participate in virulence or provide nucleic acid precursors for bacterial growth, its exact role is still unknown.

Journal Article↗
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↗
PubMed1993

Relationship of middle cerebral artery blood flow velocity to intensity during dynamic exercise in normal subjects.

Cerebral blood flow has been reported to increase during dynamic exercise, but whether this occurs in proportion to the intensity remains unsettled. We measured middle cerebral artery blood flow velocity (vm) by transcranial Doppler ultrasound in 14 healthy young adults, at rest and during dynamic exercise performed on a cycle ergometer at a intensity progressively increasing, by 50 W every 4 min until exhaustion. Arterial blood pressure, heart rate, end-tidal, partial pressure of carbon dioxide (PETCO2), oxygen uptake (VO2) and carbon dioxide output were determined at exercise intensity. Mean vM increased from 53 (SEM 2) cm.s-1 at rest to a maximum of 75 (SEM 4) cm.s-1 at 57% of the maximal attained VO2 (VO2max), and thereafter progressively decreased to 59 (SEM 4) cm.s-1 at VO2max. The respiratory exchange ratio (R) was 0.97 (SEM 0.01) at 57% of VO2max and 1.10 (SEM 0.01) at VO2max. The PETCO2 increased from 5.9 (SEM 0.2) kPa at rest to 7.4 (SEM 0.2) kPa at 57% of VO2max, and thereafter decreased to 5.9 (SEM 0.2) kPa at VO2max. Mean arterial pressure increased from 98 (SEM 1) mmHg (13.1 kPa) at rest to 116 (SEM 1) mmHg (15.5 kPa) at 90% of VO2max, and decreased slightly to 108 (SEM 1) mmHg (14.4 kPa) at VO2max. In all the subjects, the maximal value of vm was recorded at the highest attained exercise intensity below the anaerobic threshold (defined by R greater than 1). We concluded that cerebral blood flow as evaluated by middle cerebral artery flow velocity increased during dynamic exercise as a function of exercise intensity below the anaerobic threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Equivalent source estimation based on the calculation of the electric field from depth EEG data.

This paper describes a method for the estimation of equivalent source position and strength based on the estimation of the electric field from depth electroencephalographic (EEG) data. The calculation method for the electric field is based on a tetrahedral geometry. The proposed approach for source parametrization is twofold. Firstly, the distribution of electrical energy by the squared norm of the electric field vector can give an estimate of the source position, without having to assume a dipole source. Secondly, the average electric field can be related to the dipole magnitude and orientation of the equivalent source. Simulation results demonstrate the potential usefulness of the method. The effects of noise and sampling, and the geometry of the measurement system (i.e., implanted electrodes) relative to the source are also investigated through simulations.

Artifacts↗
PubMed1990

[Hemodynamic impact of pressotherapy].

We study the hemodynamic effects of pressotherapy in 11 patients (mean age : 68 +/- 10 years) with uncomplicated acute myocardial infarction (n = 6) or with chronic ischemic heart failure (n = 5). We measure the right auricular pressure (RAP), the mean pulmonary arterial pressure (MPAP) and the pulmonary wedge pressure (PWP), before, during pressotherapy (MPAP) and the pulmonary wedge pressure (PWP), before, during pressotherapy (T 20 min) and 30 minutes after the end of pressotherapy (T 30 min). We use five-chambered leg garments with 80 mm Hg pressure during 20 minutes. The wavelike action (from the bottom to the top) is intermittent: the compression time is 10 second (sec); compression is maintained during 60 sec; deflation time is 15 sec. After 20 minutes pressotherapy (t 20) the 3 variables increase: RAP: from 3.6 +/- 5 to 7 +/- 7 mm Hg (P less than 0.001), MPAP: from 25 +/- 14 to 29 +/- 17 mm Hg (p less than 0.01) and the PWP from 10 +/- 8 to 17 +/- 11 Hg (p less than 0.01). This rise is particularly important in heart failure patients: from 18 +/- 8 to 29 +/- 8 mm Hg for the PWP, with cough in one patient. At T 30 these 3 variables decrease and return nearly to initial values: respectively 2.7 +/- 4.7 (RAP), 24 +/- 14 (MPAP), 12 +/- 8 mm Hg (PWP). In conclusion pressotherapy increases RAP and pulmonary pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Exercise therapy in E.N.T].

A non exhaustive survey of physiotherapy methods and techniques in "soft E.N.T. treatment" is briefly described. Without using "strength or brutality" which might retard the patient's recovery, the physiotherapist should focus his efforts to regain optimal functioning of the affected structure. So, physiotherapy techniques such as relaxation, bio-feedback, massage, exercise and electrotherapy, are used for a successful treatment of headache, migraine, vertigo, peripheral facial palsy, neck, cervico-facial (awkward positioning) and temporo-mandibular joint problems. Manual lymphatic drainage in post-surgical regeneration of skin and underlying structures, an example of very soft technique suits perfectly in the context of "soft E.N.T."

Exercise Therapy↗