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Biomedical subjects

C Pelletier

Publications and source records attributed to C Pelletier.

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

Perioperative variation in phagocytic activity against Candida albicans measured by a flow-cytometric assay in cardiovascular-surgery patients.

Candidiasis is an opportunistic fungal infection that frequently occurs following modifications of host defenses. Major surgery can be responsible for such alterations, and therefore it increases the risk of fungal infection. The purpose of this study was to evaluate the perioperative impairment of leukocyte function in patients after cardiovascular surgery by measuring the phagocytic activity against Candida albicans by a flow-cytometric method. The average postsurgical decrease in phagocytosis in our patients was 11.4%. By univariate analysis, three factors, all related to antibiotic therapy, were significantly associated with an important decrease in phagocytosis; the use of antimicrobial therapy before surgery, the number of different antibiotics taken, and the length of antibiotic treatment. The results of our study showed that the use of antibiotics in patients undergoing cardiovascular surgery alters the normal phagocytic activity of the host immune system against C. albicans and that flow cytometry is a rapid and simple technique that helps in early identification of patients at high risk for Candida infections. The mechanisms by which surgery and antibiotics decrease phagocytosis remain to be elucidated.

Adult↗
PubMed1997

Simultaneous quantitation of specific IgE against 20 purified allergens in allergic patients sera by checkerboard immunoblotting (CBIB).

A simple technique, checkerboard immunoblotting (CBIB), is described for simultaneous quantitation of specific IgE antibodies against several allergens in human sera. Using as little as 50 microliters of each of the 20 sera examined against 20 different allergens, it was possible in a single run to achieve 400 tests. To guarantee high specificity and sensitivity of the assay, this new application of CBIB employs purified allergens, cyanogen bromide-activated nitrocellulose membrane, and Phosphorimager technology. Results are expressed both qualitatively (five classes) and quantitatively in kilo units per liter equilibrated against the World Health Organization (WHO) standard for IgE. There was excellent agreement between the results of CBIB and the results of Pharmacia Cap System, an alternative method widely used for measuring serum-specific IgE. The CBIB method certainly could be useful in any laboratory interested in allergy clinical research for easy screening and relative quantitation of allergen-specific human IgE.

Allergens↗
PubMed1996

Expression of alpha v and beta 3 integrin chains on murine lymphocytes.

The vitronectin receptor is a member of the integrin family of adhesion protein receptors and binds a broad spectrum of ligands, including fibronectin and fibrinogen in addition to vitronectin. We have generated four mAbs that recognize the murine alpha v beta 3 vitronectin receptor. Biochemical and expression analyses showed that two of the mAbs are specific for the alpha v chain, and two are specific for the beta 3 chain. The mAbs are effective blocking reagents and inhibited cell adhesion to vitronectin, fibrinogen, and fibronectin. Staining analysis revealed expression of alpha v and beta 3 on certain populations of murine thymocytes, splenocytes, and bone marrow cells. The expression of alpha v and beta 3 appeared to be modulated at specific stages of thymocyte development, suggesting a possible function for the alpha v beta 3 vitronectin receptor in T cell development.

Animals↗
PubMed1996

Development of a model system to compare cell separation methods for the isolation of fetal cells from maternal blood.

Three major methods have been described for the isolation of fetal cells from maternal blood: fluorescence-activated cell sorting (FACS), immunomagnetic beads, and magnetic-activated cell sorting (MACS). To date, no study has directly compared fetal cell recovery using each of these methods. Here we describe our system using a "model' male fetal cell mixed into female peripheral blood mononuclear cells. Fetal cell yields and purities were assayed by a quantitative polymerase chain reaction (qPCR) using chromosomes Y- and 7-specific sequences. Fetal cell recovery was investigated by selection of CD71+ cells or depletion of CD45+ cells. Our data demonstrated variation in fetal cell recovery for all methods tested, although CD71+ selection by FACS gave the best and most consistent results.

Antigens, CD↗
PubMed1995

Roles of divalent cations and pH in mechanism of action of nitroxoline against Escherichia coli strains.

The antibacterial activity of nitroxoline (NIT), an antibiotic used in the treatment of acute or recurrent urinary tract infections caused by Escherichia coli, is decreased in the presence of Mg2+ and Mn2+ but not Ca2+. In order to elucidate the interaction between this drug and the divalent cations, spectrophotometric studies based on the natural absorption of the nitroxoline moiety were conducted. In the presence of the divalent metal ions, a shift in the NIT A448 suggested the formation of drug-ion complexes, for which the stability followed the order Mn2+ > Mg2+ > Ca2+. A clear correlation was found between the chelating property and antibacterial activity of NIT; both were pH dependent. A convenient colorimetric method for the determination of NIT uptake by bacterial cells was also developed. Uptake was energy independent and showed biphasic kinetics: a rapid association with cells and then a slower increase in cell-associated NIT which reached a plateau. NIT uptake was reduced in the presence of magnesium. The implications of metal ion complexation and pH on the clinical efficacy of NIT are discussed.

Anti-Infective Agents, Urinary↗
PubMed1994

Effects of sub-minimal inhibitory concentrations of EDTA on growth of Escherichia coli and the release of lipopolysaccharide.

Release of lipopolysaccharide from E. coli was studied in the presence of sub-minimal inhibitory concentrations of ethylenediaminetetraacetic acid (EDTA). In untreated cells no release was detected with 50 mM Mg2+ in the medium, but a steady release of over 50% of the synthesized lipopolysaccharide was observed with 0.1 mM Mg2+. EDTA at MIC/8 led to a 2- to 3-fold higher release, presumably by an adjustment of the concentration of unchelated Mg2+ to a value still sustaining normal growth but giving rise to a highly unstable outer membrane. No structural difference was observed between cell-bound and released lipopolysaccharide.

Culture Media↗
PubMed1994

[Microbiological consequences of chelation of bivalent metal cations by nitroxoline].

The present work deals with the physico-chemical and microbiological investigations made in order to explain the role of divalent cations in the mechanism of the action of nitroxoline (NIT), an antibiotic used in the treatment of uncomplicated urinary tract infections. Preliminary studies reported that bacteriostatic and bactericidal activities of NIT on Escherichia coli strains are decreased in the presence of Mg2+ and Mn2+ but not with Ca2+. A spectrophotometric study, conducted in order to elucidate the interaction between metal ions and NIT, showed the formation of drug-metal ion complexes. In addition, we examined the relationships between the metal ions-chelating property of NIT and its effects on the decrease of the mannose sensitive hemagglutination titer and the production of siderophores from E. coli. The results suggested that these antimicrobial activities of NIT would also be due to the complexation of metal ions by this molecule.

Anti-Infective Agents, Urinary↗
PubMed1994

[Update on inhalation therapy in asthma and obstructive bronchopulmonary diseases].

Significant changes have occurred in aerosol therapy in the last few years. New devices have been developed to facilitate the administration of bronchodilator or anti-inflammatory drugs into the airways. Metered-dose inhaler with or without a spacer or powder devices are now considered the ideal mode of administration of aerosolized medications in the regular treatment of child or adult asthma as well as in COPD. In mild to moderate acute asthma, bronchodilators are ideally administered with a metered dose inhaler with a spacer device, nebulisation being required in only a minority of patients. Powder devices such as the Turbuhaler may also be useful in acute asthma but inspiratory flow should be sufficient, and their usefulness in this context remains to be better determined. In severe acute asthma or in patients unable to properly use the other inhalation devices, nebulisation can be used, with oxygen in the case of acute asthma. In patients requiring mechanical ventilation, administration of bronchodilators can be done with a metered-dose inhaler with a spacer device specifically designed for this purpose: it will replace nebulisation in most cases. In young children and infants unable to use spacer devices with a mouthpiece (< 5 years), wet nebulisation is still used during acute attacks of asthma. In these circumstances, the use of metered-dose inhalers with a spacer and mask are probably appropriate in some children but further studies are required to recommend their use.

Adult↗
PubMed1993

Somatosensory evoked potential monitoring during Cotrel-Dubousset instrumentation. Report of a case.

Somatosensory evoked potentials produced by electrical stimulation of the posterior tibial nerve were recorded from surface electrodes at the scalp and cervical spine of a patient with scoliosis undergoing posterior spinal fusion with Cotrel-Dubousset instrumentation. During spinal derotation when hypotension and anemia were also present, the cortical and subcortical somatosensory evoked potentials disappeared. During a wake-up test, the patient demonstrated weakness of the left lower extremity, and derotation was stopped. The patient was given pharmacologic hypertensive agents and blood transfusions to increase blood pressure. Forty minutes later, somatosensory evoked potentials returned and a second wake-up test demonstrated normal function in both lower extremities. This report demonstrates the accuracy and usefulness of somatosensory evoked potential monitoring during spinal fusion with Cotrel-Dubousset instrumentation. To the authors knowledge, this is the first report demonstrating a correlation between abnormal SEP responses and intraoperative neurologic deficit during the derotation maneuver with Cotrel-Dubousset instrumentation and corrected by transfusion and restoration of normotension.

Adolescent↗
PubMed1991

Morbidity and mortality of reoperation for coronary artery bypass grafting: significance of atheromatous vein grafts.

Reoperation ('redo') for coronary artery disease shows a significant increase in morbidity and mortality compared to primary surgery. Some technical approaches have been advocated to decrease myocardial injury, presumably due to coronary artery embolization from atheromatous vein grafts. From 1984 to 1989, 321 'redo' operations were performed at the Montreal Heart Institute. Patients with patent and atherosclerotic vein grafts at preoperative coronary angiography (239 patients) were compared to those with normal or occluded grafts (82 patients). Perioperative myocardial infarction and death rates were 19% and 13%, respectively. They were particularly high among patients with three or more patent and atherosclerotic vein grafts at reoperation (32% and 29%, respectively). Among the 239 patients with patent atherosclerotic grafts, the results of three different surgical techniques were studied retrospectively. A first group of 66 patients had early ligation of patent atheromatous grafts before cardioplegia was administered by antegrade infusion during single aortic clamping for coronary anastomoses, and maintained for the confection of aortic anastomoses. In a second group of 35 patients, early ligation of diseased graft, antegrade cardioplegic delivery, and partial aortic cross clamping for aortic anastomoses of vein grafts was done. In the third group of 138 patients, venous grafts were not interrupted before antegrade cardioplegic infusion and partial aortic cross clamping for aortic anastomoses of vein grafts was used. No significant difference in hospital mortality or perioperative myocardial infarction rate was observed between the three groups of patients. Thus, the modified techniques so far recommended for repeat coronary artery bypass grafting, such as early ligation of patent atherosclerotic grafts, have failed to improve the early results of 'redo' operations.

Adult↗
PubMed1990

Effects of lung resection on pulmonary function and exercise capacity.

The effects of lung resection on exercise capacity and perception of symptoms were studied in 47 patients aged 39-73 (mean 58.3) years. Twenty had a pneumonectomy and 27 a lobectomy, all for lung cancer. Forced expiratory volume, maximal inspiratory and expiratory pressures, and progressive maximal one minute incremental cycle ergometer exercise performance were measured before and after surgery. Breathlessness and leg discomfort were assessed with a modified Borg scale (0-10). Mean FEV1 decreased from 79% (SD 22%) to 53% (11%) of the predicted value after pneumonectomy and from 89% (22%) to 74% (18%) after lobectomy. Exercise capacity, measured as the highest work load completed, Wmax, decreased from 78% (25%) to 58% (28%) predicted in the pneumonectomy group and from 77% (21%) to 67% (20%) in the lobectomy group. There was only a weak relation between changes in FEV1 and changes in Wmax (r = 0.54, r2 = 0.30). The slope of the relation between the intensity of dyspnoea and work load or the intensity of dyspnoea and ventilation increased significantly after pneumonectomy, but not after lobectomy. Leg discomfort increased more rapidly when related to work load after both pneumonectomy and lobectomy. After resection dyspnoea was rarely the only limiting factor at maximal exercise. It is concluded that (1) change in FEV1 is a poor predictor of change in exercise capacity after lung resection; (2) pneumonectomy results in a 25% decrease in Wmax and in an appreciable increase in dyspnoea during exercise; (3) lobectomy has little or no effect on Wmax or the intensity of postoperative dyspnoea; (4) after both pneumonectomy and lobectomy leg discomfort makes an important contribution to exercise limitation.

Adult↗
PubMed1988

Sputum gram stain assessment in community-acquired bacteremic pneumonia.

A prospective study was performed over a 4.5-year period to determine the ability of a sputum Gram stain to predict the cause of community-acquired bacterial pneumonia. A blood culture isolate, rather than a sputum culture, served as the reference standard to provide precise identification of the etiologic agent. The study population comprised 59 bacteremic adults who expectorated a valid sputum sample. Data are presented that indicate that a physician, aided by the morphology of the stained sputum, could theoretically select appropriate monotherapy approximately 94% of the time when selective, defined criteria for the microbiology of valid sputum are met. Three of the five patients with pneumonia caused by Haemophilus influenzae, however, had sputum stains that suggested alternative pathogens. This study reaffirms that the Gram-stained sputum is a reliable, but not infallible, guide to direct initial antibiotic therapy in adults with community-acquired bacterial pneumonia.

Adolescent↗
PubMed1987

A six-year study of the Omniscience valve in four Canadian centers.

Stimulated by the recent controversy over the Omniscience valve, we conducted a follow-up study on 413 hospital survivors in whom this prosthesis was implanted at four Canadian centers from 1979 to 1985. One hundred forty-seven underwent aortic valve replacement (AVR), 203 had mitral valve replacement (MVR), 10 had tricuspid valve replacement (TVR) and 53 underwent multiple valve replacement (45 AVR + MVR, 5 MVR + TVR, and 3 AVR + MVR + TVR). The mean age was 50.8 +/- 13 years (range, 2 months to 75 years). Follow-up of 96% was achieved for a mean of 2.6 years and a maximum of 6 years with a total of 1,076 patient-years. Complications were defined and graded according to severity. Analyses were performed to yield linearized and actuarial rates for complications. There were 30 late deaths (2.8% per patient-year). At 5 years, the actuarial survival was 89 +/- 3% (AVR, 89 +/- 3% and MVR, 91 +/- 3%). Percentages for freedom from each complication are as follows: endocarditis, 96 +/- 1% (AVR, 96 +/- 2% and MVR, 98 +/- 1%); periprosthetic leak, 99 +/- 0.6% (AVR, 98 +/- 1% and MVR, 99 +/- 0.6%); thrombotic complications, 87 +/- 3% (AVR, 84 +/- 6% and MVR, 90 +/- 3%); valve thrombosis 99.4% (AVR and MVR, 100%); anti-coagulant-related hemorrhage, 94 +/- 2% (AVR, 97 +/- 2% and MVR, 94 +/- 2%); and all valve-related complications, 77 +/- 3% (AVR, 77 +/- 6% and MVR, 79 +/- 4%). Reoperation was required at the rate of 1.2% per patient-year.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1987

[Macrogeodic coxitis in ankylosing spondylitis].

The authors report 6 cases of hip disease with macrocavities during ankylosing spondylarthritis, including 5 cases from a series of 57 coxites which occurred in 34 patients out of 340 ankylosing spondylarthritis, observed at Hospital Begin, between 1973 and 1982. In light of their observations, they propose a classification of the hip manifestations of ankylosing spondylarthritis. The hip involvement with microcavities in ankylosing spondyloarthritis is quite different from coxites with macrocavities present in rheumatoid polyarthritis, and represent more likely a post-inflammatory arthritic type of hip disease than a particular form of coxitis. Hip disease with macrocavities in ankylosing spondylarthritis is a severe form of hip disease, and frequently requires the installation of a total prosthetic replacement.

Acetabulum↗