Biomedical subjects

J J Gauthier

Publications and source records attributed to J J Gauthier.

16 recordsLinked to original sources

PubMed1998

[Quebec spirometry reference values].

Lung volumes forced expiratory flow rates and carbon monoxide diffusing capacity (apnea) were measured in 397 non-smoking, nonatopic, asymptomatic subjects (219 women, 178 men). The equipments and methods for measurements met the ATS criteria. The linear regression of the different variables according to age and height allowed the elaboration of a new set of predictive equations (Quebec). When comparing the different reference values used in North America and Europe, it is found that those of Miller and associates as well as those recommended by the CECA provide the best description of the Quebec situation. However, we would eventually prefer the reference values of Miller and associates over those of the CECA, because they better fit the current ATS criteria and also provide references for smokers. Lung volumes and forced expiratory flow rates of 97 non-smoking, nonatopic, asymptomatic manual workers were measured in the same conditions and submitted to the same comparisons. Quebec predictive values as well as those of Miller and associates isolated the same individuals in the so called abnormal zone. We therefore conclude that Quebec's standards should be preferred in the Province of Quebec pulmonary function laboratories.

Adult↗

PubMed1996

Biodegradability and microbial activities during composting of poultry litter.

Poultry litter is composted to reduce odor and pathogens and to improve its quality as a soil amendment. Organic material, e.g., sawdust, is added to increase the C:N ratio to achieve optimum degradation of organic C and retention of N through microbial biomass formation. However, the relative biodegradabilities of the organic material in poultry litter and the amendment are usually not known. Furthermore, it is assumed that as microorganisms metabolize organic compounds and produce CO2, they increase in biomass and, therefore, retain N. In this study, bench-scale compost reactors were used to determine the relative contributions of poultry litter and of the amendment (sawdust) to the biodegradability of a compost mix. Approximately 29% of the volatiles lost from the poultry litter mix came from the sawdust. Fiber analyses revealed that only a small portion of cellulose was degraded. Although microbial subpopulations able to degrade selected macromolecules were present at varying levels, the overall level of microorganisms did not change markedly. Populations capable of degrading bacterial cell walls were present throughout the composting period, and microbiological assays indicated that inorganic nutrients were available to support limited microbial growth. These results suggest that N compounds and inorganic nutrients are recycled, rather than fixed during composting.

Animals↗

PubMed1995

Relationship between glycocalyx and povidone-iodine resistance in Pseudomonas aeruginosa (ATCC 27853) biofilms.

Biofilm-embedded bacteria are generally more resistant to antimicrobial agents than are planktonic bacteria. Two possible mechanisms for biofilm resistance are that the glycocalyx matrix secreted by cells in a biofilm reacts with and neutralizes the antimicrobial agent and that the matrix creates a diffusion barrier to the antimicrobial agent. This study was therefore conducted to examine the relationship between glycocalyx and enhanced povidone-iodine resistance in biofilms of Pseudomonas aeruginosa (ATCC 27853). Biofilms were generated by inoculation of polycarbonate membranes with broth-grown cells and incubation of them on the surfaces of nutrient agar plates. The quantities of glycocalyx material per cell were found not to be significantly different between biofilm and planktonic samples. Transmission electron microscopy showed that the distributions of glycocalyx material around cells differed in biofilm and in planktonic samples. Addition of alginic acid to planktonic cell suspensions resulted in a slight increase in resistance to povidone-iodine, suggesting some neutralizing interaction. However, the iodine demands created by biofilm and planktonic samples of equivalent biomass were not significantly different and, therefore, do not explain the contrast in resistance observed between biofilm and planktonic samples. Examination of the relationship between cell death and biomass detachment from the glycocalyx matrix revealed that most cell death occurred in the fraction of biomass that detached from a biofilm during treatment. The overall rate of iodine diffusion through biofilms was not different from that of planktonic cells collected on a polycarbonate membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Biofilms↗

PubMed1994

Use of image analysis to measure handwashing effectiveness.

BACKGROUND: This study tested a unique quantification technology (image analysis of fluorescent particles) for the measurement of handwashing effectiveness, comparing an automated system with traditional manual handwashing. In this instance, handwashing "effectiveness" was defined as ability of the technique to remove surface soil, as opposed to removal of microorganisms. METHODS: Sixty-five subjects washed their hands by manual handwashing (day 1) and automated handwashing (day 2). Hands were coated with an oil-based fluorescent suspension, photographed under controlled conditions, washed for 10 seconds, and rephotographed. Photographs from before and after handwashing were subjected to image analysis. RESULTS: Manual handwashing removed 73.1% of the particles; the automated method removed 23.2%. Parameters for use of image analysis as a technique to examine removal of gross contamination from the hands are given in the text. CONCLUSIONS: Although this method will not replace traditional culture methods for examining microbial removal, it is useful for measuring removal of particles (gross contamination) from skin or other surfaces. Under the conditions tested, manual handwashing was found to be decidedly superior to use of an automated system for removal of oil-based soil on the hands.

Automation↗

PubMed1992

Work-related mesothelioma in Québec, 1967-1990.

Prior surveys of malignant mesothelioma in Québec have noted that almost all the excess in occupational exposure related mesothelioma was in the manufacture and industrial application of asbestos rather than in the mining and milling operations. To evaluate the current status of malignant pleural mesothelioma in the Québec workforce, we reviewed all cases of pleural mesothelioma seen and accepted by the Québec Workman's Compensation Board (CSST) for work related compensation of industrial disease. We identified 120 cases, 7 of whom were females. They were of an average age of 59 +/- 8.5 yrs (sd) (range 42-84); they were exposed to asbestos dust in the workplace for an average of 26 +/- 14.3 yrs (range 0.5-50). The cases were subdivided into 3 groups according to workplace asbestos exposures. There were 49 cases originating in the mines and mills of the Québec Eastern Township region (primary industry, group 1), 50 cases from the manufacture and industrial application sector (secondary industry, group 2), and 21 cases from industries where asbestos was not a major work material, often an "incidental" material (tertiary industry, group 3). Group 1 was of an average age of 62 +/- 8 years, exposed to asbestos dust 31 +/- 14 years and the distribution of exposure time was as follows: 15% cases with < or = 10 year-exposure and 77% > or = 25 year-exposure. In group 2, the age was significantly lower at 57 +/- 9 years; the exposure time was also significantly lower at 22 +/- 14 years, and the distribution of exposure time differed from the above (29% cases with < or = 10 year-exposure and 48% > or = 25 year-exposure). In group 3, the average age was 58 +/- 7 years, the exposure time was also significantly lower at 28 +/- 12 years and the distribution of exposure time differed from the above (33% cases with < or = 10 year-exposure and 62% > or = 25 year-exposure). Analyses of the yearly incidence of new cases in each group documented the general incremental trend in all groups, with the sharpest rises in group 3. In the mining towns of Thetford and Asbestos, the incidence of mesothelioma was proportional to the workforce, thus suggesting that the tremolite air contamination, which is 7.5 x higher in Thetford, may not be a significant determinant of the disease in these workers.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1987

Surgical treatment of bronchogenic carcinoma: the importance of staging in evaluating late survival.

From 1971 to 1980, 1292 patients with lung cancer were admitted to the Hôpital du Sacré-Coeur de Montréal. This diagnosis represented 0.5% of admissions in 1971 and 1.7% in 1980 (240% increase). Only 4% of patients were nonsmokers. Patients ranged in age from 30 to 93 years with a male to female ratio of 5.5 to 1. Of 414 cervical mediastinoscopies carried out for right and left pulmonary tumours, 120 (29%) showed mediastinal lymph-node metastasis (positive biopsy). For 35 left-sided lesions, both cervical and left parasternal mediastinoscopies produced 13 (37%) positive biopsies. For 45 left upper lobe and left hilum tumours, left parasternal mediastinoscopy alone yielded 18 (40%) positive biopsies. Only 297 (23%) of the 1292 patients were considered to have operable lesions and they underwent thoracotomy - 164 (55%) lobectomies, 104 (35%) pneumonectomies, 2 (1%) segmentectomies and 27 (9%) exploratory thoracotomies. The most common postoperative complication was respiratory failure - in 27 cases (9%); there were 12 (4%) bronchopleural fistulas. The operative death rate was 5% - 1.8% for lobectomy, 7.4% for exploratory thoracotomy and 9.6% for pneumonectomy. Causes of death were respiratory failure (60% of the deaths), hemorrhage (13%), cardiac events (13%) and bronchopleural fistula (13%). The overall 5-year survival was 9.2%. For the 297 patients operated on, the survival at 5 and 10 years was 55% and 36% for stage I disease, 30% and 20% for stage II disease and 10% and 8% for stage III disease, respectively. The mean postoperative follow-up was 41.5 months (range from 3.5 to 14 years).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1984

Functional effects of pneumonectomy and bilobectomy for lung cancer.

28 patients with lung cancer had pulmonary function studies before and 3 months to 3 years after pneumonectomy or bilobectomy. Preoperative profiles showed a slight obstructive pattern with air trapping and perturbated gas exchange. The obstructive pattern was not related to endoscopy findings, but the alveoloarterial gradient oxygen gradient was smaller in those with complete lobar occlusion. After surgery, the volume loss was related to the amount resected, being greater after right pneumonectomy than after left pneumonectomy and least after bilobectomy. The obstructive pattern remained unchanged. Diffusion of carbon monoxide decreased significantly less than volumes after pneumonectomy but proportionally after bilobectomy. Those with increased alveoloarterial oxygen gradient or increased physiologic dead space experienced a significant improvement of their gas exchange after surgery.

Adult↗

PubMed1982

Bactericidal activity of human lactoferrin: differentiation from the stasis of iron deprivation.

Previous studies have demonstrated a direct iron-irreversible inhibition of a variety of microorganisms by human apolactoferrin. The present study compared the bactericidal effects of lactoferrin on Streptococcus mutans with the bacteriostatic effects of iron deprivation. Growth (as determined by change in optical density) and macromolecular synthesis, as determined by incorporation of (14)C-labeled uracil, thymidine, and lysine, were inhibited by incubation of washed exponential-phase S. mutans NCTC 10449 with purified human apolactoferrin. Similarly, apolactoferrin inhibited glucose uptake and metabolism. Iron-saturated lactoferrin had no effect on bacterial growth or metabolism and was capable of serving as a source of iron in iron-depleted medium. S. mutans failed to grow, and there was no indication of macromolecular synthesis in iron-depleted partially defined medium; however, glucose metabolism continued, though at a reduced rate, and viability was retained for 72 h. There was no detectable metabolism of glucose by cells maintained for 18 h in iron-free medium. Metabolism was restored by transfer of iron-depleted S. mutans to iron-complete medium. This was in contrast to the irreversible inhibition by lactoferrin after 1 h of incubation. Inhibition could not be reversed by removal of cell surface-associated lactoferrin as detected by rhodamine isothiocyanate-labeled antilactoferrin. This inhibition of metabolism and rapid loss in viability observed with lactoferrin treatment suggest that lactoferrin has a direct bactericidal effect on S. mutans that cannot be attributed to simple iron deprivation.

Glucose↗

PubMed1981

Bactericidal activity of human lactoferrin: influence of physical conditions and metabolic state of the target microorganism.

Lactoferrin is an iron-binding protein that is bactericidal against Streptococcus mutans and several other microorganisms. In this study, the influence of several physical conditions as well as the metabolic state of S. mutans on lactoferrin susceptibility were investigated. After exposure to lactoferrin, a 15-min lag period occurred before the initiation of killing, indicating that a two-step process is involved in lactoferrin killing. Cultures harvested during the early exponential phase were very sensitive to lactoferrin, whereas cultures harvested in the early stationary phase were markedly more resistant. The rate of killing was dependent on temperature; there was no loss of viability at 2 degrees C. Killing occurred at pH 5.0 to 6.0 in water and 20 mM glycine, but did not occur at any pH in 50 mM sodium phosphate or N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer. Addition of exogenous ferrous or ferric ions did not reverse or prevent lactoferrin killing, nor did addition of 1 mM magnesium chloride.

Humans↗

PubMed1980

Bactericidal activity of human lactoferrin: sensitivity of a variety of microorganisms.

Lactoferrin is an iron-binding protein that has been detected in secretions that bathe human mucosal tissues. Previous studies have shown that, when this protein is in the iron-free state, it is capable of a direct bactericidal effect on Streptococcus mutans and Vibrio cholerae. The present study demonstrates variable susceptibilities for a variety of different microorganisms. The list of susceptible organisms includes gram-positive and gram-negative microbes, rods and cocci, facultative anaerobes, and aerotolerant anaerobes. Similar morphological and physiological types are represented among the lalctoferrin-resistant bacteria. S. mutans was more resistant to lactoferrin when grown on a sucrose-contaning medium than when it was grown on brain heart infusion broth without added scurose. When a lactoferrin-sensitive, avirulent strain of Streptococcus pneumoniae was passed through mice, the resultant virulent culture became lactoferrin resistant. Since organisms of the same species and even of the same strain (S. pneumoniae) can differ in susceptibility to lactoferrin, it appears that accessibility to the lactoferrin target site may account for differences in susceptibility. It appears that there may be a relation between virulence and resistance to lactoferrin.

Bacteria↗

PubMed1979