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M Rossignol

Publications and source records attributed to M Rossignol.

124 records · Page 7Linked to original sources
PubMed1976

Genetic analysis of membrane differentiation in Paramecium. Freeze-fracture study of the trichocyst cycle in wild-type and mutant strains.

Using a series of mutants of Paramecium tetraurelia, we demonstrate, for the first time, changes in the internal structure of the cell membrane, as revealed by freeze-fracture, that correspond to specific single gene mutations. On the plasma membrane of Paramecium circular arrays of particles mark the sites of attachment of the tips of the intracellular secretory organelles-trichocysts. In wild-type paramecia, where attached trichocysts can be expelled by exocytosis under various stimuli, the plasma membrane array is composed of a double outer ring of particles (300 nm in diameter) and inside the ring a central rosette (fusion rosette) of particles (76 nm in diameter). Mutant nd9, characterized by a thermosensitive ability to discharge trichocysts, shows the same organization in cells grown at the permissive temperature (18 degrees C), while in cells grown at the nonpermissive temperature (27 degrees C) the rosette is missing. In mutant tam 8, characterized by normal but unattached trichocysts, and in mutant tl, completely devoid of trichocysts, no rosette is formed and the outer rings always show a modified configuration called "parentheses", also found in wild-type and in nd9 (18 degrees C) cells. From this comparison between wild type and mutants, we conclude: (a) that the formation of parentheses is a primary differentiation of the plasma membrane, independent of the presence of trichocysts, while the secondary transformation of parentheses into circular arrays and the formation of the rosette are triggered by interaction between trichocysts and plasma membranes; and (b) that the formation of the rosette is a prerequisite for trichocyst exocytosis.

Animals↗
PubMedDate not supplied

Towards the recovery of hydrophobic proteins on two-dimensional electrophoresis gels.

An extensive proteomic approach relies on the possibility to visualize and analyze various types of proteins, including hydrophobic proteins which are rarely detectable on two-dimensional electrophoresis (2-DE) gels. In this study, two methods were employed for the purification of hydrophobic proteins from Arabidopsis thaliana leaf plasma membrane (PM) model plants, prior to analysis on 2-DE immobilized pH gradient (IPG) gels. Solubilization efficiency of two detergents, (3-[(3-cholomidopropyl)-1-propanesulfonic acid (CHAPS) and C8phi, were tested for the recovery of hydrophobic proteins. An immunological approach was used to determine the efficiency of the above methods. Fractionation of proteins by Triton X-114 combined with solubilization with CHAPS resulted in the inability to detect hydrophobic proteins on 2-DE gels. The use of C8phi for protein solubilization did not improve this result. On the contrary, after treatment of membranes with alkaline buffer, the solubilization of PM proteins with detergent C8phi permitted the recovery of such proteins on 2-DE gels. The combination of membrane washing and the use of zwitterionic detergent resulted in the resolution of several integral proteins and the disappearance of peripheral proteins. In the resolution of expressed genome proteins, both large pH gradients in the first dimension and various acrylamide concentrations in the second dimension must be used. Notwithstanding, it is important to combine various sample treatments and different detergents in order to resolve soluble and hydrophobic proteins.

Acrylic Resins↗
PubMedDate not supplied

Construction of a directory of tobacco plasma membrane proteins by combined two-dimensional gel electrophoresis and protein sequencing.

The polypeptide pattern of the plasma membrane from tobacco was studied by two-dimensional gel electrophoresis. When using classical carrier ampholyte isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis (IEF/SDS-PAGE) approximately 400 polypeptide spots were detected after silver staining and computer analysis using the QUEST software. This resolution was sufficient to assess physiological effects such as changes in a phytohormone concentration. By using pH 4-8 immobilized pH gradient (IPG)-IEF and 10%T SDS-PAGE gels, approximately 600 polypeptides, corresponding to ca. 80% of the total population expected, were resolved. This cross-section of the plasma membrane polypeptide population was mainly constituted by low or intermediate molecular mass (25 to 45 kDa) and acidic (5.2 < pI < 6.1) polypeptides. After sample application by in-gel rehydration, large amounts of plasma membrane protein (between 5 mg and 10 mg protein) were analyzed using IPG-IEF, and N-terminal protein sequencing was performed for polypeptides collected from one gel. Internal protein sequences were also obtained. Nearly all protein sequences corresponded to unidentified proteins but several of them matched translated sequences from unidentified plant expressed sequence tags (ESTs). It is concluded that the combined use of IPG-IEF gels and in-gel rehydration allows, in the case of plant membrane protein, both analytical and micropreparative separations with an efficiency comparable to that demonstrated for soluble proteins. Finally, it is suggested that a systematic investigation of plant plasma membrane polypeptides is feasible and would constitute a source of new and plant-specific genes.

Amino Acid Sequence↗
PubMedDate not supplied

Perception of difficulties for the back related to assembly work: general findings and impact of back health.

The study objective was to describe the perceptions of airplane assemblers on job demand for the back and how back pain modulated these perceptions. One hundred and seventy-six workers answered two questionnaires concerning back pain and the perception of work related difficulties (work activities, work contexts, tools, work positions, efforts). Results show that positions and work contexts are perceived as greater sources of difficulty than efforts or dynamic activities. The duration of a given position is more important than its frequency. Back pain has a significant but complex impact on the perception of difficulty. Assemblers appear to integrate several factors when evaluating their difficulties as opposed to individual aspects, as it is often measured in ergonomic studies. The results have important implications for the measurement of ergonomic factors in the genesis of back pain and illustrates the potential for misclassification and biases in current epidemiologic studies.

Adult↗
PubMedDate not supplied

The performance of spinal anesthesia is marginally more difficult in the elderly.

BACKGROUND AND OBJECTIVES: We sought to determine if spinal anesthesia is more difficult to perform in the elderly. METHODS: All spinal anesthetics administered over 18 months by 18 anesthesiologists were eligible. We excluded anesthetics for hip fractures and cesarean deliveries. We recorded time to completion, number of spinal needles used, and number of approaches. The patients were prospectively divided into three age categories: patients <50 years of age (group 1); 50-70 years of age (group 2); and >70 years of age (group 3). Descriptive statistics and chi-square test were performed. RESULTS: Nine hundred and ninety-nine anesthetics were analyzed. There were 368, 336, and 295 entries in groups 1, 2, and 3, respectively. Although the mean +/- SD (in min) times to accomplish the spinal technique were not significantly different (4.3 +/- 4.1, 4.4 +/- 3.2, and 4.6 +/- 3.4 for groups 1, 2, and 3), there was a statistically greater frequency of more than one spinal needle used and more than one approach needed in the elderly. CONCLUSIONS: We conclude that patient age is a minor independent predictor of increased technical difficulty with spinal anesthesia.

Age Factors↗
PubMedDate not supplied

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Education, Nursing, Baccalaureate↗
PubMedDate not supplied

Piloting use of computerized practice tests.

This study piloted the use of computerized practice tests in an undergraduate nursing pathopharmacology course and collected questionnaire data on the students' experiences. Two computer-administered practice tests were available to help students prepare for the course's paper-and-pencil unit examinations. The software testing package, LXR-Test 5.1, was used to generate the practice tests. Twenty-eight students took one or both computer practice tests. Group mean course examination scores were higher for subjects taking the computer practice tests compared with subjects who did not take the computer practice tests, but these scores were not found to be significantly different (P = 0.29; P = 0.07). Final questionnaire results showed students enjoyed taking the computerized practice tests to prepare for course examinations and liked the immediate scoring and test summary printouts. After this experience, students felt more prepared to take the computerized licensure examination. Did students feel ready to take required course examinations via computer in future courses? Responses were mixed.

Computer-Assisted Instruction↗
PubMedDate not supplied

Planning preventive occupational health services at the community level.

Socio-sanitary data on occupational injuries and disease-specific exposures were used to plan preventive occupational health services in the territory of a Community Health Department in an industrial sector of Montreal, Quebec. Information was obtained from two complementary sources: Worker's Compensation and plant surveys. For prevention of injuries, three groups of planning options were identified: territorial injury surveillance, protection of the extremities and eyes, and the ergonomic diagnosis of the workplace for prevention of non-accidental injuries. In the prevention of occupational diseases, medical screening and worker's registry were two possible options. These options were put in perspective with the type of resources needed and the kind of commitment required for planning these services.

Accidents, Occupational↗
PubMedDate not supplied

Classification of fatal occupational electrocutions.

The objective of this study was to describe fatal occupational electrocutions that occurred in Quebec between 1981 and 1988 and propose a classification suitable for setting up a prevention agenda. Of 63 fatalities, an investigation report was available in 57 (90.5%). They all occurred among males, 70.2% of whom were under the age of 35; 49.1% were performing a task related to the construction sector. A principal factor analysis allowed classification of 90.2% of the fatalities in two categories: victims assigned to electrical tasks indoors and those assigned to non-electrical tasks outdoors. The first group (56.5% of the cases) were electrocuted by direct contact with voltage less than 10 Kvolts and the second by the intermediary of a vector with voltage above 10 Kvolts. The identification of the two patterns of electrocutions provided an additional argument for shifting recommendations for prevention from educating the workers, to reducing the electrical hazards at the source.

Accidents, Occupational↗
PubMedDate not supplied

Completeness of provincial workers' compensation files to identify fatal occupational injuries.

The objective of the study was to ascertain the completeness of Workers' Compensation files to identify fatal occupational injuries. The number of fatalities was counted using two independent sources: the Quebec Workers' Compensation Board (QWCB), and the Coroner's Death Certificates (CDCs), for the years 1987 and 1988. The observed number of cases was 352. The QWCB identified 83.8% of those and CDCs 69.3%. The true number of deaths was estimated, using the capture-recapture methods, to be between 369 and 401. The compensation coverage of work-related fatalities was 66.1% in workers 55 years of age and older and 8.3% in farming occupations. Therefore, Workers' Compensation statistics are inadequate as the single source in these two categories and their exclusive use thus far has led to a failure in recognizing these issues as public health priorities.

Accidents, Occupational↗