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Biomedical subjects

L Levasseur

Publications and source records attributed to L Levasseur.

13 recordsLinked to original sources
PubMed1996

Eliciting macroporosity in polyacrylamide and agarose gels with polyethylene glycol.

Preparation of highly porous polyacrylamide has recently been described (Righetti et al., Electrophoresis, 1992, 13, 587-595). In this report we add new observations on the conditions of promoting macroporosity in polyacrylamide gels and extend the possibility of eliciting this phenomenon to agarose matrices by the combined use of polyethylene glycol and glycerol. The process of cluster formation in hot agarose solutions was studied and gel structures were examined by scanning electron microscopy. A definition of macroporosity in gel, related to controlled microsyneresis during gelation, is tentatively proposed. The unexpected influence of acrylamide and agarose concentrations upon the size of macroporous structures in the corresponding gels is revealed.

Acrylic Resins↗
PubMed1996

Effects of mode of inhalation of carbon monoxide and of normobaric oxygen administration on carbon monoxide elimination from the blood.

1. The half-life of carbon monoxide (CO) in blood was studied retrospectively in 26 fire victims and in 19 cases of CO poisoning. Normobaric oxygen therapy was administered via mechanical ventilation in 19 fire victims, and by facial mask to the rest of the casualties. 2. Arterial pH was significantly lower (P < 0.05) and PaO2 significantly greater (P < 0.01) in the mechanically ventilated fire victims compared to the spontaneously breathing fire victims. 3. The blood CO half-lives were 91 +/- 38 min for the 26 fire victims and 87 +/- 40 min for the 19 pure CO intoxications. 4. The blood CO half-lives were 92 +/- 40 min for the 19 mechanically ventilated fire victims and 87 +/- 37 min for the 26 spontaneously breathing subjects. 5. We conclude that the elimination of CO from blood was a slow process with no significant effects on the blood CO half-life of either the cause of the CO poisoning or the mode of normobaric oxygen therapy. These data suggest that enhancement of the elimination of carbon monoxide by normobaric oxygen in both pure CO poisoning and fire victims is more difficult to achieve and more complex than has previously been reported.

Adolescent↗
PubMed1992

An objective structured clinical examination for the licentiate: report of the pilot project of the Medical Council of Canada.

The Medical Council of Canada (MCC) administers a qualifying examination for the issuance of a license to practice medicine. To date, this examination does not test the clinical skills of history taking, physical examination, and communication. The MCC is implementing an objective structured clinical examination (OSCE) to test these skills in October 1992. A pilot examination was developed to test the feasibility, reliability, and validity of running a multisite, two-form, four-hour, 20-station OSCE for national licensure. In February 1991, 240 volunteer first- and second-year residents were tested at four sites. The candidates were randomly assigned to one of two forms of the test and one of two sites for two of the four sites. Generalizability analysis revealed that the variance due to form was 0.0 and that due to site was .16 compared with a total variance of 280.86. The reliabilities (inter-station) were .56 and .60 for the two forms. Station total-test score correlations, used to measure station validity, were significant for 38 of the 40 stations used (range .14-.60). The results of the OSCE correlated moderately with the MCC qualifying examination; these correlations were .32 and .35 for the two test forms. Content validity was assessed by postexamination questionnaires given to the physician examiners using a scale of 0 (low) to 10 (high). The physicians' mean ratings were: importance of the stations, 8.1 (SD, 1.8); success of the examination in testing core skills, 8.1 (SD, 1.6); and degree of challenge, 7.8 (SD, 2.1). The results indicate that a full-scale national administration of an OSCE for licensure is feasible using the model developed. Aspects of validity have been established and strategies to augment reliability have been developed.

Canada↗
PubMed1987

Focal ectasia of the terminal bowel accompanying low anal deformities.

Three patients were treated at birth for low anal deformities and developed intractable constipation, not imputable to usual causes of rectal inertia. Barium enema, done the first time at ten days of age in one case, revealed focal ectasia of the terminal bowel, with a peculiar "balloon-like" aspect of the rectum. Optimal treatment includes resection of the terminal bowel down to the dentate line. Incidence of this anomaly in association with low anal deformities has been 5% in our series.

Abnormalities, Multiple↗
PubMed1987

Measuring higher cognitive levels by multiple choice questions: a myth?

Available evidence is inconclusive as to the ability of multiple choice items to measure different taxonomic levels of the cognitive domain. The present study analysed the tests of the Examen de Synthèse for the years 1982, 1983 and 1984. Items used in the study were those for which a consensus was reached between three judges and committees for a given taxonomic level. The initial part of the study showed that judges do not classify items at random but according to a mental representation which is individual, personal and relatively stable. In examining results obtained by students, the study failed to show any significant difference in item difficulty or discrimination for items classified as measuring memorization, interpretation of data and problem-solving. Correlations between results (scores and ranks) obtained for items involving memorization and those obtained for items involving higher cognitive levels fail to show that different traits are measured. If further studies corroborate these results, then future efforts should be directed at developing other instruments to measure higher cognitive levels.

Clinical Competence↗
PubMed1983

Reversion to fetal circulation in congenital diaphragmatic hernia: a preventable postoperative complication.

A review of 26 patients with congenital diaphragmatic hernia, diagnosed in the first 24 hours of life, supports the hypothesis that the postoperative fetal circulation syndrome is an iatrogenic complication, due to the rapid expansion of both lungs, when they are severely hypoplastic. This complication is preventable, when no aspiration of air from the chest cavity is done, and when no tube attached to an underwater seal is inserted. When assisted ventilation is necessary, small volumes at a rapid rate allows satisfactory gaseous exchanges, without pulmonary overinflation.

Female↗
PubMed1979

The surgical separation of pygopagous twins.

A set of female pygopagous twins was successfully separated. Preparation for the main operative procedure and the surgical anatomy encountered are described in details.

Anal Canal↗
PubMed1977

Dacron as arterial prosthetic material: nature, properties, brands, fate and perspectives.

Dacron graft prostheses are routinely implanted to overcome impairment of arterial flow to distal tissues. Many different fabric configurations have been developped and evaluated. Unfortunately, after implantation the flow surface of any graft persists as a fibrinous lining. No human specimen has a commonly ingrown extension of tissue exceeding some millimeters in length. Full wall healing and endothelialization of arterial prosthesis is a goal that must be pursued intensively because it seems that the goal is attainable.

Animals↗
PubMed1976

Effect of thyroxine on the inactivation of thyrotrophin-releasing hormone by rat and human plasma.

The inactivation of synthetic [3H]thyrotrophin-releasing hormone (TRH) by plasma was studied in rats treated with propylthiouracil (PTU) alone or with PTU and thyroxine. 48 h after the onset of treatment with thyroxine, the capacity of rat plasma to inactivate [3H]TRH was significantly increased. The percentage of deamidation of TRH to TRH-free acid was increased 2-fold after 4 days of administration of thyroid hormone. The inactivation of TRH by plasma from hypothyroid patients was compared to that obtained from hyperthyroid patients. Extraction of human plasma incubated with [3H]TRH, followed by thin-layer electrophoresis, showed that transformation of [3H[TRH into TRH-free acid was 44% higher in plasma from hyperthyroid than from hypothyroid patients (P less than 0-05). These data suggest that the inactivation process of TRH by blood proteins could be an important factor in the regulation of the hypothalamo-hypophyseal-thyroid axis in rat and man.

Animals↗