Biomedical subjects

S Ducharme

Publications and source records attributed to S Ducharme.

9 recordsLinked to original sources

PubMed2000

Intrinsic ferroelectric coercive field

The Landau-Ginzburg theory of ferroelectricity predicts the intrinsic coercive field for polarization reversal, but the observed extrinsic coercive field is always much smaller as a result of nucleation, dynamic processes not covered by the static theory. We have realized the intrinsic coercive field for the first time, in two-dimensional Langmuir-Blodgett polymer films as thin as 1 nm. The measured coercive field is in good agreement with the theoretical intrinsic value, exhibits the expected dependence on temperature, and does not depend on thickness below 15 nm.

Journal Article↗

PubMed1999

Employment after spinal cord injury: an analysis of cases from the Model Spinal Cord Injury Systems.

OBJECTIVE: To describe the relationship of multiple biographic, injury-related, and educational factors with employment outcomes after spinal cord injury (SCI). DESIGN: Cross-sectional. SETTING: Data were collected through 18 model SCI systems, a nationwide network of hospitals that treat approximately 14% of all SCIs in the United States. PARTICIPANTS: A total of 3,756 persons with traumatic SCI who completed the Form II data collection during their annual follow-up at years 1, 2, 5, 10, 15, 20, or 25 years (the most recent Form II was accepted). MAIN OUTCOME MEASURES: The Model Systems Forms I and II were used to identify biographic, injury-related status, employment at injury, and productivity status upon follow-up (Form I is used to elicit basic demographic and discharge information, whereas Form II is used to track multiple outcomes during annual follow-ups). The Craig Handicap Assessment Reporting Technique (CHART) was used to assess hours spent in gainful employment and other productive activities. RESULTS: CHART data revealed only a modestly higher Employment rate (24.8%) than that of the traditional single Form II item (22%). Being Caucasian, younger at injury, having lived more years with SCI, having a less severe injury, and having more years of education were all predictive of being employed. Violence at injury was associated with lower employment rates (only 12.9% employed), especially among Caucasians (only 24% employed). Being employed at injury was associated with a greater probability of postinjury employment, but only in the first few years after injury. Among employed participants, women and those who had been injured fewer years averaged fewer hours spent at work. CONCLUSIONS: Findings were consistent with those in previous studies. Interventions to improve employability should focus on education and the needs of individuals from minority backgrounds.

Adolescent↗

PubMed1997

Tissue distribution of the cytofectin component of a plasmid-DNA/cationic lipid complex following intravenous administration in mice.

Allovectin-7 is a gene therapy agent that consists of plasmid DNA (pDNA) encoding the human HLA-B7 class I and beta2-microglobulin genes (VCL-1005), complexed with the cationic lipid DMRIE Br and DOPE. A tritiated version of the cytofectin component, DMRIE Br, was synthesized by regiospecific isotope incorporation to a very high specific activity. The 3H-labeled DMRIE/DOPE mixture was complexed with VCL-1005 to produce a radiolabeled version of Allovectin-7. The VCL-1005/3H-DMRIE/DOPE complex was administered intravenously to mice, and the tissue distribution of radioactivity was analyzed 24 hr later. Excretion of radioisotope was monitored for 96 hr post dosing. At 24 hr post administration, a tissue distribution for the radioisotope of liver >> spleen > lung >> heart > brain approximately muscle approximately blood was observed. During the 96-hr period post dose, very little administered radioactivity (<17%) was excreted and the majority of the isotope (83%) remained in the animal. This is the first report on the biodistribution of the cytofectin component of a pDNA-cationic lipid complex for which the distribution of the plasmid component has also been reported.

Animals↗

PubMed1997

Absorption, distribution and excretion of GT31-104, a novel bile acid sequestrant, in rats and dogs after acute and subchronic administration.

The absorption, distribution, and excretion of GT31-104, a novel bile acid sequestrant, was studied in rats and dogs after both acute and subchronic oral administration. The polyallylamine backbone of GT31-104 was labeled with tritium and one of the alkyl side chains was labeled with 14C. The mean blood and plasma concentration of [3H, 14C]GT31-104 in rats, in both treatment regimens, was negligible at all time points, with the highest amount observed being 0.69 microgram eq/g blood; in dogs the mean blood and plasma concentration of [3H, 14C]GT31-104 was below the limit of quantitation (< 0.001% total dose) at all time points. In both rats and dogs, the mean total urinary excretion of [3H, 14C]GT31-104 was approximately 0.06% of the total dose. The fecal excretion data indicates that both 3H- and 14C-derived radioactivity was excreted entirely in the feces. Mean total radioactivity excreted in the feces ranged from approximately 95 to 105% in the rats and 92 to 102% in the dogs. Across the different treatment regimens, in both species, tissue concentrations were negligible (< 0.01% total dose) and no differences in tissue profile were noted, indicating that there was no effect of pretreatment on [3H, 14C]GT31-104 absorption. GT31-104 was extracted with water, and the water-soluble portion contained radioactivity that would correlate to approximately 0.19% of the 3H dose and 0.41% of the 14C dose; this portion probably accounted for the negligible radioactivity observed systemically. Analysis of gastrointestinal (GI) tract tissues with contents indicated that GT31-104 is rapidly cleared from the GI tract. These data indicate that GT31-104 is not absorbed from the GI tract in rats and dogs.

Allylamine↗

PubMed1991