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Biomedical subjects

R Boudreau

Publications and source records attributed to R Boudreau.

13 recordsLinked to original sources
PubMed2001

Epimorphin mediates mammary luminal morphogenesis through control of C/EBPbeta.

We have shown previously that epimorphin (EPM), a protein expressed on the surface of myoepithelial and fibroblast cells of the mammary gland, acts as a multifunctional morphogen of mammary epithelial cells. Here, we present the molecular mechanism by which EPM mediates luminal morphogenesis. Treatment of cells with EPM to induce lumen formation greatly increases the overall expression of transcription factor CCAAT/enhancer binding protein (C/EBP)beta and alters the relative expression of its two principal isoforms, LIP and LAP. These alterations were shown to be essential for the morphogenetic activities, since constitutive expression of LIP was sufficient to produce lumen formation, whereas constitutive expression of LAP blocked EPM-mediated luminal morphogenesis. Furthermore, in a transgenic mouse model in which EPM expression was expressed in an apolar fashion on the surface of mammary epithelial cells, we found increased expression of C/EBPbeta, increased relative expression of LIP to LAP, and enlarged ductal lumina. Together, our studies demonstrate a role for EPM in luminal morphogenesis through control of C/EBPbeta expression.

Animals↗
PubMed2000

Genetic algorithm for ellipsometric data inversion of absorbing layers.

A new data reduction method is presented for single-wavelength ellipsometry. A genetic algorithm is applied to ellipsometric data to find the best fit. The sample consists of a single absorbing layer on a semi-infinite substrate. The genetic algorithm has good convergence and is applicable to many different problems, including those with different independent measurements and situations with more than two angles of incidence. Results are similar to those obtained by other inversion techniques.

Algorithms↗
PubMed1998

TL antigen is not linked to radioinduced thymic lymphoma.

X irradiation of C57BL/Ka mice induces thymic lymphoma after a period of 8 to 36 weeks. This latency period represents an ideal time window in which to follow the development of prelymphoma cells that give rise to overt thymic lymphoma. Several attempts have been made to identify an unequivocal prelymphoma cell marker but these efforts have so far been unsuccessful. We monitored the evolution of thymocyte populations containing prelymphoma cells during the latency period, using CD3 and TL as markers, in a transfer assay. We demonstrated that: (1) particular cell populations could appear or disappear; (2) there were at least two prelymphoma phenotypes: CD3loTL+ and CD3hiTL-; (3) TL could be present transiently; and (4) TL could be absent throughout the latency period. We conclude that split-dose irradiation may induce both TL gene expression and a prelymphoma state but that the two are not necessarily related.

Animals↗
PubMed1989

Human hepatic sinusoidal endothelial cells in culture produce von Willebrand factor and contain Weibel-Palade bodies.

Human hepatic sinusoidal endothelial cells were derived from cadaveric human livers. Cells were grown in culture for several weeks to produce small patches of confluent endothelial cells. The ultrastructure of sinusoidal endothelial cells was examined, cell monolayers were stained immunocytochemically for von Willebrand factor antigen, and antigen in cell culture media was measured by enzyme-linked immunosorbent assay. Human hepatic sinusoidal endothelial cells contained von Willebrand factor antigen and Weibel-Palade bodies, were fenestrated, and released von Willebrand factor antigen into media in a time-dependent manner. Although in some respects human hepatic endothelial cells were different from vascular cells, there was no evidence that there were qualitative differences in their capacity to produce von Willebrand factor.

Cells, Cultured↗
PubMed1985

Modeling the isovolumic relaxation period.

The isovolumic relaxation period of the left ventricular pressure curve in man has been assumed to be best represented by an exponential decay. To determine which model most closely approximates the empiric pressure data of isovolumic relaxation in man, several models were compared. They included linear, exponential with a zero mmHg pressure asymptote, exponential with a variable asymptote, and second-to fifth-order polynomials. In addition, four different methods of computing parameters of isovolumic relaxation by the exponential model with a variable asymptote were tested. It was found that the isovolumic relaxation period approximates an exponential, that the theoretic asymptote is variable, and that the Levenburg-Marquardt algorithm can be used efficiently to model this period.

Adult↗
PubMed1983

Effect of 99mTc-Sn-colloid incubation time on in vivo distribution.

The in vitro particle size of 99mTc-Sn-colloid preparation increases with the length of incubation time after reconstitution. It was found that the percentage of particles trapped (T) by a 1-micron filter as a function of time (t) could be represented by the logarithmic equation T = 5.3 + 15.7 ln t (r = 0.96). This material was applied to a crossover study involving 25 patients each of whom received preparations of the same reconstituted 99mTc-Sn-colloid that had been incubated for 15 min and (each patient received both) 5 h. It was found that there was a significant shift of radioactivity to the spleen and a significant decrease in background with the material that had been incubated longer. The 99mTc-Sn-colloid is adequate for the disclosure of space-occupying disease in the liver and spleen, but unreliable for drawing conclusions on the status of liver function based on the changes in splenic concentration.

Adult↗
PubMed1983

Phase and amplitude imaging in the diagnosis of acute right ventricular damage in inferior infarction.

Right ventricular infarction is not uncommon in patients with inferior myocardial infarcts. Phase and amplitude analysis of equilibrium gated cardiac blood pool studies is useful in documenting right ventricular damage complicating left ventricular infarction. In 15 of 37 patients with acute inferior infarction, right ventricular extension of the infarct was demonstrated by this approach, complementing the findings of infarct avid imaging with Tc-99m pyrophosphate (Tc-99m PYP).

Aged↗
PubMedDate not supplied

Red blood cell transfusions for elective hip and knee arthroplasty: opportunity to improve quality of care and documentation.

OBJECTIVES: To assess current practice for red blood cell transfusion relative to the American College of Physicians guideline for red blood cell transfusion; to determine comparative rates and relative appropriateness of autologous versus allogeneic blood use; and, to assess cost implications of current transfusion practices. DESIGN: Computerized quality-of-care algorithm applied retrospectively to medical-record and blood-bank data. SETTING: Twenty-six hospitals in Colorado, Connecticut, Georgia, Oklahoma, and Virginia. PATIENTS: Medicare beneficiaries (2,137) who were hospitalized in 1993 for two elective surgical procedures: total hip arthroplasty and total knee arthroplasty. Of the 1,195 patients who received a preoperative or postoperative transfusion, 728 were excluded from the analysis because the hospital medical record did not contain the clinical documentation necessary to apply the American College of Physicians guideline to each unit transfused. The remaining 467 patients comprised the sample. RESULTS: For 467 patients who underwent these two procedures and received a total of 651 units of preoperative or postoperative blood, there were 256 excess units transfused. Two hundred four of these units were autologous, and 52 were allogeneic. These excess units accounted for $48,200 of the total $121,000 direct cost of transfused units. CONCLUSIONS: These findings demonstrate that current medical records lack the documentation necessary to evaluate transfusion practice for the majority of Medicare beneficiaries undergoing elective hip and knee arthroplasty. The direct costs of preoperative and postoperative blood transfusion for these two procedures could be reduced by nearly 40% through adherence to the American College of Physicians guideline. The majority of this cost saving would be realized through reduction in unnecessary collection and use of autologous blood.

Algorithms↗