Biomedical subjects

O Ornatsky

Publications and source records attributed to O Ornatsky.

3 recordsLinked to original sources

PubMed2005

Multiple cellular antigen detection by ICP-MS.

There is a great need in cell biology for the simultaneous detection of many intracellular and extracellular proteins within single cells. Current optical methods based on fluorescence activated flow cytometry are difficult to multiplex. We have developed a novel application of ICP-MS-linked metal-tagged immunophenotyping which has great potential for highly multiplexed proteomic analysis. Expression of intracellular oncogenic kinase BCR/Abl, myeloid cell surface antigen CD33, human stem cell factor receptor c-Kit and integrin receptor VLA-4 were investigated using model human leukemia cell lines. Antigens to which specific antibodies are available and are distinguishably tagged can be determined simultaneously, or multiplexed. Four commercially available tags (Au, Sm, Eu, and Tb) conjugated to secondary antibodies enable a 4-plex assay assuming that the primary antibodies are not cross-reactive. Results obtained by ICP-MS were compared with data from FACS. ICP-MS as an analytical detector possesses several advantages that enhance the performance of immunoassays, which are discussed in detail. Although multiplexing using metal-conjugated reagents is in a very early stage of research and feasibility studies, it is already apparent that more than four antigens could be accurately detected simultaneously using the ICP-MS instrument.

Animals↗

PubMed2001

Administration of exogenous endothelin-1 following vascular balloon injury: early and late effects on intimal hyperplasia.

Administration of exogenous endothelin-1 (ET-1) has been shown to stimulate neointimal hyperplasia following arterial balloon angioplasty (BA). However, the specific effects of ET-1 on the cellular and extracellular matrix response of the vessel wall after balloon injury and the persistence of these ET-1 effects have not been studied. The objectives of this study were to determine the acute (1 week) and long term (10 weeks) effects of administering exogenous ET-1 after arterial BA on neointimal hyperplasia, collagen synthesis and content, cellular proliferation, and ET(A) and ET(B) receptor expression. Thirty-one rabbits were randomized to receive subcutaneous ET-1 (500 pmol/kg/day for 1 week) or placebo time-release pellets and sacrificed at either 1 or 10 weeks after BA. At 1 week, there was a significant two-fold increase in intimal cross-sectional area (CSA) in ET-1 treated animals compared with placebo. ET-1 treated animals showed significant increases in collagen synthesis (ten-fold) and collagen content (three-fold) compared to placebo treated animals. ET-1 treated animals also had a significant increase (two-fold) in proliferation rates. In addition, ET(A) and ET(B) receptor expression were significantly upregulated in ET-1 treated animals. By 10 weeks these stimulatory effects on intimal CSA and collagen content were no longer evident with a 'catch up' phenomenon observed in the placebo treated animals. Similarly, ET(A) and ET(B) mRNA levels had declined significantly in both groups. Therefore, exogenous ET-1 acutely stimulates extracellular and cellular processes including increased expression of ET(A) and ET(B) receptors contributing to intimal hyperplasia. However, these effects are transient and not maintained long term after withdrawal of exogenous ET-1 stimulation.

Analysis of Variance↗

PubMed2000

Effects of estrogen replacement on infarct size, cardiac remodeling, and the endothelin system after myocardial infarction in ovariectomized rats.

BACKGROUND: Estrogen may increase the long-term survival of women who have suffered from a myocardial infarction (MI). We examined the acute and chronic influence of estrogen on MI in the rat left coronary artery ligation model. METHODS AND RESULTS: Female Sprague-Dawley rats (10 to 12 weeks, n=93), divided into 3 groups (rats with intact ovaries, ovariectomized rats administered 17beta-estradiol [17beta-E(2)] replacement, and ovariectomized rats administered placebo 2 weeks before MI), were randomized to left coronary artery ligation (n=66) or sham-operated (n=27) groups. Ten to 11 weeks after MI, rats were randomly assigned to either (1) assessment of left ventricular (LV) function and morphometric analysis or (2) measurement of cardiopulmonary mRNA expression of preproendothelin-1 and endothelin A and B receptors. Acutely, estrogen was associated with a trend toward increased mortality. Infarct size was increased in the 17beta-E(2) group compared with the placebo group (42+/-2% versus 26+/-3%, respectively; P:=0.01). Chronically, wall tension was normalized through a reduction in LV cavity size with estrogen treatment (419+/-41 mm Hg/mm for 17beta-E(2) versus 946+/-300 mm Hg/mm for placebo, P:=0.039). In the LV, there was a 2.5-fold increase in endothelin B mRNA expression after MI in placebo-treated rats (P:=0.004 versus sham-operated rats) that was prevented in the 17beta-E(2) group (P:=NS versus sham-operated rats). CONCLUSIONS: These results suggest that estrogen is detrimental at the time of MI or early post-MI period, resulting in an increased size of infarct or infarct expansion, but chronically, it can normalize wall tension and inhibit LV dilatation, which may in turn lead to increased long-term survival. Regulation of the endothelin system, particularly the expression of the endothelin B receptor, may contribute to these estrogenic effects.

Animals↗