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C Ordonez

Publications and source records attributed to C Ordonez.

8 recordsLinked to original sources
PubMed2000

Time-correlated soliton tunneling in charge and spin density waves

We consider a model in which an electric field induces quantum nucleation of kink-antikink pairs in a pinned charge or spin density wave. Pair nucleation events, prevented by Coulomb blockade below a pair creation threshold, become correlated in time above threshold. The model provides a natural explanation for the observed (i) small density wave polarization below threshold in NbSe (3), (ii) narrow band noise, (iii) coherent oscillations, and (iv) mode-locking at high drift frequencies.

Journal Article↗
PubMed1996

SIV infection of monkey spleen cells including follicular dendritic cells in different stages of disease.

Immunoaffinity enriched spleen follicular dendritic cells (FDCs), lymphocytes, and macrophages from SIVsm-inoculated cynomolgus monkeys (Macaca fascicularis) at different stages of disease were compared for latent and productive SIV infection. Analysis of FDCs by in situ hybridization, electron microscopy, and coculture assays indicated that comparatively high levels of virus were associated with the FDC fraction. Polymerase chain reaction (PCR) and RT-PCR results revealed that the levels for SIVpol DNA did not correlate with the level of env mRNA in the various cell subsets, suggesting differences in latency. Limiting dilution assays for spliced env mRNA showed a 10-100-fold higher amount of env mRNA in FDCs than in other spleen cell subsets early during SIV infection. At late stages of disease, the number of productively infected FDCs significantly decreased in parallel with a marked reduction of the FDC network and follicular involution. Our findings indicate that destruction of FDCs probably reflects a cytopathic effect of SIV and/or the activity of specific antiviral cytotoxic T lymphocytes.

Animals↗
PubMed1995

Heterogeneity of spindle cells in Kaposi's sarcoma: comparison of cells in lesions and in culture.

The immunophenotype of spindle cells in epidemic, endemic, and classic (sporadic) Kaposi's sarcoma (KS) lesions was defined by the demonstration of various cell markers and compared with that of KS-derived cell lines. No significant histological or immunophenotypic differences were observed between the three clinical types of KS at comparable stages. The spindle-cell compartment of the different KS types was composed predominantly of a mixture of proliferating CD45+/CD68+ bone-marrow-derived monocytes and TE7+/collagen+ fibroblastic cells with varying expression of EN4/PAL-E/CD31/CD34/CD36 endothelial-associated antigens and/or smooth-muscle-specific alpha-actin (alpha-actin). The latter cells appeared to represent transitional forms of fibroendothelial and fibromyocytic cells. The in vitro cultured KS-derived cell lines (KS-3, KS-6, and KS-8) expressed the fibroblastic antigen TE7 and smooth-muscle-specific alpha-actin but not leukocytic or endothelial-associated antigens consistent with the phenotype of fibromyoid spindle cells of primary lesions. Neither HIV antigen nor provirus DNA was demonstrable in the epidemic KS lesions. The observed heterogeneity of the spindle-cell compartment further substantiates the view that Kaposi's sarcoma, irrespective of clinical setting, expresses salient features more compatible with reactive, tumor-like lesion than clonal sarcoma.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Evidence for protein tyrosine kinase involvement in CD6-induced T cell proliferation.

Several studies have demonstrated that addition of soluble anti-CD6 mAbs to 12-O-tetradecanoylphorbol 13-acetate (TPA)-treated naive T cells can induce cell proliferation. We showed in the present study that cell proliferation in TPA-treated T cell cultures can be enhanced several fold when the anti-CD6 mAbs are either immobilized or crosslinked with rabbit anti-mouse immunoglobulins (RAM Ig). Using a src family protein tyrosine kinase (PTK) inhibitor, herbimycin A, the cell proliferation induced by the anti-CD6 mAb, IOR-T1, in TPA-treated T cells were effectively abolished. Analysis of the cellular proteins in these cells after crosslinking the CD6 receptor with IOR-T1 (followed by RAM Ig) in the presence of TPA resulted in an increased level of tyrosine phosphorylation. Pretreatment of native T cells with herbimycin A (0.5 and 1 microgram/ml) for 18 hr completely inhibited the tyrosine phosphorylation on cellular substrates in T cell cultures stimulated with IOR-T1/RAM Ig and TPA. Similar concentrations of herbimycin A also inhibited the increase in IL-2 mRNA expression and cell proliferation in T cell cultures after IOR-T1/RAM Ig and TPA treatment. Furthermore, the increase in cytosolic free Ca2+ concentration in naive T cells after crosslinking of the CD6 receptor with IOR-T1/RAM Ig was also inhibited by herbimycin A. Taken together, our results suggest that CD6-mediated T cell proliferation is IL-2 dependent, and involves tyrosine kinase activity which is strictly dependent on protein kinase C activation.

Adult↗
PubMed1982

Diagnostic accuracy of phleborheography in deep venous thrombosis.

The clinical diagnosis of acute deep thrombophlebitis of the lower extremities is notoriously grossly inaccurate, even in experienced hands. Phleborheography (PRG) is one of the noninvasive diagnostic methods developed to make diagnosis accurate, noninvasive, and easily reproducible. The records of the first 272 patients studied by this method at South Fulton Hospital were examined, beginning June 1977 and ending August 1979. In those patients who had PRG and radiologic phlebography, the two methods were compared. Phlebography was considered as the standard for comparison. There were 36 patients who had both studies performed. Of the 36 patients studied, the PRG and the x-ray studies agreed in 34. Both were normal in 21 patients; and in 13 patients both were abnormal and in agreement. The studies did not agree in two of the 36 patients. There were none where the PRG was normal and the x-ray abnormal, and two where the PRG was abnormal and the x-ray normal. The diagnostic accuracy of a normal PRG in this study was 100 per cent, with no false-negatives. There were two false-positives with an accuracy of 87 per cent. The overall accuracy was 94 per cent. There were no complications.

False Negative Reactions↗