Heterosexual transmission of human immunodeficiency virus (HIV-1) is the predominant mode of infection world-wide. To better understand sexual transmission of HIV-1 in women we have analysed virus co-receptor and cellular activation marker expression on T lymphocyte subsets from the cervical epithelium and have made comparisons with peripheral blood T cells. Intraepithelial cervical T lymphocytes were obtained with a cytobrush, immunolabelled and analysed by flow cytometry. Activation markers (CD69, CD25 and HLA-DR) were found to be more highly expressed on cervical than on blood T lymphocytes. These higher levels of activation on cervical T lymphocyte subsets could facilitate HIV-1 infection. CXCR4 was expressed at marginally higher levels than CCR5 on T cells from the cervical epithelium and peripheral blood. Thus, the preferential transmission of macrophage tropic strains of HIV-1 following sexual contact cannot be explained solely on the expression of chemokine co-receptors by T lymphocyte subsets.

Adult↗

PubMedDate not supplied

Phantom and animal tissues for modelling the electrical properties of human liver.

The dielectric properties of human liver were characterized over the frequency range of 0.3-3 GHz for freshly excised tissue samples of primary hepatocellular carcinoma, metastatic colorectal carcinoma, and normal liver tissues resected from the tumour margin. On average, the dielectric constant (epsilon(r)) of freshly excised human liver tumour was 12% higher than that of surrounding normal liver, and the electrical conductivity (sigma) of tumour was 24% higher. In order to establish suitable tissue models for human liver, the electrical properties were compared to measurements of homogenous phantom mixtures, in vitro bovine liver, and in vivo canine and porcine liver tissues. The data demonstrate that there are several animal tissues that can be used to model the average dielectric properties of human liver reasonably accurately, and use of the most readily available bovine liver appears well-justified, even when stored for up to 10 days in a refrigerator. Additionally, the dielectric properties of in vitro liver remained stable over a large temperature range, with sigma rising only 1.1%/ degrees C in porcine liver (15-37 degrees C) and 2.0%/ degrees C in bovine liver (10-90 degrees C), and epsilon(r) decreasing < or =0.2%/ degrees C in both tissues. This effort identifies homogeneous solid and liquid phantom models and several heterogeneous in vitro tissues that adequately model the dielectric properties of human liver tumours for use in quantitative studies of microwave power deposition in liver.

Animals↗