Terahertz multilevel phase Fresnel lenses fabricated by laser patterning of silicon.

Multilevel phase Fresnel lenses (MPFLs) with a high numerical aperture for 0.58 THz frequencies were developed. The components based on a monocrystalline silicon wafer are prepared by patterning by a high-speed industrial-scale laser direct writing (LDW) system. Two consistent series of the terahertz-MPFLs with phase quantization levels varying between 2 and the continuous kinoform shape for the focal lengths of 5 and 10 mm were produced employing inherent flexibility of the LDW fabrication process. The focusing performance was studied at the optimal 0.58 THz frequency using a Gaussian beam profile and scanning 2D intensity distribution with a terahertz detector along the optical axis. The efficiency of the terahertz-MPFL was found to be dependent of the number of subzones. The position and orientation angles of the patterned plane of the silicon wafer were considered to reduce the effect of standing waves formation in the experiment.

Electrically controllable photonic molecule laser.

We have studied the coherent intercavity coupling of the evanescent fields of two microdisk terahertz quantum-cascade lasers. The electrically controllable optical coupling of the single-mode operating lasers has been observed for cavity spacings up to 30 mum. The strongest coupled photonic molecule with 2 mum intercavity spacing allows to conditionally switch the optical emission by the electrical modulation of only one microdisk. The lasing threshold characteristics demonstrate the linear dependence of the gain of a quantum-cascade laser on the applied electric field.

The eradication experience of enzootic bovine leukosis from Lithuania.

Before 1985 the situation regarding enzootic bovine leukosis (EBL) in Lithuanian cattle was described only haphazardly. In 1986 serological investigations were initiated together with an eradication programme. The EBL bovine leukosis virus (BLV) situation was monitored by the Institute of Immunology Vilnius University, national and regional veterinary laboratories. Starting in 1986 all EBL-positive cattle were separated from negative cattle into BLV-infected and BLV-free herds. To create the latter, calves were fed pasteurized milk. The seroprevalence in 1990 was 7.29%, but it steadily declined to 0.32% in 2006.

Partial characterization of bovine leukemic cell populations.

Peripheral blood lymphocytes (LL) from cows with chronic lymphocytic leukemia (CLL) have been studied using a number of surface markers. Cell populations were obtained by partial enrichment and depletion using Sephadex G-200-anti-F(ab')2 and Sephadex G-200-anti-LL-Ig immunoadsorbent columns. It was shown that cell populations having different markers, i.e., surface immunoglobulins (sIg) and leukemia-associated antigens (LAA), are characterized by similar parameters. Thus the adherent cells obtained by both fractionation methods formed 1.1-4.0% of rosettes with sheep red blood cells, while 90.6-94.3% were sIg positive cells. The cytotoxicity test (CTT) performed with anti-B and anti-LL sera indicated that a vast majority of adherent cells reacted to the sera. Thus the adherent cells represent a population with a high percentage of B-cells.

Quantitative studies of Fc receptors on bovine leukemic blood lymphocytes: characterization by binding of homologous IgG1 and IgG2.

Receptors for IgG1 and IgG2 (FcR) on peripheral blood lymphocytes from cows with chronic lymphocytic leukemia (CLL) were detected by their ability to bind homologous IgG1 and IgG2 in fluorometric binding assay. Scatchard plots at 4 degrees C demonstrated that IgG1 bound the same number of FcR per cell (3.12 +/- 0.69 X 10(5)) as IgG2 (2.89 +/- 0.69 X 10(5)). The receptors bound IgG2 with an affinity of 4.09 +/- 1.08 X 10(5) 1/M and IgG1 with an affinity of 2.73 +/- 0.55 X 10(5) 1/M, although the difference was not of statistical significance (0.1 greater than P greater than 0.05). Inhibition studies demonstrated that the two ligands could inhibit each other. It might be assumed that FcR for the two subclasses were identical.

Establishment of a cell line from leucocytes of a cow with chronic lymphocytic leukemia.

A cell line was established from blood leucocytes of a cow with chronic lymphocytic leukemia. The leucocytes were cultured with conditioned medium (culture fluid of mouse cell line L). In vitro cell transformation was demonstrated by adaptation to permanent growth, modification of cell morphology, the alteration of cell surface phenotype, kinetic behaviour and the loss of the euploid stability of the cell karyotype. Ultrastructural studies showed rather a uniform cell pattern in a culture population heterogeneous for degree of cell vacuolization. A wide variation in the expression of surface markers in cells was demonstrated by E-, EA- and EAC-rosetting. In suspension culture the cell population was found to be sIg negative. Expression of leukemia-associated antigens by a fraction of the cultured cells was evidenced by a cytotoxic technique using complement and heterologous antisera against bovine leukemic lymphocytes, absorbed with normal lymphoid cells. Virus-like particles and BLV antigens were not identified. Culture cells failed to show spontaneous or antibody-dependent killer cytotoxicity. Comparison with blood lymphocytes of healthy and leukemic cattle was done. The established culture should be useful as a model for experimental immunology and oncology.

T cell and eosinophil activation in mild and moderate atopic and nonatopic children's asthma in remission.

BACKGROUND: Inflammation in the pathogenesis of asthma is associated with products of activated T cells and eosinophils. The aim of this study was to determine whether ongoing inflammation persists in children with different phenotypes of asthma despite the disease in remission. METHODS: Serum samples were collected from 68 children with atopic or nonatopic asthma in remission and from 15 healthy children. Soluble interleukin-2 receptor (sIL-2R), IL-2 and IL-4 were examined by using an enzyme-linked immunosorbent assay. Total and specific immunoglobulin E, and eosinophil cationic protein (ECP) were analysed by fluoroimmunoassay (Pharmacia CAP System). RESULTS: In patients with moderate persistent atopic asthma, sIL-2R was increased significantly when compared with mild persistent atopic asthma (P < 0.05). No changes of sIL-2R were seen in nonatopic asthmatics compared with atopics and controls. The level of IL-2 was elevated in moderate persistent atopic and nonatopic asthmatic children compared with controls (P < 0.05 and P < 0.05 respectively) and compared with mild persistent atopic asthmatics and mild persistent nonatopic asthmatics (P < 0.05 in both cases). The levels of IL-4 in most patients and controls remained below the sensitivity of the assay. Eosinophil cationic protein levels in moderate persistent atopic and nonatopic asthmatics were significantly higher than in mild persistent asthma severity cases (P < 0.001 and P < 0.01 respectively) and in healthy children (P < 0.01 in both cases). CONCLUSION: Changes in the concentration of sIL-2R, IL-2 and ECP reflect increased T cell and eosinophil activity in relation to the level of severity of asthma in atopic and nonatopic children, thereby proving the presence of persistent inflammation despite the absence of disease symptoms.

Assessment of the role of leucocyte function-associated antigen-1 in homotypic adhesion of activated B lymphocytes.

In this study we investigated how T-cell-dependent stimuli, via interleukin-4 (IL-4) or CD40 ligation, influence homotypic B-cell adhesion when compared with induction by the T-cell-independent stimulus lipopolysaccharide (LPS). Using primary murine B cells, we found that T-cell-dependent stimulation led to increased aggregation as compared to that induced by LPS. The adhesion was to a large extent dependent on the adhesion molecule, lymphocyte function-associated antigen-1 (LFA-1). We found that activation of B cells with the mitogenic stimuli induced an increased avidity of LFA-1 for its ligand, intercellular adhesion molecule-1 (ICAM-1). The increase was stable and different from that induced by phorbol esters. Although adhesion was reduced using B cells from LFA-1(-/-) mice, aggregation occurred in response to T-cell-dependent stimuli. Our data suggest that adhesion of B lymphocytes is regulated in different modes. One is induced by antigen and leads to a transient conformational change of the LFA-1 molecule. Another is induced by mitogenic stimuli and leads to stable avidity increase of LFA-1, possibly via activation of cytoskeletal anchorage. A third is LFA-1 independent, of low avidity and is induced by T-cell-dependent stimuli.

T mu- and T gamma-cell subsets in normal and leukemic cattle.

T-cell subsets in the peripheral blood and lymphoid organs of normal and chronic lymphocytic leukemia (CLL) cattle were studied. Purified T lymphocytes were examined for the numbers of cells with the receptors for IgM (T mu) and IgG (T gamma). The expression of surface receptors on T mu- and T gamma-cell subsets was determined according to their capacity to bind different numbers of erythrocyte antibody complexes EAM or EAG. During the various times of preincubation of T cells at 37 degrees C, an increased release of receptors on the surface of T mu and partly T gamma cells was observed. For the optimal detection of bovine T mu cells, preincubation at 4 degrees C fro 24 h was necessary. The number of T gamma cells in the peripheral blood (P less than 0.001) and spleen (P less than 0.001) of CLL cattle was higher in comparison with controls. A considerably reduced number of T mu cells in the peripheral blood (P less than 0.001) and lymph nodes (P less than 0.02) of CLL cattle was observed. With the exception of thymus, T gamma cells from the lymphoid organs of CLL cattle had a higher expression of receptors than normal T gamma cells.

Contact Effects of Mononuclear Cells on L929 Fibroblast Morphological Phenotype.

We studied the contact interactions of human peripheral blood mononuclear cells (MNC) and transformed mouse fibroblast cell line L929 (L-cells), namely their effects on morphological phenotype of L-cells. The morphological characteristics of the fibroblast, (cell area, nucleus-cytoplasmic ratio, cell spreading, cell shape) were estimated with the aid of fight scanning microscopy, followed by computer image analysis. Contact interaction between fibroblasts and MNC caused normalization of morphological phenotype of the fibroblasts (increase of cell area, shape factor, spreading and decrease of nucleus-cytoplasmic ratio). This phenomenon was revealed by analysis of both average morphological characteristics and population contents. Only a particular subpopulation of L-cells, but not the whole population, was shown to be normalized by the effects of MNC. For elucidation of responsible MNC population, which was capable of influencing on fibroblast morphological phenotype, we separated MNC in several cell types: adherent cells, non-adherent cells, which were separated in E-rosetting cells, and non-E-rosetting cells. Only non-adherent and E-rosetting cells could normalize the morphological phenotype. E-rosetting population consisted of 85% of CD3(+) (T lymphocytes) and 15percnt; of CD56(+)/CD16(+) (natural killers). Supernatants of MNC, and MNC cocultured L-cells, obtained after 24 h incubation in the cell culture medium, were not able to normalize the morphological phenotype of the fibroblasts. They had small denormalizing effect on the fibroblasts (decrease of cell area, shape factor, spreading and increase of nucleus-cytoplasmic ratio). The results of this study indicate that the contact interaction between MNC and fibroblasts may normalize transformed fibroblast morphological phenotype. The dependence of fibroblast functional state on their morphological phenotype imply the presence of regulatory mechanism of contact interaction between fibroblasts and MNC, which determines many live processes in fibroblast.