UV lasers for flow cytometric analysis: HeCd versus argon laser excitation

Applying flow cytometric single cell analysis, we compared the performance of UV excitation from argon ion and HeCd lasers using various UV-excitable fluorochromes of cell kinetic and cell physiological relevance. The AT-specific DNA fluorochromes DAPI, Hoechst 33258, and Hoechst 33342 showed no significant differences of G1-phase resolution and cell cycle distribution. With the HeCd laser, high-resolution cell kinetic analysis applying the novel BrdU/Hoechst-PI quenching technique showed superior resolution and an almost normalized G2M/G1 channel ratio of the first cell cycle. Indo-1 analysis for detection of intracellular free calcium gave similar results for both excitation sources, although the indo-1 ratio of activated cells was lower for HeCd excitation. Monochlorobimane as an indicator fluorochrome of glutathione content could not be excited sufficiently with the 325-nm line of the HeCd laser and exhibited poor resolution between positive and negative cells. However, the second glutathione-specific fluorochrome o-phtalaldehyde gave even better results with the HeCd laser. Our data indicate that air-cooled HeCd lasers are cheap and reliable UV-excitation sources for most UV-excitable fluorochromes, and might be an alternative to the expensive water-cooled argon and krypton laser.

Investigation of model uncertainties in Bayesian structural model updating

Model updating procedures are applied in order to improve the matching between experimental data and corresponding model output. The updated, i.e. improved, finite element (FE) model can be used for more reliable predictions of the structural performance in the target mechanical environment. The discrepancies between the output of the FE-model and the results of tests are due to the uncertainties that are involved in the modeling process. These uncertainties concern the structural parameters, measurement errors, the incompleteness of the test data and also the FE-model itself. The latter type of uncertainties is often referred to as model uncertainties and is caused by simplifications of the real structure that are made in order to reduce the complexity of reality. Several approaches have been proposed for taking model uncertainties into consideration, where the focus of this manuscript will be set on the updating procedure within the Bayesian statistical framework. A numerical example involving different degrees of nonlinearity will be used for demonstrating how this type of uncertainty is considered within the Bayesian updating procedure.

Highly-efficient gene transfer with retroviral vectors into human T lymphocytes on fibronectin

Genetically modified lymphocytes have been successfully used for correction of ADA deficiency in children and in controlling graft-versus-host disease (GvHD) after allogeneic bone marrow transplantation. Low transduction efficiencies are, however, limiting for gene therapeutic strategies based on lymphocytes. In this study we compared protocols for highly efficient gene transfer into human T cells using retroviral vector-containing supernatant. We showed that infection of both human primary T cells and CD4+ Jurkat cells is most efficient on the matrix component fibronectin. Transduction was carried out with a retroviral vector encoding both the human intracytoplasmatically truncated low-affinity nerve growth factor receptor (deltaLNGFR) as a gene transfer marker and the Herpes simplex virus thymidine kinase for negative selection. Based on LNGFR expression genetically modified cells were enriched to near purity by magnetic cell sorting (MACS). Enriched cells could be shown to be highly sensitive to ganciclovir.

Improved BrdUrd-Hoechst bivariate cell kinetic analysis by helium-cadmium single laser excitation

In laser based flow cytometers, UV excitation of Hoechst 33258 and propidium iodide (PI) or ethidium bromide (EB) is performed with 351/364 nm high power lines of UV-capable argon ion lasers, which are expensive and short-lived. In this paper we note for the first time that helium-cadmium lasers emitting 10 to 30 mW at 325 nm are even more superior for cell kinetic bivariate bromodeoxyuridine (BrdUrd)/Hoechst PI or EB cell cycle analysis. HeCd single laser UV excitation gives comparable CVs for cell cycle distributions, and almost normal G2M/G1 ratios of 1.9 to 2.0 for all cell cycles. This is shown for synchronous and asynchronous cell populations on a FACStar+ and an Ortho Cytofluorograf. Therefore we recommend helium-cadmium lasers as low-power, cheap, and long-lived UV excitation sources for the cytochemically simple but high resolution multiparameter BrdUrd-Hoechst cell kinetic analysis.

Glutathione restores normal cell activation and cell cycle progression in cis-platinum treated human lymphocytes

Cis-platinum (CDDP) induces severe inhibition of cell activation and cell cycle progression in PHA-stimulated human PBL's. Applying the novel BrdU/Hoechst flow cytometric technique for high resolution cell cycle analysis we show that CDDP induced multiple cell kinetic disturbances occur simultaneously comprising G0/G1-arrest, and slow down and arrest of cells in S and G2/M-phase. We investigated whether the administration of reduced glutathione (GSH) might rescue cells from proliferative disturbances induced by CDDP. GSH at 0.15 mg ml-1 only partially restored normal cell activation and cell cycle progression. However, at 1.5 mg ml-1 a complete normal proliferation pattern was obtained. At the highest GSH dose rescue from inhibition of cell activation (G0/G1-phase arrest) as well as of cell cycle progression (S- and G2/M-phase arrest) was also present after delayed addition of GSH (1, 4 and 20 h) to CDDP treated PBL's. In addition cell viability of CDDP exposed PBL's is restored after GSH treatment. Our in vitro experiments give evidence that an increase of WBC found in CDDP/GSH treated patients has a real underlying cellular physiological mechanism protecting human peripheral lymphocytes from CDDP toxicity.

Complex Ca2+ flux inhibition as primary mechanism of staurosporine-induced impairment of T cell activation

The inhibitory effect of the highly effective drug staurosporine on the early activation signal Ca2+ flux was investigated via multiparameter flow cytometry in human peripheral blood T lymphocytes. Staurosporine has been reported to be a specific inhibitor of protein kinase C. However, we show that it inhibits the Ca2+ influx in anti-CD3 and phytohemagglutinin-stimulated human CD4+ and CD8+ lymphocytes at concentrations between 1.0 and 10.0 ng/ml. Staurosporine decreases the number of Ca2+-positive CD4+ and CD8+ lymphocytes as well as the Ca2+ influx per cell; the drug also delays the time of the maximum response to polyclonal stimulation. In addition, we demonstrate that staurosporine affects the primary Ca2+ response via inhibition of the release of the membrane-bound Ca2+ from the endoplasmic reticulum in CD4+ and CD8+ lymphocytes. Binding studies of the anti-CD3 antibody to T lymphocytes indicate normal binding capacities in the presence of staurosporine. With respect to the classical scheme of T cell activation via phospholipase C, our data suggest that staurosporine may inhibit T cell activation primarily by its effect on the early Ca2+ flux signal.

A new ELISA-based assay for quantitation of human T-lymphocyte subpopulations

In order to circumvent the problems associated with the available methods, we have developed a simple, reliable ELISA for quantitation of T-cells and their subpopulations, T-helper/inducer and T-suppressor/cytotoxic cells. Standard curves with three concentrations of sheep anti-mouse IgG-coupled beads for each T-cell population were used for the determination of the T-cell content in blood. Enzyme-labelled monoclonal antibodies against T-Pan, T-S and T-H cell surface markers were readily able to bind to such beads and the test system was calibrated with T-lymphocytes by comparing cytofluorographic and enzyme immunometric results. Purified preparations of monocytes and granulocytes were negative in the test. Lymphocytes from 50 healthy blood donors gave results which correlated closely with cytofluorograph determinations.

Fibrinolysis activation after operation of spermatic cord

The authors report a case of fibrinolytic haemorrhagic diathesis after operation of vas deferens carried out under epidural analgesia. Attention is called to the diagnostic difficulties in the rare complication of these operations. Treatment of fibrinolytic haemorrhagic diathesis is discussed stressing the advantages of trasylol, which is a drug of choice in emergency states associated with bleeding from the surface of the wound when difficulties arise in carrying out full blood clotting tests.