Modeling liquid-crystal gradient-index lenses.

The optical properties of one-dimensional gradient-refractive-index lens arrays based on liquid crystals are studied. We find that it is quite possible, using theoretical methods, to predict angular distributions of the light emanating from such arrays when they are illuminated with collimated monochromatic light. We compare four theoretical methods in relation to experiments. The experimental data and the model, based on a combination of eikonal methods and diffraction, are in close correspondence. Features such as maximal beam width and number of extrema in the angular light distribution are discussed and explained theoretically. We also studied dispersion effects, both experimentally and theoretically, with good agreement between the two.

Serum amyloid P component bound to gram-negative bacteria prevents lipopolysaccharide-mediated classical pathway complement activation.

Although serum amyloid P component (SAP) is known to bind many ligands, its biological function is not yet clear. Recently, it was demonstrated that SAP binds to lipopolysaccharide (LPS). In the present study, SAP was shown to bind to gram-negative bacteria expressing short types of LPS or lipo-oligosaccharide (LOS), such as Salmonella enterica serovar Copenhagen Re and Escherichia coli J5, and also to clinical isolates of Haemophilus influenzae. It was hypothesized that SAP binds to the bacteria via the lipid A part of LPS or LOS, since the htrB mutant of the nontypeable H. influenzae strain NTHi 2019-B29-3, which expresses a nonacetylated lipid A, did not bind SAP. This was in contrast to the parental strain NTHi 2019. The binding of SAP resulted in a clear inhibition of the deposition of complement component C3 on the bacteria. SAP inhibited only the activation of the classical complement pathway; the alternative route remained unaffected. In the classical route, SAP prevented the deposition of the first complement component, Clq, probably by interfering with the binding of Clq to LPS. Since antibody-mediated Clq activation was not inhibited by SAP, SAP seems to inhibit only the LPS-induced classical complement pathway activation. The SAP-induced inhibition of C3 deposition strongly diminished the complement-mediated lysis as well as the phagocytosis of the bacteria. The binding of SAP to gram-negative bacteria, therefore, might influence the pathophysiology of an infection with such bacteria.

Lipopolysaccharide-coated erythrocytes activate human neutrophils via CD14 while subsequent binding is through CD11b/CD18.

Interaction of LPS with monocytes and neutrophils is known to occur via CD14 and is strongly enhanced by LPS-binding protein (LBP). Integrins as well as CD14 play a role in the interaction of erythrocytes (E) coated with LPS or whole Gram-negative bacteria with phagocytes. We reasoned that the density of LPS on a particle is an important determinant in these interactions. Therefore, E were coated with different concentrations of LPS (ELPS). The binding of these ELPS to neutrophils was evaluated by flow cytometry. Simultaneously, we measured fMLP receptor expression to evaluate neutrophil activation. ELPS only bound to neutrophils in the presence of LBP. Blocking CD14 inhibited both activation and binding, whereas blocking complement (C) receptor 3 (CR3) inhibited binding but not activation. TNF activation restored ELPS binding in CD14-blocked cells but not in cells in which CR3 was blocked. Salmonella minnesota did bind to neutrophils independent of CR3 or CD14. The addition of LBP enhanced binding twofold, and this surplus was dependent upon CD14 but not on CR3. We conclude that ELPS interact with neutrophils via CD14, initially giving rise to cell activation; subsequently, binding is solely mediated by activated CR3.

Human immunodeficiency virus type 1 drug susceptibility determination by using recombinant viruses generated from patient sera tested in a cell-killing assay.

A simple approach for the determination of drug susceptibilities by using human immunodeficiency virus type 1 (HIV-1) RNA from the sera of patients is described. HIV-1 RNA was extracted from patient sera, and the 5' part of the reverse transcriptase (RT) gene was transcribed into DNA and amplified in a nested PCR. The amplified fragment covers the 3' part of the protease gene and amino acids 1 to 304 of the RT gene. This fragment can be introduced through homologous recombination, as described previously, into a novel HIV-1 reference strain (pHXB2 delta 2-261RT) from which amino acids 2 to 261 of RT have been deleted. The resulting recombinant virus expresses all properties of the HXB2 reference strain except for those encoded by the introduced part of the patient RT gene. Recombinant viruses were subsequently tested for drug susceptibility in a microtiter format killing assay [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay] as well as in the standard HeLa CD4+ plaque reduction assay. Similar susceptibility profiles were obtained by each assay with recombinant viruses derived from patients receiving alternating nevirapine and zidovudine treatment or lamivudine-zidovudine combination therapy. In conclusion, this approach enables high-through-put determination of the drug susceptibilities of serum RNA-derived RT genes, independent of the patient's viral background, and generates the possibility of relating changes in susceptibility to changes in viral genotypes.

Safety, pharmacokinetics, and antiviral activity of A77003, a C2 symmetry-based human immunodeficiency virus protease inhibitor.

A77003, an inhibitor of the human immunodeficiency virus type 1 (HIV-1) protease, was administered to asymptomatic HIV-1-infected patients in a phase I trial. The drug was given by continuous intravenous infusion at dosages of 0.035, 0.07, 0.14, and 0.28 mg/kg of body weight per h. The drug was given first for 24 h and then for up to an additional 4 weeks in a second infusion period following at least a 6-day washout. Apart from reversible increases in hepatic transaminase levels in some patients, no systemic toxicities occurred during extended infusion of the drug. Dose-related local vein irritation, despite dilution of the infusate, however, caused severe infusion site phlebitis precluding dosage escalation beyond 0.28 mg/kg/h. Pharmacokinetic analysis demonstrated dose linear increases in mean steady-state concentrations. However, clearance of the drug from plasma was unexpectedly high, averaging 62 liters/h across all groups. The concentrations of A77003 in plasma achieved the in vitro 50% inhibitory concentration (0.16 microgram/ml) only in the 0.28-mg/kg/h dosage group, but it did not attain the 90% inhibitory concentration (0.48 micrograms/ml). No statistically significant effect on CD4 cell numbers occurred in any of the groups, and there was no evidence of antiviral activity, as determined by HIV-1 p24 antigen level, quantitative plasma and cell culture, and quantitation of viral RNA in plasma. In conclusion, A77003, as formulated in the present study, causes severe phlebitis, which prevents administration of the infusates necessary to achieve high concentrations of the drug in plasma. In conclusion, A77003, as formulated in the present study, causes severe phlebitis, which prevents administration of the infusates necessary to achieve high concentrations of the drug in plasma. The lack of antiviral activity observed in the study may be a consequence of the low concentrations in plasma in all groups.

[Characteristics of the relative humidity and temperature in the inspiratory part of the Dräger circle system and their influence on the function of the ciliary epithelium]. / Das Verhalten von relativer Luftfeuchtigkeit und Temperatur im Inspirationsteil des Dräger-Kreissystems und deren Einfluss auf die Funktion des Flimmerepithels.

Changes in relative humidity and temperature of the anaesthetic gases were measured in the inspiratory limb of the Dräger circle system next to the carbon dioxide absorber in 29 patients requiring ENT surgery under general anaesthesia. Immediately following intubation and prior to extubation, nasal and tracheal cytologic samples were taken with a brush technique and ciliary beat frequency was determined. At a fresh gas flow of 6 l/min, relative humidity increased from 57.6 +/- 1.5 to 62.5 +/- 1.8% (p less than 0.05) after 110 minutes. Temperature increased continuously from 21.96 +/- 0.97 degrees C to 23.83 +/- 0.48 degrees C after 200 minutes. The number of vital ciliated cells in the tracheal samples decreased from 24.4% following induction of anaesthesia to 6% at the end of anaesthesia (p less than 0.05), and from 35.7% to 26.8% (p less than 0.05) in the nasal samples. Ciliary beat frequency remained unchanged at the end of anaesthesia as compared to control in tracheal as well as in nasal samples. It is concluded that the output of relative humidity and temperature in the circle system is not sufficient to prevent broncho-epithelial damage. Ciliary beat automaticity appears to behave according to an all or nothing principle.

Effects of high-dose medroxyprogesterone acetate and various other steroid hormones on plasma membrane lipid mobility in CAMA-1 mammary cancer cells.

The influence of medroxyprogesterone acetate (MPA) and various other steroid hormones on the lateral diffusion of the fluorescent lipid probe 1-acyl-2-(N-4-nitrobenzo-2-oxa-1.3-diazolyl)-aminocarpropylphos phatidylcholine (NBD-PC) in the plasma membrane of intact mammary cancer cells (CAMA-1 cell line) has been studied by fluorescence recovery after photobleaching technique. Incubation of cells with MPA in serum free medium at ambient temperature for 1 hr led to a significant decrease in the lateral diffusion coefficient of NBD-PC. MPA induced this change over a limited concentration range with 10(-7)-10(-5) mol/l near-maximal or maximal effects, and 10(-8) mol/l exhibiting no effect. Exposure of the CAMA-1 cells to 10(-7) mol/l MPA in undiluted serum induced a significant effect following 1.5 hr of treatment with no increase in effectiveness up to 4 hr of incubation. As compared to MPA, the other steroids tested were less effective or ineffective. The influence on lateral lipid mobility diminished as follows: MPA greater than progesterone greater than 5a-DHT approximately 17 beta-estradiol greater than dexamethasone, and roughly seems to parallel their lipid solubility as estimated by partition coefficients in an n-octanol-water system. Any involvement of classical steroid hormone receptors in the mechanism of membrane action could be excluded. Nongenomic steroid effects on the plasma membrane are assumed. As the structure and function of biomembranes are modulated by lipid-bilayer fluidity and membranes crucially participate in nearly all aspects of cell biology, it is concluded that direct interactions of MPA with membranes potentially play a role in the antitumor activity of the compound.