13C NMR spectroscopic studies on polyanion-polycation complexes and their component polyelectrolytes

Position and intensities of the ¹³C NMR signals and relaxation times T₁ of several anionic and cationic polyelectrolytes in the solid state were compared with those of the appropriate polyanion-polycation complexes. At a high charge density of the components, the most significant changes of the parameters in question due to complex formation are observed for the C atoms adjacent to the charge centers, indicating a strong Coulombic interaction. At lower charge density, conformational changes of the polymer chains have also to be taken into consideration.     

Effect of fetal tissue transplantation on reparative processes in experimental liver cirrhosis

Reparative regeneration after fetal tissue transplantation and after surgical stimulation was studied in rats with experimental cirrhosis of the liver. Fetal tissue restored the morphology and function of cirrhotic liver and modified functional activity of peritoneal macrophages. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 216–219, August, 2000     

Experimental infection of chimpanzees with antihemophilic (factor VIII) materials: recovery of virus-like particles associated with non-A, non-B hepatitis.

Non-A, non-B viral hepatitis was transmitted to four colony-born chimpanzees by infusion of three lots of antihemophilic factor (factor VIII) implicated in the transmission of non-A, non-B hepatitis to two human recipients. All four inoculated animals showed histopathological evidence of viral hepatitis, and all demonstrated significant ALT elevations between seven and one-half weeks after inoculation. Acute-phase plasma from one of the infected chimpanzees (no. 771) was shown to induce non-A, non-B hepatitis in two other chimpanzees approximately three weeks after their inoculation. In addition, an acute-phase open liver wedge biopsy obtained from animal no. 771 was processed and examined by immune electron microscopy (IEM) for virus-like particles with convalescent serum from a serologically confirmed case of non-A, non-B hepatitis. Twenty-five to 30 nm (mean = 27 nm) diameter virus-like particles that were either "full" or "empty" were identified in this liver preparation by IEM. Two additional chimpanzees inoculated with a cesium chloride gradient fraction of an isopycnically banded liver homogenate (animal no. 771) also developed elevated ALT activity two to two and one-half weeks later. Our findings have experimentally verified that commercially produced factor VIII materials can induce non-A, non-B hepatitis in champanzees and that the disease can be subpassaged in these animals by inoculation of either acute-phase plasma or liver. These results also provide evidence for the association of 27 nm-diameter virus-like particles with non-A, non-B viral hepatitis.     

Hepatitis E virus infection in chimpanzees: a retrospective analysis

Summary.  Different patterns of disease were observed among 11 chimpanzees who were inoculated intravenously with hepatitis E virus (HEV) positive fecal specimens from four different outbreaks (Nepal 1981, Uzbekistan 1981, Pakistan 1985, and Mexico 1986). Five chimpanzees had marginal or no liver enzyme elevations within 70 days of inoculation. Two of the chimpanzees had limited viremia, but did not produce detectable antibody. The four remaining chimpanzees had liver enzyme elevations, viral shedding, viremia, seroconversion to anti-HEV, and detectable HEV antigen in liver biopsy specimens. These results may reflect the range of infection patterns that develop in humans after natural exposure to the HEV. Received December 29, 1999/Accepted February 21, 2000     

Interaction of antithrombin III with preadsorbed albumin-heparin conjugates

The adsorption of antithrombin III (AT III) onto polystyrene surfaces preadsorbed with albumin or albuminheparin conjugates was studied using a two step enzyme immuno assay. When AT III-buffer solutions were used, the highest adsorption values were measured on high affinity albumin-heparin conjugate pretreated surfaces. Less AT III adsorption was found on nonfractionated albumin-heparin conjugate preadsorbed surfaces. AT III adsorption could also be detected on low affinity conjugate and albumin coated surfaces. When AT III was adsorbed from plasma or plasma dilutions with buffer, only AT III on surfaces preadsorbed with high affinity or nonfractionated albumin-heparin conjugate was found. These results demonstrate that the heparin moiety of the conjugate is directed to the solution phase whereas the albumin moiety contacts the polystyrene surfaca     

Conformation and gas permeability of poly(α-amino acid) membranes

The permeability of some poly(?-amino acid) (PAA) membranes like such of poly(N,δ-carbobenzoxy-L -lysine) (PCBL), poly(N,δ-carbobenzoxy-L -ornithine) (PCBO) as well as of copolymers of L -lysine and carbobenzoxy-L -lysine to oxygen and carbon dioxide were determined at different water content especially with regard to their use for artificial lungs. The conformations of these polymer membranes were studied by means of IR-spectra and X-ray diffraction. The results on the diffusion coefficient obtained for PCBL and PCBO were analysed in terms of Eyring's theory. They suggest that the microvoids in the interstices between the α-helices, assumed on the basis of X-ray analyses, play an important role, especially below the glass transition temperature T_g of the side-chains. This seems also to contribute partly to the diffusion of gas through the membrane even above T_g and results in an abnormally high “apparent activation energy” of diffusion in the wet state below T_g. It was found that the permeability of the membrane of partially decarbobenzoxylated PCBL for oxygen in a certain temperature range is higher than that for carbon dioxide. This has never been observed for any other synthetic polymer, because usually carbon dioxide has a higher solubility in these materials than oxygen. In the case of the partially decarbobenzoxylated PCBL membranes, however, the diffusion coefficient of carbon dioxide, and therefore the permeation of this gas, decreases much more than that of oxygen with increasing decarbobenzoxylation accompanied by the formation of β-structure and concomitantly the formation of intermolecular hydrogen bonds. Obviously, this phenomenon may be responsible for the permselectivity of these membranes for oxygen compared with carbon dioxide.     

Composition of TCR-CD3 complex in human intestinal intraepithelial lymphocytes: lack of Fc{varepsilon}Rl{gamma} chain

Human intestinal intraepithelial lymphocytes (DEL) are a uniquepopulation of predominantly CD8ß⁺ TCRß⁺lymphocytes and, to a lesser extent, TCR⁺ lymphocytes that proliferatepoorly to anti-CD3 mitogenic signals but display significantcytolytic activity. Studies in mouse model systems have shownthat the chain of the high-CD3 affinity receptor for IgE (FcRl)may substitute for the chain in the TCR-CD3 complex of iIEL.This has suggested that the functional properties of these cellsmay be associated with an altered composition of the TCR-CD3complex. We therefore analyzed the TCR-CD3 complex of normalhuman iIEL. One-and two-dimensional non-reducing/reducing SDS-PAGEanalysis of CD3, CD3, CD3, and FcRr chain immunopreclpitatesof cell surface radiolabeled proteins with subunit-specificantibodies revealed a TCR-CD3 complex without associated FcRrchains. Thus, normal human NEL contain a TCR-CD3 complex thatconsists predominantly of , homodimers in association with theß TCR and CD3, and , similar to the majority of peripherallymphocytes. This indicates that the distinct properties ofhuman DEL are not associated with substitutions of the FcRlchain in the TCR-CD3 complex.     

On the kinetics and mechanism of thermal degradation of polystyrene

The thermal degradation of polydisperse polystyrene samples with mol. wts. (M?_n) between 60000 and 22000 has been investigated at different temperatures under oxygen free conditions. Product analysis has been carried out by GPC. The experimental degradation could be simulated by a model consisting of scission and depolymerization. The dynamical behaviour of this model is expressed in a matrix from. The ratio of scission and depolymerization is constant for all polymers and different temperatures during degradation. Therefore, a master curve could be evaluated, which gives a general relation between the decrease of mol. wt. and the mass of volatiles. Finally a radical chain mechanism has been proposed in a lumped form which is consistent with the kinetic model and the experimental results.