Identification of receptors for platelet-activating factor in rat Kupffer cells

Ligand binding studies demonstrated that isolated rat Kupffer cells possess high affinity binding sites for platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, AGEPC). AGEPC binding reached saturation within 10 min at 25 degrees C and was reversible. A Scatchard analysis revealed a single class of AGEPC receptors numbering about 10,600 sites/cell and possessing a dissociation constant of 0.45 nM. Similar values for the dissociation constant for AGEPC (0.12 and 0.34 nM) were obtained independently by kinetic analysis of specific AGEPC binding. AGEPC binding was stereospecific and was inhibited by Zn2+ and AGEPC receptor antagonists including BN52021 and U66985. The AGEPC receptor was functionally active since it was shown to mediate arachidonic acid release and eicosanoid production in Kupffer cells, and these events were inhibited by AGEPC receptor antagonist BN52021. The receptor-mediated arachidonic acid release was extracellular calcium-dependent and was abolished by calcium channel blocker prenylamine and by [ethylenebis(oxyethylenenitrilo)]tetraacetic acid, indicating that calcium influx through a receptor-regulated calcium channel in the plasma membrane is involved in the AGEPC-induced arachidonic acid release. It is suggested that rat Kupffer cells have specific and functionally active AGEPC receptors which are involved in signaling mechanisms which govern the production of several other autacoid-type mediators in the liver.

Phagocytosis of Treponema pallidum pertenue by hamster macrophages on membrane filters

The role of the macrophage in destruction of virulent treponemes is disputed. A major obstacle has been the inability to demonstrate quantitative phagocytosis of treponemes by macrophages. Treponema pallidum pertenue was attached to polycarbonate filters for assessment of treponemal phagocytosis by macrophages. The disappearance of treponemes due to phagocytosis was measured by enumeration with immunofluorescence. Resident and lipopolysaccharide-activated macrophages were found to phagocytize treponemes equally well. The phagocytosis of killed treponemes by macrophages was enhanced by opsonization with immune serum. Macrophages successfully phagocytized Staphylococcus aureus organisms when they were incubated on filters under identical conditions. Treatment of macrophages with cytochalasin B, a known inhibitor of phagocytosis, prevented the disappearance of treponemes and phagocytosis of S. aureus. In addition, fluorescent treponemal debris was observed only inside macrophages cultured with treponemes. These results demonstrate that macrophages can phagocytize pathogenic treponemes on polycarbonate filters.

[Clonal propagation of Gynostemma pentaphyllum (Thumb.) Makino in test tubes]

The explants taken from adventitious shoots or nodes of adventitious bud of Gynostemma pentaphyllum produced numerous shoots on MS medium supplemented with BA 1mg/L and IAA 0.05 mg/L. When the segments of shoots were grown on the 1/2MS medium supplemented with IBA 1 mg/L, roots were initiated differentiating to plantlets. Substitution of polyurethane sponge for agar can accelerate the growth of platlets.

Potentially lethal ventricular arrhythmias: from mundane to esoteric

Patients with potentially lethal ventricular arrhythmias (VAs) represent a heterogenous group with frequent and high grade ventricular arrhythmias (including couplets and runs of nonsustained ventricular tachycardia), structural heart disease and decreased left ventricular function. This is a group at intermediate risk of sudden death, with risks varying from 10% to 38%. The electrical and mechanical risks of patients with potentially lethal VA is discussed in relation to their ability of promoting sudden death. The studies reviewing the impact of antiarrhythmic treatment on survival of patients with potentially lethal VA is discussed.

[Fiberscopic study of velopharyngeal function in 170 normal subjects]

This paper established a quantitative methodology for evaluating the velopharyngeal function (VPF) using NPF. The reliability of this method was testified. On the basis of this result, the observation of normal velopharyngeal function was carried out in 170 normal individuals. The authors presented the percentage of VPI during phonating five Chinese vowels, the highest one was "a" (52.3%), the lowest ones were "i" and "u" (7.1% and 5.3%). The extent of VPI was measured, the mean of "a"'s RVPI was 13.9%, and the means of "i"'s and "u"'s RVPI were 9.3% and 9.7% respectively. The authors suggested the RVPI "i" and RVPI "u" as two parameters for assessing VPF.

Effects of tensile stress on the R lines of Cr(3+) in a sapphire fiber

We have investigated the spectroscopic properties of a crystalline sapphire fiber unintentionally doped with Cr(3+). We find that tensile stress produces blue shifts of the R lines and changes in their radiative lifetimes and integrated intensities that can be correlated to stress-induced changes of the crystal-field parameters.

Synergistic effect of macrophage activation and immune serum, especially IgG2, on resistance to infection with Treponema pallidum ssp. endemicum in hamsters

Experimental studies have indicated that macrophages are involved in the pathogenesis of syphilis. Whether macrophages alone or with immune serum are ultimately responsible for killing of treponemes is disputed. We have demonstrated that BCG-vaccinated hamsters administered normal serum contained fewer treponemes in the inguinal and popliteal lymph nodes than did the nonvaccinated controls. When BCG-vaccinated hamsters were injected with syphilitic immune serum and challenged with Treponema pallidum ssp. endemicum, treponemicidal activity was enhanced. Treponemicidal activity was also detected in BCG-vaccinated hamsters challenged with treponemes treated in vitro with immune serum and its immunoglobulin fractions, especially IgG2. The immune IgG2 fraction had more treponemicidal activity than did the immune IgG1 fraction and the unfractionated immune serum. Our observations indicate an important synergistic role for macrophages and immune serum, especially IgG2, for elimination of T. pallidum ssp. endemicum from the host.

[Study of anticancer human monoclonal antibody--establishment of human monoclonal antibody to gastric cancer by human-mouse hybridoma]

A human immunoglobulin M (IgM) antibody secreting hybridoma, HMG1, has been established and studied for its reactivity against human gastric cancer cells. Lymphocytes isolated from a regional lymph node of patient with gastric adenocarcinoma were fused with mouse myeloma cells NS-1. Supernatants from the generated human-mouse hybrids were first screened for immunoglobulin production by ELISA. The identified human IgM-secreting hybridomas were expanded and subcloned for further analysis or cryopreservation. The screening for binding of antibodies to a panel of human cancer cell lines and normal fibroblast was carried out with PAP or indirect immunofluorescence stain. The selected hybridoma, HMG1 after being cloned three times, was stable in secreting IgM (about 4 micrograms/1 x 10(6) cells) for more than 9 months. Large amount of ascites was obtained by injecting this hybrid to BALB/C nude mice pretreated with anti-lymphocyte serum and pristane. The ascitic fluid contained 5-19 mg human Ig/ml. Subsequently this IgM was extracted from ascitic fluid by saturated ammonium sulphate solution. This crude extract was further purified with immuno-affinity chromatography. Both this purified ascite-IgM as well as IgM from HMG1 supernatant would react with gastric cancer cell line BGC-823 but not with human normal fibroblasts 350Q by PAP or immunofluorescence analysis. The human HMG1-IgM reacted with gastric cancer cells on paraffin embedded tissue section but did not react with normal gastric mucosa cells. HMG1-IgM had some complement dependent cytotoxicity against BGC-823. These results suggest that the establishment of anticancer human monoclonal antibodies with human-mouse hybridoma technique be feasible. There is a possibility for clinical applications of this human monoclonal antibody in the future.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Carbon Black on the J-Integral and Strain Energy in the Crack Tip Region in a Vulcanized Natural Rubber

1) The J-integral is path independent in both PS and SEN specimens and equals the tearing energy. 2) The critical J-integral at initiation is less in PS specimens than in SEN specimens, because the greater biaxial stress in PS restricts the process zone. 3) At initiation, the crack-tip radius, proportional to the local strain, is independent of CB. 4) The energy density within and the size of the process zone near the crack tip increase with CB; these are major contributions to CB reinforcement.