[Establishment of human glioma cell line--nude mice solid tumor model NHG-1 and its characteristics]

Establishment and its characteristics of a nude mice solid tumor model NHG-1 from human glioma cell line are reported. 5-8 week old NC nude mice of both sexes and SHG-44 cell line used in this experiment were from our laboratory. The initial successful transplantation rate was 7/11 (64%) and that of 30 passages in the subsequent 4 years was 100%. After subcutaneous inoculation, growth curve showed a latent period in week 1-2, slow growing period in week 3-4, rapid growing period in week 5-6 and a final plateau period in week 7. The doubling time was 7 days and cell cycle time was 2.5 days. The cells in G1, S and G2M phases comprised 56%, 27% and 17%, respectively. The survival time of the host was 54 +/- 15 days. The tumor tissues showed a tendency towards invading the surrounding soft tissues. By morphological observation with light and electron microscopes, LDH isozyme assay, PAP immuno-histochemistry labelling GFAP and chromosome analysis, it is confirmed that the transplantable tumor possesses the characteristics of human malignant glioma. The estrogen receptor in the transplantable tumors demonstrated by cytochemical assay indicates that the glioma carcinogenesis is related to endocrine factor of the host. The therapeutic effects of anticancer drugs, such as ACNU, BCNU and 10-hydroxy-2-decenoic acid from the royal jelly on NHG-1 model are evaluated.

The mast cell response to substance P: effects of neuraminidase, limulin, and some novel synthetic peptide antagonists

We have investigated certain aspects of the mechanism whereby substance P triggers secretion of 5-hydroxytryptamine (5-HT) from rat peritoneal mast cells in vitro. Substance P-induced release of 5-HT was inhibited following pretreatment of rat peritoneal cells with 0.01-1.0 units/ml neuraminidase; secretion induced by anti-IgE antibody was inhibited by pretreatment with 1.0 units/ml but not by lower concentrations of enzyme. Addition of the sialic acid-rich substances N-acetyl-neuraminlactose (up to 1.0 mM) and mucin (up to 1.0 mg/ml) to substance P in free solution failed to block the activity of the neuropeptide. Limulin, a sialic acid-specific lectin, failed to block substance P-induced secretion of 5-HT, but was found to possess intrinsic non-lytic secretory activity (at 5-20 micrograms/ml). Release of 5-HT induced by limulin was independent of that induced by substance P. A range of octapeptides incorporating the C-terminal sequence Gly-Ser-Phe-Phe, but differing in degree of cationicity and positioning of cationic residues in the four N-terminal positions, were tested for their capacity to antagonise the mast cell-triggering activity of substance P. A peptide incorporating two lysine residues at the N-terminus was found to have partial substance P antagonist activity; no effects on IgE-mediated secretion were observed.

Studies on beta-lactoglobulin as an experimental allergen in rats

The allergenicity of bovine beta-lactoglobulin (beta-LG) in rats was investigated by measurement of both mast cell-bound and circulating IgE antibody produced in response to immunisation with this cow's milk constituent. The responsiveness of the animals' peritoneal mast cells to in vitro challenge with beta-LG was determined by measurement of release of radiolabelled 5-hydroxytryptamine. Using aluminium hydroxide gel as adjuvant, the responsiveness of mast cells to beta-LG was transient, peaking at 21 days after immunisation. The optimal dose of injected beta-LG was 100 micrograms. Circulating IgE antibody to beta-LG, measured by ELISA, was also detected transiently during the 3rd week post-immunisation.

Investigation of the allergenicity of beta-lactoglobulin and its cleavage fragments

Fragments of beta-lactoglobulin were produced by proteolytic cleavage with trypsin, and chemical cleavage with cyanogen bromide, followed by gel filtration on Sephadex G-50. The antigenicity and allergenicity of the products were studied, before and after reductive cleavage by treatment with 2-mercaptoethanol. The former was determined by inhibition ELISA using IgG anti-beta-lactoglobulin raised in rabbits, whilst the latter was determined by inhibition ELISA and mast cell challenge, using respectively the sera and peritoneal cells of rats experimentally sensitised to beta-lactoglobulin. The findings raise interesting points about the structural basis of allergenicity in relation to antigenicity.