Presence of histamine H2-receptors on human gastric carcinoma cell line MKN-45 and their increase by retinoic acid treatment.

Histamine dose-dependently stimulated cyclic AMP production in human gastric carcinoma cell line MKN-45, and this effect was inhibited by cimetidine but not by pyrilamine. Moreover, not only histamine but also cimetidine displaced the specific binding of [3H]tiotidine to these cells, whereas pyrilamine had no effect. On the other hand, pretreatment of MKN-45 cells with retinoic acid (RA) significantly enhanced histamine-induced increase of cyclic AMP production, although the cyclic AMP response to either forskolin or NaF was not affected. Finally, RA treatment increased the number of histamine receptor without altering its affinity. Thus, it appears that histamine H2-receptors are present on MKN-45 cells, and that RA treatment enhances the action of histamine on these cells by increasing the number of H2-receptors.     

Negative ion fast atom bombardment-tandem mass spectrometry for structural analysis of isoprenoid diphosphates

Applicability of negative ion fast atom bombardment (FAB)-tandem mass spectrometry (MS/MS) was examined in trace mixture analyses and structural assignments of some isoprenoid diphosphates. Negative ion FAB-MS spectra using a glycerol matrix of these isoprenoid diphosphates showed predominantly molecular ions (M-H)- together with fragment ions at m/z 177 (H3P2O7)-, 176 (H2P2O7)-, 159 (HP2O6)-, and 79 (PO3)- which were characteristic of the diphosphate ester moiety. The molecular ions did not overlap with peaks arising from any impurities even when crude sample such as butanol extracts from enzymatic reaction mixtures were directly analyzed without any purification. Moreover, collisionally activated dissociation spectra of the molecular ion showed many structurally significant fragment ions which enabled us to elucidate the structures of such irregular alkyl chain moieties as those having a homoisoprenoid skeleton or substituted structures. These studies indicate that negative ion FAB-MS/MS is a simple and useful technique for trace mixture analysis and structure elucidation of isoprenoid diphosphates.     

Cartilage-derived factor (CDF) : II. Somatomedin-like action on cultured chondrocytes

Previously, we showed that fetal bovine cartilage contains a polypeptide that stimulates the incorporation of [³⁵S]sulfate into proteoglycans synthesized by rat and rabbit costal chondrocytes in culture. In this paper, we report that the cartilage-derived factor (CDF) increases not only [³⁵S]sulfate incorporation but also [³H]thymidine incorporation into rabbit chondrocytes in monolayer culture. The dose-response curve of CDF stimulation of DNA synthesis was similar in profile to that of CDF stimulation of proteoglycan synthesis. In addition, CDF markedly enhanced [³H]uridine incorporation into rabbit chondrocytes and significantly enhanced [³H]serine incorporation into total protein. These findings indicate that fetal bovine cartilage contains a factor that shows somatomedin-like activity in monolayer cultures of rabbit chondrocytes.     

Oxidative Degradation of Squalene by Arthrobacter Species

An organism isolated from soil and identified as Arthrobacter sp. was studied for its squalene degradation. The degradation product from squalene, which accumulated in the culture broth, was isolated and identified as trans-geranylacetone by mass spectrometry, gas chromatography, infrared spectrometry, and nuclear magnetic resonance spectrometry. Addition of a high concentration of K₂HPO₄ to the culture medium resulted in accumulation of fairly large amounts of carboxylic acids in addition to geranylacetone. These carboxylic acids were identified as isovaleric, β,β′-dimethylacrylic, geranic, and (+)-(R)-citronellic acids. Among these acids, α,β-saturated carboxylic acids were found to be predominant in quantity.     

Immunoadjuvant activities of peptidoglycan subunits from the cell walls of Staphyloccus aureus and Lactobacillus plantarum.

Attempts were made to isolate and identify the unit chemical structure essential for manifestation of the immunoadjuvant activities characteristic of bacterial cell walls. The N-acetylmuramyl-peptide subunit monomers, Nalpha-(N-acetylmuramyl-L-alanyl-D-isoglutaminyl)-Nepsilon-(glycylglycyl)-L-lysyl-D-alanine from the cell walls of Staphylococcus aureus (FDA 209P) and N-acetylmuramyl-L-alanyl-D-isoglutaminyl-meso-diaminopimelic acid and/or N-acetylmuramyl-L-alanyl-D-isoglutaminyl-meso-diaminopimelyl-D-alanine from those of Lactobacillus plantarum (ATCC 8014), were shown to be unit chemical entities with definite adjuvant activity both in stimulation of antibody production and in induction of delayed-type hypersensitivity to ovalbumin when administered to guinea-pigs as water-in-oil emulsions.     

Detection of SO2 at the ppm Level with Localized Surface Plasmon Resonance (LSPR) Sensing

Plasmonics - Detection and monitoring of SO2 is important because it is a representative toxic gas in the atmospheric environment that is emitted from industrial and natural processes. Localized...