Depolarization induced by injection of cyclic nucleotides into frog taste cell

In order to identify the intracellular transmitter involved in the taste transduction process, cyclic nucleotides were iontophoretically injected into the frog taste cells while membrane potentials were recorded intracellularly. Injection of either cyclic GMP or cyclic AMP induced a depolarization response of about 5 mV in the taste cells, but injection of Cl- had no effect. The rate of a repolarization after the depolarization elicited by cyclic GMP was larger than that after cyclic AMP. The possible role of cyclic nucleotide in the taste transduction was discussed.     

Regional assignment of five genes on human chromosome 19

A human-mouse hybrid segregant HM76Dd40-6 with new characteristics was derived from the hybrid cell line HM76Dd containing human chromosome 19 as the only human chromosome. Three virus sensitivities located on human chromosome 19 (PVS, E11S and RDRC) were lost in HM76Dd40-6, while six other genes (C3, LDLR, EF2, GPI, PEPD and MANB) were retained. Cytogenetic analysis and in situ hybridization using human or mouse repeated sequences as probes showed that the region q13.1-qter of human chromosome 19 had been replaced by a fragment of mouse chromosome. Our results permit further regional assignment for the following five genes on human chromosome 19: GPI in the region cen-q12, MANB in p13.2-q12, E11S and RDRC in q13.1-qter, and EF2 in pter-q12.     

DNA strand breaks in mammalian tissues induced by methylarsenics

DNA damage induced by administration of dimethylarsinic acid (DMAA) to rats and mice was investigated. At 12 h after administration of DMAA, DNA single-strand breaks were induced markedly in lung. The majority of dimethylarsine, one of the main metabolites, in the expired air was excreted within 6–18 h after administration of DMAA to rats. In vitro experiments using nuclei isolated from lung of mice indicated that DNA strand breaks were caused by dimethylarsine. Furthermore, the strand breaks after exposure to dimethylarsine were reduced in the presence of catalase and/or superoxide dismutase. These results strongly suggest that the strand breaks are induced not by dimethylarsine itself but by active oxygen, e.g., O ₂ ^? and ·OH, produced both by dimethylarsine and molecular oxygen. When DNA was exposed to dimethylarsine, thiobarbituric acid (TBA)-reactive intermediates andcis-thymine glycol were produced. Dimethylarsine appears to induce DNA damage by the mechanism similar to the damage produced by ionizing radiation.     

Impaired cholesterol esterification in cultured skin fibroblasts from patients with I-cell disease and pseudo-Hurler polydystrophy

Cholesterol esterification was examined in cultured skin fibroblasts from patients with I-cell disease and pseudo-Hurler polydystrophy by incubating cells pretreated without fetal calf serum for 48h, with (14C) cholesterol for 24h. Impaired cholesterol esterification was found in these cells and free cholesterol was accumulated in plasma membrane and Golgi fractions. This impairment was also induced in control cells by adding leupeptin (20 micrograms/ml) or monensin (2 micrograms/ml). These findings suggest the importance of the role of lysosomes for esterification of cholesterol and give a hint as to the basic defect in type C Niemann-Pick disease.     

Differences in Fine Structures between Normal and RNA-induced Drosophila Pole Cells

Fine structures were compared between normal pole cells and those induced in embryos that had been uv-irradiated and then injected with intact polar plasm or with poly(A)⁺RNA extracted from cleavage embryos. Nuclei in nomal pole cells were spherical. In contrast, those in the induced pole cells were deformed to variable extents depending on materials injected with. Polar granules were smaller in pole cells induced by injection of poly(A)⁺RNA than in normal pole cells. The size of polar granules in polar-plasm-induced pole cells was intermediate between those in poly(A)⁺RNA-induced and normal pole cells. Small polar granules were observed in posterior cells of embryos uv-irradiated, nevertheless those cells were columnar and with identical morphology to somatic cells. Nuclear bodies showed a similar tendency in size differences as observed in polar granules in three types of pole cells observed.     

Complete deficiency of 20 KDa homologous restriction factor (HRF20) and restoration with purified HRF20

20 KDa homologous restriction factor (HRF20) is a membrane glycoprotein which inhibits formation of membrane attack complexes of homologous complement. Erythrocytes from a patient who is completely deficient in HRF20 were readily hemolyzed by homologous complement activated by sucrose or by acidification as in paroxysmal nocturnal hemoglobinuria (PNH). After incubating PNH erythrocytes (PNH-E) with purified HRF20, the cells were analyzed by flow cytometry using a monoclonal antibody to HRF20 and shown to have the antigen absorbed. These PNH-E acquired resistance to hemolysis by homologous complement suggesting that HRF20 may be successfully used for treatment of these patients.     

Multiple expression of keratins, vimentin, and S-100 protein in pleomorphic salivary adenomas.

Immunohistochemical staining for S-100 protein and the intermediate filaments keratin and vimentin, was made in 41 salivary adenomas. In pleomorphic adenomas, great heterogeneity in the staining, as well as multiple and co-expressions of these proteins were found in the outer tumor cells of tubulo-ductal structures and modified myoepithelial cells, but not in the luminal tumor cells. All the outer tumor cells stained for S-100 protein, 97% for K8.12 keratin and 85% for vimentin. Of these cells, 29% showed multiple expression of K8.12 keratin, vimentin, and S-100 protein, and 17% showed co-expression of K8.12 and S-100 protein. Modified and neoplastic myoepithelial cells showed similar expressions of these proteins to those of outer tumor cells; myoepithelioma cells displayed the most complicated pattern, being positive for KL1, PKK1, and K8.12 keratins, vimentin and S-100 protein. In luminal tumor cells there was a heterogeneous expression of KL1 and PKK1 in 82%, and of KL1, PKK1, and K8.12 in only 14.7%. Based on the immunohistochemical findings obtained with different monoclonal antibodies in pleomorphic salivary adenomas, outer tumor cells may be derived from ductal basal cells and luminal tumor cells from intercalated duct cells.     

Peri-operative immunotherapy with OK-432

Pre- and postoperative intradermal administration of OK-432 enhanced the SU-PS skin reaction in patients with gastric cancer, but failed to prevent a fall in the NK activity induced by the operation.The change in NK activity was not associated with a change in the proportion of Leu 7-positive cells, but was related to Leu 11a-positive cells. Intradermal injection of OK-432 increased the proportion of Leu 7-positive cells in the patients in whom they accounted for less than 20% of lymphocyte population. The case was the same with Leu 11a-positive cells.Intravenous injection of OK-432 tended to increase suppressor-inducer T cells (CD4⁺2HA⁺ cells), B cells and Leu 7-positive cells. Particularly, the proportions of OK-M₁-positive cells and MHC class II antigen-positive cells increased in all patients. Immunotherapy with OK-432 given intravenously at a dose of 0.1 KE appeared to be safe because no side effects were essentially observed.