Possible involvement of calcium ions in the hatching of Schistosoma mansoni eggs in water

The possibility of involvement of calcium ions in the hatching of Schistosoma mansoni eggs in water is described. The hatching of S. mansoni eggs under low osmotic pressure was partially inhibited by EGTA (5 mM), lanthanum chloride (1-5 mM), and ruthenium red (0.1-1 mM). The reagents used in these experiments were not toxic to the eggs however, because miracidia hatched normally when the reagents were removed.     

Effects of medicinal plant extracts from Chinese herbal medicines on the mutagenic activity of benzo[a]pyrene

The effects of medicinal plants on the mutagenicity of benzo[a]pyrene were studied with Salmonella typhimurium tester strains. The chosen medicinal plants are very frequently used as Chinese herbal medicines. Each medicinal plant was extracted with hot water, which is similar to the method used in Chinese medicinal treatment. Cinnamomi cortex, Rhei rhizoma, Scutellariae radix and Rehmanniae radix were found to decrease the mutagenic activity of benzo[a]pyrene. Atractylodis rhizoma also reduced the mutagenicity of benzo[a]pyrene, but this was not certain, because it showed a killing effect on the cell survival test. Bupleuri radix and Aurantii nobilis pericarpium had an enhancing effect, but then neither of these extracts is itself mutagenic. Each medicinal plant extract showed a different effect on the mutagenicity of benzo[a]pyrene. These effects were classified into 5 types: (I) decreasing effect, (II) killing effect, (III) enhancing effect, (IV) enhancing and decreasing effect and (V) inactive.     

Selection of an atrazine-resistant tobacco cell line having a mutant psbA gene

Summary A mutant cell line that shows high resistance to the photosynthesis-inhibiting herbicide atrazine was selected from cultured photomixotrophic Nicotiana tabacum cv. Samsun NN cells by repeated exposure to toxic levels of the herbicide. This resistance was confirmed by measurements of Hill reaction activity in isolated thylakoid membranes. Nucleotide sequencing revealed that the resistant cell line had a point mutation in its chloroplast psbA gene. The 264th codon, AGT (serine) was changed to ACT (threonine) in this mutant. This new type of mutation also conferred moderate cross-resistance to diuron and subsequently was stable in the absence of continued selection pressure.     

Surface Charge Density Estimation of Vigna mungo Protoplasts Using a Fluorescent Dye, 9-Aminoacridine

We showed that the surface charge density of protoplasts canbe estimated by the 9-aminoacridine method. The estimated surfacecharge density of the protoplasts isolated from elongating regionsof Vigna mungo root was – 39 ? 8 mC/m². The negative surfacecharge density increased when protoplasts were treated withglutaraldehyde or when EDTA was added to the protoplast suspensionmedium. These results support the validity of our estimationof the surface charge density of protoplasts by the 9-aminoacridinemethod. The concentration of amino groups at the surface ofthe protoplasts was estimated to be 34 mC/m². (Received June 19, 1987; Accepted April 11, 1988)     

Application of 39K NMR Spectroscopy to Potassium Transport in Mung Bean Root Tips

The intracellular K⁺ concentration and its change in mung bean[Vigna mungo (L.) Hepper] root tips were investigated non-invasivelywith ³⁹K nuclear magnetic resonance spectroscopy using a membraneimpermeable shift reagent, dysprosium (III) tripolyphosphate[Dy(PPP_i)^7–₂]. The K⁺ resonance was shifted to highermagnetic field in proportion to the concentration of the shiftreagent. In addition to a reference capillary peak for measuringthe K⁺ concentration, two well-resolved peaks (intra- and extracellularK⁺ resonances) were observed in the 39K NMR spectra of mungbean root tips. The intracellular K⁺ concentration was determinedto be 41 mM, which was similar to the value obtained by flamephotometry. When 20 mM KCl was added to the external medium,the intensity of the intracellular K⁺ resonance gradually increasedand the net K⁺ uptake rate was calculated to be 4.1 micromolesper gram fresh weight per hour. After removal of KCl from theperfusion medium, the intracellular K⁺ concentration considerablydecreased. With ³¹P NMR method, 2.5 mM Dy(PPP_j)^7–1₂ and20 mM KCl had little effect on the ATP level in the cells. Wehave indicated that the ³⁹K NMR method can be used to determinethe K⁺ levels and net fluxes of the K⁺ transport in perfusedroot tips successively. (Received April 6, 1988; Accepted September 29, 1988)     

Autocrine activities of basic fibroblast growth factor: regulation of endothelial cell movement, plasminogen activator synthesis, and DNA synthesis

We have found that the spontaneous migration of bovine aortic endothelial cells from the edge of a denuded area in a confluent monolayer is dependent upon the release of endogenous basic fibroblast growth factor (bFGF). Cell movement is blocked by purified polyclonal rabbit IgG to bFGF as well as affinity purified anti-bFGF IgG and anti-bFGF F(ab')2 fragments. The inhibitory effect of the immunoglobulins is dependent upon antibody concentration, is reversible, is overcome by the addition of recombinant bFGF, and is removed by affinity chromatography of the antiserum through a column of bFGF-Sepharose. Cell movement is also reversibly inhibited by the addition of protamine sulfate and suramin; two agents reported to block bFGF binding to its receptor. The addition of recombinant bFGF to wounded monolayers accelerates the movement of cells into the denuded area. Transforming growth factor beta which has been shown to antagonize several other effects of bFGF also inhibits cell movement. The anti-bFGF IgG prevents the movement of bovine capillary endothelial cells, BHK-21, NIH 3T3, and human skin fibroblasts into a denuded area. Antibodies to bFGF, as well as suramin and protamine sulfate also suppress the basal levels of plasminogen activator and DNA synthesis in bovine aortic endothelial cells.     

Demonstration of 1 alpha,25-dihydroxyvitamin D3 receptor-like molecule in ST 13 and 3T3 L1 preadipocytes and its inhibitory effects on preadipocyte differentiation

The active metabolite of vitamin D3, 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3), inhibited morphologic and enzymatic expression during differentiation of preadipocyte to adipocyte. In the presence of approximately 6.4-20 X 10(-10) M 1,25(OH)2D3, the triacylglycerol accumulation was only 50% of that of fully differentiated control cells. High-affinity binding sites for 1,25-dihydroxyvitamin D3 were detected in two preadipose cell lines. The 1,25(OH)2D3 binding component sediments at 3.3 S in 4-24% (w/v) sucrose gradients prepared in hypertonic buffer. Binding assay revealed that Nmax was 70 fmol/mg protein and 90 fmol/mg protein, and Kd value was 170 pM and 37 pM in cell lines ST 13 and 3T3 L1, respectively. We also found that differentiated adipocytes did not contain specific receptors for 1,25(OH)2D3. 1,25(OH)2D3, 1(OH)D3, 24,25(OH)2D3, and 24(OH)D3 all suppressed differentiation of preadipocytes to adipocytes, and the dose required closely reflected the affinities of the various metabolites and the synthetic derivative for 1,25(OH)2D3 receptor. It is suggested that the action of vitamin D3 on preadipocyte differentiation may result from a receptor-mediated event.     

Cytokinetic effects of carboplatin and cisplatin on a human ovarian cancer cell line

The cytokinetic effects of carboplatin(CBDCA) on a human ovarian cancer cell line(KF-1) were examined by means of cell survival rate and flow cytometry in comparison with cisplatin(CDDP). CBDCA and CDDP exhibited dose dependent cytotoxicity on KF-1, and CBDCA showed compatible cell growth inhibition to that of 15 times concentration of CDDP in comparison with IC50 of 72 hrs after drug addition. From the analysis of cell cycle, CBDCA and CDDP inhibited cell cycle progression at G2 + M phase. CBDCA exhibited G2 + M phase block to that of 15 to 20 times the concentration of CDDP. We suggested that CBDCA had potential therapeutic activity against ovarian cancer, but should be evaluated carefully in the clinical use.     

Induction of LAK cells by high density dialyzing culture device and its cytotoxicity

Lymphokine activated killer (LAK) cells are generated by culture of lymphocytes with interleukin 2 (IL-2) in short term culture (3 to 5 days) and are used for adoptive immunotherapy for advanced cancer patients. The culture condition hitherto reported are essentially based on the rotating culture system, in which the maximum cell density was at 2 X 10(6) cell/ml and the cell recovery was usually less than 100%. The inability to induce LAK cells efficiently in vitro made the culturing of cells for therapy rather difficult and costly work because the mean infusion dose of LAK cells of one patient requires more than 1 X 10(10)/ml. We have therefore attempted to culture lymphocytes in 10 times higher concentration comparing with conventional methods. By using a new dialyzing culture system under continuous regulation of the amount of infused IL-2, nutrition medium, and pO2 and pCO2, we could culture cells at 2 X 10(7)/ml for more than 21 days and the resulted LAK cells showed a 100 times increase of activity on a per cell basis. By limiting dilution procedure, these killer cells mostly express T cell markers such as CD3 and CD8 but dose not express CD16.