Silicon-responsive cDNA clones isolated from the marine diatom Cylindrotheca fusiformis.

In organisms ranging from single-celled algae to mammals, including humans, silicon is essential for, and actively participates in, a variety of life processes. It has become clear that silicon (i) acts as a metabolite affecting a variety of cellular processes, and (ii) regulates gene expression. However, the mechanisms by which silicon (i.e., Na2SiO3.9H2O, in the present study) acts are not clear, due to inherent methodological difficulties. As part of our program to understand how silicon acts in biological systems, we present the first isolation of cDNA clones derived from silicon-responsive mRNAs, from the marine diatom Cylindrotheca fusiformis. We distinguish between clones responding only to silicon starvation and replenishment, and those also responding to other cellular conditions. Some of the clones can be identified by similarity to other genes, and should be useful as probes to isolate genes from other organisms. Isolation of these clones provides the means to (i) identify metabolic pathways affected by silicon, and (ii) investigate the mechanism(s) of silicon-regulated gene expression.

Excitation functions of the analyzing power in pp--> scattering from 0.45 to 2.5 GeV

Excitation functions A(N)(p(p),Theta(c.m.)) of the analyzing power in pp--> elastic scattering have been measured with a polarized atomic hydrogen target for projectile momenta p(p) between 1000 and 3300 MeV/ c. The experiment was performed for scattering angles 30 degrees

Cytokine- and calcium ionophore A23187-mediated arachidonic acid metabolism in neutrophils.

Arachidonic acid (AA) metabolism is implicated as an intracellular and/or intercellular second messenger system for the transmission of cytokine-initiated signals that affect neutrophils and mediate systemic toxicity. The purpose of the present study is to ascertain if cytokines that are known to affect neutrophil function in vivo and in vitro directly stimulate neutrophil AA metabolism in vitro. The recombinant human cytokines multi-colony stimulating factor, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 1, tumor necrosis factor (TNF), and interleukin 6 and the calcium ionophore A23187 were incubated with purified 14C-AA radiolabeled human peripheral blood neutrophils and the effects were assayed by one- and two-dimensional thin layer lipid chromatography. None of the cytokines appeared to induce the release of cell-incorporated AA or to increase the level of radiolabeled phosphatidic acid. TNF induces severe systemic toxicity that is inhibited by cyclooxygenase inhibitors, which suggests a role for AA metabolites in the pathophysiologic effects of TNF; we have confirmed that TNF and endotoxin act synergistically to induce indomethacin-inhibitable fatal shock in rats. However, when in 3H-AA radiolabeled human neutrophils were incubated with TNF in kinetic, cold-chase, and TNF preincubation experiments, TNF was not found to increase AA metabolism, although changes in the intracellular neutral lipid content were noted. GM-CSF, which has been reported by previous investigators to directly induce the release of AA, did not release neutrophil-associated 3H-AA. In conclusion, the direct release of AA from membrane-associated phospholipids does not appear to be a major second messenger pathway for cytokine-initiated activation of neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute in vivo effects of IL-3 alone and in combination with IL-6 on the blood cells of the circulation and bone marrow.

Recombinant human IL-3 administered intravenously to rats as a single injection induced peripheral neutrophilia and monocytosis beginning at 4 to 6 hours after injection, peaking at 8 hours, and subsiding to normal by 12 to 24 hours. IL-3 did not induce an initial neutropenia such as accompanies endotoxin-, G-CSF-, and TNF-induced neutrophilia, or lymphopenia such as accompanies endotoxin-, IL-1-, and TNF-induced neutrophilia. The IL-3-induced peripheral neutrophilia was accompanied by a decrease in mature marrow neutrophils, indicating that the mechanism of neutrophilia was through marrow release rather than by demargination, which occurs after the administration of epinephrine or IL-6. The release of mature marrow neutrophils further suggests that IL-3 either has intrinsic neutrophil releasing activity or indirectly causes neutrophil release through the gene expression of a second cytokine. IL-3 induced a striking left-shifted myeloid hyperplasia in the bone marrow at 8 hours that morphologically was very similar to that observed after administration of endotoxin, a finding consistent with the hypothesis of previous investigators that endotoxin may in part act indirectly on hematopoietic cells by eliciting local marrow production of IL-3. Finally, IL-3 induced an increase in marrow pronormoblasts at 8 hours, consistent with the in vitro proliferative effect of IL-3 on erythroid stem cells. The combination of IL-3 and IL-6 induced a synergistic peripheral neutrophilia and monocytosis and a striking synergistic increase in marrow mast cells. The combination of IL-3 and IL-6 also induced an erythroid and left-shifted myeloid hyperplasia such as would be expected given the individual effects of these hematopoietic growth factors.

Acute and subacute hematologic effects of multi-colony stimulating factor in combination with granulocyte colony-stimulating factor in vivo.

Multi-colony stimulating factor (Multi-CSF, interleukin-3, IL-3) and granulocyte-CSF (G-CSF) administered concurrently as an intravenous (IV) injection induce a peripheral neutrophilia that is approximately additive in comparison with the neutrophilia induced by IL-3 and G-CSF individually. The bone marrow (BM) at 12 hours is depleted of mature neutrophils and shows a left-shifted myeloid hyperplasia, consistent with the neutrophil-releasing and myeloproliferative activities of both IL-3 and G-CSF individually. The BM at 24 hours shows a replenished reserve of mature neutrophils and a synergistic left-shifted myeloid hyperplasia as compared with IL-3 and G-CSF alone. Daily IV injections of IL-3 plus G-CSF for 1 week also induce an approximately additive daily peripheral neutrophilia. The BM after a week's administration of IL-3 plus G-CSF shows a generalized myeloid hyperplasia with a synergistic increase in mature neutrophils as compared with IL-3 or G-CSF alone. Daily injection of IL-3 plus G-CSF induced a significant decrease in erythroid, lymphoid, and eosinophilic marrow precursors, possibly owing to a myelophthisic effect of the myeloid hyperplasia and despite the fact that IL-3 alone induced a significant erythroid hyperplasia.

Measurement of spin-correlation parameters ANN, ASS, and ASL at 2.1 GeV in proton-proton elastic scattering.

At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.