The expression of interleukin-1 beta (IL-1 beta) mRNA in the cerebral cortex, hippocampus, striatum, and thalamus of rats was studied after transient forebrain ischemia. IL-1 beta mRNA was not detected in all these regions of sham-operated control rats. IL-1 beta mRNA was induced after transient forebrain ischemia and reached a detectable level in all regions examined 15 min after the start of recirculation. The induction of IL-1 beta mRNA had a few peaks, that is, peaks were observed at 30 and 240 min in the four regions examined, and another peak was observed at 90 min in the striatum. One day after the start of recirculation, IL-1 beta mRNA levels were markedly decreased, but even 7 days after that, IL-1 beta mRNA was found at very low levels in all regions examined. The amounts of c-fos and beta-actin mRNAs on the same blots were also examined. The induction of c-fos mRNA was transient and had only one peak in all regions examined, whereas the levels of beta-actin mRNA in these regions were fairly constant throughout the recirculation period. Thus, we provide the first evidence for a characteristic expression of IL-1 beta mRNA in several brain regions after transient forebrain ischemia.

We evaluated the significance of the host kallikrein-kinin system in tumor angiogenesis and tumor growth using two rodent models genetically deficient in a kallikrein-kinin system. Inoculation of Walker 256 carcinoma cells into the s.c. tissues of the back of normal Brown Norway Kitasato rats (BN-Ki rats) resulted in the rapid development of solid tumors with marked angiogenesis. By contrast, in kininogen-deficient Brown Norway Katholiek rats (BN-Ka rats), which cannot generate intrinsic bradykinin (BK), the weights of the tumors and the extent of angiogenesis were significantly less than those in BN-Ki rats. Daily administration of B(2) receptor antagonists significantly reduced angiogenesis and tumor weights in BN-Ki rats to levels similar to those in BN-Ka rats but did not do so in BN-Ka rats. Angiogenesis and tumor growth were significantly suppressed in B(2) receptor knockout mice bearing sarcoma 180 compared with their wild-type counterparts. Immunoreactive vascular endothelial growth factor (VEGF) was localized in Walker tumor stroma more extensively in BN-Ki rats than in BN-Ka rats, although immunoreactive B(2) receptor also was detected in the stroma to the same extent in both types of rats. Cultured stromal fibroblasts isolated from BN-Ki rats and BN-Ka rats produced VEGF in response to BK (10(-8)-10(-6) m), and this stimulatory effect of BK was abolished with a B(2) receptor antagonist, Hoe140 (10(-5) m). These results suggest that BK generated from kininogens supplied from the host may facilitate tumor-associated angiogenesis and tumor growth by stimulating stromal B(2) signaling to up-regulate VEGF production mainly in fibroblasts.

Single-walled carbon nanotubes (SWNTs) were synthesized by chemical vapor deposition (CVD) using catalytic nanoparticles both on the substrates and above the substrates in order to investigate the effect of nanoparticle density on diameter-controlled SWNT growth. As the density of the catalytic nanoparticles increased, tube-diameter distribution broadened and the diameter itself also increased. SWNTs observed in this study were grown by the base-growth mechanism and their diameters were much smaller than those of the nanoparticles. Based on elaborate diameter measurements, we reasonably conjecture that the time evolution of catalytic nanoparticles during CVD growth can explain these large size differences.

The authors report size control of catalytic nanoparticles by thermal annealing for diameter-controlled growth of single-walled carbon nanotubes (SWNTs). They found that Co nanoparticle-size gradually decreased through repetitive annealing at 1000°C in Ar ambient. Results of x-ray photoelectron spectroscopy and secondary ion mass spectroscopy show that thermal evaporation is responsible for the decrease. After SWNT growth using this phenomenon, the authors found that thinner SWNTs with a narrower diameter distribution grew as the nanoparticles became smaller. Their results provide a rational and straightforward technique to prepare catalysts having a desirable size and uniformity toward diameter-controlled SWNT growth.

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