Hokkaido University

About: Hokkaido University is a education organization based out in Sapporo, Hokkaidô, Japan. It is known for research contribution in the topics: Catalysis & Population. The organization has 53925 authors who have published 115403 publications receiving 2651647 citations. The organization is also known as: Hokudai & Hokkaidō daigaku.

Plot-scale evidence of tundra vegetation change and links to recent summer warming.

Abstract: Temperature is increasing at unprecedented rates across most of the tundra biome(1). Remote-sensing data indicate that contemporary climate warming has already resulted in increased productivity ov ...

Misreading of DNA templates containing 8-hydroxydeoxyguanosine at the modified base and at adjacent residues

Abstract: It has been shown previously that deoxyguanosine residues in DNA are hydroxylated at the C-8 position both in vitro and in vivo to produce 8-hydroxydeoxyguanosine (8-OH-dG) by various agents that produce oxygen radicals such as reducing reagents-O2, metal ions-O2, polyphenol-H2O2-Fe3+, asbestos-H2O2 or ionizing radiation. These agents are mostly either mutagenic or carcinogenic; therefore, the formation of 8-OH-dG can also be considered a likely cause of mutation or carcinogenesis by oxygen radicals. It is of interest to know whether the 8-OH-dG residue in DNA is misread during DNA replication. To answer this question, we have examined the effect of the 8-OH-dG residue in DNA on the fidelity of DNA replication using a DNA synthesis system in vitro with Escherichia coli DNA polymerase I (Klenow fragment). The synthetic oligodeoxynucleotides, with or without an 8-OH-dG residue in a specified position, were chemically synthesized and used as templates for DNA synthesis under the conditions of the dideoxy chain termination sequencing method. Surprisingly, in addition to misreading of the 8-OH-dG residue itself, pyrimidines next to the 8-OH-dG residue (G has not yet been tested) were also misread.

Rules for biologically inspired adaptive network design

Abstract: Transport networks are ubiquitous in both social and biological systems. Robust network performance involves a complex trade-off involving cost, transport efficiency, and fault tolerance. Biological networks have been honed by many cycles of evolutionary selection pressure and are likely to yield reasonable solutions to such combinatorial optimization problems. Furthermore, they develop without centralized control and may represent a readily scalable solution for growing networks in general. We show that the slime mold Physarum polycephalum forms networks with comparable efficiency, fault tolerance, and cost to those of real-world infrastructure networks—in this case, the Tokyo rail system. The core mechanisms needed for adaptive network formation can be captured in a biologically inspired mathematical model that may be useful to guide network construction in other domains.

Studies on Absorption of Eutectic Mixture. I. A Comparison of the Behavior of Eutectic Mixture of Sulfathiazole and that of Ordinary Sulfathiazole in Man.

Abstract: 1) Sulfathiazole forms eutectic mixtures with urea, l-ascorbic acid, acetamide, nicotinic acid, nicotinamide, or succinimide. It was observed that a eutectic mixture of sulfathiazole and urea produces a microcrystalline suspension of sulfathiazole in water. 2) Sulfathiazole in a eutectic mixture with urea shows higher absorption and excretion after oral administration than ordinary sulfathiazole. 3) Since urea does not possess solubilizing action on sulfathiazole and also it does not enhance absorption of the drug physiologically, the accelerated absorption or excretion must be attributed to the physical state of sulfathiazole in its eutectic mixture with easily soluble compound, such as urea. 4) It is assumed that this new form of preparation will give a means of adjusting therapeutic effect of medical compounds.