Inhibition of epidermal growth factor-induced DNA synthesis by tyrosine kinase inhibitors

We prepared methyl 2,5-dihydroxycinnamate as a stable analogue of erbstatin, a tyrosine kinase inhibitor. This analogue was about 4 times more stable than erbstatin in calf serum. It inhibited epidermal growth factor receptor-associated tyrosine kinase in vitro with an IC₅₀ of 0.15 μg/ml. It also inhibited in situ autophosphorylation of epidermal growth factor receptor in A431 cells. Methyl 2,5-dihydroxycinnamate was shown to delay the S-phase induction by epidermal growth factor in quiescent normal rat kidney cells, without affecting the total amount ofDNA synthesis. The effect of erbstatin on S-phase induction was smaller, possibly because of its shorter life time.     

Inhibition of ischemia and reflow-induced liver injury by an SOD derivative that circulates bound to albumin

Ischemia followed by reflow often results in tissue injury. Although reactive oxygens seem to play an important role in the pathogenesis of postischemic reflow-induced tissue injury, the mechanism and an efficient way to inhibit oxidative injury are not known. We studied the mechanism by which hepatic transport function was inhibited by a transient occlusion followed by reflow of the portal vein and hepatic artery by using a superoxide dismutase (SOD) derivative (SM-SOD) which circulates bound to albumin with a half-life of 6 h. Occlusion of the hepatic vessels for 20 min followed by reflow for 60 min significantly inhibited transhepatic transport of cholephilic ligands, such as bromosulfophthalein (BSP) and taurocholic acid. Intravenous administration of SM-SOD markedly inhibited the reflow-induced decrease in transhepatic transport of these ligands. Thiobarbituric acid - reactive metabolites (TBAR) in the liver and plasma remained unchanged during occlusion and reflow, while TBAR in the bile increased significantly. Intravenous injection of SM-SOD inhibited the reflow-induced increase in biliary TBAR. Xanthine oxidase activity in plasma also increased during occlusion and reflow by an SM-SOD-inhibitable mechanism. Polymorphonuclear leukocyte-dependent chemiluminescence of the peripheral blood remained unchanged during occlusion, but increased markedly with time after reflow. SM-SOD also inhibited the increase in chemiluminescence almost completely. These and other results suggested that the superoxide radical and/or its metabolite(s) might play an important role in the pathogenesis of the reflow-induced liver injury and that SM-SOD might be useful for studying the mechanism for tissue injury caused by oxygen toxicity.     

Study on the chemical evolution of low molecular weight compounds in a highly oxidized atmosphere using electric discharges

The molecular basis for the chemical evolution of low molecular compounds was studied using electric discharges on a higly oxidized atmosphere comprised of CO₂, N₂ and H₂O. In the gas phase, O₂ and CO were formed by the decomposition of CO₂ and their yields were enhanced by the addition of N₂ to the gas mixture. It was demonstrated that H₂O suppressed the reduction of CO₂ while H₂O also had a role in producing organic compounds such as formic acid and formaldehyde. Infrared analysis of the water soluble products and the inner surface of the reaction vessel indicated the production of compounds more complex than formic acid and formaldehyde. These compounds contained the chemical bonds which were identified to be OH, CO, CN and/or CC.     

Formation of amino acids from reactor-irradiated ammonium acetate

Ammonium acetate in various conditions was irradiated in a reactor to examine the contributions of both the reactor radiations and recoiled¹⁴C nucleis to form the biologically interesting molecules. Present investigations demonstrated that several amino acids, glycine, alanine, -alanine and GABA, and may-be aspartic acid, serine and valine by prolonged irradiation, were formed in the aqueous solutions of ammonium acetate.¹⁴C-radioactivities were also found distributed in these amino acids. However, no special relationship between¹⁴C-radioactivity and these amino acids formed was observed.     

Seasonal and areal features of the lagoonal environment in Lake Nakanoumi,a shallow coastal lagoon in Japan

Lake Nakanoumi is a shallow coastal lagoon connected with the Japan Sea by a narrow channel. Over the past decade, land reclamation resulted in a 33% reduction of the lagoon's surface area. The remaining water basin of Lake Nakanoumi is scheduled to be artificially freshened to supply irrigation water for the newly reclaimed lands. This paper deals with the seasonal and areal features of the lagoonal environment prior to the beginning of the artificial desalinization.     

Changes in the levels of prostaglandins and thromboxane and their roles in the accumulation of exudate in rat carrageenin-induced pleurisy — a profile analysis using gas chromatography-mass spectrometry —

Injection of γ-carrageenin into t he pleural cavity of rats caused the accumulation of the pleural exudate. When levels of prostaglandins (PGs) and thromboxane (TX) B₂ were quantified by gas chromatography-mass spectrometry as their methyl ester (ME)-dimethyllisopropylsilyl (DMiPS) ether or ME-methoxine-DMiPS ether derivatives, 6-keto-PGF_1α reached the maximum at 1 hr after carrageenin, then PGE₂ and TXB₂ showed peaks at 3 hr and waned off before 9 hr. he PGF_2α level was kept low, but PGD₂, PGE₁ and PGF_1α were not detected. Aspirin (100 mg/kg, i.p.) significantly decreased the PG and TXB₂ levels and suppressed the rate of plasma exudation until 5 hr, but did not at 7 hr, when it was measured by the amount of exuded pontamine sky blue injected intravenously. OKY-025 (300 mg/kg, i.p.), a selective TXA synthetase inhibitor, and tranylcypromine (20 mg/kg, i.p.), a PGI synthetase inhibitor, could not extensively inhibit the accumulation of the exudate. These results suggest that the cyclooxygenase products of arachidonic acid, particularly PGE₂, definitely play an important role in the exudation during the first 5 hr.     

Electrophoretically estimated genetic distance and divergence time between chimpanzee and man

Amount of genetic differentiation between chimpanzee and man was estimated from the result of comparative electrophoretic screening of blood protein variations at 32 independent genetic loci. TheNei's genetic distance (D) was calculated as 0.4514, and from this value the divergence time between the two species was estimated as 2.26 million years; considering the variation among amino-acid substitution rate in different proteins, the corrected figures were given as genetic distance of 0.5706 and divergence time of 2.85 million years. This genetic difference is considered too small the two species to be allocated in different families, in accordance with the results of the similar kind of analyses byKing andWilson (1975) and Bruce andAyala (1979). Discussions were made for a discrepancy between the divergence times estimated by using and not by using the splitting time recognized by paleoprimatologists as a reference, and for the difference in the estimations made in different laboratories.     

Population genetics of Japanese monkeys: II. Blood protein polymorphisms and population structure

Genetic variability in individual troops of the Japanese macaque (Macaca fuscata fuscata) was quantified by the proportion of polymorphic loci and the average heterozygosity per individual from the results of starch-gel electrophoreses of blood proteins controlled by 32 independent genetic loci. The former averaged 9.2% and the latter 1.3%, the values being remarkably lower than those estimated for other animal populations. Geographical distribution of the genetic variations was not uniform in the whole species but the variants occurred only in limited areas. Assuming the selective neutrality of segregating alleles and the two-dimensional stepping-stone model of population structure, the genetic migration rate between the local demes per generation could be estimated to average less than inverse of average effective deme size. Here, the local deme is not a troop itself, but it consists of several troops tightly connected with each other by frequent exchanges of reproductive males. Analyses of correlation between geographic and genetic distances between troops revealed that the gene constitutions of two troops apart more than 100 km on an island could be regarded as practically independent of each other. These results suggest that the population structure of the Japanese macaque species has a tendency to split into a number of local subpopulations in which the effect of random genetic drift is prevailing.     

Semisynthesis and properties of some insulin analogs

The trypsin-catalyzed coupling of bovine (Boc)₂-desoctapeptide (B23-B30)-insulin with synthetic octapeptides, H-Gly-X₂-X₃-X₄-Thr-Pro-Lys(Boc)-Thr-OH (X₂ = Phe or Ala, X₃ = Phe or Ala, X₄ = Tyr or Ala), followed by deprotection and purification produced the [Ala^B24, Thr^B30]-, [Ala^B25, Thr^B30]-, and [Ala^B26, Thr^B30]-analogs of bovine insulin in yields of 32, 35, and 32%, respectively. The biological activity of these analogs decreased in the order, normal insulin ([Thr^B30]-bovine insulin) = Ala^B26-insulin > Ala^B25-insulin > Ala^B24-insulin, as assayed for receptor binding and some other biological effects, in contrast with the corresponding Leu-analogs of human insulin, in which the activity decreased in the order, normal insulin > Leu^B24-insulin > Leu^B25-insulin. The affinity to insulin antibodies greatly diminished in both Ala^B24-insulin and Leu^B24-insulin but not in the B25-substituted analogs. The CD spectra of the Leu- and the Ala-analogs were compared with those of normal insulins to show that no apparent correlation seems to exist between the decrease in biological activity and the conformational changes observed in solution. The effects of organic solvents on the peptide-bond equilibrium and on the stability of trypsin are also discussed.     

Asymmetrical radical formation in D- and L-alanines irradiated with yttrium-90β-rays

Radical formation in^{9 0}Y--irradiated D- and L-alanines was studied using ESR. It was observed that the relative radical concentration by -irradiation was distinguishably (13.9–21.5%) more in D-alanine than in L-alanine. Discussion was made on the possible mechanisms for the observed results.