Study of the effect of lithium on lymphokine-activated killer cell activity and its antitumor growth

The in vitro effect of lithium on lymphokine-activated killer cell (LAK) activity and its in vivo antitumor growth were observed. LAK activity was enhanced when LiCl was added during LAK cell induction, and this enhancement was observed both in human peripheral blood mononuclear cell and in mouse splenocytes used as LAK precursors. Cholera toxin, which can increase intracellular levels of cAMP, decreased LAK cell activity. However, lithium partially reversed this inhibitory effect, indicating that lithium increased LAK cell activity by decreasing cAMP levels. D-Sphingosine, an inhibitor of protein kinase C, and EGTA, a calcium chelator, both inhibited the LAK cell activity. However, their inhibitory effects could not be reversed by lithium because lithium was added in the culture in combination with one of these inhibitors during LAK cell induction. By using slot blot analysis, the effect of lithium on the expression of tumor necrosis factor-alpha mRNA of LAK cells was analyzed. Lithium increased the level of tumor necrosis factor-alpha mRNA when both lithium and interleukin 2 were added to induce LAK cells. The in vivo antitumor effect of lithium has also been studied. Using a mouse melanoma experimental model, the effect of lithium on tumor growth was also observed. Both lithium alone and interleukin 2/LAK had an antitumor effect, whereas the treatment of interleukin 2/LAK in combination with lithium had the strongest inhibitory effect on tumor growth, since this treatment resulted in reduction of tumor size and prolongation of survival in tumor-bearing mice. Therefore, it is hopeful that lithium can be used as a new immunomodulator for cancer immunotherapy and immune diseases.

Kinetic studies on the formation and decomposition of compounds II and III. Reactions of lignin peroxidase with H2O2

The present study characterizes the serial reactions of H2O2 with compounds I and II of lignin peroxidase isozyme H1. These two reactions constitute part of the pathway leading to formation of the oxy complex (compound III) from the ferric enzyme. Compounds II and III are the only complexes observed; no compound III* is observed. Compound III* is proposed to be an adduct of compound III with H2O2, formed from the complexation of compound III with H2O2 (Wariishi, H., and Gold, M. H. (1990) J. Biol. Chem. 265, 2070-2077). We provide evidence that demonstrates that the spectral data, on which the formation of compound III* is based, are merely an artifact caused by enzyme instability and, therefore, rule out the existence of compound III*. The reactions of compounds II and III with H2O2 are pH-dependent, similar to that observed for reactions of compounds I and II with the reducing substrate veratryl alcohol. The spontaneous decay of the compound III of lignin peroxidase results in the reduction of ferric cytochrome c. The reduction is inhibited by superoxide dismutase, indicating that superoxide is released during the decay. Therefore, the lignin peroxidase compound III decays to the ferric enzyme through the dissociation of superoxide. This mechanism is identical with that observed with oxymyoglobin and oxyhemoglobin but different from that for horseradish peroxidase. Compound III is capable of reacting with small molecules, such as tetranitromethane (a superoxide scavenger) and fluoride (a ligand for the ferric enzyme), resulting in ferric enzyme and fluoride complex formation, respectively.

A study of change in age at first marriage and first fertility of Chinese women and population control

The author examines the decline in Chinese women's "age at first marriage..., going on to analyze trends of development in women's average age at first marriage and changes in the interval before first fertility over the last few decades, and from there proposes an effective way to alleviate the population peak and control the population--gradually lengthening the interval before first fertility on the basis of maintaining the average age at first marriage." Data are from the 1982 census and other official sources.

Retinoids induce tissue transglutaminase in NIH-3T3 cells

We report that all-trans and 13-cis-retinoic acid as well as the synthetic compound CH-55 enhance tissue transglutaminase activity as they increase NIH-3T3 cell adhesiveness. The 4-hydroxyphenylretinamide (4-HPR) with low activity in inducing attachment, lectin binding and growth inhibition also fails to induce transglutaminase. Thyroxine (Thy), a compound with a response element common to RA, is inactive. The tumor promoter 12-tetradecanoyl-phorbol-13-acetate (TPA), which increases adhesiveness with different kinetics than RA, failed to enhance tranglutaminase. We conclude that retinoids with biological activity in inducing adhesion, inhibition of growth and increase of lectin binding, are also active in inducing transglutaminase activity.