Recently, it was reported that reduction in serum adiponectin levels is correlated with the incidence of breast cancer. As an effort to explain this, we screened various human breast cancer cell lines to identify those in which proliferation is directly controlled by adiponectin. Among the five tested cell lines, proliferation of MDA-MB-231 cancer cell was significantly suppressed by adiponectin within the range of physiological concentration. Furthermore, prolonged adiponectin treatment caused cell growth arrest and even apoptosis of MDA-MB-231. This result is the first to show that adiponectin can directly control cancer cell growth and provides a rationale for the theory that reduction in plasma adiponectin levels could be a risk factor for breast cancer.

β-glucan is a polysaccharide in the form of fiber and the main element of fiber in grains such as barley, oats, yeast and mushrooms. Many studies have examined the efficacy of β-glucan in terms of the lipid lowering effects, blood sugar reduction, weight reduction, immune modulator, and anticarcinogenic effect. However, there is no comprehensive review article on the biomedical issues regarding β-glucan. The authors searched for systematic reviews and clinical experiments for each relevant topic and reviewed the biomedical effects of β-glucan, for the purpose of developing research strategies for the future.

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We used an acetylene reduction assay to measure rates of nitrogen fixation on a 38-year-old Alnus hirsuta plantation in central Korea. The diurnal pattern of acetylene reduction changed significantly during May, August, and October, typically varying by 3-fold throughout the course of the day. Maximum rates occurred at 3 p.m. in May and October, but at 6 p.m. in August. Increasing trends were evident during the early growing season, with sustained high rates from mid-May through late September; July had the highest rates, averaging 7.2 ~mole g-1 dry nodule h ~. The average nodule biomass for this plantation was 220 kg ha 1. Rates of acetylene reduction were related to soil temperature, but not to soil moisture content. Combining these nodule biomass calculations with seasonal average acetylene reduction rates yielded an estimate of current annual nitrogen fixation of 60 kg N ha -~ for the plantation. This rate of annual nitrogen addition was very large in relation to the yearly nitrogen requirements of coniferous and deciduous forests in central Korea.

Changes in land use can affect the distribution and cycling of soil organic matter and nutrients. Soil organic carbon (C) and nitrogen (N) concentrations, soil CO 2 evolution, litter decomposition, and soil N availability under the three types of conversion of agricultural lands to natural vegetation (rice field conversion to forest, crop field conversion to shrub, and indigenous forest) in central Korea after 20 years of fallow were compared. There was no significant change in soil organic C and N concentrations among the three types at the three soil depths, and soil organic C and N increases were confined to the topsoil (0 -10 cm). Soil CO 2 evolution tracked seasonal soil temperature, however, there was no difference among conversion types. Annual soil CO 2 evolution (Mg CO 2 /ha/yr) was 36:0^3:7 for the rice field conversion to forest site, 33:8^4:1 for the crop field conversion to shrub site, and 40:7^4:1 for the indigenous forest site, respectively. After decomposing for one year, 55.8% for the rice field conversion site, 64.9% for the crop field conversion site, and 66.3% for the indigenous forest site of the original leaf litter mass remained. The soil moisture condition seemed to limit the rate of decomposition in the study area. Resin NO 2 3 -N concentration was higher at the rice field conversion site.