Inhibition of human B-cell lymphoma growth by CD40 stimulation

Abstract CD40 is a molecule present on B lymphocyte lineage cells that is important in B-cell differentiation and activation. Signaling through CD40 has been shown to exert costimulatory signals on normal B cells resulting in proliferative and differentiation responses. Examination of several B-cell lymphomas showed cell-surface expression of the CD40 molecule. Incubation of these lymphomas with anti-CD40 antibodies resulted in significant growth inhibition in vitro. Cross-linking of the CD40 antibodies resulted in even greater inhibition of proliferation. A recombinant soluble human CD40 ligand was also shown to inhibit lymphoma proliferation. When various human B-cell lymphomas were transferred into mice with severe combined immune deficiency, the treatment of the mice with anti-CD40 antibodies resulted in significant increases in survival showing that anti-CD40 is efficacious after in vivo administration. Thus, CD40 stimulation by either the antibody or soluble ligand directly inhibits human B-cell lymphoma growth and therefore, may be of significant clinical use in their treatment.</jats:p

Trends of Chlorinated Organic Contaminants in Great Lakes Trout and Walleye from 1970 to 1998

Levels of chlorinated organic contaminants in predator fish have been monitored annually in each of the Great Lakes since the 1970s. This article updates earlier reports with data from 1991 to 1998 for lake trout ( Salvelinus namaycush ) and (Lake Erie only) walleye ( Sander vitreus ) to provide a record that now extends nearly 30 years. Whole fish were analyzed for a number of industrial contaminants and pesticides, including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethane (DDT), dieldrin, toxaphene, and mirex, and contaminant trends were quantified using multicompartment models. As in the past, fish from Lakes Michigan, Ontario, and Huron have the highest levels of PCBs, DDT, and dieldrin; Superior has the highest levels of toxaphene; and Ontario has the highest levels of mirex. In the period after curtailment of chemical use, concentrations rapidly decreased, represented by relatively short half-lives from approximately 1 to 9 years. Although trends depend on both the contaminant and the lake, in many cases the rate of decline has been decreasing, and concentrations are gradually approaching an irreducible concentration. For dioxin-like PCBs, levels have not been decreasing during the most recent 5-year period (1994 to 1998). In some cases, the year-to-year variation in contaminant levels is large, mainly because of food-web dynamics. Although this variation sometimes obscures long-term trends, the general pattern of a rapid decrease followed by slowing or leveling-off of the downward trend seems consistent across the Great Lakes, and future improvements of the magnitude seen in the 1970s and early 1980s likely will take much longer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48086/1/244_2005_Article_1007.pd

Seasonal effect of zebra mussel colonies on benthic processes in the temperate mesotrophic Plateliai Lake, Lithuania

Sparse colonies of zebra mussel (Dreissena polymorpha) create net heterotrophic sediment patches via respiration, excretion, and biodeposition activities, but their effect as biogeochemical hotspots is scarcely investigated in nutrient-limited ecosystems. We analyzed the seasonal effect of zebra mussel colonies on benthic respiration (O2, TCO2, N2, and CH4) and nutrient fluxes (NH4+, NOx−, SRP, and SiO2) in a macrophyte-dominated mesotrophic temperate lake. Intact sediments with and without zebra mussel aggregates were collected in winter, summer, and autumn, and incubated to measure fluxes. The contribution of mussel colonies alone to benthic metabolism was also quantified. Sediments with mussels always had higher rates of respiration (O2 and TCO2) and nutrient recycling (NH4+ and SRP) as compared to bare sediments, while there was no effect on CH4, NO3−, and SiO2 fluxes. Mussel colonies stimulated nitrogen removal via denitrification, but only in the summer. The effect of colonies was particularly evident in warmer periods, due to mussel respiration and excretion and to biodeposits that increased microbial activity in sediments. In this mesotrophic lake, mussel aggregates contribute to alleviate nutrient (N and P) limitation, but their heterotrophic activity is likely buffered by nutrient uptake and oxygen production by submersed vegetation