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Previous attempts to map science using the co-citation clustering methodology are reviewed, and their shortcomings analyzed. Two enhancements of the methodology presented in Part I of the paper-fractional citation counting and variable level clustering—are briefly described and a third enhancement, the iterative clustering of clusters, is introduced. When(More)
It was previously reported that treatment with the sulfated polysaccharide fucoidan or the structurally similar dextran sulfate increased circulating mature white blood cells and hematopoietic progenitor/stem cells (HPCs) in mice and nonhuman primates; however, the mechanism mediating these effects was unclear. It is reported here that plasma concentrations(More)
Treatment of human neutrophils with tumor necrosis factor-alpha (TNF-alpha) resulted in an increase in concentration of ceramide and its catabolite, sphingosine. Sphingosine, a potent endogenous protein kinase C (PKC) inhibitor, as well as TNF-alpha, induced internucleosomal DNA fragmentation and morphological changes characteristic of apoptotic cells.(More)
Earlier experiments in the use of co-citations to cluster theScience citation Indey (SCI) database are reviewed. Two proposed improvements in the methodology are introduced: fractional citation counting and variable level clustering with a maximum cluster size limit. Results of an experiment using the 1979SCI are described comparing the new methods with(More)
Diverse physical and chemical stimuli can activate sphingomyelinases (SMases), resulting in sphingomyelin (SM) hydrolysis with ceramide release. Since ceramide can profoundly impact a host of homeostatic mechanisms, the concept of a "SM (or SMase) signaling pathway" has emerged. We recently documented that ceramide levels fall abruptly during renal(More)
Our previous work showed that sphingosine 1-phosphate (Sph-1-P) inhibits the cell motility of mouse melanoma B16/F10, and other types of cells at 10-100 nM concentrations. In the present paper, we have identified and characterized specific cell surface binding sites for Sph-1-P in F10 cells. Sph-1-P immobilized on controlled pore glass beads inhibited the(More)
Resistance to apoptosis plays an important role in tumors that are refractory to chemotherapy and ionizing radiation (IR). bax, which forms a heterodimer with bcl-2 and accelerates apoptosis, is not, or only weakly, expressed in most human breast cancer cells, and weak bax expression is considered to be related to the resistance of breast cancer cells to(More)
Disruption of collagen X function in hypertrophic cartilage undergoing endochondral ossification was previously linked to altered hematopoiesis in collagen X transgenic (Tg) and null (KO) mice (Jacenko et al., [2002] Am J Pathol 160:2019-2034). Mice displayed altered growth plates, diminished trabecular bone, and marrow hypoplasia with an aberrant(More)
The present studies were undertaken to characterize the potential role of sphingosine in the regulation of apoptosis in HL-60 promyelocytic leukemia cells. A 6-h exposure of HL-60 cells to sphingosine or its methylated derivative, N,N-dimethylsphingosine, caused internucleosomal DNA fragmentation and stereotypical morphological changes characteristic of(More)