Ganglioside GD3 sensitizes human hepatoma cells to cancer therapy

Ganglioside GD3 (GD3) has emerged as a modulator of cell death pathways due to its ability to interact with mitochondria and disable survival pathways. Because NF-kappaB activation contributes to cancer therapy resistance, this study was undertaken to test whether GD3 modulates the response of human hepatoblastoma HepG2 cells to radio- and chemotherapy. NF-kappaB was activated in HepG2 cells shortly after therapeutic doses of ionizing radiation or daunorubicin treatment that translated into up-regulation of kappaB-dependent genes. These effects were accompanied by minimal killing of HepG2 cells by either ionizing radiation or daunorubicin. However, GD3 pretreatment blocked the nuclear translocation of active kappaB members, without effect on Akt phosphorylation, induced by either treatment. The suppression of kappaB-dependent gene induction by GD3 was accompanied by enhanced apoptotic cell death caused by these therapies. Furthermore, the combination of GD3 plus ionizing radiation stimulated the formation of reactive species followed by the mitochondrial release of cytochrome c and Smac/Diablo and caspase 3 activation. Pretreatment with cyclosporin A before radiotherapy protected HepG2 cells from the therapeutic combination of GD3 plus ionizing radiation. These findings underscore a key role of mitochondria in the response of tumor cells to cancer therapy and highlight the potential relevance of GD3 to overcome resistance to cancer therapy by combining its dual action as a mitochondria-interacting and NF-kappaB-inactivating agent.     

Interferons mediate terminal differentiation of human cortical thymic epithelial cells

In the thymus, epithelial cells comprise a heterogeneous population required for the generation of functional T lymphocytes, suggesting that thymic epithelium disruption by viruses may compromise T-cell lymphopoiesis in this organ. In a previous report, we demonstrated that in vitro, measles virus induced differentiation of cortical thymic epithelial cells as characterized by (i) cell growth arrest, (ii) morphological and phenotypic changes, and (iii) apoptotis as a final step of this process. In the present report, we have analyzed the mechanisms involved. First, measles virus-induced differentiation of thymic epithelial cells is shown to be strictly dependent on beta interferon (IFN-beta) secretion. In addition, transfection with double-stranded RNA, a common intermediate of replication for a broad spectrum of viruses, is reported to similarly mediate thymic epithelial cell differentiation through IFN-beta induction. Finally, we demonstrated that recombinant IFN-alpha, IFN-beta, or IFN-gamma was sufficient to induce differentiation and apoptosis of uninfected thymic epithelial cells. These observations suggested that interferon secretion by either infected cells or activated leukocytes, such as plasmacytoid dendritic cells or lymphocytes, may induce thymic epithelium disruption in a pathological context. Thus, we have identified a new mechanism that may contribute to thymic atrophy and altered T-cell lymphopoiesis associated with many infections.     

Long-term circulation of vaccine-derived poliovirus that causes paralytic disease

Successful implementation of the global poliomyelitis eradication program raises the problem of vaccination against poliomyelitis in the posteradication era. One of the options under consideration envisions completely stopping worldwide the use of the Sabin vaccine. This strategy is based on the assumption that the natural circulation of attenuated strains and their derivatives is strictly limited. Here, we report the characterization of a highly evolved derivative of the Sabin vaccine strain isolated in a case of paralytic poliomyelitis from a 7-month-old immunocompetent baby in an apparently adequately immunized population. Analysis of the genome of this isolate showed that it is a double (type 1-type 2-type 1) vaccine-derived recombinant. The number of mutations accumulated in both the type 1-derived and type 2-derived portions of the recombinant genome suggests that both had diverged from their vaccine predecessors approximately 2 years before the onset of the illness. This fact, along with other recent observations, points to the possibility of long-term circulation of Sabin vaccine strain derivatives associated with an increase in their neurovirulence. Comparison of genomic sequences of this and other evolved vaccine-derived isolates reveals some general features of natural poliovirus evolution. They include a very high preponderance and nonrandom distribution of synonymous substitutions, conservation of secondary structures of important cis-acting elements of the genome, and an apparently adaptive character of most of the amino acid mutations, with only a few of them occurring in the antigenic determinants. Another interesting feature is a frequent occurrence of tripartite intertypic recombinants with either type 1 or type 3 homotypic genomic ends.     

Stable variants of sperm aneuploidy among healthy men show associations between germinal and somatic aneuploidy

Repeated semen specimens from healthy men were analyzed by sperm fluorescence in situ hybridization (FISH), to identify men who consistently produced elevated frequencies of aneuploid sperm and to determine whether men who were identified as stable variants of sperm aneuploidy also exhibited higher frequencies of aneuploidy in their peripheral blood lymphocytes. Seven semen specimens were provided by each of 15 men over a 2-year period and were evaluated by the X-Y-8 multicolor sperm FISH method (i.e., approximately 1,050,000 sperm were analyzed from 105 specimens). Three men were identified as stable aneuploidy variants producing significantly higher frequencies of XY, disomy X, disomy Y, disomy 8, and/or diploid sperm over time. In addition, one man and three men were identified as sperm-morphology and sperm-motility variants, respectively. Strong correlations were found between the frequencies of sperm with autosomal and sex-chromosome aneuploidies and between the two types of meiosis II diploidy; but not between sperm aneuploidy and semen quality. A significant association was found between the frequencies of sex-chromosome aneuploidies in sperm and lymphocytes in a subset of 10 men (r2=0.67, P=.004), especially between XY sperm and sex-chromosome aneuploidy in lymphocytes (r2=0.70, P=.003). These findings suggest that certain apparently healthy men can produce significantly higher frequencies of both aneuploid sperm and lymphocytes. Serious long-term somatic and reproductive health consequences may include increased risks of aneuploidy-related somatic diseases and of having children with paternally transmitted aneuploidies, such as Klinefelter, Turner, triple-X, and XYY syndromes.     

Two highly oxygenated eudesmanes and 10 lignans from Achillea holosericea

Two new highly oxygenated eudesmanes and 10 known lignans were isolated from the aerial parts of Achillea holosericea. Their structures were elucidated by extensive application of one- and two-dimensional 1H and 13C NMR spectroscopy.     

Accumulation of plant small heat-stress proteins in storage organs

Plant small heat-stress proteins (sHSPs) have been shown to be expressed not only after exposure to elevated temperatures, but also at particular developmental stages such as embryogenesis, microsporogenesis, and fruit maturation. This paper presents new data on the occurrence of sHSPs in vegetative tissues, their tissue-specific distribution, and cellular localization. We have found sHSPs in 1-year-old twigs of Acer platanoides L. and Sambucus nigra L. and in the liana Aristolochia macrophylla Lamk. exclusively in the winter months. In tendrils of Aristolochia, sHSPs were localized in vascular cambium cells. After budding, in spring, these proteins were no longer present. Furthermore, accumulation of sHSPs was demonstrated in tubers and bulbs of Allium cepa L., Amaryllis ( Hippeastrum hybridum hort.), Crocus albiflorus L., Hyacinthus orientalis L., Narcissus pseudonarcissus L., Tulipa gesneriana L., and Solanum tuberosum L. (potato). In potato tubers and bulb scales of Narcissus the stress proteins were localized in the central vacuoles of storage parenchyma cells. In order to obtain more information on a possible functional correlation between storage proteins and sHSPs, the accumulation of both types of protein in tobacco seeds during seed ripening and germination was monitored. The expression of sHSPs and globulins started simultaneously at about the 17th day after anthesis. During seed germination the sHSPs disappeared in parallel with the storage proteins. Furthermore, in embryos of transgenic tobacco plants, which do not contain any protein bodies or storage proteins, no sHSPs were found. Thus, the occurrence of sHSPs in perennial plant storage organs seems to be associated with the presence of storage proteins.     

Effect of experimental conditions on strong biocomplimentary pairing in high-performance monolithic disk affinity chromatography

The effect of flow-rate on quantitatively determined binding parameters for several biocomplementary pairs in affinity mode high-performance monolithic disk affinity chromatography (HPMDAC) has been investigated using frontal analysis approach. Affinity interactions were evaluated from linearized adsorption isotherms and dynamic dissociation constants of the complexes K(diss.) and the theoretical adsorption capacities Q(max) were calculated. HPMDAC isolation of a typical protein trypsin from both buffered solution and artificial mixture as well as biospecific extraction of antibodies against bovine serum albumin and recombinant protein G from such complex mixtures as blood serum and cellular lysate were examined. Immobilized counterparts soybean trypsin inhibitor, bovine serum albumin, and human immunoglobulin G were used in chromatographic experiments. The maximum adsorption capacities obtained at different flow-rates were compared with those determined at static conditions. The dependence of quantitative parameters on the surface density of immobilized ligands has also been explored. Finally, a series of experiments was carried out to evaluate the dependence of dynamic affinity binding on temperature for two complementary pairs.