Elemental changes associated with chondrocyte differentiation in rat rib growth plate

Summary Quantitative X-ray microanalysis was under-taken to follow the elemental changes that occur in the process of chondrocyte differentiation. For analysis at the cellular level, semi-thick freeze-dried cryosections of rat rib growth plate cartilage were used. For evaluation of the elemental concentrations at the subcellular level, thin sections of freeze-dried and low temperature vacuum embedded cartilage were analyzed. Levels of Na, P, S, Cl, K, and Ca were determined in the cells and extracellular matrix in different zones of the cartilage — resting, proliferative, and hypertrophic. Proliferative cells had a sodium concentration that was twice that of resting cells, suggesting that Na may play an important role in the regulation of DNA- and protein-synthesis in chondrocytes. A concomitant rise in Na and S concentration occurred between resting zone and proliferative zone cartilage matrix. The high concentrations of Na and K in the matrix are probably due to the high amount of sulfate in proteoglycans which may bind these cations.     

SAA does not induce cytokine production in physiological conditions

SAA has been shown to have potential proinflammatory properties in inflammatory diseases such as atherosclerosis. These include induction of tumor necrosis factor α, interleukin-6, and monocyte chemoattractant protein 1 in vitro. However, concern has been raised that these effects might be due to use of recombinant SAA with low level of endotoxin contaminants or its non-native forms. Therefore, physiological relevance has not been fully elucidated. In this study, we investigated the role of SAA in the production of inflammatory cytokines. Stimulation of mouse monocyte J774 cells with lipid-poor recombinant human SAA and purified SAA derived from cardiac surgery patients, but not ApoA-I and ApoA-II, elicited pro-inflammatory cytokines like granulocyte colony stimulating factor (G-CSF). However, HDL-associated SAA failed to stimulate production of these cytokines. Using neutralizing antibodies against toll like receptor (TLR) 2 and 4, we could evaluate that TLR 2 is responsible for G-CSF production by lipid-poor SAA. To confirm these data in vivo, we expressed mouse SAA in SAA deficient C57BL/6 mice using an adenoviral vector. G-CSF was identically expressed in SAA-Adenoviral infected mice as well as in control null-Adenoviral mice at the early time points (4–8 h) and could not be detected in plasma 24 h after infection when plasma SAA levels were maximally elevated, indicating that adenoviral vector rather than SAA affected G-CSF levels. Taken together, our findings suggest that lipid-poor SAA, but not HDL-associated SAA, stimulates G-CSF production and this stimulation is mediated through TLR 2 in J774 cells. However, its physiological role in vivo remains ambiguous.     

Bidimensional immunoelectrophoretic study of the antigenic composition of the membrane in various mycoplasma strains]

Membrane antigenic composition of Acheloplasma laidlawii PG9, A. granularum BTS-39, and Mycoplasma fermentans PG 18(G) was determined by means of bidimensional immunoelectrophoresis in the presence of sodium desoxycholate 0.5%. Depending upon the mycoplasma species from which membranes were obtained, 7 to 15 antigens were evidenced. Using sodium desoxycholate presents the advantage over non-ionic detergents to dissolve better the mycoplasmic membrane antigenic complexes. A comparative study of five strains belonging to the above-noted species confirms the serological heterogeneity of the Mycoplasmateles order and shows variability at the membrane antigenic composition level of Acheloplasma laidlawii.     

HAT: Hypergeometric Analysis of Tiling-arrays with application to promoter-GeneChip data

Background  

Tiling-arrays are applicable to multiple types of biological research questions. Due to its advantages (high sensitivity, resolution, unbiased), the technology is often employed in genome-wide investigations. A major challenge in the analysis of tiling-array data is to define regions-of-interest, i.e., contiguous probes with increased signal intensity (as a result of hybridization of labeled DNA) in a region. Currently, no standard criteria are available to define these regions-of-interest as there is no single probe intensity cut-off level, different regions-of-interest can contain various numbers of probes, and can vary in genomic width. Furthermore, the chromosomal distance between neighboring probes can vary across the genome among different arrays.