Scatter factor : molecular characteristics and effect on the invasiveness of epithelial cells

The generation of invasiveness in transformed cells represents an essential step of tumor progression. We have previously shown that MDCK epithelial cells, which are deprived of intracellular adhesion by the addition of anti-Arc-1/uvomorulin antibodies, become invasive for collagen gels and embryonal heart tissue (Behrens, J., M. M. Mareel, F. M. Van Roy, and W. Birchmeier. 1989. J. Cell Biol. 108: 2435-2447.). Here we examined whether invasiveness is also induced by scatter factor, which is known to dissociate epithelial cells (Stoker, M., E. Gherardi, M. Perryman, and J. Gray. 1987. Nature (Lond.). 327:239-242.). Scatter factor was purified to homogeneity from conditioned medium of human fibroblasts by heparin-Sepharose chromatography, followed by cation exchange chromatography, gel filtration, or preparative SDS gel electrophoresis. We found that scatter factor represents a 92,000 mol wt glycoprotein which, apparently, is converted by limited proteolysis into disulfide-linked 62,000 and 34/32,000 mol wt subunits. Reversed phase HPLC and sequence analysis of tryptic peptides confirmed the suggested molecular structure, and revealed further that scatter factor exhibits sequence similarities to hepatocyte growth factor and to plasminogen. Purified scatter factor in fact induces the invasiveness into collagen matrices of MDCK epithelial cells, and induces or promotes the invasiveness of a number of human carcinoma cell lines. Apparently, the effect on the human cells depends on their respective degree of differentiation, i.e., cell lines with a less pronounced epithelial phenotype were more susceptible to the factor. Scatter factor does not seem to influence synthesis, steady-state level, and phosphorylation of the cell adhesion molecule Arc-1/uvomorulin. Thus, scatter factor represents a clearly defined molecular species which induces, in vitro, the progression of epithelial cells to a more motile, i.e., invasive phenotype

The combinatorics and the homology of the poset of subgroups of p-power index

AbstractFor a finite group G and a prime p the poset Sp (G) of all subgroups H ≠ G of p-power index is studied. The Möbius number of the poset is given and the homotopy type of the poset is determined as a wedge of spheres. We describe the representation of G on the homology groups of the order complex of Sp (G) and show that this representation can be realized by matrices with entries in the set {+1, -1, 0}. Finally a CL-shellable subposet of Sp (G) is exhibited for odd primes p

Gastrointestinal Neoplasia Associated with Bowel Parasitosis: Real or Imaginary?

Several parasitic species are well known to have carcinogenic properties, namely; Schistosoma hematobium (squamous cell carcinoma of the bladder) and the liver flukes Opisthorchis and Chlonorchis (cholangiocarcinoma). A large number of parasites are known to colonize the gastrointestinal tract. We sought to review the evidence that implicates these parasites in gastrointestinal neoplasia. Schistosoma japonicum, which is endemic primarily in east Asia, has been shown in multiple studies to convey a mildly increased risk of colorectal adenocarcinoma. The data supporting a causative role for Schistosoma mansoni in colorectal or other neoplastic processes are less convincing, limited primarily to small case-control studies and case series. Reports of possible associations between other gastrointestinal parasites (e.g., E. histolytica and A. lumbricoides) and neoplasia may be found in the literature but are limited to individual cases. We conclude that, other than S. japonicum and to a lesser extent S. mansoni, there is little evidence of an association between gastrointestinal parasites and neoplasia

One-dimensional arrangements of metal atoms in transition metal carbonyl complexes of mixed main group metal alkoxides

Mixed metal alkoxides containing main group elements with ns2 electron configurations of the general formula M(OtBu)3M\u27 (M = In, Tl; M\u27 = Ge, Sn, Pb), M\u27(OtBu)3M(OtBu)3M\u27 (M = divalent metal atom, M\u27 = Ge, Sn) and (OtBu)M\u27(OtBu)2M(OtBu)2M\u27(OtBu) (M = Co, Ni; M\u27 = Ge, Sn) can be reacted with simple metal carbonyls. The products obtained are composed of a one-dimensional array of metal atoms held together by direct metal-metal bonds or by bridging alkoxide groups. The following compounds have been isolated and characterized by IR and NMR spectroscopy and X-ray diffraction (M\u27 = Ge, Sn, Pb; M = In, Tl; MT = transition metal): M\u27(OtBu)3M-MT(CO)n, (CO)nMT-M(OtBu)3M\u27-MT(CO)n, M\u27(OtBu)3M-MT(CO)nM(OtBu)3M\u27, (CO)nMT-M\u27(OtBu)3M(OtBu)3M\u27-MT(CO)n, (CO)nMT-M\u27[OtBu](OtBu)2M(OtBu)2M(OtBu)2[OtBu]M\u27-MT(CO)n and (CO)nMT-M\u27(OtBu)3M-MT(CO)nM(OtBu)3M\u27-MT(CO)n. In addition, an oligomeric species of the general formula [Sn(OtBu)3In-Mo(CO)4]n-Sn(OtBu)3In-Mo(CO)5 with n ~ 9, 10 has been isolated

Defining the optimal animal model for translational research using gene set enrichment analysis

The mouse is the main model organism used to study the functions of human genes because most biological processes in the mouse are highly conserved in humans. Recent reports that compared identical transcriptomic datasets of human inflammatory diseases with datasets from mouse models using traditional gene‐to‐gene comparison techniques resulted in contradictory conclusions regarding the relevance of animal models for translational research. To reduce susceptibility to biased interpretation, all genes of interest for the biological question under investigation should be considered. Thus, standardized approaches for systematic data analysis are needed. We analyzed the same datasets using gene set enrichment analysis focusing on pathways assigned to inflammatory processes in either humans or mice. The analyses revealed a moderate overlap between all human and mouse datasets, with average positive and negative predictive values of 48 and 57% significant correlations. Subgroups of the septic mouse models (i.e., Staphylococcus aureus injection) correlated very well with most human studies. These findings support the applicability of targeted strategies to identify the optimal animal model and protocol to improve the success of translational research

Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations

[abridged] The galactic field's late-type stellar single and binary population is calculated on the supposition that all stars form as binaries in embedded star clusters. A recently developed tool (Marks, Kroupa & Oh) is used to evolve the binary star distributions in star clusters for a few Myr so that a particular mixture of single and binary stars is achieved. On cluster dissolution the population enters the galactic field with these characteristics. The different contributions of single stars and binaries from individual star clusters which are selected from a power-law embedded star cluster mass function are then added up. This gives rise to integrated galactic field binary distribution functions (IGBDFs) resembling a galactic field's stellar content (Dynamical Population Synthesis). It is found that the binary proportion in the galactic field of a galaxy is larger the lower the minimum cluster mass, the lower the star formation rate, the steeper the embedded star cluster mass function and the larger the typical size of forming star clusters in the considered galaxy. In particular, period-, mass-ratio- and eccentricity IGBDFs for the Milky Way are modelled. The afore mentioned theoretical IGBDFs agree with independently observed distributions. Of all late-type binaries, 50% stem from M<300M_sun clusters, while 50% of all single stars were born in M>10^4M_sun clusters. Comparison of the G-dwarf and M-dwarf binary population indicates that the stars formed in mass-segregated clusters. In particular it is pointed out that although in the present model all M-dwarfs are born in binary systems, in the Milky Way's Galactic field the majority ends up being single stars. This work predicts that today's binary frequency in elliptical galaxies is lower than in spiral and in dwarf-galaxies. The period and mass-ratio distributions in these galaxies are explicitly predicted.Comment: 14 pages, 9 figures, accepted for publication in MNRA

High‐temperature ternary oxide phases in Ta/Nb‐Alumina composite materials

Coarse-grained composites of refractory ceramics and refractory metals are a novel approach for materials at application temperatures up to 1500 °C. Al$_{2}$O$_{3}$ and the refractory metals Nb and Ta are suitable candidates for enhanced thermal shock capability, as they show similar thermal expansion. During fabrication, a key aspect to consider is the possible formation of additional phases upon interaction of the constituent phases as well as through reaction with the environment. X-Ray diffraction (XRD) and investigations of the microstructure with scanning electron microscopy methods unveil Al$_{2}$O$_{3}$–Nb composite to form NbO, whereas for Al$_{2}$O$_{3}$–Ta the ternary compound aluminum tantalate (AlTaO$_{4}$) is found. Thermodynamic calculations show that the changing oxygen solubility in Nb accounts for the formation of NbO, and explain the absence of a corresponding niobate (AlNbO4) phase. AlTaO$_{4}$ is identified as the disordered tetragonal high-temperature modification