This endoscopy-based study revealed the most common histology of benign SB tumors were hamartoma and adenoma, and malignant ones were lymphomas, GISTs, adenocarcinomas and metastatic cancers. Most of them were male gender, except for GISTs, and with proximal location, except for lymphomas. Further large-scale investigation efforts are warranted to elucidate the epidemiology of SB tumors.
bBurkholderia contaminans strain MS14 produces the antifungal compound occidiofungin, which is responsible for significant antifungal activities against a broad range of plant and animal fungal pathogens. Occidiofungin is a cyclic glycolipopeptide made up of eight amino acids and one xylose. A 56-kb ocf gene cluster was determined to be essential for occidiofungin production. In this study, the ocfC gene, which is located downstream of ocfD and upstream of the ocfB gene in the ocf gene cluster, was examined. Antifungal activity of the ocfC gene mutant MS14KC1 was reduced against the indicator fungus Geotrichum candidum compared with that of the wild-type strain. Furthermore, the analysis of the protein sequence suggests that the ocfC gene encodes a glycosyltransferase. Biochemical analyses using nuclear magnetic resonance (NMR) and mass spectroscopy revealed that the ocfC mutant produced the occidiofungin without the xylose. The purified ocfC mutant MS14KC1 product had a level of bioactivity similar to that of the wild-type product. The revertant MS14KC1-R of the ocfC mutant produced the same antifungal activity level on plate assays and the same antifungal compound based on high-performance liquid chromatography (HPLC) and mass spectroscopy analysis as wild-type strain MS14. Collectively, the study demonstrates that the ocfC gene encodes a glycosyltransferase responsible to add a xylose to the occidiofungin molecule and that the presence of the xylose is not important for antifungal activity against Candida species. The finding provides a novel variant for future studies aimed at evaluating its use for inhibiting clinical and agricultural fungi, and the finding could also simplify the chemical synthesis of occidiofungin variants.
[1] One of the challenges of hydrology is modeling flow and solute transport through media that are not uniformly porous. This paper proposes a general fractal model of flow and solute transport in randomly heterogeneous porous media. We describe the random field using fractional Levy motion (fLm), which more effectively represents a field with a high degree of variability. Understanding flow and solute transport in the fLm field expands the applicability of stochastic theory. Following the work of V. Di Federico and S. P. Neuman (1997) and V. Di Federico et al. (1999), we derive truncated isotropic and anisotropic power variograms for the fLm fields. The results are analogous to but more general than those of fractional Brownian motion (fBm) (V. Di Federico and S. P. Neuman (1997) and V. Di Federico et al. (1999)). For a random field, when the Levy index a in fLm is replaced by a constant of 2, fBm is recovered. This study employs first-order perturbation analyses of flow and solute transport in two-dimensional fLm fields. For the stationary, fBm, and fLm fields, macrodispersion coefficients are compared. The plume is found to grow slowest in the fLm field but will show highest concentration. The proposed fractal model is general in the sense that when the Levy index of fLm a equals 2, the results of flow and solute transport for the commonly used fBm model are recovered. When the upper cutoff of the truncated power variogram is close to the lower cutoff, the results for the stationary exponential or Gaussian model can be well approximated. Since the proposed general fractal model has broader applications than the stationary and fBm models, it simulates flow and solute transport in more different scenarios to yield more accurate modeling results.
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