Synthesis and Phytotoxic Evaluation of Isatin Derivatives Supported by 3D-QSAR Study.

Concerned about weed infestation, a major threat to food production and herbicide resistance that interferes in the mechanism of action of the main herbicides, we have synthesized eight isatin derivatives using the "Click Chemistry" approach through copper-catalyzed azide-alkyne cycloadditions (CuAAC). Sixteen isatin derivatives were evaluated for their phytotoxic activity against the seed culture of the model plants, Lactuca sativa and Allium cepa. Six of them showed phytotoxic activity similar to the positive control, trifluralin. Hypocotyl length measurement analysis in L. sativa revealed that triazole derivative 8 is more active than trifluralin. For A. cepa, root length measurement analyses revealed that 3, 10, 14, 16, and 17 were similar to the positive control trifluralin. Three-dimensional quantitative structure-activity relationship (3D-QSAR) comparative molecular field analysis (CoMFA) model construction using the acetolactate synthase (ALS) crystallographic structure displayed pki values of predicted inhibitory activity and contour maps revealing sterically bulky groups for 11, the CF3 group in ortho, and for 17, Br in ortho, favoring the inhibitory ALS activity.

Elemental characterization of oral cavity squamous cell carcinoma and its relationship with smoking, prognosis and survival.

Oral cancer squamous cell carcinoma (OCSCC) mainly affects individuals aged between 50 and 70 years who consume tobacco and alcohol. Tobacco smoke contains hundreds of known toxic and carcinogenic molecules, and a few studies have sought to verify the relationship of such trace elements as risk or prognostic factors for head and neck cancer. We obtained 78 samples of tumor tissues from patients with OCSCC, and performed a qualitative elemental characterization using the micro X-Ray Fluorescence technique based on synchrotron radiation. We found the presence of magnesium, phosphorus, sulfur, chlorine, potassium, calcium, chromium, manganese, iron, zinc, cobalt, nickel, copper, arsenic and bromine in OCSCC samples. Magnesium, chlorine, chromium, manganese, nickel, arsenic and bromine are associated with smoking. We observed a significant association between relapse and chlorine and chromium. The presence of chlorine in the samples was an independent protective factor against relapse (OR = 0.105, CI = 0.01-0.63) and for best disease-free survival (HR = 0.194, CI = 0.04-0.87). Reporting for the first time in oral cancer, these results suggest a key relationship between smoking and the presence of certain elements. In addition, chlorine proved to be important in the context of patient prognosis and survival.

Graph cuts and neural networks for segmentation and porosity quantification in Synchrotron Radiation X-ray µCT of an igneous rock sample.

X-ray Synchrotron Radiation Micro-Computed Tomography (SR-µCT) allows a better visualization in three dimensions with a higher spatial resolution, contributing for the discovery of aspects that could not be observable through conventional radiography. The automatic segmentation of SR-µCT scans is highly valuable due to its innumerous applications in geological sciences, especially for morphology, typology, and characterization of rocks. For a great number of µCT scan slices, a manual process of segmentation would be impractical, either for the time expended and for the accuracy of results. Aiming the automatic segmentation of SR-µCT geological sample images, we applied and compared Energy Minimization via Graph Cuts (GC) algorithms and Artificial Neural Networks (ANNs), as well as the well-known K-means and Fuzzy C-Means algorithms. The Dice Similarity Coefficient (DSC), Sensitivity and Precision were the metrics used for comparison. Kruskal-Wallis and Dunn's tests were applied and the best methods were the GC algorithms and ANNs (with Levenberg-Marquardt and Bayesian Regularization). For those algorithms, an approximate Dice Similarity Coefficient of 95% was achieved. Our results confirm the possibility of usage of those algorithms for segmentation and posterior quantification of porosity of an igneous rock sample SR-µCT scan.