Various reduced-order surrogate models for fluid flow and mass transfer in human bronchial tree

Biomechanics and Modeling in Mechanobiology - The bronchial tree plays a main role in the human respiratory system because the air distribution throughout the lungs and gas exchange with blood...     

Candida albicans possess a highly versatile and dynamic high‐affinity iron transport system important for its commensal‐pathogenic lifestyle

Iron is an essential nutrient for nearly all organisms, but iron overdose is toxic. The human commensal‐pathogenic fungus Candida albicans traverses host niches with markedly different iron availability. During systemic infection, C. albicans must activate the high‐affinity iron permease Ftr1 to acquire iron sequestered by the host's iron‐withholding defense and suppresses iron uptake while residing in the iron‐rich gut to avoid toxicity. Ftr1 associates with a ferroxidase to form an iron transporter. C. albicans contains four permeases and five ferroxidase homologs, suggesting 20 possible subunit combinations. Here, we investigated the iron‐dependent expression, cellular localization and interacting partners of all permeases and ferroxidases and the significance of each subunit for gastrointestinal colonization and systemic infection in mice. We uncovered three distinct patterns of iron‐dependent expression and highly flexible ferroxidase‐permease partnerships, which underlie a dynamic iron transport system that can be deftly tuned according to iron availability. We found functional differentiation as well as redundancy among the ferroxidases and permeases during both gastrointestinal colonization and bloodstream infection. We propose that C. albicans possesses a sophisticated iron acquisition and utilization system befitting its commensal‐pathogenic lifestyle. Our findings reveal new possibilities for medical intervention of C. albicans infection.     

Synthesis of new uracil derivatives and their sugar hydrazones with potent antimicrobial,antioxidant and anticancer activities

Abstract

6-(4-Chloro-3-nitrophenyl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile (4) was prepared and was reacted with ethyl chloroacetate, hydrazine hydrate, 4-chloroaniline, formaldehyde, acetic anhydride, formic acid, carbon disulfide, 4-cyanobenzaldehyde, triethyl orthoformate, D-sugars, 4-aminoacetophenone, benzoyl choride and cyclohexanone to afford a series of new uracil derivatives (5–18). Examination of some of the prepared compounds for their antimicrobial, antioxidant and anticancer activities was conducted. Among the tested samples, compound 17 was the most active substance against the gram-positive bacteria and was more potent than the reference drug Cefoperazone. Moreover, the antibacterial activity of 17 was higher against gram-negative bacteria. Compounds 6 and 13 reached a higher scavenging ability toward DPPH radicals and are better candidates for antioxidant activity. Also, compounds 6 and 13 had no significant anticancer activity toward liver cancer (Hep G2) and breast cancer (MCF-7) cell lines.     

Herbicide tolerance in maize is related to increased levels of glutathione and glutathione-associated enzymes

Treatment of 10 days old maize seedlings with metribuzin and pretilachlor near the recommended field-dose resulted in differential reductions in shoot fresh and dry weights during the following 16 days. Metribuzin showed great and consistent reductions, however, the reduction induced by pretilachlor, mostly nullified by the end of the experiment. Moreover, there were differential accumulations of lipid peroxides, carbonyl groups and H₂O₂ in maize leaves; metribuzin caused the greatest accumulation. Meanwhile, levels of thiol forms and reduced glutathione (GSH) were much more induced by pretilachlor than metribuzin; the contrary was true regarding oxidized glutathione (GSSG). The ratio of GSH/GSSG was highest following pretilachlor treatment and least by metribuzin. On the other hand, activities of glutathione-S-transferases (GSTs, EC 2.5.1.18), γ-glutamyl-cysteine synthetase (γ-GCS, EC 6.3.2.2), glutathione synthetase (GS, EC 6.3.2.3), glutathione peroxidase (GPX, EC 1.15.1.1) and glutathione reductase (GR, EC 1.6.4.2) were more enhanced in maize leaves by pretilachlor than metribuzin. These findings suggest the occurrence of an oxidative stress differentially induced in maize by the herbicides, a state that was most pronounced with metribuzin. Pretilachlor was concluded to be the least phytotoxic to maize, while metribuzin was the most, this differential tolerance seemed to be related to the induction of GSH and GSH-associated enzymes.     

New Arylazo-Based (Chromene-Thiazole) Hybrids as Potential MRSA Inhibitors

A three-component protocol was established to efficiently synthesize (chromene-thiazole) and related arylazo analogs in good to excellent yields. The desired products were prepared by reacting the appropriate salicylaldehydes, 2-cyanothioacetamide, and chloroacetone or hydrazonyl chlorides. Using piperidine as a mediator in ethanol at 80 °C for 4–6 h, the three-component protocol produce the target hybrids in 87–96 % yields. The newly synthesized products showed a broad range of antibacterial activity. The addition of an arylazo unit at the chromene-C6 position significantly improved the antibacterial activity, while the impact of adding an arylazo group at the thiazole-C5 position varied based on the electronic characteristics of the para-substituted arene unit. Generally, series that is linked to two arylazo units, one at chromene-C6 and the other at thiazole-C5, showed the best activity. Some new hybrids showed effective antibacterial activity than ciprofloxacin with MIC/MBC values up to 1.9/3.9 μM against S. aureus and E. coli. Additionally, they demonstrated better effectiveness against MRSA ATCC:33591 and ATCC:43300 compared to linezolid, with MIC/MBC values up to 4.0/16.1 and 3.9/15.6 μM, respectively. The data predicted for the physicochemical properties, lipophilicity, pharmacokinetics, and drug-likeness of new arylazo-based chromene-thiazole hybrids evaluated by SwissADME. As a result of the above, products that are linked to two arylazo units can be considered drug-like scaffolds.