Enantio- and Regioselective Baeyer-Villiger Oxidations of 2- and 3-Substituted Cyclopentanones Using Engineered Bakers' Yeast.
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
Gang Chen
Publications and source records attributed to Gang Chen.
A "Designer Yeast" That Catalyzes the Kinetic Resolutions of 2-Alkyl-Substituted Cyclohexanones by Enantioselective Baeyer-Villiger Oxidations.
Explore the source record for details and available documents.
Journal Article↗
Bacterial deposition in porous medium as impacted by solution chemistry.
Bacterial transport in porous medium was investigated by means of column experiments using typical rod-shaped bacteria of Escherichia coli and Pseudomonas fluorescens. Mobility of E. coli and P. fluorescens in silica gel decreased with increasing ionic strength of the solution. In the presence of nonionic surfactants, the mobility of E. coli and P. fluorescens increased, and this was more pronounced at lower than at higher ionic strength. Bacterial transport in the porous medium was described by the equilibrium-kinetic two-region model and bacterial deposition was assumed to occur in the kinetic adsorption region only. Quantified bacterial deposition from bacterial column breakthrough curves was related to electrostatic and Lifshitz-van der Waals interactions between bacterial cells and medium surfaces. It was found that electrostatic interactions played a more important role than Lifshitz-van der Waals interactions in determining bacterial deposition in the porous medium, and were actually the barrier for bacteria to attach to the porous medium.
Bacterial Physiological Phenomena↗
Soil microbial activities and carbon and nitrogen fixation.
Soil microbial activity that reflects microbiological processes of soil microorganisms is the potential indicator of soil quality, as plants rely on soil microorganisms to mineralize organic nutrients for growth and development. Soil microorganisms also process plant litter and residues into soil organic matter, a direct and stable reservoir of carbon and nitrogen that consists of living and dead organic materials subject to rapid biological decomposition. In natural systems, the action of soil microorganisms is a major determinant of efficient nutrient cycling. This paper reviews the current state of knowledge on the fate of soil microorganisms in terms of carbon and nitrogen fixation.
Bacteria↗
Focused combinatorial library design based on structural diversity, druglikeness and binding affinity score.
The advent of focused library and virtual screening has reduced the disadvantage of combinatorial chemistry and changed it to a realizable and cost-effective tool in drug discovery. Usually, genetic algorithms (GAs) are used to quickly finding high-scoring molecules by sampling a small subset of the total combinatorial space. Therefore, scoring functions play essential roles in focused library design. Reported here is our initial attempt to establish a new approach for generating a target-focused library using the combination of the scores of structural diversity and binding affinity with our newly improved drug-likeness scoring functions. Meanwhile, a software package, named LD1.0, was developed on the basis of the new approach. One test on a cyclooxygenase (COX)2-focused library successfully reproduced the structures that have been experimentally studied as COX2-selective inhibitors. Another test is on a peroxisome proliferator-activated receptors gamma-focused library design, which not only reproduces the key fragments in the approved (thiazolidinedione) TZD drugs, but also generates some new structures that are more active than the approved drugs or published ligands. Both of the two tests took approximately 15% of the running time of the ordinary molecular docking method. Thus, our new approach is an effective, reliable, and practical way for building up a properly sized focused library with a high hit rate, novel structure, and good ADME/T profile.
Algorithms↗
A new rapid and effective chemistry space filter in recognizing a druglike database.
To develop a new chemistry space filter with high efficiency and accuracy, an analysis on distributions of as many as 50 structural and physicochemical properties was carried out on both druglike and nondruglike databases, viz. MACCS-II Drug Data Report (MDDR), Comprehensive Medicinal Chemistry (CMC), and Available Chemicals Directory (ACD). Based on the analysis results, a chemistry space filter was developed that can effectively discriminate a druglike database from a nondruglike database. The filter is composed of two descriptors: one is a molecular saturation related descriptor, and the other is associated with the proportion of heteroatoms in a molecule. Both are molecular size independent. Therefore, the profiles of a druglike database could be characterized as proper molecular saturation and proper percentage of heteroatoms, revealing direct indices for designing and optimizing combinatorial libraries. The application of the new filter on the Chinese Natural Product Database (CNPD) suggested that CNPD is, as expected, a potential druglike database, testifying that the new filter is reliable. Therefore, this newly developed chemistry space filter should be a potent tool for identifying druglike molecules, thus, it would have potential applications in the research of combinatorial library design and virtual high throughput screening using computational approaches for drug discovery.
Combinatorial Chemistry Techniques↗
Influence of lactation history on breast nipple aspirate fluid yields and fluid composition.
Analysis of nipple aspirate fluid (NAF) can be useful for understanding the impact that various lifestyle factors have on the biology of the breast. In this study, breast NAF was obtained at baseline from premenopausal women who volunteered for a dietary intervention trial. The influence of lactation history on both fluid yields and fluid composition was explored. We examined the levels of fat-soluble micronutrients (tocopherols, carotenoids, retinol), one lipid oxidation product (8-isoprostane), cholesterol, and protein in NAF. Roughly half of the women in the trial had never lactated, but this did not affect fluid yields appreciably. Carotenoid and tocopherol levels were significantly higher in NAF from women who lactated 6 months or more versus women who had lactated for shorter periods of time or never, but 8-isoprostane, protein, and cholesterol levels were not affected appreciably by lifetime lactation history. Longer times after weaning were associated with higher cholesterol levels, and there also was a suggestion the fat-soluble micronutrients declined with time after weaning. This is of interest since high cholesterol levels in breast fluid have been associated with an increased breast cancer risk, while carotenoids and tocopherols are thought to be protective. The results of this study provide further evidence of the potential benefits of prolonged lactation via its influence on NAF composition.
Adult↗
Food safety issues for cancer and organ transplant patients.
This paper explores reasons why cancer and transplant patients are at greater risk for food-borne illnesses and which pathogens and food-handling behaviors are of particular concern. Cancer and bone marrow transplant patients experience neutropenia because of medical treatments, whereas patients with solid organ transplants become immunosuppressed from a pharmacological regimen to prevent rejection of the transplanted organ. Opportunistic infections, including food-borne illnesses, may occur during periods of immunosuppression. Food-handling behaviors and practices to control food-borne illnesses were presented to focus groups and during interviews with cancer and transplant patients and health care providers. Credibility of the food safety information, credibility of the person providing the advice, and sensitivity to the restrictions imposed on the patient's lifestyle by food safety guidance were key themes from the focus group and interview study. The information gathered will help health care providers aid the cancer or transplant patient with their knowledge and understanding of food safety and their greater risk for food-borne infections.
Consumer Product Safety↗
Evaluation of anti-vascular therapy with texture analysis.
BACKGROUND: Texture analysis can be used to identify and discriminate between objects in an image and has already been used for the characterization of diseases. The present study evaluated the potential of texture analysis for monitoring tumor cell viability during treatment with an anti-vascular drug. MATERIALS AND METHODS: Texture analysis of T2-weighted magnetic resonance images of C3H mammary carcinomas in mice was used to study tumor cell viability during treatment with the anti-vascular drug combretastatin A-4 disodium phosphate (CA4DP). Texture analysis was done by MaZda, and boot strap statistics were used to analyze the results. RESULTS: The results revealed significant differences in the textures of T2-weighted images when non-tumor tissue and tumor tissue were compared. Furthermore, selected texture parameters were significantly different when image data from before and after CA4DP administration were analyzed. CONCLUSION: Texture analysis is helpful in the diagnosis of different types of tissues, especially when these tissues can not be recognized by human observers. Some functional changes, such as perfusion changes in the tumor, can also be detected by texture analysis.
Animals↗