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It is important to have tools to measure the bioavailability to assess the risks of pollutants because the bioavailability is defined as the portions of pollutants showing the biological effects on living organisms. This study described the construction of tunable Escherichia coli whole-cell bioreporter (WCB) using the promoter region of zinc-inducible operon and its application on contaminated soils. It was verified that this WCB system showed specific and sensitive responses to cadmium rather than zinc in the experimental conditions. It was inferred that Cd(II) associates stronger with ZntR, a regulatory protein of zinc-inducible operon, than other metal ions. Moreover, the expression of reporter genes, egfp and mcherry, were proportional to the concentration of cadmium, thereby being a quantitative sensor to monitor bioavailable cadmium. The capability to determine bioavailable cadmium was verified with Cd(II) amended LUFA soils, and then the applicability on environmental systems was investigated with field soils collected from smelter area in Korea before and after soil-washing. The total amount of cadmium was decreased after soil washing, while the bioavailability was increased. Consequently, it would be valuable to have tools to assess bioavailability and the effectiveness of soil remediation should be evaluated in the aspect of bioavailability as well as removal efficiency.

Metals are essential to all organisms; accordingly, cells employ numerous genes to maintain metal homeostasis as high levels can be toxic. In the present study, the gene operons responsive to metal(loid)s were employed to generate bacterial cell-based biosensors to detect target metal(loid)s. The cluster of genes related to copper transport known as the cop-operon is regulated by the interaction between the copA promoter region ( copAp) and CueR, turning on and off gene expression upon copper ion binding. Therefore, the detection of copper ions could be achieved by inserting a plasmid harboring the fusion of copAp and reporter genes, such as enzymes and fluorescent genes. However, copAp is not as strong a promoter as other metal-inducible promoters, such as znt-, mer-, and ars-operons; thereby, its sensitivity toward copper ions was not sufficient for quantification. To overcome this problem, we engineered Escherichia coli with a deletion of copA to interfere with copper export from cells. The engineered E. coli whole-cell bioreporter was able to detect copper ions at 0 to 10 μM in an aqueous solution. Most importantly, it was specific to copper among several tested heavy metal(loid)s. Therefore, it will likely be useful to detect copper in diverse environmental systems. Although additional improvements are still required to optimize the E. coli-based copper-sensing whole-cell bioreporters presented in this study, our results suggest that there is huge potential to generate whole-cell bioreporters for additional targets by molecular engineering. [ABSTRACT FROM AUTHOR]

We investigated the quantification of bioavailable arsenic in contaminated soils and evaluation of soil-washing processes in the aspect of bioavailability using a novel bacterial bioreporter developed in present study. The whole-cell bioreporter (WCB) was genetically engineered by fusing the promoter of nik operon from Escherichia coli and green fluorescent protein as a sensing domain and reporter domain. Among eight well-known hazardous heavy metals and metalloid, this system responded specifically to arsenic, thereby inferring association of As(III) with NikR inhibits the repression. Moreover, the response was proportional to the concentration of As(III), thereby it was capable to determine the amount of bioavailable arsenic quantitatively in contaminated soils. The bioavailable portion of arsenic was 5.9 (3.46-10.96) and 0.9 (0.27-1.74) % of total from amended and site soils, respectively, suggesting the bioavailability of arsenic in soils was related to the soil properties and duration of aging. On the other hand, only 1.37 (0.21-2.97) % of total arsenic was extracted into soil solutions and 19.88 (11.86-28.27) % of arsenic in soil solution was bioavailable. This result showed that the soluble arsenic is not all bioavailable and most of bioavailable arsenic in soils is water non-extractable. In addition, the bioavailable arsenic was increased after soil-washing while total amount was decreased, thereby suggesting the soil-washing processes release arsenic associated with soil materials to be bioavailable. Therefore, it would be valuable to have a tool to assess bioavailability and the bioavailability should be taken into consideration for soil remediation plans. [ABSTRACT FROM AUTHOR]

Background: Spinal anesthesia-induced hypotension (SAH) frequently occurs in older patients, many of whom have mild left ventricular (LV) diastolic dysfunction, often asymptomatic at rest. This study investigated the association between preoperative echocardiographic measurements and SAH in older patients with mild LV diastolic dysfunction., Methods: We conducted a retrospective observational study using data from electronic medical records. The patients ≥ 65 years old who underwent spinal anesthesia for urologic surgery between January 2016 and December 2017 and whose preoperative echocardiography within 6 months before surgery revealed grade I LV diastolic dysfunction were recruited. SAH was investigated using the anesthesia records. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed., Results: A total of 163 patients were analyzed. SAH and significant SAH developed in 55 (33.7%) patients. The mitral inflow E velocity was an independent risk factor for SAH (odds ratio [OR], 0.886; 95% confidence interval [CI], 0.845-0.929; P < 0.001). The area under the ROC curve for mitral inflow E velocity to predict SAH was 0.819 (95% CI, 0.752-0.875; P < 0.001). If mitral inflow E velocity was ≤ 60 cm/s, SAH was predicted with a sensitivity of 83.6% and specificity of 70.4%., Conclusions: The preoperative mitral inflow E velocity demonstrated the greatest predictability of SAH in older patients with mild LV diastolic dysfunction. This may assist in identifying patients at high risk of SAH and guiding preventive strategies in the future.

The serine-threonine kinase AKT plays a pivotal role in tumor progression and is frequently overactivated in cancer cells; this protein is therefore a critical therapeutic target for cancer intervention. We aimed to identify small molecule inhibitors of the pleckstrin homology (PH) domain of AKT to disrupt binding of phosphatidylinositol-3,4,5-trisphosphate (PIP3), thereby downregulating AKT activity. Liposome pulldown assays coupled with fluorescence spectrometry were used to screen flavonoids for inhibition of the AKT PH-PIP3 interaction. Western blotting was used to determine the effects of the inhibitors on AKT activation in cancer cells, and in silico docking was used for structural analysis and optimization of inhibitor structure. Several flavonoids showing up to 50% inhibition of the AKT PH-PIP3 interaction decreased the level of AKT activation at the cellular level. In addition, the modified flavonoid showed increased inhibitory effects and the approach would be applied to develop anticancer drug candidates. In this study, we provide a rationale for targeting the lipid-binding domain of AKT, rather than the catalytic kinase domain, in anticancer drug development.