Environmental risk assessment of selected pharmaceuticals in hospital wastewater in nothern Vietnam.

Pharmaceuticals are progressively employed in both human and veterinary medicine and increasingly recognized as environmental contaminants. This study investigated the occurrence of selected pharmaceuticals in influent and effluent of wastewater treatment plants of 12 hospitals in Hanoi and 3 northern cities of Vietnam during dry and rainy seasons. In addition, environmental risk of pharmaceuticals in both hospital influents and effluents were evaluated based on risk quotients (RQs). Nine selected pharmaceutical compounds including sulfamethoxazole (SMX), naproxen (NPX), diclofenac (DCF), ibuprofen (IBU), acetaminophen (ACT), carbamazepine (CBM), iopromide (IOP), atenolol (ATN), and caffeine (CAF) were frequently detected in most influent and effluent wastewaters of 12 investigated hospitals. Detected compound levels exhibited a wide range, from as low as 1 ng/L for DCF to as high as 61,772 ng/L for ACT. Among these compounds, ACT, CAF, SMX, and IOP were consistently detected at substantial concentrations in both influents and effluents. This investigation also highlighted potential risks posed by SMX, ACT, and CAF residues present in influents and effluents of hospital wastewater treatment plants (WWTPs) to aquatic ecosystem. These finding are expected to provide scientific-based evidence for the development of hospital waste management and environmental management programs in Vietnam.

Mitigation of arsenic accumulation in crop plants using biofertilizer.

Elevated levels of arsenic in crop plants have been found in various regions worldwide, especially where agricultural soils have been affected by arsenic-enriched aquifers and human activities including mining, smelting, and pesticide application. Given the highly toxic nature of arsenic, remediation should be carried out immediately to reduce this potentially toxic element transport from soil to crop plants. This study focused on the utilization of biofertilizer which is a combination of arsenic-accumulating microorganisms and adsorbent (carrier) in order to achieve high efficiency of arsenic immobilization and ability to apply in the field. Thirty-two bacterial strains were isolated from 9 soil samples collected from the Dongjin and Duckum mining areas in Korea using a nutrient medium amended with 2 mM sodium arsenite. Among isolates, strain DE12 identified as Bacillus megaterium exhibited the greatest arsenic accumulation capacity (0.236 mg/g dry biomass) and ability to resist up to 18 mM arsenite. Among the three agricultural waste adsorbents studied, rice straw was proved to have a higher adsorption capacity (0.104 mg/g) than rice husk and corn husk. Therefore, rice straw was chosen to be the carrier to form biofertilizer together with strain DE12. Inoculation of biofertilizer in soil showed a reduction of arsenic content in the edible part of lettuce, water spinach, and sweet basil by 17.5%, 34.1%, and 34,1%, respectively compared to the control group. The use of biofertilizer may open up the potential application in the field for other food plants.

Incorporating thioamides into proteins by native chemical ligation.

The thioamide is a versatile replacement of the peptide backbone with altered hydrogen bonding and conformational preferences, as well the ability participate in energy and electron transfer processes. Semi-synthetic incorporation of a thioamide into a protein can be used to study protein folding or protein/protein interactions using these properties. Semi-synthesis also provides the opportunity to study the role of thioamides in natural proteins. Here we outline the semi-synthesis of a model protein, the B1 domain of protein G (GB1) with a thioamide at the N-terminus or the C-terminus. The thioamide is synthetically incorporated into a fragment by solid-phase peptide synthesis, whereas the remainder of the protein is recombinantly expressed. Then, the two fragments are joined by native chemical ligation. The explicit protocol for GB1 synthesis is accompanied by examples of applications with GB1 and other proteins in structural biology and protein misfolding studies.

Expanding the Differential During the COVID-19 Pandemic: Fatal West Nile Virus Neuroinvasive Disease.

The ever-evolving pandemic of Coronavirus disease 2019 (COVID-19) has the potential to drown out other viruses continuing to infect communities. To highlight this, we present 2 cases of fatal West Nile virus neuroinvasive disease that occurred within 2 weeks of each other. Since the first positive case of West Nile virus in the United States, there have been 2 epidemics in the past 2 decades, most often occurring in regions of North Texas and Southern California, which have been areas of high-incidence for COVID-19. It is important for the health care provider to recognize diagnostic biases and maintain broad differentials for the patient presenting with fever and other symptoms associated with COVID-19.

Somatostatin Receptor as a Molecular Imaging Target in Human and Canine Cushing Disease.

OBJECTIVES: Fluorescence-guided surgery may improve completeness of resection in transsphenoidal surgery for Cushing disease (CD) by enabling visualization of residual tumor tissue at the margins. In this review we discuss somatostatin receptors (SSTRs) as targets for fluorescence-guided surgery and overview existing SSTR-specific imaging agents. We also compare SSTR expression in normal pituitary and corticotrophinoma tissues from human and canine CD patients to assess canines as a translational model for CD. METHODS: A PubMed literature search was conducted for publications containing the terms canine, somatostatin receptor, Cushing's disease, and corticotroph adenoma. SSTR expression data from each study was documented as the presence or absence of expression or, when possible, the number of tumors expressing a given SSTR subtype within a group of tumors being studied. Studies that used reverse transcription polymerase chain reaction to quantify SSTR expression were selected for additional comparative analysis. RESULTS: SSTR5 is strongly expressed in human corticotroph adenomas and weakly expressed in surrounding pituitary parenchyma, a pattern not conclusively observed in canine patients. SSTR2 mRNA expression is similar in human normal pituitary and corticotrophinoma cells but may be significantly higher in canine normal pituitary tissue than in corticotroph tumoral tissue. Limited data were available on SSTR subtypes 1, 3, and 4. CONCLUSIONS: Further studies must fill the knowledge gaps related to species-specific SSTR expression, so using canine CD as a translational model may be premature. We do conclude that the expression profile of SSTR5 (i.e., high local expression in pituitary adenomas relative to normal surrounding tissues) makes SSTR5 a promising molecular target for FGS.

Short Meal-to-Bed Time Is a Predominant Risk Factor of Gastroesophageal Reflux Disease in Pregnancy.

BACKGROUND: Short meal-to-bed time (MTBT) has been reported to relate to gastroesophageal reflux disease (GERD), but evidence is lacking in pregnant women. We aimed to assess the characteristics of GERD and the association between MTBT and GERD during pregnancy. PATIENTS AND METHODS: A cross-sectional study was carried out on 400 pregnant women aged 18 years and older visiting the antenatal clinic of Gia-Dinh People's Hospital, Vietnam. GERD was defined as having troublesome heartburn and/or regurgitation at least once a week. Reflux-related insomnia was defined as having difficulties in initiating or maintaining sleep through the night. MTBT was defined as "short" if it was ≤2 hours in more than two thirds of days in a week. RESULTS: There were 154 (38.5%) patients with GERD and 20 (13.0%) patients with reflux-related insomnia. In multivariate analysis, there were 3 factors significantly associated with GERD: third trimester [odds ratio (OR)=1.66; 95% confidence interval (CI): 1.03-2.69], previous history of typical reflux symptoms (OR=9.05; 95% CI: 5.29-15.50), and short MTBT (OR=12.73; 95% CI: 2.92-55.45). The frequency of reflux symptoms progressively increased across subgroups of patients with no short MTBT, either daytime or nighttime short MTBT, and with both daytime and nighttime short MTBT. Nighttime MTBT was also a significant risk factor for reflux-related insomnia (OR=4.60; 95% CI: 1.64-12.92). CONCLUSIONS: We reported for the first time that short MTBT was a predominant risk factor of GERD in pregnancy. This dieting habit was significantly associated with reflux symptom frequency and reflux-related insomnia.

Rational design of thioamide peptides as selective inhibitors of cysteine protease cathepsin L.

Aberrant levels of cathepsin L (Cts L), a ubiquitously expressed endosomal cysteine protease, have been implicated in many diseases such as cancer and diabetes. Significantly, Cts L has been identified as a potential target for the treatment of COVID-19 due to its recently unveiled critical role in SARS-CoV-2 entry into the host cells. However, there are currently no clinically approved specific inhibitors of Cts L, as it is often challenging to obtain specificity against the many highly homologous cathepsin family cysteine proteases. Peptide-based agents are often promising protease inhibitors as they offer high selectivity and potency, but unfortunately are subject to degradation in vivo. Thioamide substitution, a single-atom O-to-S modification in the peptide backbone, has been shown to improve the proteolytic stability of peptides addressing this issue. Utilizing this approach, we demonstrate herein that good peptidyl substrates can be converted into sub-micromolar inhibitors of Cts L by a single thioamide substitution in the peptide backbone. We have designed and scanned several thioamide stabilized peptide scaffolds, in which one peptide, RS 1A, was stabilized against proteolysis by all five cathepsins (Cts L, Cts V, Cts K, Cts S, and Cts B) while inhibiting Cts L with >25-fold specificity against the other cathepsins. We further showed that this stabilized RS 1A peptide could inhibit Cts L in human liver carcinoma lysates (IC50 = 19 µM). Our study demonstrates that one can rationally design a stabilized, specific peptidyl protease inhibitor by strategic placement of a thioamide and reaffirms the place of this single-atom modification in the toolbox of peptide-based rational drug design.

Rosetta Machine Learning Models Accurately Classify Positional Effects of Thioamides on Proteolysis.

Thioamide substitutions of the peptide backbone have been shown to stabilize therapeutic and imaging peptides toward proteolysis. In order to rationally design thioamide modifications, we have developed a novel Rosetta custom score function to classify thioamide positional effects on proteolysis in substrates of serine and cysteine proteases. Peptides of interest were docked into proteases using the FlexPepDock application in Rosetta. Docked complexes were modified to contain thioamides parametrized through the creation of custom atom types in Rosetta based on ab intio simulations. Thioamide complexes were simulated, and the resultant structural complexes provided features for machine learning classification as the decomposed values of the Rosetta score function. An ensemble, majority voting model was developed to be a robust predictor of previously unpublished thioamide proteolysis holdout data. Theoretical control simulations with pseudo-atoms that modulate only one physical characteristic of the thioamide show differential effects on prediction accuracy by the optimized voting classification model. These pseudo-atom model simulations, as well as statistical analyses of the full thioamide simulations, implicate steric effects on peptide binding as being primarily responsible for thioamide positional effects on proteolytic resistance.

Studies of Thioamide Effects on Serine Protease Activity Enable Two-Site Stabilization of Cancer Imaging Peptides.

Thioamide substitutions in peptides can be used as fluorescence quenchers in protease sensors and as stabilizing modifications of hormone analogs. To guide these applications in the context of serine proteases, we here examine the cleavage of several model substrates, scanning a thioamide between the P3 and P3' positions, and identify perturbing positions for thioamide substitution. While all serine proteases tested were affected by P1 thioamidation, certain proteases were also significantly affected by other thioamide positions. We demonstrate how these findings can be applied by harnessing the combined P3/P1 effect of a single thioamide on kallikrein proteolysis to protect two key positions in a neuropeptide Y-based imaging probe, increasing its serum half-life to >24 h while maintaining potency for binding to Y1 receptor expressing cells. Such stabilized peptide probes could find application in imaging cell populations in animal models or even in clinical applications such as fluorescence-guided surgery.

Water Reclamation Using a Ceramic Nanofiltration Membrane and Surface Flushing with Ozonated Water.

A new membrane fouling control technique using ozonated water flushing was evaluated for direct nanofiltration (NF) of secondary wastewater effluent using a ceramic NF membrane. Experiments were conducted at a permeate flux of 44 L/m²h to evaluate the ozonated water flushing technique for fouling mitigation. Surface flushing with clean water did not effectively remove foulants from the NF membrane. In contrast, surface flushing with ozonated water (4 mg/L dissolved ozone) could effectively remove most foulants to restore the membrane permeability. This surface flushing technique using ozonated water was able to limit the progression of fouling to 35% in transmembrane pressure increase over five filtration cycles. Results from this study also heighten the need for further development of ceramic NF membrane to ensure adequate removal of pharmaceuticals and personal care products (PPCPs) for water recycling applications. The ceramic NF membrane used in this study showed approximately 40% TOC rejection, and the rejection of PPCPs was generally low and highly variable. It is expected that the fouling mitigation technique developed here is even more important for ceramic NF membranes with smaller pore size and thus better PPCP rejection.

Soy flour as an alternative to purified lipoxygenase for the enzymatic synthesis of resolvin analogues.

Specialized pro-resolving mediators are lipid signaling molecules synthesized from omega-3 and -6 polyunsaturated fatty acids, which promote the resolution of the inflammatory response. They are potential drug targets for the treatment of numerous conditions linked with uncontrolled inflammation. Many of these mediators can be effectively synthesized using enzymes, such as lipoxygenases. However, these enzymes are expensive to purchase and can be difficult to isolate. In this work, we show that commercial soy flour can be used directly as a source of lipoxygenase for the biosynthesis of specialized pro-resolving mediators from DHA and other biologically important fatty acids. The reaction was optimized and the products characterized. We found that the reaction yield and products were comparable to those synthesized using a commercial 15-lipoxygenase preparation.

Charge Transport in LDPE Nanocomposites Part I-Experimental Approach.

This work presents results of bulk conductivity and surface potential decay measurements on low-density polyethylene and its nanocomposites filled with uncoated MgO and Al2O3, with the aim to highlight the effect of the nanofillers on charge transport processes. Material samples at various filler contents, up to 9 wt %, were prepared in the form of thin films. The performed measurements show a significant impact of the nanofillers on reduction of material's direct current (dc) conductivity. The investigations thus focused on the nanocomposites having the lowest dc conductivity. Various mechanisms of charge generation and transport in solids, including space charge limited current, Poole-Frenkel effect and Schottky injection, were utilized for examining the experimental results. The mobilities of charge carriers were deduced from the measured surface potential decay characteristics and were found to be at least two times lower for the nanocomposites. The temperature dependencies of the mobilities were compared for different materials.

Charge Transport in LDPE Nanocomposites Part II-Computational Approach.

A bipolar charge transport model is employed to investigate the remarkable reduction in dc conductivity of low-density polyethylene (LDPE) based material filled with uncoated nanofillers (reported in the first part of this work). The effect of temperature on charge transport is considered and the model outcomes are compared with measured conduction currents. The simulations reveal that the contribution of charge carrier recombination to the total transport process becomes more significant at elevated temperatures. Among the effects caused by the presence of nanoparticles, a reduced charge injection at electrodes has been found as the most essential one. Possible mechanisms for charge injection at different temperatures are therefore discussed.