Location bias: A "Hidden Variable" in GPCR pharmacology.

G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and primarily signal through two main effector proteins: G proteins and ß-arrestins. Many agonists of GPCRs promote "biased" responses, in which different cellular signaling pathways are activated with varying efficacies. The mechanisms underlying biased signaling have not been fully elucidated, with many potential "hidden variables" that regulate this behavior. One contributor is "location bias," which refers to the generation of unique signaling cascades from a given GPCR depending upon the cellular location at which the receptor is signaling. Here, we review evidence that GPCRs are expressed at and traffic to various subcellular locations and discuss how location bias can impact the pharmacologic properties and characterization of GPCR agonists. We also evaluate how differences in subcellular environments can modulate GPCR signaling, highlight the physiological significance of subcellular GPCR signaling, and discuss the therapeutic potential of exploiting GPCR location bias.

High-Intensity Interval Training is Safe, Feasible and Efficacious in Nonalcoholic Steatohepatitis: A Randomized Controlled Trial.

BACKGROUND: High-Intensity Interval Training (HIIT) involves bursts of high-intensity exercise interspersed with lower-intensity exercise recovery. HIIT may benefit cardiometabolic health in people with nonalcoholic steatohepatitis (NASH). AIMS: We aimed to examine the safety, feasibility, and efficacy of 12-weeks of supervised HIIT compared with a sham-exercise control (CON) for improving aerobic fitness and peripheral insulin sensitivity in biopsy-proven NASH. METHODS: Participants based in the community [(n = 14, 56 ± 10 years, BMI 39.2 ± 6.7 kg/m2, 64% male), NAFLD Activity Score 5 (range 3-7)] were randomized to 12-weeks of supervised HIIT (n = 8, 4 × 4 min at 85-95% maximal heart rate, interspersed with 3 min active recovery; 3 days/week) or CON (n = 6, stretching; 3 days/week). Safety (adverse events) and feasibility determined as ≥ 70% program completion and ≥ 70% global adherence (including session attendance, interval intensity adherence, and duration adherence) were assessed. Changes in cardiorespiratory fitness (V̇O2peak), exercise capacity (time-on-test) and peripheral insulin sensitivity (euglycemic hyperinsulinemic clamp) were assessed. Data were analysed using ANCOVA with baseline value as the covariate. RESULTS: There were no HIIT-related adverse events and HIIT was globally feasible [program completion 75%, global adherence 100% (including adherence to session 95.4 ± 7.3%, interval intensity 95.3 ± 6.0% and duration 96.8 ± 2.4%)]. A large between-group effect was observed for exercise capacity [mean difference 134.2 s (95% CI 19.8, 248.6 s), ƞ2 0.44, p = 0.03], improving in HIIT (106.2 ± 97.5 s) but not CON (- 33.4 ± 43.3 s), and for peripheral insulin sensitivity [mean difference 3.4 mg/KgLegFFM/min (95% CI 0.9,6.8 mg/KgLegFFM/min), ƞ2 0.32, p = 0.046], improving in HIIT (1.0 ± 0.8 mg/KgLegFFM/min) but not CON (- 3.1 ± 1.2 mg/KgLegFFM/min). CONCLUSIONS: HIIT is safe, feasible and efficacious for improving exercise capacity and peripheral insulin sensitivity in people with NASH. CLINICAL TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trial Registry (anzctr.org.au) identifier ACTRN12616000305426 (09/03/2016).

Revealing A-T and G-C Hoogsteen base pairs in stressed protein-bound duplex DNA.

Watson-Crick base pairs (bps) are the fundamental unit of genetic information and the building blocks of the DNA double helix. However, A-T and G-C can also form alternative 'Hoogsteen' bps, expanding the functional complexity of DNA. We developed 'Hoog-finder', which uses structural fingerprints to rapidly screen Hoogsteen bps, which may have been mismodeled as Watson-Crick in crystal structures of protein-DNA complexes. We uncovered 17 Hoogsteen bps, 7 of which were in complex with 6 proteins never before shown to bind Hoogsteen bps. The Hoogsteen bps occur near mismatches, nicks and lesions and some appear to participate in recognition and damage repair. Our results suggest a potentially broad role for Hoogsteen bps in stressed regions of the genome and call for a community-wide effort to identify these bps in current and future crystal structures of DNA and its complexes.

GPCR systems pharmacology: a different perspective on the development of biased therapeutics.

G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and are the target of approximately one-third of all Food and Drug Administration (FDA)-approved pharmaceutical drugs. GPCRs interact with many transducers, such as heterotrimeric G proteins, GPCR kinases (GRKs), and ß-arrestins. Recent experiments have demonstrated that some ligands can activate distinct effector proteins over others, a phenomenon termed "biased agonism." These discoveries have raised the potential of developing drugs which preferentially activate therapeutic signaling pathways over those that lead to deleterious side effects. However, to date, only one biased GPCR therapeutic has received FDA approval and many others have either failed to meet their specified primary end points and or demonstrate superiority over currently available treatments. In addition, there is a lack of understanding regarding how biased agonism measured at a GPCR leads to specific downstream physiological responses. Here, we briefly summarize the history and current status of biased agonism at GPCRs and suggest adoption of a "systems pharmacology" approach upon which to develop GPCR-targeted drugs that demonstrate heightened therapeutic efficacy with improved side effect profiles.

Hoogsteen base pairs increase the susceptibility of double-stranded DNA to cytotoxic damage.

As the Watson-Crick faces of nucleobases are protected in dsDNA, it is commonly assumed that deleterious alkylation damage to the Watson-Crick faces of nucleobases predominantly occurs when DNA becomes single-stranded during replication and transcription. However, damage to the Watson-Crick faces of nucleobases has been reported in dsDNA in vitro through mechanisms that are not understood. In addition, the extent of protection from methylation damage conferred by dsDNA relative to ssDNA has not been quantified. Watson-Crick base pairs in dsDNA exist in dynamic equilibrium with Hoogsteen base pairs that expose the Watson-Crick faces of purine nucleobases to solvent. Whether this can influence the damage susceptibility of dsDNA remains unknown. Using dot-blot and primer extension assays, we measured the susceptibility of adenine-N1 to methylation by dimethyl sulfate (DMS) when in an A-T Watson-Crick versus Hoogsteen conformation. Relative to unpaired adenines in a bulge, Watson-Crick A-T base pairs in dsDNA only conferred ∼130-fold protection against adenine-N1 methylation, and this protection was reduced to ∼40-fold for A(syn)-T Hoogsteen base pairs embedded in a DNA-drug complex. Our results indicate that Watson-Crick faces of nucleobases are accessible to alkylating agents in canonical dsDNA and that Hoogsteen base pairs increase this accessibility. Given the higher abundance of dsDNA relative to ssDNA, these results suggest that dsDNA could be a substantial source of cytotoxic damage. The work establishes DMS probing as a method for characterizing A(syn)-T Hoogsteen base pairs in vitro and also lays the foundation for a sequencing approach to map A(syn)-T Hoogsteen and unpaired adenines genome-wide in vivo.

Separation of short and medium-chain fatty acids using capillary electrophoresis with indirect photometric detection: Part I: Identification of fatty acids in rat feces.

Short and medium-chain fatty acids (SMCFAs) are known as essential metabolites found in gut microbiota that function as modulators in the development and progression of many inflammatory conditions as well as in the regulation of cell metabolism. Currently, there are few simple and low-cost analytical methods available for the determination of SMCFA. This report focuses on SMCFA analysis utilizing CE with indirect photometric detection (CE-IPD). A ribonucleotide electrolyte, 5'-adenosine mono-phosphate (5'-AMP), is investigated as an IPD reagent due to its high molar absorptivity and dynamic reserve compatible with separation and detection of SMCFA. The operating parameters like the composition of organic solvent, millimolar concentrations of the complexing agent (alpha-cyclodextrin), 5'-AMP and non-absorbing electrolyte (boric acid), as well as the applied voltage, are optimized for resolution, efficiency, and signal-to-noise ratio. A baseline resolution of all nine SMCFAs is achieved in less than 15 min. Additionally, the developed CE-IPD method shows promising potential to identifying SMCFA in rat fecal supernatant. The presented analytical assay is simple, economical, and has considerably good repeatability. The intraday and interday RSD of less than 1 and 2% for relative migration time, as well as less than 14 and 15% for peak area, respectively, were obtained for SMCFA in fecal solution.

Caveolin-3 plays a critical role in autophagy after ischemia-reperfusion.

Autophagy is a dynamic recycling process responsible for the breakdown of misfolded proteins and damaged organelles, providing nutrients and energy for cellular renovation and homeostasis. Loss of autophagy is associated with cardiovascular diseases. Caveolin-3 (Cav-3), a muscle-specific isoform, is a structural protein within caveolae and is critical to stress adaptation in the heart. Whether Cav-3 plays a role in regulating autophagy to modulate cardiac stress responses remains unknown. In the present study, we used HL-1 cells, a cardiac muscle cell line, with stable Cav-3 knockdown (Cav-3 KD) and Cav-3 overexpression (Cav-3 OE) to study the impact of Cav-3 in regulation of autophagy. We show that traditional stimulators of autophagy (i.e., rapamycin and starvation) result in upregulation of the process in Cav-3 OE cells while Cav-3 KD cells have a blunted response. Cav-3 coimmunoprecipitated with beclin-1 and Atg12, showing an interaction of caveolin with autophagy-related proteins. In the heart, autophagy may be a major regulator of protection from ischemic stress. We found that Cav-3 KD cells have a decreased expression of autophagy markers [beclin-1, light chain (LC3-II)] after simulated ischemia and ischemia-reperfusion (I/R) compared with WT, whereas OE cells showed increased expression. Moreover, Cav-3 KD cells showed increased cell death and higher level of apoptotic proteins (cleaved caspase-3 and cytochrome c) with suppressed mitochondrial function in response to simulated ischemia and I/R, whereas Cav-3 OE cells were protected and had preserved mitochondrial function. Taken together, these results indicate that autophagy regulates adaptation to cardiac stress in a Cav-3-dependent manner.

Characterization of the caleosin gene family in the Triticeae.

BACKGROUND: The caleosin genes encode proteins with a single conserved EF hand calcium-binding domain and comprise small gene families found in a wide range of plant species. Some members of the gene family have been shown to be upregulated by environmental stresses including low water availability and high salinity. Caleosin 3 from wheat has been shown to interact with the α-subunit of the heterotrimeric G proteins, and to act as a GTPase activating protein (GAP). This study characterizes the size and diversity of the gene family in wheat and related species and characterizes the differential tissue-specific expression of members of the gene family. RESULTS: A total of 34 gene family members that belong to eleven paralogous groups of caleosins were identified in the hexaploid bread wheat, T. aestivum. Each group was represented by three homeologous copies of the gene located on corresponding homeologous chromosomes, except the caleosin 10, which has four gene copies. Ten gene family members were identified in diploid barley, Hordeum vulgare, and in rye, Secale cereale, seven in Brachypodium distachyon, and six in rice, Oryza sativa. The analysis of gene expression was assayed in triticale and rye by RNA-Seq analysis of 454 sequence sets and members of the gene family were found to have diverse patterns of gene expression in the different tissues that were sampled in rye and in triticale, the hybrid hexaploid species derived from wheat and rye. Expression of the gene family in wheat and barley was also previously determined by microarray analysis, and changes in expression during development and in response to environmental stresses are presented. CONCLUSIONS: The caleosin gene family had a greater degree of expansion in the Triticeae than in the other monocot species, Brachypodium and rice. The prior implication of one member of the gene family in the stress response and heterotrimeric G protein signaling, points to the potential importance of the caleosin gene family. The complexity of the family and differential expression in various tissues and under conditions of abiotic stress suggests the possibility that caleosin family members may play diverse roles in signaling and development that warrants further investigation.

Methods for measuring CoA and CoA derivatives in biological samples.

CoA (coenzyme A) is a ubiquitous and essential cofactor that acts as an acyl group carrier in biochemical reactions. Apart from participating in numerous metabolic pathways as substrates and intermediates, CoA and a number of its thioester derivatives, such as acetyl-CoA, can also directly regulate the activity of proteins by allosteric mechanisms and by affecting protein acetylation reactions. Cellular levels of CoA and CoA thioesters change under various physiological and pathological conditions. Defective CoA biosynthesis is implicated in NBIA (neurodegeneration with brain iron accumulation). However, the exact role of CoA in the pathogenesis of NBIA is not well understood. Accurate and reliable assays for measuring CoA species in biological samples are essential for studying the roles of CoA and CoA derivatives in health and disease. The present mini-review discusses methods that are commonly used to measure CoA species in biological samples.

GPCR kinases differentially modulate biased signaling downstream of CXCR3 depending on their subcellular localization.

Some G protein-coupled receptors (GPCRs) demonstrate biased signaling such that ligands of the same receptor exclusively or preferentially activate certain downstream signaling pathways over others. This phenomenon may result from ligand-specific receptor phosphorylation by GPCR kinases (GRKs). GPCR signaling can also exhibit location bias because GPCRs traffic to and signal from subcellular compartments in addition to the plasma membrane. Here, we investigated whether GRKs contributed to location bias in GPCR signaling. GRKs translocated to endosomes after stimulation of the chemokine receptor CXCR3 or other GPCRs in cultured cells. GRK2, GRK3, GRK5, and GRK6 showed distinct patterns of recruitment to the plasma membrane and to endosomes depending on the identity of the biased ligand used to activate CXCR3. Analysis of engineered forms of GRKs that localized to either the plasma membrane or endosomes demonstrated that biased CXCR3 ligands elicited different signaling profiles that depended on the subcellular location of the GRK. Each GRK exerted a distinct effect on the regulation of CXCR3 engagement of ß-arrestin, internalization, and activation of the downstream effector kinase ERK. Our work highlights a role for GRKs in location-biased GPCR signaling and demonstrates the complex interactions between ligands, GRKs, and cellular location that contribute to biased signaling.

ACKR3 Proximity Labeling Identifies Novel G protein- and ß-arrestin-independent GPCR Interacting Proteins.

The canonical paradigm of GPCR signaling recognizes G proteins and ß-arrestins as the two primary transducers that promote GPCR signaling. Recent evidence suggests the atypical chemokine receptor 3 (ACKR3) does not couple to G proteins, and ß-arrestins are dispensable for some of its functions. Here, we employed proximity labeling to identify proteins that interact with ACKR3 in cells devoid of ß-arrestin. We identified proteins involved in the endocytic machinery and evaluated a subset of proteins conserved across several GPCR-based proximity labeling experiments. We discovered that the bone morphogenic protein 2-inducible kinase (BMP2K) interacts with many different GPCRs with varying dependency on ß-arrestin. Together, our work highlights the existence of modulators that can act independently of G proteins and ß-arrestins to regulate GPCR signaling and provides important evidence for other targets that may regulate GPCR signaling.

Simple and Rapid Method of Microwell Array Fabrication for Drug Testing on 3D Cancer Spheroids.

Three-dimensional (3D) cell culture systems are becoming increasingly popular due to their ability to mimic the complex process of angiogenesis in cancer, providing more accurate and physiologically relevant data than traditional two-dimensional (2D) cell culture systems. Microwell systems are particularly useful in this context as they provide a microenvironment that more closely resembles the in vivo environment than traditional microwells. Poly(ethylene glycol) (PEG) microwells are particularly advantageous due to their bio-inertness and the ability to tailor their material characteristics depending on the PEG molecular weight. Although there are several methods available for microwell fabrication, most of them are time-consuming and expensive. The current study utilizes a low-cost laser etching technique on poly(methyl methacrylate) materials followed by molding with PDMS to produce microwells. The optimal conditions for making concave microwells are an engraving parameter speed of 600 mm/s, power of 20%, and a design diameter of the microwell of 0.4 mm. The artificial tumor achieved its full size after 7 days of cell growth in a microwell system, and the cells developed drugs through a live/dead assay test. The results of the drug testing revealed that the IC50 value of zerumbone-loaded liposomes in HepG2 was 4.53 pM, which is greater than the IC50 value of zerumbone. The HepG2 cancer sphere's 3D platform for medication testing revealed that zerumbone-loaded liposomes were very effective at high doses. These findings generally imply that zerumbone-loaded liposomes have the capacity to target the liver and maintain medication delivery.

Phosphorylation patterns in the AT1R C-terminal tail specify distinct downstream signaling pathways.

Different ligands stabilize specific conformations of the angiotensin II type 1 receptor (AT1R) that direct distinct signaling cascades mediated by heterotrimeric G proteins or ß-arrestin. These different active conformations are thought to engage distinct intracellular transducers because of differential phosphorylation patterns in the receptor C-terminal tail (the "barcode" hypothesis). Here, we identified the AT1R barcodes for the endogenous agonist AngII, which stimulates both G protein activation and ß-arrestin recruitment, and for a synthetic biased agonist that only stimulates ß-arrestin recruitment. The endogenous and ß-arrestin-biased agonists induced two different ensembles of phosphorylation sites along the C-terminal tail. The phosphorylation of eight serine and threonine residues in the proximal and middle portions of the tail was required for full ß-arrestin functionality, whereas phosphorylation of the serine and threonine residues in the distal portion of the tail had little influence on ß-arrestin function. Similarly, molecular dynamics simulations showed that the proximal and middle clusters of phosphorylated residues were critical for stable ß-arrestin-receptor interactions. These findings demonstrate that ligands that stabilize different receptor conformations induce different phosphorylation clusters in the C-terminal tail as barcodes to evoke distinct receptor-transducer engagement, receptor trafficking, and signaling.

Fabrication of a Low-Cost Microfluidic Device for High-Throughput Drug Testing on Static and Dynamic Cancer Spheroid Culture Models.

Drug development is a complex and expensive process from new drug discovery to product approval. Most drug screening and testing rely on in vitro 2D cell culture models; however, they generally lack in vivo tissue microarchitecture and physiological functionality. Therefore, many researchers have used engineering methods, such as microfluidic devices, to culture 3D cells in dynamic conditions. In this study, a simple and low-cost microfluidic device was fabricated using Poly Methyl Methacrylate (PMMA), a widely available material, and the total cost of the completed device was USD 17.75. Dynamic and static cell culture examinations were applied to monitor the growth of 3D cells. α-MG-loaded GA liposomes were used as the drug to test cell viability in 3D cancer spheroids. Two cell culture conditions (i.e., static and dynamic) were also used in drug testing to simulate the effect of flow on drug cytotoxicity. Results from all assays showed that with the velocity of 0.005 mL/min, cell viability was significantly impaired to nearly 30% after 72 h in a dynamic culture. This device is expected to improve in vitro testing models, reduce and eliminate unsuitable compounds, and select more accurate combinations for in vivo testing.

Spatiotemporal Analysis and Assessment of Risk Factors in Transmission of African Swine Fever Along the Major Pig Value Chain in Lao Cai Province, Vietnam.

African swine fever (ASF) is a contagious and lethal hemorrhagic disease with a case fatality rate approaching 100% in domestic pigs. The main objectives of this study were to describe the spatiotemporal analysis as well as to assess the potential risk factors along the pig value chain in Lao Cai province, Vietnam. A total of 925 outbreaks were reported from 2019 to 2020. The three clusters (primary, secondary and 5th) were observed near the Chinese border. The most temporal clusters were detected between May and August during the study period. In addition, we evaluated the association between ASF outbreak locations to the nearest main roads and elevation. For ASF outbreak locations to the nearest main roads, compared with the reference (<5,000 m), <1,000 m (10.22 times) and 1,000-2,000 m (1.98 times) were significantly higher occurrences of ASF. For elevation, compared to the reference (>1,500 m), the farm locations with <500 m (55.31 times) showed a significantly increased risk of ASF outbreaks. Farmers perceived that the highest risk of ASF transmission may come from collectors and slaughterers, intermediaries inside and outside the commune, feed agents and maize agents in the commune, and pig retailers. Both commercial and household pig producers considered minimizing the number of people going in and out of pig stables and improving healthcare and husbandry procedures to be both very important and feasible. There is a need for compliance by all pig producers and other actors in the pig value chain to adopt biosecurity practices. Therefore, awareness, knowledge and understanding of infection and risks of ASF need to be improved. Veterinary officials at the provincial and district levels need to improve capacity and resources to perform laboratory analysis for ASF and need to coordinate with local actors on the control and prevention of ASF in the community.

Computational investigation into intramolecular hydrogen bonding controlling the isomer formation and pKa of octahedral nickel(II) proton reduction catalysts.

This work demonstrates the impact of intramolecular hydrogen bonding (H-bonding) on the calculated pKa of octahedral tris-(pyridinethiolato)nickel(II), [Ni(PyS)3]-, proton reduction catalysts. Density Functional Theory (DFT) calculations on a [Ni(PyS)3]- catalyst, and eleven derivatives, demonstrate geometric isomer formation in the protonation step of the catalytic cycle. Through Quantum Theory of Atoms in Molecules (QTAIM), we show that the pKa of each isomer is driven by intramolecular H-bonding of the proton on the pyridyl nitrogen to a sulfur on a neighboring ligand. This work demonstrates that ligand modification via the placement of electron-donating (ED) or electron-withdrawing (EW) groups may have unexpected effects on the catalyst's pKa due to intramolecular H-bonding and isomer formation. These factors need to be considered in computational work. This work suggests the possibility that modification of substituent placement on the ligands to manipulate H-bonding in homogeneous metal catalysts could be explored as a tool to simultaneously target both desired pKa and E° values in small molecule catalysts.

Location bias contributes to functionally selective responses of biased CXCR3 agonists.

Some G protein-coupled receptor (GPCR) ligands act as "biased agonists" that preferentially activate specific signaling transducers over others. Although GPCRs are primarily found at the plasma membrane, GPCRs can traffic to and signal from many subcellular compartments. Here, we determine that differential subcellular signaling contributes to the biased signaling generated by three endogenous ligands of the GPCR CXC chemokine receptor 3 (CXCR3). The signaling profile of CXCR3 changes as it traffics from the plasma membrane to endosomes in a ligand-specific manner. Endosomal signaling is critical for biased activation of G proteins, ß-arrestins, and extracellular-signal-regulated kinase (ERK). In CD8 + T cells, the chemokines promote unique transcriptional responses predicted to regulate inflammatory pathways. In a mouse model of contact hypersensitivity, ß-arrestin-biased CXCR3-mediated inflammation is dependent on receptor internalization. Our work demonstrates that differential subcellular signaling is critical to the overall biased response observed at CXCR3, which has important implications for drugs targeting chemokine receptors and other GPCRs.

Clinical Characteristics and Implications of Bradycardia in COVID-19 Patients Treated with Remdesivir: A Single-Center Retrospective Cohort Study.

BACKGROUND AND OBJECTIVES: Remdesivir is an antiviral drug used to treat coronavirus disease 2019 (COVID-19) with a relatively obscure cardiac effect profile. Previous studies have reported bradycardia associated with remdesivir, but few have examined its clinical characteristics. The objective of this study was to investigate remdesivir associated bradycardia and its associated clinical characteristics and outcomes. METHODS: This is a single-institution retrospective study that investigated bradycardia in 600 patients who received remdesivir for treatment of COVID-19. A total of 375 patients were included in the study after screening for other known causes of bradycardia (atrioventricular [AV] nodal blockers). All patients were analyzed for episodes of bradycardia from when remdesivir was initiated up to 5 days after completion, a time frame based on the drug's putative elimination half-life. Univariate and multivariate statistical tests were conducted to analyze the data. RESULTS: The mean age of the sample was 56.63 ± 13.23 years. Of patients who met inclusion criteria, 49% were found to have bradycardia within 5 days of remdesivir administration. Compared to the cohort without a documented bradycardic episode, patients with bradycardia were significantly more likely to experience inpatient mortality (22% vs 12%, p = 0.01). The patients with bradycardia were found to have marginally higher serum D-dimer levels (5.2 vs 3.4 µg/mL, p = 0.05) and were more likely to undergo endotracheal intubation (28% vs 14%, p = 0.008). Male sex, hyperlipidemia, and bradycardia within 5 days of completing remdesivir were significant predictors of inpatient mortality. No significant differences in length of stay were found. CONCLUSIONS: Bradycardia that occurs during or shortly after remdesivir treatment in COVID-19 patients may be associated with an increased rate of in-hospital mortality. However, COVID-19 and its cardiac complications cannot be excluded as potential contributors of bradycardia in the present study. Future studies are needed to further delineate the cardiac characteristics of COVID-19 and remdesivir.

Detection of maternal carriers of common α-thalassemia deletions from cell-free DNA.

α-Thalassemia is a common inherited blood disorder manifested mainly by the deletions of α-globin genes. In geographical areas with high carrier frequencies, screening of α-thalassemia carrier state is therefore of vital importance. This study presents a novel method for identifying female carriers of common α-thalassemia deletions using samples routinely taken for non-invasive prenatal tests for screening of fetal chromosomal aneuploidies. A total of 68,885 Vietnamese pregnant women were recruited and α-thalassemia statuses were determined by gap-PCR, revealing 5344 women (7.76%) carried deletions including αα/--SEA (4.066%), αα/-α3.7 (2.934%), αα/-α4.2 (0.656%), and rare genotypes (0.102%). A two-stage model was built to predict these α-thalassemia deletions from targeted sequencing of the HBA gene cluster on maternal cfDNA. Our method achieved F1-scores of 97.14-99.55% for detecting the three common genotypes and 94.74% for detecting rare genotypes (-α3.7/-α4.2, αα/--THAI, -α3.7/--SEA, -α4.2/--SEA). Additionally, the positive predictive values were 100.00% for αα/αα, 99.29% for αα/--SEA, 94.87% for αα/-α3.7, and 96.51% for αα/-α4.2; and the negative predictive values were 97.63%, 99.99%, 99.99%, and 100.00%, respectively. As NIPT is increasingly adopted for pregnant women, utilizing cfDNA from NIPT to detect maternal carriers of common α-thalassemia deletions will be cost-effective and expand the benefits of NIPT.

Multi-agent reinforcement learning approach for hedging portfolio problem.

Developing a hedging strategy to reduce risk of losses for a given set of stocks in a portfolio is a difficult task due to cost of the hedge. In Vietnam stock market, cross-hedge is involved hedging a long position of a stock because there is no put option for the stock. In addition, only VN30 stock index futures contracts are traded on Hanoi Stock Exchange. Inspired by recently achievement of deep reinforcement learning, we explore feasibility to construct a hedging strategy automatically by leveraging cooperative multi-agent in reinforcement learning techniques without advanced domain knowledge. In this work, we use 10 popular stocks on Ho Chi Minh Stock Exchange, and VN30F1M (VN30 Index Futures contracts within one month settlement) to develop a stock market simulator (including transaction fee, tax, and settlement date of transactions) for reinforcement learning agent training. We use daily return as input data for training process. Results suggest that the agent can learn trading and hedging policy to make profit and reduce losses. Furthermore, we also find that our agent can protect portfolios and make positive profit in case market collapses systematically. In practice, this work can help Vietnam's stock market investors to improve performance and reduce losses in trading, especially when the volatility cannot be controlled.