Environmental behaviors and toxic mechanisms of engineered nanomaterials in soil.

Engineered nanomaterials (ENMs) are inevitably released into the environment with the exponential application of nanotechnology. Parts of ENMs eventually accumulate in the soil environment leading to potential adverse effects on soil ecology, crop production, and human health. Therefore, the safety application of ENMs on soil has been widely discussed in recent years. More detailed safety information and potential soil environmental risks are urgently needed. However, most of the studies on the environmental effects of metal-based ENMs have been limited to single-species experiments, ecosystem processes, or abiotic processes. The present review formulated the source and the behaviors of the ENMs in soil, and the potential effects of single and co-exposure ENMs on soil microorganisms, soil fauna, and plants were introduced. The toxicity mechanism of ENMs to soil organisms was also reviewed including oxidative stress, the release of toxic metal ions, and physical contact. Soil properties affect the transport, transformation, and toxicity of ENMs. Toxic mechanisms of ENMs include oxidative stress, ion release, and physical contact. Joint toxic effects occur through adsorption, photodegradation, and loading. Besides, future research should focus on the toxic effects of ENMs at the food chain levels, the effects of ENMs on plant whole-lifecycle, and the co-exposure and long-term toxicity effects. A fast and accurate toxicity evaluation system and model method are urgently needed to solve the current difficulties. It is of great significance for the sustainable development of ENMs to provide the theoretical basis for the ecological risk assessment and environmental management of ENMs.

Fundamental Determinants of the Accuracy of Equilibrium Constants for Affinity Complexes.

The equilibrium constant of a chemical reaction is arguably the key thermodynamic parameter in chemistry; we naturally expect that equilibrium constants are determined accurately. The majority of equilibrium constants determined today are those of binding reactions that form affinity complexes, such as protein-protein, protein-DNA, and protein-small molecule. There is growing awareness that the determination of equilibrium constants for highly stable affinity complexes may be very inaccurate. However, fundamental (i.e., method-independent) determinants of accuracy are poorly understood. Here, we present a study that explicitly shows what the accuracy of equilibrium constants of affinity complexes depends on. This study reveals the critical importance of the choice of concentration of interacting components and creates a theoretical foundation for improving the accuracy of the equilibrium constants. The predicted influence of concentrations on accuracy was confirmed experimentally. The results of this fundamental study provide instructive guidance for experimentalists independently on the method they use.

Hierarchically engineered nanostructures from compositionally anisotropic molecular building blocks.

The inability to synthesize hierarchical structures with independently tailored nanoscale and mesoscale features limits the discovery of next-generation multifunctional materials. Here we present a predictable molecular self-assembly strategy to craft nanostructured materials with a variety of phase-in-phase hierarchical morphologies. The compositionally anisotropic building blocks employed in the assembly process are formed by multicomponent graft block copolymers containing sequence-defined side chains. The judicious design of various structural parameters in the graft block copolymers enables broadly tunable compositions, morphologies and lattice parameters across the nanoscale and mesoscale in the assembled structures. Our strategy introduces advanced design principles for the efficient creation of complex hierarchical structures and provides a facile synthetic platform to access nanomaterials with multiple precisely integrated functionalities.

Wearing masks as a protective measure for children against traffic-related air pollution: A comparison of perceptions between school children and their caregivers in Ho Chi Minh City, Vietnam.

BACKGROUND: Traffic-related air pollution (TRAP) problems are unlikely to be solved in the short term, making it imperative to educate children on protective measures to mitigate the negative impact on their health. Children and their caregivers may hold differing views on wearing a face mask as a safeguard against air pollution. While many studies have focused on predicting children's health-protective behaviours against air pollution, few have explored the differences in perceptions between children and their caregivers. OBJECTIVES: To examine this, we conducted a study that compared the health beliefs of two generations and evaluated the factors that influence the use of masks by children to reduce air pollution exposure. METHODS: The study was conducted in 24 secondary schools and involved 8420 children aged 13-14 and their caregivers. We used a Health Belief Model (HBM)-based instrument containing 17-item self-administered health beliefs questionnaires to gather data. The results were analysed using hierarchical logistic regression to determine the probability of children frequently wearing masks to protect against TRAP. RESULTS: Our study showed both children and caregivers recognised that several factors could influence mask-wearing among children: discomfort or difficulty breathing while wearing a mask and forgetting to bring a mask when going outside; perceived threats of the poor quality of air and children's respiratory health problems; and cues to mask use (i.e., seeing most of their friends wearing facemasks and ease of finding masks in local stores). However, only children were significantly concerned with public perception of their appearance while wearing a mask. Females were more likely to wear masks, and caregivers with higher levels of education were more likely to encourage their children to wear masks. Children who commuted to schools by walking, biking, or motorbiking were also more accepting of mask-wearing than those who travelled by car or bus. CONCLUSIONS: Children and their caregivers hold different perceptions of wearing masks to protect against air pollution. Children are more susceptible to social judgements regarding their appearance when wearing a mask.

Liver Complications in Untreated Treatment-Ineligible versus Treated Treatment-Eligible Patients with Hepatitis B.

BACKGROUND: A substantial number of patients who do not meet treatment criteria for chronic hepatitis B (CHB) later develop adverse outcomes such as cirrhosis and hepatocellular carcinoma (HCC). Our aim was to determine whether current practice guidelines adequately identify CHB patients who will benefit from antiviral therapy. METHODS: We performed a retrospective cohort study comparing the incidence of adverse liver outcomes (cirrhosis and/or HCC) in untreated treatment-ineligible (at baseline and throughout follow-up) versus treated treatment-eligible patients according to standard American Association for the Study of Liver Diseases (AASLD) 2018 guidance (alanine aminotransferase [ALT] >70/50 U/L for men/women plus hepatitis B virus [HBV] DNA >20,000/2,000 IU/mL for HBeAg+/-) and with a sensitivity analyses using a lower threshold (ALT >40 U/L and HBV DNA >2,000 IU/mL). RESULTS: We reviewed records of 5,840 patients from 5 clinics in California and identified 2,987 treatment-naive non-HCC CHB patients. Of those, 271 patients remained untreated treatment-ineligible, 514 patients were treatment-eligible and initiated treatment, with 5-year cumulative adverse liver incidences of 12.5% versus 7.2%, p = 0.074. On multivariable analysis adjusting for age, sex, diabetes, albumin, platelet count, and HBV DNA, compared to treated treatment-eligible patients, untreated treatment-ineligible patients had a significantly higher risk of adverse liver outcomes (adjusted hazard ratio: 2.38, 95% confidence interval 1.03-5.48, p = 0.04) in main analysis by AASLD 2018 criteria but not in sensitivity analysis using the lower treatment threshold (p = 0.09). CONCLUSION: Patients never meeting standard AASLD 2018 criteria for antiviral therapy and never treated had twice the risk of developing cirrhosis and/or HCC when compared to eligible and treated patients.

Burden of asthma-like symptoms and a lack of recognition of asthma in Vietnamese children.

OBJECTIVE: Lack of recognition of asthma in childhood results in unmet asthma treatment needs and leads to the risk of sub-optimal respiratory health. The present study assessed the prevalence of asthmatic under-recognition in middle school children in Vietnam. METHODS: We conducted a school-based survey among 15,112 Vietnamese children. Most of them are aged from 13 to 14. Schools and students were recruited using multi-stage sampling. Respiratory symptoms were collected via self-report using a standardized tool from the International Study of Asthma and Allergies in Childhood. Under-recognition of asthma was defined as a presence of at least one asthma-like symptom but a negative response to having ever asthma. Associations were investigated using logistic regression. RESULTS: Prevalence of asthma-like symptoms was 27.3% and prevalence of physician-diagnosed asthma was 8.5%. Over 80% of symptomatic children were not diagnosed with asthma. Under-recognition of asthma was found more in girls (adjusted odds ratio; aOR = 1.75; 95%CI: 1.54 to 1.98). CONCLUSIONS: Asthma is significantly under-recognized in Vietnamese middle-school children. Urgent action is required to improve the recognition of asthma in Vietnam.

Prevalence of depressive disorders in a primary care setting in Ho Chi Minh City, Vietnam: A cross-sectional epidemiological study.

OBJECTIVE: This research was conducted to identify the prevalence and associated factors of depressive disorders, as well as evaluate the recognition rate of general practitioners in detecting these mental health issues in primary care. METHOD: Five hundred and twelve participants (55.3% female, mean age = 46.35 years) were assessed by psychiatrists based on the DSM-5 clinical procedures over a two-month survey in a primary care facility in Ho Chi Minh City, Vietnam. RESULTS: There were 15.8% (95% confidence interval [CI] 12.9-19.2) of the population having depressive disorders, with major depressive disorder being the most prevalent subtype at 8% (95% CI 5.9-10.6). General practitioners could detect depressive disorders in 2.5% of all cases (95% CI .5-7.7). Significantly linked with depressive disorders in multivariable analysis were Chinese ethnic or other minority races (adjusted odds ratios [aOR] = 4.10, 95% CI 1.04-16.12), and low economic status (aOR = 5.41, 95% CI 1.29-22.59). CONCLUSIONS: The high prevalence of depressive disorders in outpatients of primary care clinics may raise the awareness of the practitioners about screening and other appropriate actions to tackle the issue.

Classification of COPD as ABCD according to GOLD 2011 and 2017 versions in COPD patients at University Medical Center in Ho Chi Minh City, Vietnam.

In 2017, Global Initiative for Chronic Lung Disease (GOLD) made substantial changes to its ABCD group categorization. Although several studies had been conducted to assess the impact of the new GOLD category, there was no research on the change of the GOLD classification in Vietnam. This retrospective analysis was conducted at Asthma and COPD clinic at the University Medical Center in Ho Chi Minh City, Vietnam. Our study population comprised patients visiting Medical Center from January 2018 to January 2020. We categorized patients' demographic, clinical characteristics and pharmacotherapy based on GOLD 2011 and 2017 guidelines. A comparison between the two versions was also determined. A total of 457 patients were included in this study. The percentage of groups A, B, C and D according to GOLD 2011 was 5%, 20.8%, 13.1% and 61.1%; and according to GOLD 2017 was 6.1%, 34.1%, 12% and 47.8%, respectively. In terms of gender, male patients constituted nearly 95% of the study's population (433/457 patients). Regarding pharmacotherapy, approximately 20% of the low-risk group (group A-B) was overtreated with ICS components: LABA+ICS (15.8%) and LAMA+LABA+ICS (3.8%). There were 13.3% and 1.1% of patients transferred from D to B and from C to A, respectively. All of them had lower FVC% pred, FEV1% pred and FEV1/FVC than the patients remained in group B or A (p<0.005). This is the first research in Vietnam to show the distribution of COPD patients using both the GOLD 2011 and GOLD 2017 criteria. There was 14% of patients reclassified from high-risk groups to low-risk groups when changing from 2011 to 2017 version and discordance of medications between guidelines and real-life practice. Therefore, clinicians should use their clinical competence to consider patients' conditions before deciding the appropriate therapeutic approach. Consequently, further studies were required to evaluate the effect of the change in GOLD classification.

Natural History and Hepatocellular Carcinoma Risk in Untreated Chronic Hepatitis B Patients With Indeterminate Phase.

BACKGROUND & AIMS: Many patients with chronic hepatitis B (CHB) may not conform to any of the defined phases and hence are classified as indeterminate. We aimed to characterize the baseline prevalence of indeterminate patients and their natural history, phase transition, and hepatocellular carcinoma (HCC) risk. METHODS: This was a retrospective cohort study of 3366 adult untreated noncirrhotic CHB patients seen at 5 US clinics and 7 Taiwanese townships who had at least 1 year of serial laboratory data before enrollment with a mean follow-up period of 12.5 years. Patients' clinical phases were determined at baseline and through serial data during follow-up evaluation, based on the American Association for the Study of Liver Diseases 2018 guidance. RESULTS: At baseline, 1303 (38.7%) patients were in the indeterminate phase. By up to year 10 of follow-up evaluation, 686 patients (52.7%) remained indeterminate, while 283 patients (21.7%) became immune active. Compared with patients who remained inactive, patients who remained indeterminate had a higher 10-year cumulative HCC incidence (4.6% vs 0.5%; P < .0001) and adjusted hazard ratio for HCC of 14.1 (P = .03). Among patients who remained indeterminate, age 45 years and older (adjusted hazard ratio, 18.4; P = .005) was associated independently with HCC development. CONCLUSIONS: Nearly 40% of patients had indeterminate CHB phase. Of these, half remained indeterminate and one-fifth transitioned to the immune active phase. HCC risk in persistently indeterminate CHB was 14 times higher than inactive CHB. Among persistently indeterminate CHB patients, age 45 years and older was associated with an 18 times higher risk for HCC development. Further studies are needed to evaluate the potential benefit of antiviral therapy for indeterminate patients, especially in the older subgroup.

Progression Rates by Age, Sex, Treatment, and Disease Activity by AASLD and EASL Criteria: Data for Precision Medicine.

BACKGROUND & AIMS: Antiviral treatment criteria are based on disease progression risk, and hepatocellular carcinoma (HCC) surveillance recommendations for patients with chronic hepatitis B (CHB) without cirrhosis is based on an annual incidence threshold of 0.2%. However, accurate and precise disease progression estimate data are limited. Thus, we aimed to determine rates of cirrhosis and HCC development stratified by age, sex, treatment status, and disease activity based on the 2018 American Association for the Study of Liver Diseases and 2017 European Association for the Study of the Liver guidelines. METHODS: We analyzed 18,338 patients (8914 treated, 9424 untreated) from 6 centers from the United States and 27 centers from Asia-Pacific countries. The Kaplan-Meier method was used to estimate annual progression rates to cirrhosis or HCC in person-years. RESULTS: The cohort was 63% male, with a mean age of 46.19 years, with baseline cirrhosis of 14.3% and median follow up of 9.60 years. By American Association for the Study of Liver Diseases criteria, depending on age, sex, and disease activity, annual incidence rates ranged from 0.07% to 3.94% for cirrhosis, from 0.04% to 2.19% for HCC in patients without cirrhosis, and from 0.40% to 8.83% for HCC in patients with cirrhosis. Several subgroups of patients without cirrhosis including males younger than 40 years of age and females younger than 50 years of age had annual HCC risk near or exceeding 0.2%. Similar results were found using European Association for the Study of the Liver criteria. CONCLUSION: There is great variability in CHB disease progression rates even among "lower-risk" populations. Future CHB modeling studies, public health planning, and HCC surveillance recommendation should be based on more precise disease progression rates based on sex, age, and disease activity, plus treatment status.

Quantitative Characterization of Partitioning in Selection of DNA Aptamers for Protein Targets by Capillary Electrophoresis.

Partitioning of protein-DNA complexes from protein-unbound DNA is a key step in selection of DNA aptamers. Conceptually, the partitioning step is characterized by two parameters: transmittance for protein-bound DNA (binders) and transmittance for unbound DNA (nonbinders). Here, we present the first study to reveal how these transmittances depend on experimental conditions; such studies are pivotal to the effective planning and control of selection. Our focus was capillary electrophoresis (CE), which is a partitioning approach of high efficiency. By combining a theoretical model and experimental data, we evaluated the dependence of transmittances of binders and nonbinders on the molecular weight of the protein target in two modes of CE-based partitioning: nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) and ideal-filter capillary electrophoresis (IFCE). Our data suggest that as the molecular weight of the protein target decreases: (i) the transmittance for binders remains close to unity in NECEEM but decreases drastically in IFCE and (ii) the transmittance for nonbinders increases orders of magnitude in NECEEM but remains relatively stable at a very low level in IFCE. To determine the optimal CE conditions for a given size of protein target, a balance between transmittances of binders and nonbinders must be reached; such a balance would ensure the collection of binders of sufficient purity and quantity. We conclude that, as a rule of thumb, IFCE is preferable for large-size protein targets while NECEEM should be the method of choice for small-size protein targets.

Bulk Affinity Assays in Aptamer Selection: Challenges, Theory, and Workflow.

Selection of oligonucleotide aptamers involves consecutive rounds of affinity isolation of target-binding oligonucleotides from a random-sequence oligonucleotide library. Every next round produces an aptamer-enriched library with progressively higher fitness for tight binding to the target. The progress of enrichment can only be accurately assessed with bulk affinity assays in which a library is mixed with the target and one of two quantitative parameters, the fraction of the unbound library (R) or the equilibrium dissociation constant (Kd), is determined. These quantitative parameters are used to help researchers make a key decision of either continuing or stopping the selection. Despite the importance of this decision, the suitability of R and Kd for bulk affinity assays has never been studied theoretically, and researchers rely on intuition when choosing between them. Different approaches used for bulk affinity assays expectedly hinder comparative analyses of selections. Our current work has two goals: to give bulk affinity assays a thorough theoretical consideration and to propose a scientifically justified and practical bulk-affinity-assay approach. We postulate a formal criterion of suitability: a quantitative parameter must satisfy the principle of superposition. R satisfies this principle, while Kd does not, suggesting R as a theoretically preferable parameter. Further, we propose a solution for two limitations of R: its dependence on target concentration and narrow dynamic range. Finally, we demonstrate the use of this algorithm in both computer-simulated and experimental aptamer selection. This study sets a cornerstone in the theory of bulk affinity assays, and it provides researchers with a scientifically sound and instructive approach for conducting bulk affinity assays.

Transient Incomplete Separation of Species with Close Diffusivity to Study the Stability of Affinity Complexes.

Large molecules can be generically separated from small ones, though partially and temporarily, in a pressure-driven flow inside a capillary. This transient incomplete separation has been only applied to species with diffusion coefficients different by at least an order of magnitude. Here, we demonstrate, for the first time, the analytical utility of transient incomplete separation for species with close diffusion coefficients. First, we prove in silico that even a small difference in diffusivity can lead to detectable transient incomplete separation of species. Second, we use computer simulation to prove that such a separation can be used for the reliable determination of equilibrium dissociation constant (Kd) of complexes composed of similar-sized molecules. Finally, we demonstrate experimentally the use of this separation for the accurate determination of Kd value for a protein-aptamer complex. We conclude that "accurate constant via transient incomplete separation" (ACTIS) can serve as a reference method for affinity characterization of protein-aptamer binding in solution.

Aerobic vaginitis in the third trimester and its impact on pregnancy outcomes.

BACKGROUND: Aerobic vaginitis (AV) is a vaginal inflammation characterized by disruption of the lactobacillus microbiota and increased counts of different aerobic bacteria. AV may result in severe complications, especially during pregnancy, including preterm delivery, neonatal and maternal infections. This study aimed to determine the prevalence of AV in the third trimester of pregnancy, and the relationship between AV and pregnancy outcomes.  METHODS: A cross-sectional descriptive study included 323 pregnant women attending for routine antenatal care in the Hue University Hospital. Vaginal samples collected at the third trimester of pregnancy were evaluated for AV according to the scoring system of Donders and cultured for identification of predominant bacteria. Pregnancy was followed to its end, and pregnancy outcomes were recorded for both mothers and infants. RESULTS: The proportion of pregnant women diagnosed with AV in the third trimester was found to be 15.5%, with the vast majority of the cases (84%) displaying the light AV and 16% the moderate AV. The vaginal cultures in the women with AV revealed most frequently Streptococcus agalactiae (6%), followed by Enterococcus spp (4%), Staphylococcus aureus (4%), and Acinetobacter baumannii (2%). In addition, AV during the last trimester of pregnancy was associated with an increased risk of puerperal sepsis (OR 8.65, 95% CI: 1.41-53.16, p = 0.020) and there was a slightly increased risk for neonatal infections, which was statistically insignificant. CONCLUSIONS: The proportion of AV is relatively high in Vietnamese pregnant women. Since it is associated with an increased risk of puerperal sepsis, it needs to be diagnosed and treated before delivery.

Development and Validation of a Risk Score for Liver Cirrhosis Prediction in Untreated and Treated Chronic Hepatitis B.

BACKGROUND: Chronic hepatitis B (CHB) can progress to cirrhosis, but there are limited noninvasive tools available to estimate cirrhosis risk, including in patients receiving antiviral therapy. This study developed and validated a simple model to assess risk in CHB patients. METHODS: The derivation cohort included 3000 CHB patients from 6 centers in the United States, with 52.60% receiving antiviral therapy. External validation was performed for 4552 CHB individuals from similar cohorts in Taiwan, with 21.27% receiving therapy. Cox proportional hazards regression analyses were used to screen predictors and develop the risk score for cirrhosis. Areas under receiver operating characteristic curves (AUROCs) were calculated for predictive value. RESULTS: Sex, age, diabetes, antiviral treatment status/duration, hepatitis B e-antigen, and baseline alanine aminotransferase/aspartate aminotransferase levels were significantly associated with increased cirrhosis risk. A 13-point risk score was developed based on these predictors. The AUROCs for predicting cirrhosis risk were 0.82 at 3 years, 0.85 at 5 years, and 0.89 at 10 years in the derivation cohort, and 0.82, 0.79, and 0.77 in the validation cohort, respectively. CONCLUSIONS: We developed and validated a simple cirrhosis prediction model with an independent external cohort that can be applied to both treatment-naive and treatment-experienced CHB patients in diverse settings and locations.

Association Between Fatty Liver and Cirrhosis, Hepatocellular Carcinoma, and Hepatitis B Surface Antigen Seroclearance in Chronic Hepatitis B.

BACKGROUND: Chronic hepatitis B (CHB) and fatty liver (FL) are common, natural history data on concurrent FL and CHB (FL-CHB) are limited. This study aimed to evaluate the effect of FL on cirrhosis, hepatocellular carcinoma (HCC), and hepatitis B surface antigen (HBsAg) seroclearance incidence in CHB patients. METHODS: In a retrospective cohort study of 6786 adult CHB patients, we used propensity score matching (PSM) to balance the FL-CHB and non-FL CHB groups. Kaplan-Meier methods were used to compare cumulative cirrhosis, HCC, and HBsAg seroclearance rates between subgroups. RESULTS: Before PSM, compared to non-FL CHB, FL-CHB patients had lower 10-year cumulative rates of cirrhosis, HCC, and a higher HBsAg seroclearance rate. Similar results were found in the matched FL-CHB and non-FL CHB patients, as well as in the antiviral-treated PSM cohort. Cox proportional hazards model indicated FL to remain significantly and strongly associated with lower risk of cirrhosis and HCC (hazard ratio [HR], 0.19 [95% confidence interval {CI}, .12-.33], P < .001 and HR, 0.21 [95% CI, .09-.51], P = .001, respectively) in antiviral-treated patients but not in untreated patients. CONCLUSIONS: FL was significantly associated with lower cirrhosis and HCC risk and higher HBsAg seroclearance. Further studies are needed to confirm our funding and investigate the mechanisms underlying the impact of FL on CHB.

Rapid Access to Diverse Multicomponent Hierarchical Nanostructures from Mixed-Graft Block Copolymers.

Multicomponent nanostructured materials assembled from molecular building blocks received wide attention due to their precisely integrated multifunctionalities. However, discovery of these materials with desirable composition and morphology was limited by their low synthetic scalability and narrow structural tuning window with given building blocks. Here, we report a scalable and diversity-oriented synthetic approach to hierarchically structured nanomaterials based on a few readily accessible building blocks. Mixed-graft block copolymers containing sequence-defined side chains were prepared through ring-opening metathesis copolymerization of three or four types of macromonomers. Intramolecularly defined interfaces promoted the formation of ordered hierarchical structures with lattice sizes tunable across multiple length scales. The same set of macromonomers were arranged and combined in different ways, providing access to diverse morphologies in the resultant structures.

Highly Enantioselective Synthesis of N-Unprotected Unnatural α-Amino Acid Derivatives by Ruthenium-Catalyzed Direct Asymmetric Reductive Amination.

An unprecedented highly enantioselective Ru-catalyzed direct asymmetric reductive amination of α-keto amides with ammonium salts has been disclosed, efficiently offering valuable enantioenriched N-unprotected unnatural α-amino acid derivatives bearing a broad range of aryl or alkyl α-substituents. This protocol features easily accessible substrates, good functional-group tolerance and excellent enantiocontrol, making it a good complementary approach to the known methods. Moreover, this method is also applicable to the preparation of N-unprotected unnatural α-amino acid derivatives containing an additional stereogenic center at the ß-position through a dynamic kinetic resolution (DKR) process. Convenient transformations of the obtained products into chiral N-unprotected unnatural α-amino acids, drug intermediates, peptides, and organocatalysts/ligands further showcase the utility of this method.

Loss of HIF1A From Pancreatic Cancer Cells Increases Expression of PPP1R1B and Degradation of p53 to Promote Invasion and Metastasis.

BACKGROUND & AIMS: Pancreatic ductal adenocarcinomas (PDACs) are hypovascular, resulting in the up-regulation of hypoxia inducible factor 1 alpha (HIF1A), which promotes the survival of cells under low-oxygen conditions. We studied the roles of HIF1A in the development of pancreatic tumors in mice. METHODS: We performed studies with KrasLSL-G12D/+;Trp53LSL-R172H/+;Pdx1-Cre (KPC) mice, KPC mice with labeled pancreatic epithelial cells (EKPC), and EKPC mice with pancreas-specific depletion of HIF1A. Pancreatic and other tissues were collected and analyzed by histology and immunohistochemistry. Cancer cells were cultured from PDACs from mice and analyzed in cell migration and invasion assays and by immunoblots, real-time polymerase chain reaction, and liquid chromatography-mass spectrometry. We performed studies with the human pancreatic cancer cell lines PATU-8988T, BxPC-3, PANC-1, and MiaPACA-2, which have no or low metastatic activity, and PATU-8988S, AsPC-1, SUIT-2 and Capan-1, which have high metastatic activity. Expression of genes was knocked down in primary cancer cells and pancreatic cancer cell lines by using small hairpin RNAs; cells were injected intravenously into immune-competent and NOD/SCID mice, and lung metastases were quantified. We compared levels of messenger RNAs in pancreatic tumors and normal pancreas in The Cancer Genome Atlas. RESULTS: EKPC mice with pancreas-specific deletion of HIF1A developed more advanced pancreatic neoplasias and PDACs with more invasion and metastasis, and had significantly shorter survival times, than EKPC mice. Pancreatic cancer cells from these tumors had higher invasive and metastatic activity in culture than cells from tumors of EKPC mice. HIF1A-knockout pancreatic cancer cells had increased expression of protein phosphatase 1 regulatory inhibitor subunit 1B (PPP1R1B). There was an inverse correlation between levels of HIF1A and PPP1R1B in human PDAC tumors; higher expression of PPP1R1B correlated with shorter survival times of patients. Metastatic human pancreatic cancer cell lines had increased levels of PPP1R1B and lower levels of HIF1A compared with nonmetastatic cancer cell lines; knockdown of PPP1R1B significantly reduced the ability of pancreatic cancer cells to form lung metastases in mice. PPP1R1B promoted degradation of p53 by stabilizing phosphorylation of MDM2 at Ser166. CONCLUSIONS: HIF1A can act a tumor suppressor by preventing the expression of PPP1R1B and subsequent degradation of the p53 protein in pancreatic cancer cells. Loss of HIF1A from pancreatic cancer cells increases their invasive and metastatic activity.

How to Develop and Prove High-Efficiency Selection of Ligands from Oligonucleotide Libraries: A Universal Framework for Aptamers and DNA-Encoded Small-Molecule Ligands.

Screening molecular libraries for ligands capable of binding proteins is widely used for hit identification in the early drug discovery process. Oligonucleotide libraries provide a very high diversity of compounds, while the combination of the polymerase chain reaction and DNA sequencing allow the identification of ligands in low copy numbers selected from such libraries. Ligand selection from oligonucleotide libraries requires mixing the library with the target followed by the physical separation of the ligand-target complexes from the unbound library. Cumulatively, the low abundance of ligands in the library and the low efficiency of available separation methods necessitate multiple consecutive rounds of partitioning. Multiple rounds of inefficient partitioning make the selection process ineffective and prone to failures. There are continuing efforts to develop a separation method capable of reliably generating a pure pool of ligands in a single round of partitioning; however, none of the proposed methods for single-round selection have been universally adopted. Our analysis revealed that the developers' efforts are disconnected from each other and hindered by the lack of quantitative criteria of selection quality assessment. Here, we present a formalism that describes single-round selection mathematically and provides parameters for quantitative characterization of selection quality. We use this formalism to define a universal strategy for development and validation of single-round selection methods. Finally, we analyze the existing partitioning methods, the published single-round selection reports, and some pertinent practical considerations through the prism of this formalism. This formalism is not an experimental protocol but a framework for correct development of experimental protocols. While single-round selection is not a goal by itself and may not always suffice selection of good-quality ligands, our work will help developers of highly efficient selection approaches to consolidate their efforts under an umbrella of universal quantitative criteria of method development and assessment.