Cdk5 inhibition in the SOD1G93A transgenic mouse model of amyotrophic lateral sclerosis suppresses neurodegeneration and extends survival.

Deregulated cyclin-dependent kinase 5 (Cdk5) activity closely correlates with hyperphosphorylated tau, a common pathology found in neurodegenerative diseases. Previous postmortem studies had revealed increased Cdk5 immunoreactivity in amyotrophic lateral sclerosis (ALS); hence, we investigated the effects of Cdk5 inhibition on ALS model mice and neurons in this study. For the in vitro study, motor neuron cell lines with wild-type superoxide dismutase 1 (SOD1) or SOD1G93A and primary neuronal cultures from SOD1G93A transgenic (TG) mice or non-TG mice were compared for the expression of proteins involved in tau pathology, neuroinflammation, apoptosis, and neuritic outgrowth by applying Cdk5-small interfering RNA or Cdk5-short hairpin RNA (shRNA). For the in vivo study, SOD1G93A mice and non-TG mice were intrathecally injected with adeno-associated virus 9 (AAV9)-scramble (SCR)-shRNA or AAV9-Cdk5-shRNA at the age of 5 weeks. Weight and motor function were measured three times per week from 60 days of age, longevity was evaluated, and the tissues were collected from 90-day-old or 120-day-old mice. Neurons with SOD1G93A showed increased phosphorylated tau, attenuated neuritic growth, mislocalization of SOD1, and enhanced neuroinflammation and apoptosis, all of which were reversed by Cdk5 inhibition. Weights did not show significant differences among non-TG and SOD1G93A mice with or without Cdk5 silencing. SOD1G93A mice treated with AAV9-Cdk5-shRNA showed significantly delayed disease onset, delayed rotarod failure, and prolonged survival compared with those treated with AAV9-SCR-shRNA. The brain and spinal cord of SOD1G93A mice intrathecally injected with AAV9-Cdk5-shRNA exhibited suppressed tau pathology, neuroinflammation, apoptosis, and an increased number of motor neurons compared to those of SOD1G93A mice injected with AAV9-SCR-shRNA. Cdk5 inhibition could be an important mechanism in the development of a new therapeutic strategy for ALS.

Dual effects of TGF-ß inhibitor in ALS - inhibit contracture and neurodegeneration.

As persistent elevation of transforming growth factor-ß (TGF-ß) promotes fibrosis of muscles and joints and accelerates disease progression in amyotrophic lateral sclerosis (ALS), we investigated whether inhibition of TGF-ß would be effective against both exacerbations. The effects of TGF-ß and its inhibitor on myoblasts and fibroblasts were tested in vitro and confirmed in vivo, and the dual action of a TGF-ß inhibitor in ameliorating the pathogenic role of TGF-ß in ALS mice was identified. In the peripheral neuromuscular system, fibrosis in the muscles and joint cavities induced by excessive TGF-ß causes joint contracture and muscular degeneration, which leads to motor dysfunction. In an ALS mouse model, an increase in TGF-ß in the central nervous system (CNS), consistent with astrocyte activity, was associated with M1 microglial activity and pro-inflammatory conditions, as well as with neuronal cell death. Treatment with the TGF-ß inhibitor halofuginone could prevent musculoskeletal fibrosis, resulting in the alleviation of joint contracture and delay of motor deterioration in ALS mice. Halofuginone could also reduce glial cell-induced neuroinflammation and neuronal apoptosis. These dual therapeutic effects on both the neuromuscular system and the CNS were observed from the beginning to the end stages of ALS; as a result, treatment with a TGF-ß inhibitor from the early stage of disease delayed the time of symptom exacerbation in ALS mice, which led to prolonged survival.

Performance enhancement of HfO2-based resistive random-access memory devices using ZnO nanoparticles.

In this study, resistive random-access memory (ReRAM) devices with ZnO nanoparticles (NPs) are suggested to enhance performance and reduce variation in device switching parameters. The ZnO NPs are formed by annealing ZnO prepared via atomic layer deposition on HfO2, which is verified using transmission electron microscopy, x-ray diffraction pattern, and atomic force microscopy. The depth profile analysis of x-ray photoelectron spectroscopy shows that oxygen diffuses from HfO2to ZnO NPs during annealing. This can be explained by the calculation results using density functional theory (DFT) where the formation energy of oxygen vacancies is reduced at the interface of ZnO NPs and HfO2compared to single HfO2. The fabricated ZnO NPs ReRAM demonstrates reduced forming voltage, stable resistive switching behavior, and improved cycle-to-cycle uniformity in a high-resistance state.

Lactobacillus plantarum Metabolites Elicit Anticancer Effects by Inhibiting Autophagy-Related Responses.

Lactobacillus plantarum (L. plantarum) is a probiotic that has emerged as novel therapeutic agents for managing various diseases, such as cancer, atopic dermatitis, inflammatory bowel disease, and infections. In this study, we investigated the potential mechanisms underlying the anticancer effect of the metabolites of L. plantarum. We cultured L. plantarum cells to obtain their metabolites, created several dilutions, and used these solutions to treat human colonic Caco-2 cells. Our results showed a 10% dilution of L. plantarum metabolites decreased cell viability and reduced the expression of autophagy-related proteins. Moreover, we found co-treatment with L. plantarum metabolites and chloroquine, a known autophagy inhibitor, had a synergistic effect on cytotoxicity and downregulation of autophagy-related protein expression. In conclusion, we showed the metabolites from the probiotic, L. plantarum, work synergistically with chloroquine in killing Caco-2 cells and downregulating the expression of autophagy-related proteins, suggesting the involvement of autophagy, rather than apoptosis, in their cytotoxic effect. Hence, this study provides new insights into new therapeutic methods via inhibiting autophagy.

Hybrid model for daily streamflow and phosphorus load prediction.

Environmental factors, such as climate change and land use changes, affect water quality drastically. To consider these, various predictive models, both process-based and data-driven, have been used. However, each model has distinct limitations. In this study, a hybrid model combining the soil and water assessment tool and the reverse time attention mechanism (SWAT-RETAIN) was proposed for predicting daily streamflow and total phosphorus (TP) load of a watershed. SWAT-RETAIN was applied to Hwangryong River, South Korea. The hybrid model uses the SWAT output as input data for the RETAIN. Spatial, meteorological, and hydrological data were collected to develop the SWAT to generate high temporal resolution data. RETAIN facilitated effective simultaneous prediction. The SWAT-RETAIN exhibited high accuracy in predicting streamflow (Nash-Sutcliffe efficiency (NSE): 0.45, root mean square error (RMSE): 27.74, percent bias (PBIAS): 22.63 for test sets), and TP load (NSE: 0.50, RMSE: 423.93, PBIAS: 22.09 for test sets). This result was evident in the performance evaluation using flow duration and load duration curves. The SWAT-RETAIN provides enhanced temporal resolution and performance, enabling the simultaneous prediction of multiple variables. It can be applied to predict various water quality variables in larger watersheds.

Bottom-Gated ZnO TFT Pressure Sensor with 1D Nanorods.

In this study, a bottom-gated ZnO thin film transistor (TFT) pressure sensor with nanorods (NRs) is suggested. The NRs are formed on a planar channel of the TFT by hydrothermal synthesis for the mediators of pressure amplification. The fabricated devices show enhanced sensitivity by 16~20 times better than that of the thin film structure because NRs have a small pressure transmission area and causes more strain in the underlayered piezoelectric channel material. When making a sensor with a three-terminal structure, the leakage current in stand-by mode and optimal conductance state for pressure sensor is expected to be controlled by the gate voltage. A scanning electron microscope (SEM) was used to identify the nanorods grown by hydrothermal synthesis. X-ray diffraction (XRD) was used to compare ZnO crystallinity according to device structure and process conditions. To investigate the effect of NRs, channel mobility is also extracted experimentally and the lateral flow of current density is analyzed with simulation (COMSOL) showing that when the piezopotential due to polarization is formed vertically in the channel, the effective mobility is degraded.

ALS-Linked Mutant SOD1 Associates with TIA-1 and Alters Stress Granule Dynamics.

Amyotrophic lateral sclerosis (ALS) is a degenerative disorder caused by motor neuron loss. T-cell intracellular antigen-1 (TIA-1), a cytotoxic T lymphocyte granule-associated RNA binding protein, is a key component of stress granules. However, it remains uncertain whether ALS-causing superoxide dismutase-1 (SOD1) toxicity alters the dynamics of stress granules. Thus, through mouse and cell line models, and human cells and tissues, we showed the subcellular location of TIA-1 and its recruitment by stress granules following mutant SOD1-related stimuli. An overexpression of MTSOD1 resulted in increased TIA-1-positive cytoplasmic inclusions in the spinal cord tissue of SOD1G93A transgenic mouse and the SOD1G86S familial ALS patient. Moreover, we demonstrated the stages of ALS-like disease-dependent increase in TIA-1 in the spinal cord of transgenic mice. A similar increase of TIA-1 was found in the spinal cord of the SOD1G86S patient and induced pluripotent stem cell-derived neural stem cells from the SOD1G17S patient. By using immunoprecipitation assays in wild type (WT) human SOD1 (hSOD1) or mutant (MT) hSOD1-transfected motor neuronal cell lines and SOD1G93A transgenic mouse model, we observed that MTSOD1 interacts with TIA-1. In WT or MT hSOD1-transfected HEK293 and NSC-34 cells, the formation of TIA-1-positive stress granules was delayed in MTSOD1 by sodium arsenite treatment. These findings suggest that MTSOD1 could affect the dynamics of stress granules through the abnormal MTSOD1-TIA-1 interaction. Consequently, the resulting pathological TIA-1 may be involved in RNA metabolism found in ALS.

Oxygen Transfer Capacity of Pseudobrookite Particles Derived from Ilmenite Mineral (x wt.%CuO/y wt.%red Mud-z wt.%ilmenite).

The minerals have a somewhat slower than other transition metals at critical reduction rates in their ability to deliver oxygen. Thus, single minerals alone do not exhibit a higher oxygen transfer capacity than metal oxide oxygen carriers. In this study, we try to solve the problem of single mineral ilmenite (FeTiO3) by combining it with Fe-based red mud and Cu oxide. When the ilmenite was used without calcination, the CH4-CO/air redox cycle showed rapid decayed. However, when ilmenite was calcined, the CH4-CO/air redox cycle became stable, and the oxygen transfer rate increased to 4.2%. This is because the FeTiO3 structure was converted to the pseudobrookite (Fe2TiO5) structure through the calcination process. That is, the Fe2+ ion in the ilmenite structure was converted into an Fe3+ ion. When 30 wt.% of red mud was added to the Fe ion, it reacted with the rutile-type titania mixed with pseudobrookite-typed Fe2TiO5, producing an almost perfect pseudobrookite crystal. This resulted in a slight increase in the capacity of oxygen transfer to 4.9%. When 15 wt.% of Cu oxide was added, the oxygen transfer capacity increased to 6.0%. This performance was indicated by the cyclic voltammetry curve that remained constant even after 200 cycles. Here, we argue that if low-cost minerals as a base material are used in appropriate amounts, the production of a lowest-cost oxygen carrier can be achieved.

Label-Free Detection of Salivary Pepsin Using Gold Nanoparticle/Polypyrrole Nanocoral Modified Screen-Printed Electrode.

Detection of salivary pepsin has been given attention as a new diagnostic tool for laryngopharyngeal reflux (LPR) disease, because saliva collection is non-invasive and relatively comfortable. In this study, we prepared polypyrrole nanocorals (PPNCs) on a screen-printed carbon electrode (SPCE) by a soft template synthesis method, using β-naphthalenesulfonic acid (NSA) (for short, PPNCs/SPCE). Gold nanoparticles (GNPs) were then decorated on PPNCs/SPCE by electrodeposition (for short, GNP/PPNCs/SPCE). To construct the immunosensor, pepsin antibody was immobilized on GNP/PPNCs/SPCE. Next, citric acid was applied to prevent non-specific binding and change the electrode surface charge before pepsin incubation. Electrochemical stepwise characterization was performed using cyclic voltammetry, and immunosensor response toward different pepsin concentrations was measured by differential pulsed voltammetry. As a result, our electrochemical immunosensor showed a sensitive detection performance toward pepsin with a linear range from 6.25 to 100 ng/mL and high specificity toward pepsin, as well as a low limit of detection of 2.2 ng/mL. Finally, we quantified the pepsin levels in saliva samples of LPR patients (n = 2), showing that the results were concordant with those of a conventional ELISA method. Therefore, we expect that this electrochemical immunosensor could be helpful for preliminarily diagnosing LPR through the detection of pepsin in saliva.

Forensic utility of carboxyhemoglobin levels in postmortem spleen specimens in South Korea.

In order to determine whether CO poisoning was the definitive cause of death, the concentration of carboxyhemoglobin (COHb) in spleen specimens was analyzed using a gas chromatography-thermal conductivity detector. 125 cases of forensic autopsy reports containing COHb analysis requests were analyzed and subdivided into two groups, improbable and highly probable of CO intoxication. In the first group which consists of 100 cases, the results of COHb analysis were negative, and the circumstances of death, as well as the postmortem findings could not validate the exposure to CO. In the second group which consists of 25 cases, the results of COHb were positive, and both postmortem findings and circumstances of death confirmed the exposure to CO. In the cases of indoors and vehicle fires or those including the use of briquettes, COHb levels reached 43.1-97.5 %, whereas in individuals without any feature of CO poisoning had COHb level high as 29.8 %. However, certain cases without any connection to fire nor CO exposure also contained significant amount of CO based on post-mortem analysis. This study focuses on cases without any relationship to fire or CO and proves that COHb levels below 30 % may be considered as a contributing factor to but not exclusively as the cause of death.

Recovery of gaseous fuels through CO2-mediated pyrolysis of thermosetting polymer waste.

Thermosetting polymers are used in a wide range of applications due to their robust mechanical strength and superior flame retardancy. Despite these technical benefits, recycling of thermosetting polymers has been challenging because of their crosslinking nature. Moreover, their disposal through conventional methods (landfill and combustion) poses environmental concerns, such as microplastics and air pollutants. To address these issues, this study introduces a thermo-chemical disposal platform for thermosetting polymer wastes that employs carbon dioxide (CO2) as a reactive medium. In this work, melamine-formaldehyde was used as model compound of thermosetting polymers. In single-stage pyrolysis, it was revealed that CO2 plays a crucial role in controlling in the compositional matrices of pyrolytic gases, liquid products, and wax. These compositional changes were attributed to the homogeneous reactions between CO2 and the volatile compounds released from the thermolysis of MF. To enhance the thermal cracking of the MF, a double-stage pyrolysis process was tested, which increased the production of pyrolytic gases and eliminated wax formation. However, the slow kinetics governing the reactivity of CO2 limits the occurrence of homogeneous reactions. A nickel-based catalyst was used to accelerate reaction kinetics. The catalytic pyrolysis under CO2 conditions led to substantial increases in syngas (H2 and CO) production of 880% and 460%, respectively, compared with double-stage pyrolysis. These findings demonstrate that thermosetting polymer wastes can be valorized into gaseous fuels through thermo-chemical process, and CO2 enhances the recovery of energy and chemicals. Therefore, this study presents an innovative technical platform to convert thermosetting polymer wastes and CO2 into syngas.

Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage.

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500 nm and yields the ≈5 nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5 nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Oxygen-enriched carbon quantum dots from coffee waste: Extremely active organic photocatalyst for sustainable solar-to-H2O2 conversion.

Solar-driven artificial photosynthesis offers a promising avenue for hydrogen peroxide (H2O2) generation, an efficient and economical replacement for current methods. The efficiency and selectivity hurdles of the two-electron oxygen reduction reaction (ORR) in solar-to- H2O2 conversion are substantial barriers to large scale production. In this manuscript, a simple biomass-assisted synthesis was performed to produce oxygen-enriched carbon quantum dots (OE-CQDs) from spent coffee waste, acting as an efficient photocatalyst for solar-powered H2O2 production. OE-CQDs can stabilize and store light-generated electrons effectively, boosting charge separation and enhancing photocatalytic performance with longevity. The maximal photocatalytic H2O2 production was achieved viz the utilization of OE-CQDs with generation rate of 356.86 µmol g-1 h-1 by retaining 80% activity without any external sacrificial donors. The outstanding performance of synthesized OE-CQDs under light exposure at wavelength (λ) of 280 nm has been ensured by the quantum yield value of 9.4% upon H2O2 generation. The combinatorial benefits of OE-CQDs with their authentic crystalline structure and oxygen enrichment, is expected to be enhancing the ORR activity through accelerating charge transfer, and optimizing oxygen diffusion. Consequently, our eco-friendly method holds considerable promise for creating highly efficient, metal-free photocatalysts for artificial H2O2 production.

Impact of essential and optional ingredients on microbial and metabolic profiles of kimchi.

This study aimed to examine the impacts of essential and optional ingredients on the microbial and metabolic profiles of kimchi during 100 days of fermentation, using a mix-omics approach. Kimchi manufactured without essential ingredients (e.g., red pepper, garlic, ginger, green onion, and radish) had lower lactic acid content. The absence of garlic was associated with a higher proportion of Latilactobacillus and Lactococcus, while the absence of red pepper was associated with a greater proportion of Leuconostoc than the control group. In addition, red pepper and garlic served as primary determinants of the levels of organic acids and biogenic amines. Sugar was positively correlated with the levels of melibiose, and anchovy sauce was positively correlated with the levels of amino acids such as methionine, leucine, and glycine. These findings contribute to a fundamental understanding of how ingredients influence kimchi fermentation, offering valuable insights for optimizing kimchi production to meet various preferences.

GLP-1 increases preingestive satiation via hypothalamic circuits in mice and humans.

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) are effective antiobesity drugs. However, the precise central mechanisms of GLP-1RAs remain elusive. We administered GLP-1RAs to patients with obesity and observed a heightened sense of preingestive satiation. Analysis of human and mouse brain samples pinpointed GLP-1 receptor (GLP-1R) neurons in the dorsomedial hypothalamus (DMH) as candidates for encoding preingestive satiation. Optogenetic manipulation of DMHGLP-1R neurons caused satiation. Calcium imaging demonstrated that these neurons are actively involved in encoding preingestive satiation. GLP-1RA administration increased the activity of DMHGLP-1R neurons selectively during eating behavior. We further identified that an intricate interplay between DMHGLP-1R neurons and neuropeptide Y/agouti-related peptide neurons of the arcuate nucleus (ARCNPY/AgRP neurons) occurs to regulate food intake. Our findings reveal a hypothalamic mechanism through which GLP-1RAs control preingestive satiation, offering previously unexplored neural targets for obesity and metabolic diseases.

Synthetic colourants in capsule dietary supplements on the Korean market.

This study developed a rapid and easy analytical method for the simultaneous determination of nine synthetic colourants (SCs) in capsule dietary supplements. Sample pretreatment involved thermal treatment to dissolve gelatin, using the enzymes protease and amylase to prevent the gelation of gelatin and fat-soluble substances removal using petroleum ether. The method was linear (r2 ≥0.999), with LOD of 0.009-0.029 µg/mL and LOQ of 0.42-1.40 µg/g. Recovery ranged from 90.9 to 108.9%. The relative expanded measurement uncertainty ranged from 4.1 to 6.3%. Allura Red AC (R40) and Brilliant Blue FCF (B1) were commonly detected in 20 of the 28 samples. Up to six SCs such as Tartrazine (Y4), Sunset yellow (Y5), Amaranth (R2), Erythrosine B (R3), R40 and B1 were detected in a single sample, ranging from 30.5 to 40.2 µg/g. Total content of SCs in various capsule supplements ranged from 0.3 to 73.7 µg/g.

Strategies for Effective Management of Indoor Air Quality in a Kindergarten: CO2 and Fine Particulate Matter Concentrations.

The educational and play-related activities of children proceed mainly indoors in a kindergarten. High concentrations of indoor PM2.5 and CO2 have been linked to various harmful effects on children, considerably impacting their educational outcomes in kindergarten. In this study, we explore different scenarios involving the operation of mechanical ventilation systems and air purifiers in kindergartens. Using numerical models to analyze indoor CO2 and PM2.5 concentration, we aim to optimize strategies that effectively reduce these harmful pollutants. We found that the amount of ventilation required to maintain good air quality, per child, was approximately 20.4 m3/h. However, we also found that as the amount of ventilation increased, so did the concentration of indoor PM2.5; we found that this issue can be resolved using a high-grade filter (i.e., a MERV 13 grade filter with a collection efficiency of 75%). This study provides a scientific basis for reducing PM2.5 concentrations in kindergartens, while keeping CO2 levels low.

Comprehensive elucidation of the terroir of Korean kimchi through the study of recipes, metabolites, microbiota, and sensory characteristics.

The aim of this study was to investigate the differences in characteristics of the fermented food kimchi based on the regions where it is produced. A total of 108 kimchi samples were collected from five different provinces in Korea to analyze the recipes, metabolites, microbes, and sensory characteristics. Overall, 18 ingredients (including salted anchovy and seaweed), 7 quality indicators (such as salinity and moisture content), 14 genera of microorganisms (mainly Tetragenococcus and Weissella belonging to LAB), and 38 metabolites contributed to the characteristics of kimchi by region. Kimchi from the southern and northern regions showed distinct metabolite profile (collected 108 kimchi) and flavor profile differences (kimchi manufactured using the standard regional recipes). This is the first study to investigate the terroir effect of kimchi by identifying differences in ingredients, metabolites, microbes, and sensory characteristics based on the region of production, and the correlations between these factors.

Public R&D Projects-Based Investment and Collaboration Framework for an Overarching South Korean National Strategy of Personalized Medicine.

Since the South Korean government designated personalized medicine (PM) as a national strategic task in 2016, it has spared no investment to achieve its goals, which were recently accelerated by the COVID-19 pandemic. This study analyzed investment trends in 17 regions and eight technology clusters related to PM, consisting of 5727 public R&D projects worth USD 148.5 million, from 2015 to 2020. We also illustrated the level of investment for different PM-related technology clusters in each region; various research organizations explicitly verified comparable innovation capabilities for all eight technology fields in 17 regions, showing individual differences in technology areas per region. Our framework provided information to allow implementation of two goals: administering successful PM and improving regional equality in public health and healthcare according to technical and organizational levels. This study empirically demonstrates that it can provide a precise overarching innovation scheme with regional, technical, and organizational dimensions to establish collaboration among different stakeholders, thereby creating a foundation for an overarching national PM strategy.

Learning hierarchical Bayesian networks to assess the interaction effects of controlling factors on spatiotemporal patterns of fecal pollution in streams.

The dynamics of fecal indicator bacteria, such as fecal coliforms (FC) in streams, are influenced by the interactions of a myriad of factors. To predict complex spatiotemporal patterns of FC in streams and assess the relative importance of numerous controlling factors, the adoption of a hierarchical Bayesian network (HBN) was proposed in this study. By introducing latent variables correlated to the observed variables into a Bayesian network, the HBN can represent causal relationships among a large set of variables with a multilevel hierarchy. The study area encompasses 215 sites across the watersheds of the four major rivers in South Korea. The monitoring data collected during the 2012-2019 period included 32 input variables pertaining to meteorology, geography, soil characteristics, land cover, urbanization index, livestock density, and point sources. As model endpoints, the exceedance probability of the FC standard concentration as well as two pollution characteristics (i.e., pollution degree and type), derived from FC load duration curves were used. The probability of exceeding an FC threshold value (200 CFU/100 mL) showed spatiotemporal variations, whereas pollution degree and type showed spatial variations that represent long-term severity and relative dominance of nonpoint and point source fecal pollution, respectively. The conceptual model was validated using structural equation modeling to develop the HBN. The results demonstrate that the HBN effectively simplified the model structure, while showing strong model performance (AUC = 0.81, accuracy = 0.74). The results of the sensitivity analysis indicate that land cover is the most important factor in predicting the probability of exceedance and pollution degree, whereas the urbanization index explains most of the variability in pollution type. Furthermore, the results of the scenario analysis suggest that the HBN provides an interpretable framework in which the interaction of controlling factors has causal relationships at different levels that can be identified and visualized.