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Kang, J.

Publications and source records attributed to Kang, J..

At least 127 records · Page 7Linked to original sources

Transcranial photoacoustic characterization of neurovascular physiology during early-stage photothrombotic stroke in neonatal piglets in vivo

Perinatal ischemic stroke is estimated to occur in 1/2300-1/5000 live births, but early differential diagnosis from global hypoxia-ischemia is often difficult. In this study, we tested the ability of a hand-held transcranial photoacoustic (PA) imaging to non-invasively detect a focal photothrombotic stroke (PTS) within 2 hours of stroke onset in a gyrencephalic piglet brain. 17 stroke lesions of approximately 1-cm2 area were introduced randomly in anterior or posterior cortex via the light/dye PTS technique in anesthetized neonatal piglets (n = 11). The contralateral non-ischemic region served as control tissue for discrimination contrast for the PA hemoglobin metrics: HbO2 saturation, total hemoglobin (tHb), and individual quantities of oxygenated and deoxygenated hemoglobin (HbO2 and HbR). The PA-derived tissue HbO2 saturation at 2 hours yielded a significant separation between control and affected regions-of-interest (p < 0.0001), which were well matched with 24-hr post-stroke cerebral infarction confirmed in the triphenyltetrazolium chloride (TTC)-stained image. The quantity of HbO2 also displayed a significant contrast (p = 0.021), whereas tHb and HbR did not. The analysis on receiver operating characteristic curves and multivariate data analysis also agreed with the results above. This study shows that a hand-held transcranial PA neuroimaging can detect a regional thrombotic stroke in cerebral cortex of a neonatal piglet. In particular, we conclude that the HbO2 saturation metric can be used alone to identify regional stroke lesions. The lack of change in tHb may be related to arbitrary hand-held imaging configuration and/or entrapment of red blood cells within the thrombotic stroke.

biophysics↗

Cystathionine-β-synthase is essential for AKT-induced senescence and suppresses the development of gastric cancers with PI3K/AKT activation

Hyperactivation of oncogenic pathways downstream of RAS and PI3K/AKT in normal cells induces a senescence-like phenotype that acts as a tumor-suppressive mechanism that must be overcome during transformation. We previously demonstrated that AKT-induced senescence (AIS) is associated with profound transcriptional and metabolic changes. Here, we demonstrate that human fibroblasts undergoing AIS display increased Cystathionine-{beta}-synthase (CBS) expression and consequent activation of the transsulfuration pathway controlling hydrogen sulfide (H2S) and glutathione (GSH) metabolism. Activated transsulfuration pathway during AIS maintenance enhances the antioxidant capacity, protecting senescent cells from ROS-induced cell death via GSH and H2S. Importantly, CBS depletion allows cells that have undergone AIS to escape senescence and re-enter the cell cycle, indicating the importance of CBS activity in maintaining AIS. Mechanistically, we show this restoration of proliferation is mediated through suppressing mitochondrial respiration and reactive oxygen species (ROS) production and increasing GSH metabolism. These findings implicate a potential tumor-suppressive role for CBS in cells with inappropriately activated PI3K/AKT signaling. Consistent with this concept, in human gastric cancer cells with activated PI3K/AKT signaling, we demonstrate that CBS expression is suppressed due to promoter hypermethylation. CBS loss cooperates with activated PI3K/AKT signaling in promoting anchorage-independent growth of gastric epithelial cells, while CBS restoration suppresses the growth of gastric tumors in vivo. Taken together, we find that CBS is a novel regulator of AIS and a potential tumor suppressor in PI3K/AKT-driven gastric cancers, providing a new exploitable metabolic vulnerability in these cancers.

cell biology↗

Mucosal immunization with DTaP confers protection against Bordetella pertussis infection and cough in Sprague-Dawley rats

Pertussis is a respiratory disease caused by the Gram-negative pathogen, Bordetella pertussis (Bp). The transition from a whole cell pertussis vaccine (wP; DTP) to an acellular pertussis vaccine (aP; DTaP; Tdap) correlates with an increase in pertussis cases, despite widespread vaccine implementation and coverage, and it is now appreciated that the protection provided by aP rapidly wanes. To recapitulate the localized immunity observed from natural infection, mucosal vaccination with aP was explored using the coughing rat model of pertussis. Immunity induced by both oral gavage (OG) and intranasal (IN) vaccination of aP in Bp challenged rats over a nine-day infection was compared to intramuscular (IM)-wP and IM-aP immunized rats that were used as positive controls as IM immunization is the current route for wP and aP vaccination. Our data demonstrate that both IN and OG immunization of aP resulted in production of anti-Bp IgG antibody titers similar to IM-wP and IM-aP vaccinated controls post-challenge. IN-aP also induced anti-Bp IgA antibodies in the nasal cavity. Immunization with IM-wP, IM-aP, IN-aP, and OG-aP immunization protected against Bp induced cough, while OG-aP immunization did not protect against respiratory distress. Mucosal immunization (IN-aP and OG-aP) also protected against acute inflammation and decreased bacterial burden in the lung compared to mock vaccinated challenge (MVC) rats. The data presented in this study suggests that mucosal vaccination with aP can induce a mucosal immune response and provide protection against Bp challenge.

microbiology↗

Identification of DIR1-dependant cellular responses required for guard cell systemic acquired resistance

After localized invasion by bacterial pathogens, systemic acquired resistance (SAR) is induced in uninfected plant tissues, resulting in enhanced defense against a broad range of pathogens. Although SAR requires mobilization of signaling molecules via the plant vasculature, the specific molecular mechanisms remain elusive. The lipid transfer protein-defective in induced resistance 1-1 (DIR1-1) was identified in Arabidopsis thaliana by screening for mutants that were defective in SAR. Here we demonstrate that stomatal response to pathogens is altered in systemic leaves by SAR, and this guard cell SAR defense requires DIR1. Using a multi-omics approach, we have determined potential SAR signaling mechanisms specific for guard cells in systemic leaves by profiling metabolite, lipid, and protein differences between guard cells in wild type and dir1-1 mutant during SAR. We identified two 18C fatty acids and two 16C wax esters as putative SAR-related molecules dependent on DIR1. Proteins and metabolites related to amino acid biosynthesis and response to stimulus were also changed in guard cells of dir1-1 compared to wild type. Identification of guard cell-specific SAR-related molecules may lead to new avenues of genetic modification/molecular breeding for disease resistant plants. One-sentence summaryDIR1 affects many biological processes in stomatal guard cells during systemic acquired resistance (SAR), as revealed by multi-omics, and it may function through transporting two 18C fatty acids during SAR.

plant biology↗

Early cross-coronavirus reactive signatures of protective humoral immunity against COVID-19

The introduction of vaccines has inspired new hope in the battle against SARS-CoV-2. However, the emergence of viral variants, in the absence of potent antivirals, has left the world struggling with the uncertain nature of this disease. Antibodies currently represent the strongest correlate of immunity against COVID-19, thus we profiled the earliest humoral signatures in a large cohort of severe and asymptomatic COVID-19 individuals. While a SARS-CoV-2-specific immune response evolved rapidly in survivors of COVID-19, non-survivors exhibited blunted and delayed humoral immune evolution, particularly with respect to S2-specific antibody evolution. Given the conservation of S2 across {beta}-coronaviruses, we found the early development of SARS-CoV-2-specific immunity occurred in tandem with pre-existing common {beta}-coronavirus OC43 humoral immunity in survivors, which was selectively also expanded in individuals that develop paucisymptomatic infection. These data point to the importance of cross-coronavirus immunity as a correlate of protection against COVID-19.

immunology↗

Spatial analysis of tumor infiltrating lymphocytes based on deep learning using histopathology image to predict progression-free survival in colorectal cancer

PurposeThis study aimed to explore the prognostic impact of spatial distribution of tumor infiltrating lymphocytes (TILs) quantified by deep learning (DL) approaches based on digitalized whole slide images stained with hematoxylin and eosin in patients with colorectal cancer (CRC). MethodsThe prognostic impact of spatial distributions of TILs in patients with CRC was explored in the Yonsei cohort (n=180) and validated in the TCGA cohort (n=268). Concurrently, two experienced pathologists manually measured TILs at the most invasive margin as 0-3 by the Klintrup-Makinen (KM) grading method and compared to DL approaches. Interobserver agreement for TILs was measured using Cohens kappa coefficient. ResultsOn multivariate analysis of spatial TILs features derived by DL approaches and clinicopathological variables including tumor stage, Microsatellite instability, and KRAS mutations, TILs densities within 200 m of the invasive margin (f_im200) was remained as the most significant prognostic factor for progression-free survival (PFS) (HR 0.004 [95% CI, 0.0001-0.1502], p=.002) in the Yonsei cohort. On multivariate analysis using the TCGA dataset, f_im200 retained prognostic significance for PFS (HR 0.031, [95% CI 0.001-0.645], p=.024). Interobserver agreement of manual KM grading based on Cohens kappa coefficient was insignificant in the Yonsei ({kappa}=.109) and the TCGA ({kappa}=.121), respectively. The survival analysis based on KM grading showed statistically significant different PFS from the TCGA cohort, but not the Yonsei cohort. ConclusionsAutomatic quantification of TILs at the invasive margin based on DL approaches showed a prognostic utility to predict PFS, and could provide robust and reproducible TILs density measurement in patients with CRC. Data and Code AvailabilitySource code and data used for this study is available at the following link: https://github.com/hwanglab/TILs_Analysis

bioinformatics↗

Potential transmission chains of variant B.1.1.7 and co-mutations of SARS-CoV-2

The presence of SARS-CoV-2 mutants, including the emerging variant B.1.1.7, has raised great concerns in terms of pathogenesis, transmission, and immune escape. Characterizing SARS-CoV-2 mutations, evolution, and effects on infectivity and pathogenicity is crucial to the design of antibody therapies and surveillance strategies. Here we analyzed 454,443 SARS-CoV-2 spike genes/proteins and 14,427 whole-genome sequences. We demonstrated that the early variant B.1.1.7 may not have evolved spontaneously in the United Kingdom or within human populations. Our extensive analyses suggested that Canidae, Mustelidae or Felidae, especially the Canidae family (for example, dog) could be a possible host of the direct progenitor of variant B.1.1.7. An alternative hypothesis is that the variant was simply yet to be sampled. Notably, the SARS-CoV-2 whole genome represents a large number of potential co-mutations with very strong statistical significances (p value<E- 44). In addition, we used an experimental SARS-CoV-2 reporter replicon system to introduce the dominant co-mutations NSP12_c14408t, 5UTR_c241t, and NSP3_c3037t into the viral genome, and to monitor the effect of the mutations on viral replication. Our experimental results demonstrated that the co-mutations significantly attenuated the viral replication. The study provides valuable clues for discovering the transmission chains of variant B.1.1.7 and understanding the evolutionary process of SARS-CoV-2.

microbiology↗

Re-investigating the coughing rat model of pertussis to understand Bordetella pertussis pathogenesis

Bordetella pertussis (Bp) is a highly contagious bacterium that is the causative agent of whooping cough (pertussis). Currently, acellular pertussis vaccines (aP; DTaP; Tdap) are used to prevent pertussis disease. However, it is clear that the aP vaccine efficacy quickly wanes, resulting in the re-emergence of pertussis. Furthermore, recent work performed by the CDC suggest that current circulating strains are genetically distinct from strains of the past. Emergence of genetically diverging strains combined with waning aP vaccine efficacy call for re-evaluation of current animal models of pertussis. In this study, we used the rat model of pertussis to compare two genetically divergent strains Tohama 1 and D420. We intranasally challenged seven-week-old Sprague-Dawley rats with 108 viable Tohama 1 and D420 and measured the hallmark signs/symptoms of Bp infection such as neutrophilia, pulmonary inflammation, and paroxysmal cough using whole body plethysmography. Onset of cough occurred between 2-4 days after Bp challenge averaging five coughs per fifteen minutes, with peak coughing occurring at day eight post infection averaging upward of thirteen coughs per fifteen minutes. However, we observed an increase of coughs in rats infected with clinical isolate D420 through 12 days post challenge. The rats exhibited increased bronchial restriction following Bp infection. Histology of the lung and flow cytometry confirm both cellular infiltration and pulmonary inflammation. D420 infection induced higher production of anti-Bp IgM antibodies compared to Tohama 1 infection. The coughing rat model provides a way of characterizing disease manifestation differences between Bp strains.

immunology↗

Whole-Genome Sequencing on 220 Alfalfa (Medicago sativa L.) Accessions Identified Association of DREB1C Gene with Fall Dormancy Height

Fall dormancy (FD) is one of the most important traits of alfalfa (Medicago sativa) for cultivar selection to overcome winter stress. Although transcriptomics, proteomics analysis, and QTL mapping have revealed some important genes correlated with FD, the genetic architecture of this trait is still unclear. There are no applicable genes or markers for selection, which hinders progress in the genetic research and molecular breeding for the trait. We conducted whole-genome sequencing (WGS) on 220 alfalfa accessions at 10x depth. Among the 875,023 SNPs, four of them were associated with FD height using GWAS. One SNP located on chromosome 6 is in linkage disequilibrium with dehydration-responsive element-binding protein 1C (DREB1C). Furthermore, seven DREB genes are clustered in this region, one of which has previously been shown to enhance freezing tolerance in the model plant Medicago truncatula. The candidate genes uncovered by our research will benefit the transgenic and CRISPR-Cas9 research of FD in alfalfa. This gene will also be useful for molecular marker development and marker-associated breeding of FD for alfalfa.

genomics↗

Assembly of chromosome-scale and allele-aware autotetraploid genome of the Chinese alfalfa cultivar Zhongmu-4 and identification of SNP loci associated with 27 agronomic traits

Alfalfa (Medicago sativa L.), the most valuable perennial legume crop, referred to as "Queen of the Forages" for its high nutritional value and yield production among forage crops. Comprehensive genomic information of germplasm resources from different ecological regions and modern breeding strategies, such as molecular-marker assisted breeding are of great importance to breed new alfalfa varieties with environmental resilience. Here, we report assembly of the genome sequence of Zhongmu-4 (ZM-4), one of the most planted cultivars in China, and identification of SNPs associated with alfalfa agronomic traits by Genome-wide Association Studies (GWAS). Sequence of 32 allelic chromosomes was assembled successfully by single molecule real time sequencing and Hi-C technique with ALLHiC algorithm. About 2.74 Gbp contigs, accounting for 88.39% of the estimated genome, were assembled with 2.56 Gbp contigs anchored to 32 pseudo-chromosomes. In comparison with M. truncatula A17, distinctive inversion and translocation on chromosome 1, and between chromosome 4 and 8, respectively, were detected. Moreover, we conducted resequencing of 220 alfalfa accessions collected globally and performed GWAS analysis based on our assembled genome. Population structure analysis demonstrated that alfalfa has a complex genetic relationship among germplasm with different geographic origins. GWAS identified 101 SNPs associated with 27 out of 93 agronomic traits. The updated chromosome-scale and allele-aware genome sequence, coupled with the resequencing data of most global alfalfa germplasm, provides valuable information for alfalfa genetic research, and further analysis of major SNP loci will accelerate unravelling the molecular basis of important agronomic traits and facilitate genetic improvement of alfalfa.

plant biology↗

Crowdsourced Identification of Multi-Target Kinase Inhibitors for RET- and TAU- Based Disease: the Multi-Targeting Drug DREAM Challenge

A continuing challenge in modern medicine is the identification of safer and more efficacious drugs. Precision therapeutics, which have one molecular target, have been long promised to be safer and more effective than traditional therapies. This approach has proven to be challenging for multiple reasons including lack of efficacy, rapidly acquired drug resistance, and narrow patient eligibility criteria. An alternative approach is the development of drugs that address the overall disease network by targeting multiple biological targets ( polypharmacology). Rational development of these molecules will require improved methods for predicting single chemical structures that target multiple drug targets. To address this need, we developed the Multi-Targeting Drug DREAM Challenge, in which we challenged participants to predict single chemical entities that target pro-targets but avoid anti-targets for two unrelated diseases: RET-based tumors and a common form of inherited Tauopathy. Here, we report the results of this DREAM Challenge and the development of two neural network-based machine learning approaches that were applied to the challenge of rational polypharmacology. Together, these platforms provide a potentially useful first step towards developing lead therapeutic compounds that address disease complexity through rational polypharmacology. Author SummaryMany modern drugs are developed with the goal of modulating a single cellular pathway or target. However, many drugs are, in fact, dirty; they target multiple cellular pathways or targets. This phenomenon is known as multi-targeting or polypharmacology. While some strive to develop cleaner therapeutics that eliminate secondary targets, recent work has shown that multi-targeting therapeutics have key advantages for a variety of diseases. However, while multi-targeting drugs that affect a precisely-defined profile of targets may be more effective, it is difficult to computationally predict which molecules have desirable target profiles. Here, we report the results of a competitive crowdsourcing project (the Multi-Targeting Drug DREAM Challenge), where we challenged participants to predict chemicals that have desired target profiles for cancer and neurodegenerative disease.

pharmacology and toxicology↗

Histone H3K4me1 and H3K27ac play roles in nucleosome depletion and eRNA transcription, respectively, at enhancers

Histone H3K4me1 and H3K27ac are enhancer specific modifications and are required for enhancers to activate transcription of target genes. However the reciprocal effects of these histone modifications on each other and their roles in enhancers are not clear. Here to comparatively analyze the role of these modifications, we inhibited H3K4me1 and H3K27ac by deleting SET domain of histone methyltransferases MLL3 and MLL4 and HAT domain of histone acetyltransferase p300, respectively, in erythroid K562 cells. The loss of H3K4me1 reduced H3K27ac at the {beta}-globin enhancer LCR HSs, but H3K27ac reduction did not affect H3K4me1. This unequal relationship between two modifications was revealed in putative enhancers by genome-wide analysis using ChIP-seq. Histone H3 depletion at putative enhancers was weakened by the loss of H3K4me1 but not by the loss of H3K27ac. Chromatin remodeling complexes were recruited into the {beta}-globin LCR HSs in a H3K4me1-dependent manner. In contrast, H3K27ac was required for enhancer RNA (eRNA) transcription, and H3K4me1 was not enough for it. Forced H3K27ac induced eRNA transcription without affecting H3K4me1 at the {beta}-globin LCR HSs. These results indicate that H3K4me1 and H3K27ac affect each other in different ways and play more direct roles in nucleosome depletion and eRNA transcription, respectively, at enhancers.

molecular biology↗

Psychological Well-being, Age and Gender can Mediate Soundscapes Pleasantness and Eventfulness: A large sample study

Soundscape studies aim to consider the holistic human perception of a sound environment, including both the physical phenomena and how these are mediated by internal factors: the mechanisms underpinning the interactions between these two aspects are not well understood. This study aims to assess the influence of psychological well-being and demographic factors including age, gender, occupation status, and education levels on the dimensions of the soundscape circumplex, i.e., Pleasantness and Eventfulness. Data was collected in eleven urban locations in London through a large-scale (N=1134) soundscape survey according to the ISO 12913-2 technical specifications and incorporating the WHO-5 well-being index. Linear mixed-effects modelling applying backwards-step feature selection was used to model the interactions between internal factors including psychological well-being, age, gender, occupation status, education levels and the soundscape Pleasantness and Eventfulness, while accounting for the random effects of the survey location. The findings suggest that internal factors account for approximately 1.4% of the variance for Pleasantness and 3.9% for Eventfulness, while the influence of the locations accounted for approximately 34% and 14%, respectively. Psychological well-being is positively associated with perceived Pleasantness, while there is a negative association with Eventfulness only for males. Occupation status, in particular retirement as a proxy of age and gender, was identified as a significant factor for both dimensions. These findings offer empirical grounds for developing theories of the interaction between internal factors and soundscape formation whilst highlighting the importance of the location, namely: the context.

neuroscience↗

Novel inhibitors of E. coli lipoprotein diacylglyceryl transferase are insensitive to resistance caused by lpp deletion

Lipoprotein diacylglyceryl transferase (Lgt) catalyzes the first step in the biogenesis of Gram-negative bacterial lipoproteins which play crucial roles in bacterial growth and pathogenesis. We demonstrate that Lgt depletion in a clinical uropathogenic Escherichia coli strain leads to permeabilization of the outer membrane and increased sensitivity to serum killing and antibiotics. Importantly, we identify the first ever described Lgt inhibitors that potently inhibit Lgt biochemical activity in vitro and are bactericidal against wild-type Acinetobacter baumannii and E. coli strains. Unlike inhibition of other steps in lipoprotein biosynthesis, deletion of the major outer membrane lipoprotein, lpp, is not sufficient to rescue growth after Lgt depletion or provide resistance to Lgt inhibitors. Our data validate Lgt as a novel druggable antibacterial target and suggest that inhibition of Lgt may not be sensitive to one of the most common resistance mechanisms that invalidate inhibitors of downstream steps of bacterial lipoprotein biosynthesis and transport.

microbiology↗

Leaf form diversification in an heirloom tomato results from alterations in two different HOMEOBOX genes

Domesticated plants and animals display tremendous diversity in various phenotypic traits and often this diversity is seen within the same species. Tomato (Solanum lycopersicum; Solanaceae) cultivars show wide variation in leaf morphology, but the influence of breeding efforts in sculpting this diversity is not known. Here, we demonstrate that a single nucleotide deletion in the homeobox motif of BIPINNATA, which is a BEL-LIKE HOMEODOMAIN gene, led to a highly complex leaf phenotype in an heirloom tomato, Silvery Fir Tree (SiFT). Additionally, a comparative gene network analysis revealed that reduced expression of the ortholog of WUSCHEL RELATED HOMEOBOX 1 is also important for the narrow leaflet phenotype seen in SiFT. Phylogenetic and comparative genome analysis using whole-genome sequencing data suggests that the bip mutation in SiFT is likely a de novo mutation, instead of standing genetic variation. These results provide new insights into natural variation in phenotypic traits introduced into crops during improvement processes after domestication.

plant biology↗

Expansion Revealing: Decrowding Proteins to Unmask Invisible Brain Nanostructures

Cells and tissues are made out of nanoscale building blocks, such as proteins, organized in crowded nanostructures. We show that many biomolecules, and the nanostructures in which they are embedded, may be invisible to prior imaging techniques, due to the inaccessibility of labels (e.g., antibodies) to biomolecules embedded within such crowded structures. We developed a technology, expansion revealing (ExR), which isotropically decrowds proteins from each other, to enable their labeling. We use ExR to discover the alignment of presynaptic calcium channels with postsynaptic machinery in intact brain circuits, as well as the existence of periodic amyloid nanoclusters containing ion channel proteins in Alzheimers model mice. Thus, ExR reveals nanostructures within complex biological specimens that were not previously visualizable, and may find broad use in biology. One Sentence SummaryDe-crowding biomolecules with Expansion Revealing unmasks fundamentally new nanostructures in intact brain tissue, which remained invisible otherwise.

bioengineering↗

Light-emitting diode-based transcranial photoacoustic measurement of sagittal sinus oxyhemoglobin saturation in hypoxic neonatal piglets

We present a light-emitting diode (LED)-based transcranial photoacoustic measurement (LED-trPA) of oxyhemoglobin (HbO2) saturation at superior sagittal sinus (SSS) in hypoxic neonatal piglets. The optimal LED imaging wavelengths and frame averaging scheme were determined based on in vivo characterization of transcranial sensitivity. Based on the framework (690/850 nm with >20 frame averaging), graded hypoxia was successfully identified in neonatal piglets in vivo with less than 10.0 % of root mean squared error (RMSE). This preclinical study suggests the feasibility of a rapid, cost-effective, and safe LED-trPA monitoring of perinatal hypoxia-ischemia and prompt interventions for clinical use.

biophysics↗

Assessing Study Reproducibility through MMRI: A Novel Approach for Large-scale High-throughput Association Studies

Magnetic Resonance Imaging (MRI) technology has been increasingly used in large-scale association studies. Reproducibility of statistically significant findings generated by MRI-based association studies, especially structural MRI (sMRI) and functional MRI (fMRI), has been recently heavily debated. However, there is still a lack of overall reproducibility assessment for MRI-based association studies. It is also crucial to elucidate the relationship between overall reproducibility and sample size in an experimental design. In this study, we proposed an overall reproducibility index for large-scale high-throughput MRI-based association studies. We performed the overall reproducibility assessments for several recent large sMRI/fMRI databases and observed satisfactory overall reproducibility. Furthermore, we performed the sample size evaluation for the purpose of achieving a desirable overall reproducibility. Additionally, we evaluated the overall reproducibility of GMV changes for UKB vs. PPMI and UKB vs. HCP. We demonstrated that both sample size and some experimental factors play important roles in the overall reproducibility for different experiments. In summary, a systematic assessment of overall reproducibility is fundamental and crucial in the current large-scale high-throughput MRI-based research.

neuroscience↗