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Bei Liu

Publications and source records attributed to Bei Liu.

At least 19 recordsLinked to original sources
PubMed2026

Bacteroides cellulosilyticus-derived 2-hydroxyphenylacetic acid rectifies hepatic lipid homeostasis in MASLD by targeting the PPARγ-CD36 axis.

The gut microbiota plays an important role in the occurrence and development of metabolic dysfunction-associated steatotic liver disease (MASLD), but the specific molecular mechanisms involved have not been fully elucidated. In this study, human cohort studies were performed to identify that the relative abundance of Bacteroides cellulosilyticus (B. cellulosilyticus) was significantly decreased in patients with MASLD. Through the integration of metagenomic and metabolomic analyses, it was confirmed that B. cellulosilyticus and its metabolite 2-hydroxyphenylacetic acid (2HPAA) are key factors regulating the occurrence and development of MASLD. Single-cell sequencing and lipidomic analyses revealed that 2HPAA can enter the liver through the enterohepatic circulation to exert regulatory effects. Specifically, 2HPAA inhibits the peroxisome proliferator-activated receptor γ (PPARγ) signaling pathway, thereby suppressing the expression of the fatty acid transporter CD36. Meanwhile, 2HPAA regulates lipid metabolism in hepatocytes by significantly enhancing palmitate conversion efficiency and inhibiting CD36 palmitoylation. This dual regulatory effect on CD36 expression and palmitoylation can reduce lipid accumulation in hepatocytes and ultimately alleviate MASLD progression. These findings reveal the mechanism by which B. cellulosilyticus and 2HPAA alleviate MASLD by targeting the PPARγ-CD36 pathway. This work provides a new perspective for the study of gut microbiota-host interactions in regulating liver diseases.

PPAR gamma↗
PubMed2026

Comparative proteomic analysis reveals the pathological mechanisms of overuse achilles tendinopathy and the therapeutic mechanisms of ESWT and PRP.

BACKGROUND: Achilles tendinopathy is a common musculoskeletal disorder with limited self-repair capacity. Although extracorporeal shock wave therapy (ESWT) and platelet-rich plasma (PRP) are widely used, their therapeutic mechanisms remain unclear. METHODS: A rat model of overuse Achilles tendinopathy was established by uphill treadmill running. Tendon morphology and structure were assessed by ultrasound and histology, and proteomic profiling was performed to identify differentially expressed proteins (DEPs) and enriched pathways. RESULTS: Ultrasound revealed subcutaneous edematous infiltration after overuse, and histology showed disorganized collagen fibers and altered cellular density. Compared with the normal group, the injury group showed 429 DEPs, which were enriched in pathways related to actin cytoskeleton and complement and coagulation cascades. Both ESWT and PRP treatments ameliorated these overuse-induced pathological changes. Compared with the rest group, the ESWT group showed 30 DEPs, while the PRP group showed 244, with 17 DEPs overlapping between the two comparisons. In the ESWT group, enriched pathways included actin cytoskeleton organization, protein stabilization, and sulfur metabolism. In the PRP group, enriched pathways included FcγR-mediated phagocytosis, lysosome, and endoplasmic reticulum protein processing. Compared with the normal group, the ESWT group showed 32 DEPs, whereas the PRP group showed only one (Serpina6), which was the only protein shared between the two comparisons. CONCLUSION: ESWT and PRP improve tendon healing in overuse Achilles tendinopathy through different molecular mechanisms. The PRP group showed a proteomic profile more similar to the normal group than the ESWT group. These findings provide a molecular basis for optimizing clinical treatment strategies.

Animals↗
PubMed2025

Exposure to zinc oxide nanoparticles inhibits preimplantation embryonic development by disrupting zygotic genome activation.

The potential adverse effects of zinc oxide nanoparticles (ZnONPs) on human reproductive health may arise from their increasing industrial and commercial applications. However, their effects on preimplantation embryonic development and the related molecular mechanisms are still not well understood. Here, we demonstrate that ZnONPs exposure exhibit toxicity to a critical developmental period in mice. We observed that sustained exposure to ZnONPs in vitro resulted in embryonic development arrest at the 2-cell stage. To identify the susceptible stage, we controlled experiments to treat embryos with ZnONPs in the different processes of early embryonic development and determined that ZnONPs mainly to affect 2-cell stage embryos. According to the RNA-seq and EU (5-ethynyl uridine) analysis, the transcriptional activity of minor ZGA genes increased in the late 2-cell embryos following ZnONPs exposure. Subsequently, we employed multi-omics assays, including CUT&Tag and ATAC-seq. We found that ZnONPs exposure led to increased enrichment of H3K27ac (Histone H3 acetylated lysine 27) in late 2-cell embryos and enhanced chromatin accessibility, which led to abnormal upregulation of minor zygotic genome activation (ZGA) genes. In addition, the direct occupancy of ZnONPs at H3K27ac modification sites was verified through pulldown and immunoprecipitation. In conclusion, our findings demonstrate that ZnONPs exposure disrupting minor ZGA by interfering with H3K27ac erasure on the embryonic genome and ultimately impairing the developmental potential of embryos.

Animals↗
PubMed2006

TLR4 up-regulation at protein or gene level is pathogenic for lupus-like autoimmune disease.

TLR4 is the receptor for the Gram-negative bacterial cell wall component LPS. TLR4 signaling is controlled by both positive and negative regulators to balance optimal immune response and potential sepsis. Unchecked TLR4 activation might result in autoimmune diseases, a hypothesis that has not been formally resolved. In this study, we found that TLR4 signaling to LPS can be positively enforced by expressing gp96 on cell surfaces through the chaperone function of, but not the direct signaling by, gp96; TLR4 as well as the commensal flora are essential for the production of anti-dsDNA Ab and the immune complex-mediated glomerulonephritis in transgenic mice that express surface gp96. Moreover, a similar constellation of autoimmunity was evident in mice that encode multiple copies of tlr4 gene. Our study has revealed that increased TLR4 signaling alone without exogenous insult can break immunological tolerance. It provides a strong experimental evidence for TLR4 dysregulation as an etiology of lupus-like renal disease.

Animals↗
PubMed2006

Angiotensin II induces NF-kappa B activation in HUVEC via the p38MAPK pathway.

Angiotensin II (Ang II) is the main active peptide of the renin-angiotensin system (RAS), producing a number of inflammatory mediators that lead to endothelial dysfunction and the progression of atherosclerosis. Ang II-induced NF-kappaB nuclear translocation plays a pivotal role in this response. This study examines the NF-kappaB activation mechanism elicited by Ang II in human umbilical vein endothelial cells (HUVEC). Electrophoretic mobility shift assays and Western blotting revealed that Ang II, signaling via AT(1), produces a time-dependent increase in NF-kappaB DNA binding and IkappaBalpha degradation. These results also demonstrate that Ang II leads to MAPK phosphorylation and p38MAPK pathway-induced NF-kappaB activation. Furthermore, AT(1) is required for p38MAPK phosphorylation induced by Ang II. This study provides evidence that Ang II elicits NF-kappaB activation via the p38MAPK pathway in HUVEC.

Angiotensin II↗
PubMed2006

Evaluation of a new force field for describing the adsorption behavior of alkanes in various pure silica zeolites.

The recently proposed united atom force field by Dubbeldam et al. (Phys. Rev. Lett. 2004, 93, 088302) for the adsorption of alkanes in MFI-type zeolites was extended to other zeolites in this work. Its applicability to FER-type zeolites was evaluated in detail, for which the Henry coefficients, the isosteric heat of adsorption, the adsorption isotherms, as well as the locations of alkanes in the FER-type zeolites were computed and compared to experimental values. The results show that the new force field works well for FER zeolites. Furthermore, its applicability to MWW-, MTW-, CFI-, LTA-, and STF-type zeolites was investigated, and we found that the experimental isotherms could be accurately predicted except for STF-type zeolites. This work shows that the new united atom force field proposed by Dubbeldam et al. is applicable to most pure silica zeolites.

Journal Article↗
PubMed2006

Cadherin2 (N-cadherin) plays an essential role in zebrafish cardiovascular development.

BACKGROUND: Cadherins are cell surface adhesion molecules that play important roles in development of vertebrate tissues and organs. We studied cadherin2 expression in developing zebrafish heart using in situ hybridization and immunocytochemical methods, and we found that cadherin2 was strongly expressed by the myocardium of the embryonic zebrafish. To gain insight into cadherin2 role in the formation and function of the heart, we analyzed cardiac differentiation and performance in a cadherin2 mutant, glass onion (glo). RESULTS: We found that the cadherin2 mutant had enlarged pericardial cavity, disorganized atrium and ventricle, and reduced expression of a ventricular specific marker vmhc. Individual myocardiocytes in the glo mutant embryos became round shaped and loosely aggregated. In vivo measurements of cardiac performance revealed that the mutant heart had significantly reduced heart rate, stroke volume and cardiac output compared to control embryos. Formation of the embryonic vascular system in the glo mutants was also affected. CONCLUSION: Our results suggest that cadherin2 plays an essential role in zebrafish cardiovascular development. Although the exact mechanisms remain unknown as to the formation of the enlarged pericardium and reduced peripheral blood flow, it is clear that myocardiocyte differentiation and physiological cardiovascular performance is impaired when cadherin2 function is disrupted.

Animals↗
PubMed2006

Cloning and expression analysis of cadherin7 in the central nervous system of the embryonic zebrafish.

Cadherin cell adhesion molecules exhibit unique expression patterns during development of the vertebrate central nervous system. In this study, we obtained a full-length cDNA of a novel zebrafish cadherin using reverse transcriptase-polymerase chain reaction (RT-PCR) and 5' and 3' rapid amplification of cDNA ends (RACE). The deduced amino acid sequence of this molecule is most similar to the published amino acid sequences of chicken and mammalian cadherin7 (Cdh7), a member of the type II cadherin subfamily. cadherin7 message (cdh7) expression in embryonic zebrafish was studied using in situ hybridization and RT-PCR methods. cdh7 expression begins at about 12h postfertilization (hpf) in a small patch in the anterior neural keel, and along the midline of the posterior neural keel. By 24 hpf, cdh7 expression in the brain shows a distinct segmental pattern that reflects the neuromeric organization of the brain, while its expression domain in the spinal cord is continuous, but confined to the middle region of the spinal cord. As development proceeds, cdh7 expression is detected in more regions of the brain, including the major visual structures in the fore- and midbrains, while its expression domain in the hindbrain becomes more restricted, and its expression in the spinal cord becomes undetectable. cdh7 expression becomes reduced in 3-day old embryos. Our results show that cdh7 expression in the zebrafish developing central nervous system is both spatially and temporally regulated.

Amino Acid Sequence↗
PubMed2006

Molecular simulation of adsorption of alkanes in sodium MOR-type zeolites using a new force field.

The applicability of a recently proposed force field of Calero et al. (J. Am. Chem. Soc., 2004, 126, 11377) to Na-MOR zeolites is evaluated. The Henry law coefficients of ethane and C(5)-C(9) as well as the adsorption isotherms of ethane, propane, butane, and hexane in various Na-MOR zeolites are computed and compared with experimental values. These comparisons show that the new force field is suitable for Na-MOR zeolites. Furthermore, this force field is used to study the effects of sodium cations on the adsorption behavior of larger alkanes, such as C(4)-C(7), in MOR-type zeolites. These simulations give a better understanding of the underlying mechanisms of the cations' position and density influence on adsorption. In addition, a characteristic pressure named "reversal pressure" is introduced which characterizes the efficiency of the presence of cations in zeolites.

Adsorption↗
PubMed2006

Expression of cadherin10, a type II classic cadherin gene, in the nervous system of the embryonic zebrafish.

Cadherins are cell surface adhesion molecules that play important roles in development of tissues and organs. In this study, we analyzed expression pattern of cadherin10, a member of the type II classic cadherin subfamily, in the embryonic zebrafish using in situ hybridization methods. cadherin10 message (cdh10) is first and transiently expressed by the notochord. In the developing nervous system, cdh10 was first detected in a subset of the cranial ganglia, then in restricted brain regions and neural retina. As development proceeds, cdh10 expression domain and/or expression levels increased in the embryonic nervous system. Our results show that cdh10 expression in the zebrafish developing nervous system is both spatially and temporally regulated.

Amino Acid Sequence↗
PubMed2006

cadherin-6 message expression in the nervous system of developing zebrafish.

Cadherins are cell surface adhesion molecules that play important roles in development of a variety of tissues including the nervous system. In this study, we analyzed expression pattern of cadherin-6, a member of the type II cadherin subfamily, in the embryonic zebrafish nervous system using in situ hybridization methods. cadherin-6 message is first expressed by the neural keel, then by restricted regions in the brain and spinal cord. cadherin-6 expression in the brain transiently delineates specific brain regions. In the peripheral nervous system, cadherin-6 message is expressed by the neurogenic placodes and the dorsal root ganglia. As development proceeds, cadherin-6 expression domain and/or expression levels increased in the embryonic nervous system. Our results show that cadherin-6 expression in the zebrafish developing nervous system is both spatially and temporally regulated, implicating a role for cadherin-6 in the formation of these nervous structures.

Animals↗
PubMed2005

Combination of imatinib mesylate with autologous leukocyte-derived heat shock protein and chronic myelogenous leukemia.

PURPOSE: To test the feasibility, safety, immunogenicity, and clinical efficacy of an autologous vaccine of leukocyte-derived heat shock protein 70-peptide complexes (Hsp70PC), in conjunction with imatinib mesylate, in patients with chronic myeloid leukemia (CML) in chronic phase. EXPERIMENTAL DESIGN: Patients had cytogenetic or molecular evidence of disease, despite treatment with imatinib mesylate for all except one patient, at the beginning of study. Hsp70PCs were purified from the leukopheresed peripheral blood mononuclear cells and were administered in eight weekly intradermal injections at 50 microg/dose without adjuvant. Clinical responses were assessed by bone marrow analysis before and after vaccinations. An IFN-gamma enzyme-linked immunospot assay was used to estimate the effect of treatment on natural killer cells and T cells against CML. RESULTS: Twenty patients were treated. The manufacturing of Hsp70PCs was successful and the administration was safe for all patients. Minimal or no side effects were reported. Clinical responses were seen in 13 of 20 patients as measured by cytogenetic analysis of bone marrow Philadelphia chromosome-positive cells in metaphases and/or, when possible, the level of Bcr/Abl transcript by PCR. Immunologic responses were observed in 9 of 16 patients analyzed, characterized by an increase in the frequency of CML-specific IFN-gamma-producing cells and IFN-gamma-secreting natural killer cells in the blood. A significant correlation between clinical responses and immunologic responses was observed. CONCLUSIONS: Autologous Hsp70PC vaccination is feasible and safe. When combined with imatinib mesylate, it is associated with immunologic and possible clinical responses against CML in chronic phase.

Adult↗
PubMed2005

Self-assembled photoactive polyelectrolyte/perylene-diimide composites.

A new class of polyelectrolyte-surfactant (PE-surf) composites having potential applications as thin film organic semiconductors is introduced. These materials are comprised of cationic asymmetrically substituted perylene diimides and oppositely charged poly(acrylate) polyanions. Thin films of the composite materials are prepared by mixing and drop casting aqueous solutions of the two precursors onto appropriate substrates. The resulting materials yield photovoltages of >140 mV for approximately equal to 0.6 W/cm(2) illumination intensities, when incorporated in p-n heterojunction devices. Solution-phase spectra obtained from the PE-surf complexes exhibit excimer-like emission and evidence for formation of weakly coupled aggregates in the ground state. Wide-angle X-ray scattering data show the composite films are locally amorphous, while small-angle X-ray data are consistent with a mixture of polymorphic structures that incorporate planar PE-surf bilayers of 3.9-nm repeat distances. Images obtained by conventional far-field light microscopy and multiphoton-excited fluorescence microscopy (MPEFM) indicate that the films are heterogeneous, incorporating submicrometer sized clusters dispersed among much thinner film regions that also incorporate dye. Polarization-dependent MPEFM studies prove the clusters are semiorganized, yielding order parameters (s and P(4)) of 0.09 and 0.01 for in-plane alignment of the chromophores, consistent with a relatively high degree of disorder.

Journal Article↗
PubMed2005

Effect of correlation on combining diagnostic information from two images of the same patient.

We have shown previously, in the context of computer-aided diagnosis (CAD), that information derived from multiple images of the same patient can be used to improve diagnostic performance. In that work, we ignored the correlation among multiple images of the same patient. In the present study, we investigate theoretically, within the framework of receiver operating characteristic (ROC) analysis, the effect of correlation on three methods for combining quantitative diagnostic information from two images: taking the average, the maximum, and the minimum of a pair of normally distributed decision variables. We assume, as in our previous work, that the quantitative diagnostic information obtained from the two images of a given patient can be transformed monotonically to two latent decision variables that are normally distributed. Similar to the situation of uncorrelated images, we found that (1) the average always improves the area under the ROC curve (AUC) compared to the single-view image; (2) the maximum and the minimum can also, but not always, improve the AUC; and (3) each method can be the best method in certain situations. In addition, as the correlation strength increases, the average performs the best less often, whereas the maximum and the minimum perform the best more often. These theoretical results are illustrated with analysis of a mammography study.

Area Under Curve↗
PubMed2004

An ROC comparison of four methods of combining information from multiple images of the same patient.

Variance of diagnostic information contained in an image degrades diagnostic accuracy. Acquiring multiple images of the same patient (e.g., mediolateral oblique and craniocaudal view mammograms) can, in principle, help reduce this degradation. We demonstrate how this can be accomplished in the context of computer-aided diagnosis (CAD). Assuming that computer outputs obtained from multiple images of the same patient can be transformed monotonically to the same pair of truth-conditional normal distributions and, for simplicity, ignoring correlation among images, we investigate theoretically four methods of combining the computer outputs: taking the average, the median, the maximum, or the minimum. We found, as one would expect, that both the average and the median always produce an improved area under the receiver operating characteristic (ROC) curve (AUC) compared to the single-view images, while the average always produces better performance than the median. However, the maximum and minimum also can produce improved AUCs in some situations, and under certain conditions can outperform the average. Surprisingly, we found that the maximum and minimum of normally-distributed decision variables produce nearly binormal ROC curves. These results can be used as a guide in attempting to increase the efficacy of CAD when multiple images are available from the same patient.

Algorithms↗
PubMed2003

Cell surface expression of an endoplasmic reticulum resident heat shock protein gp96 triggers MyD88-dependent systemic autoimmune diseases.

Heat shock proteins have been implicated as endogenous activators for dendritic cells (DCs). Without tissue distress or death, these intracellular molecules are inaccessible to surface receptor(s) on DCs, possibly to avoid uncontrolled DC activation and breakdown of immunologic tolerance. We herein addressed this hypothesis in transgenic mice by enforcing cell surface expression of gp96, a ubiquitous heat shock protein of the endoplasmic reticulum. Although a pan-specific promoter is used for transgene expression, neither the expression level nor the tissue distribution of the endogenous gp96 was altered by this maneuver. However, cell surface gp96 induced significant DC activations and spontaneous lupus-like autoimmune diseases, even though the development/functions of lymphocytic compartments were unaltered. Using a bone marrow chimera approach, we further demonstrated that both DC activation and autoimmunity elicited by cell surface gp96 are dependent on the downstream adaptor protein MyD88 for signaling by Toll/IL-1 receptor family. Our study not only established the proinflammatory property of cell surface gp96 in vivo, but also suggested a chronic stimulation of DCs by gp96 as a pathway to initiate spontaneous autoimmune diseases.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Cell surface expression of heat shock protein gp96 enhances cross-presentation of cellular antigens and the generation of tumor-specific T cell memory.

Gp96 is an endoplasmic reticular heat shock protein (HSP). We have shown previously that surface expression of gp96 (96tm) on tumor cells led to the activation of dendritic cells and increased anti-tumor immunity. In this report, we have found that protective immunity elicited by 96tm+ tumor cells was tumor-specific and long-lasting. Both CD4+ and CD8+ T cell memory were elicited. By immunizing with tumor cells loaded with the chicken ovalbumin (ova) model antigen, we demonstrated that the priming of adoptively transferred ova-specific CD8+ T cells could occur across MHC haplotypes. The efficiency of this cross priming can be significantly increased when mice were immunized with whole cells that express both ova and cell surface gp96 (ova+96tm+). Mere mixture of soluble ova with 96tm-expressing tumor cells (ova-96tm+) was insufficient, arguing for further processing of ova and perhaps the participation of 96tm-ova complexes in this process. We further compared the relative efficiency of two whole cell vaccines based on the manipulation of gp96 expression in one system: 96tm+ whole cells and cells that secrete the gp96-Ig fusion protein. We found that both vaccines are effective in a prophylactic model against tumors. Our study has reinforced the notion that the manipulation of the site of expression of HSPs may be an effective approach for cancer immunotherapy.

Animals↗