Oxidative desulfurization pathway for complete catabolism of sulfoquinovose by bacteria.

Catabolism of sulfoquinovose (SQ; 6-deoxy-6-sulfoglucose), the ubiquitous sulfosugar produced by photosynthetic organisms, is an important component of the biogeochemical carbon and sulfur cycles. Here, we describe a pathway for SQ degradation that involves oxidative desulfurization to release sulfite and enable utilization of the entire carbon skeleton of the sugar to support the growth of the plant pathogen Agrobacterium tumefaciens SQ or its glycoside sulfoquinovosyl glycerol are imported into the cell by an ATP-binding cassette transporter system with an associated SQ binding protein. A sulfoquinovosidase hydrolyzes the SQ glycoside and the liberated SQ is acted on by a flavin mononucleotide-dependent sulfoquinovose monooxygenase, in concert with an NADH-dependent flavin reductase, to release sulfite and 6-oxo-glucose. An NAD(P)H-dependent oxidoreductase reduces the 6-oxo-glucose to glucose, enabling entry into primary metabolic pathways. Structural and biochemical studies provide detailed insights into the recognition of key metabolites by proteins in this pathway. Bioinformatic analyses reveal that the sulfoquinovose monooxygenase pathway is distributed across Alpha- and Betaproteobacteria and is especially prevalent within the Rhizobiales order. This strategy for SQ catabolism is distinct from previously described pathways because it enables the complete utilization of all carbons within SQ by a single organism with concomitant production of inorganic sulfite.

Capture-and-release of a sulfoquinovose-binding protein on sulfoquinovose-modified agarose.

The solute-binding protein (SBP) components of periplasmic binding protein-dependent ATP-binding cassette (ABC)-type transporters often possess exquisite selectivity for their cognate ligands. Maltose binding protein (MBP), the best studied of these SBPs, has been extensively used as a fusion partner to enable the affinity purification of recombinant proteins. However, other SBPs and SBP-ligand based affinity systems remain underexplored. The sulfoquinovose-binding protein SmoF, is a substrate-binding protein component of the ABC transporter cassette in Agrobacterium tumefaciens involved in importing sulfoquinovose (SQ) and its derivatives for SQ catabolism. Here, we show that SmoF binds with high affinity to the octyl glycoside of SQ (octyl-SQ), demonstrating remarkable tolerance to extension of the anomeric substituent. The 3D X-ray structure of the SmoF·octyl-SQ complex reveals accommodation of the octyl chain, which projects to the protein surface, providing impetus for the synthesis of a linker-equipped SQ-amine using a thiol-ene reaction as a key step, and its conjugation to cyanogen bromide modified agarose. We demonstrate the successful capture and release of SmoF from SQ-agarose resin using SQ as competitive eluant, and selectivity for release versus other organosulfonates. We show that SmoF can be captured and purified from a cell lysate, demonstrating the utility of SQ-agarose in capturing SQ binding proteins from complex mixtures. The present work provides a pathway for development of 'capture-and-release' affinity resins for the discovery and study of SBPs.

Ribosomal protein eL39 is important for maturation of the nascent polypeptide exit tunnel and proper protein folding during translation.

During translation, nascent polypeptide chains travel from the peptidyl transferase center through the nascent polypeptide exit tunnel (NPET) to emerge from 60S subunits. The NPET includes portions of five of the six 25S/5.8S rRNA domains and ribosomal proteins uL4, uL22, and eL39. Internal loops of uL4 and uL22 form the constriction sites of the NPET and are important for both assembly and function of ribosomes. Here, we investigated the roles of eL39 in tunnel construction, 60S biogenesis, and protein synthesis. We show that eL39 is important for proper protein folding during translation. Consistent with a delay in processing of 27S and 7S pre-rRNAs, eL39 functions in pre-60S assembly during middle nucleolar stages. Our biochemical assays suggest the presence of eL39 in particles at these stages, although it is not visualized in them by cryo-electron microscopy. This indicates that eL39 takes part in assembly even when it is not fully accommodated into the body of pre-60S particles. eL39 is also important for later steps of assembly, rotation of the 5S ribonucleoprotein complex, likely through long range rRNA interactions. Finally, our data strongly suggest the presence of alternative pathways of ribosome assembly, previously observed in the biogenesis of bacterial ribosomal subunits.

[Effect and mechanism of Jiming Powder on myocardial fibrosis in mice with myocardial infarction].

Jiming Powder is a traditional ancient prescription with good therapeutic effect in the treatment of heart failure, but its mechanism lacks further exploration. In this study, a mouse model of coronary artery ligation was used to evaluate the effect and mechanism of Jiming Powder on myocardial fibrosis in mice with myocardial infarction. The study constructed a mouse model of heart failure after myocardial infarction using the method of left anterior descending coronary artery ligation. The efficacy of Jiming Powder was evaluated from multiple angles, including ultrasound imaging, hematoxylin-eosin(HE) staining, Masson staining, Sirius Red staining, and serum myocardial enzyme spectrum detection. Western blot analysis was performed to detect key proteins involved in ventricular remodeling, including transforming growth factor-ß1(TGF-ß1), α-smooth muscle actin(α-SMA), wingless-type MMTV integration site family member 3a(Wnt3a), ß-catenin, matrix metallopeptidase 2(MMP2), matrix metallopeptidase 3(MMP3), TIMP metallopeptidase inhibitor 1(TIMP1), and TIMP metallopeptidase inhibitor 2(TIMP2). The results showed that compared with the model group, the high and low-dose Jiming Powder significantly reduced the left ventricular internal diameter in systole(LVID;s) and diastole(LVID;d), increased the left ventricular ejection fraction(LVEF) and left ventricular fractional shortening(LVFS), effectively improved cardiac function in mice after myocardial infarction, and effectively reduced the levels of myocardial injury markers such as creatine kinase(CK), creatine kinase isoenzyme(CK-MB), and lactic dehydrogenase(LDH), thus protecting ischemic myocardium. HE staining showed that Jiming Powder could attenuate myocardial inflammatory cell infiltration after myocardial infarction. Masson and Sirius Red staining demonstrated that Jiming Powder effectively inhibited myocardial fibrosis, reduced the collagen Ⅰ/Ⅲ ratio in myocardial tissues, and improved collagen remodeling after myocardial infarction. Western blot results showed that Jiming Powder reduced the expression of TGF-ß1, α-SMA, Wnt3a, and ß-catenin, decreased the levels of MMP2, MMP3, and TIMP2, and increased the level of TIMP1, suggesting its role in inhibiting cardiac fibroblast transformation, reducing extracellular matrix metabolism in myocardial cells, and lowering collagen Ⅰ and α-SMA content, thus exerting an anti-myocardial fibrosis effect after myocardial infarction. This study revealed the role of Jiming Powder in improving ventricular remodeling and treating myocardial infarction, laying the foundation for further research on the pharmacological effect of Jiming Powder.

Characterization of Transverse Aortic Constriction in Mice Based on the Specific Recruitment of Leukocytes to the Hypertrophic Myocardium and the Aorta Ascendens.

Transverse aortic constriction (TAC) is a model that mimics pressure overload-induced left ventricular (LV) hypertrophy in mice. Alterations in immune cell functionality can promote cardiac and vascular remodeling. In the present study, we characterized the time course in innate immune cell dynamics in response to TAC in the different tissues of mice. It was determined whether TAC induces a characteristic leukocyte-driven immune response in the myocardium, aorta ascendens and descendens, spleen, blood, and draining lymph nodes supported by cytokine-driven chemotaxis in mice at 3, 6, and 21 days following surgery. We used complex flow cytometry staining combinations to characterize the various innate immune cell subsets and a multiplex array to determine cytokine concentrations in the serum. The results of the current study indicated that leukocytes accumulate in the myocardium and aorta ascendens in response to TAC. The leukocyte dynamics in the myocardium were dominated by the Ly6Clow macrophages with an early accumulation, whereas the response in the aorta ascendens was characterized by a long-lasting proinflammatory phenotype driven by Ly6Chigh macrophages, neutrophils, and activated DCs. In contrast to the high-pressure environment of the aorta ascendens, the tissue of the aorta descendens did not react to TAC with any leukocyte increase. The levels of proinflammatory cytokines in the blood were elevated in response to TAC, indicating a systemic reaction. Moreover, our findings strongly suggest that cardiac macrophages could origin from splenic pools and reach the site of the inflammation via the blood. Based on the current findings, it can be concluded that the high-pressure conditions in the aorta ascendens cause a characteristic immune response, dominated by the accumulation of leukocytes and the activation of DCs that varies in comparison to the immune cell dynamics in the myocardium and the aorta descendens.

The identification of six risk genes for ovarian cancer platinum response based on global network algorithm and verification analysis.

Ovarian cancer is the most lethal gynaecological cancer, and resistance of platinum-based chemotherapy is the main reason for treatment failure. The aim of the present study was to identify candidate genes involved in ovarian cancer platinum response by analysing genes from homologous recombination and Fanconi anaemia pathways. Associations between these two functional genes were explored in the study, and we performed a random walk algorithm based on reconstructed gene-gene network, including protein-protein interaction and co-expression relations. Following the random walk, all genes were ranked and GSEA analysis showed that the biological functions focused primarily on autophagy, histone modification and gluconeogenesis. Based on three types of seed nodes, the top two genes were utilized as examples. We selected a total of six candidate genes (FANCA, FANCG, POLD1, KDM1A, BLM and BRCA1) for subsequent verification. The validation results of the six candidate genes have significance in three independent ovarian cancer data sets with platinum-resistant and platinum-sensitive information. To explore the correlation between biomarkers and clinical prognostic factors, we performed differential analysis and multivariate clinical subgroup analysis for six candidate genes at both mRNA and protein levels. And each of the six candidate genes and their neighbouring genes with a mutation rate greater than 10% were also analysed by network construction and functional enrichment analysis. In the meanwhile, the survival analysis for platinum-treated patients was performed in the current study. Finally, the RT-qPCR assay was used to determine the performance of candidate genes in ovarian cancer platinum response. Taken together, this research demonstrated that comprehensive bioinformatics methods could help to understand the molecular mechanism of platinum response and provide new strategies for overcoming platinum resistance in ovarian cancer treatment.

Concise synthesis of sulfoquinovose and sulfoquinovosyl diacylglycerides, and development of a fluorogenic substrate for sulfoquinovosidases.

The sulfolipid sulfoquinovosyl diacylglycerol (SQDG) and its headgroup, the sulfosugar sulfoquinovose (SQ), are estimated to harbour up to half of all organosulfur in the biosphere. SQ is liberated from SQDG and related glycosides by the action of sulfoquinovosidases (SQases). We report a 10-step synthesis of SQDG that we apply to the preparation of saturated and unsaturated lipoforms. We also report an expeditious synthesis of SQ and (13C6)SQ, and X-ray crystal structures of sodium and potassium salts of SQ. Finally, we report the synthesis of a fluorogenic SQase substrate, methylumbelliferyl α-d-sulfoquinovoside, and examination of its cleavage kinetics by two recombinant SQases. These compounds will assist in dissecting the role of sulfoglycolysis in the biogeochemical sulfur cycle and understanding the molecular basis of sulfoglycolysis.

Comprehensive Synthesis of Substrates, Intermediates, and Products of the Sulfoglycolytic Embden-Meyerhoff-Parnas Pathway.

Sulfoglycolysis is a metabolic pathway dedicated to the catabolism of the sulfosugar sulfoquinovose (SQ) into smaller organosulfur fragments. An estimated 10 billion tonnes of SQ fluxes through sulfoglycolysis pathways each year, making it a significant aspect of the biogeochemical sulfur cycle. Delineating the molecular details of sulfoglycolysis requires authentic samples of the various metabolites in these pathways. To this end, we have established chemical and chemoenzymatic methods for the synthesis of the key organosulfur metabolites sulfoquinovosylglycerol, SQ (also in 13C6-labeled form), sulfofructose, sulfofructose-1-phosphate, sulfolactaldehyde, and 2,3-dihydroxypropanesulfonate, as well as an improved route to the chromogenic sulfoquinovosidase substrate 4-nitrophenyl α-sulfoquinovoside.

Evaluation of Chitosan-Oleuropein Nanoparticles on the Durability of Dentin Bonding.

Purpose: To evaluate the effects of dentin pretreatment with chitosan-loaded oleuropein nanoparticles (CONPs) on the durability of resin-dentin bonding interfaces. Methods: Eighty freshly extracted non-carious human third molars were randomly divided into four groups (n = 20 each): a de-ionized water (DW) group, a chitosan (CS) group, a chlorhexidine (CHX) group and a CONP group. The dentin in the DW, CS, CHX, and CONP groups were pretreated with de-ionized water, 1.0 mg/L CS solution, 2% chlorhexidine solution, and CONP suspension (prepared with 100 mg/L oleuropein), respectively, followed by the universal adhesive and resin composites. The bonded teeth of each group were randomly divided into two subgroups: an immediate subgroup and an aged subgroup. The bonded teeth of each group were then cut into the bonded beams. We measured their microtensile bond strength (µTBS), observed the characteristics of bonding interface by atomic force microscope, calculated the percentage of silver particles in a selected area for interfacial nanoleakage analysis, and evaluated the endogenous gelatinase activity within the bonding interface for in-situ zymogram analysis. Data were analyzed with two-way ANOVA and LSD multiple comparison test (P < 0.05). Results: Regardless of after 24 h or after thermocycling, CONP exhibited better µTBS (P < 0.05) than the other three groups except that there was not a statistical significance (P > 0.05) in the CONP and CHX groups after 24 h. Besides, the CONP group presented significantly higher modulus of elasticity in the hybrid layers (P < 0.05), lower expression of nanoleakage (P < 0.05), and better inhibitory effect of matrix metalloproteinases than the other three groups before and after thermocycling. Conclusion: Altogether, the CONPs had the potential to act as a dentin primer, which could effectively improve the dentin-resin binding durability.

Biological Scaffolds Assembled with Magnetic Nanoparticles for Bone Tissue Engineering: A Review.

Superparamagnetic iron oxide nanoparticles (SPION) are widely used in bone tissue engineering because of their unique physical and chemical properties and their excellent biocompatibility. Under the action of a magnetic field, SPIONs loaded in a biological scaffold can effectively promote osteoblast proliferation, differentiation, angiogenesis, and so on. SPIONs have very broad application prospects in bone repair, bone reconstruction, bone regeneration, and other fields. In this paper, several methods for forming biological scaffolds via the biological assembly of SPIONs are reviewed, and the specific applications of these biological scaffolds in bone tissue engineering are discussed.

Visualizing the nucleoplasmic maturation of human pre-60S ribosomal particles.

Eukaryotic ribosome assembly is a highly orchestrated process that involves over two hundred protein factors. After early assembly events on nascent rRNA in the nucleolus, pre-60S particles undergo continuous maturation steps in the nucleoplasm, and prepare for nuclear export. Here, we report eleven cryo-EM structures of the nuclear pre-60S particles isolated from human cells through epitope-tagged GNL2, at resolutions of 2.8-4.3 Å. These high-resolution snapshots provide fine details for several major structural remodeling events at a virtual temporal resolution. Two new human nuclear factors, L10K and C11orf98, were also identified. Comparative structural analyses reveal that many assembly factors act as successive place holders to control the timing of factor association/dissociation events. They display multi-phasic binding properties for different domains and generate complex binding inter-dependencies as a means to guide the rRNA maturation process towards its mature conformation. Overall, our data reveal that nuclear assembly of human pre-60S particles is generally hierarchical with short branch pathways, and a few factors display specific roles as rRNA chaperones by confining rRNA helices locally to facilitate their folding, such as the C-terminal domain of SDAD1.

Endowing improved osteogenic activities with collagen membrane by incorporating biocompatible iron oxide nanoparticles.

Introduction: Collagen-based scaffolds, renowned for their exceptional biocompatibility, have garnered attention as promising scaffolds for advancing bone tissue regeneration. Nevertheless, these scaffolds possess inherent limitations, such as notably compromised osteo-conductivity and osteo-inductivity. Methods: Our study focused on enhancing the mechanical properties and osteogenic bioactivities of bovine-derived collagen membranes (CMs) from the Achilles tendon by incorporating FDA-approved iron oxide nanoparticles (IONPs), termed as IONP-CM. Three types of IONP-CMs (IONP-CM-0.5, IONP-CM-1, and IONPCM-1.5) were constructed by altering the amounts of feeding IONPs. Results: Surface topography analysis demonstrated comparable characteristics between the IONP-CM and neat CM, with the former exhibiting augmented mechanical properties. In vitro evaluations revealed the remarkable biocompatibility of IONP-CMs toward mouse calvarial pre-osteoblast MC3T3-E1 cells, concurrently stimulating osteogenic differentiation. Mechanistic investigations unveiled that the osteogenic differentiation induced by IONP-CMs stemmed from the activation of the Wnt/ß-catenin signaling pathway. Furthermore, in vivo bone regeneration assessment was performed by implanting IONP-CMs into the radial defect in rabbits. Results derived from micro-computed tomography and histological analyses unequivocally substantiated the capacity of IONP-CMs to expedite bone repair processes. Discussion: IONP-CMs emerged as scaffolds boasting exceptional biocompatibility and enhanced osteogenic properties, positioning them as promising candidates for facilitating bone tissue regeneration.

A Biomimetic Platelet-Rich Plasma-Based Interpenetrating Network Printable Hydrogel for Bone Regeneration.

Repair of bone defects caused by trauma or diseases is the primary focus of prosthodontics. Hydrogels are among the most promising candidates for bone tissue regeneration due to their unique features such as excellent biocompatibility, similarities to biological tissues, and plasticity. Herein, we developed a type of novel biomimetic interpenetrating polymeric network (IPN) hydrogel by combining methacrylated alginate and 4-arm poly (ethylene glycol)-acrylate (4A-PEGAcr) through photo-crosslinking. Platelet-rich plasma (PRP), a patient-specific source of autologous growth factors, was incorporated into the hydrogel, and thereafter the hydrogels were biological mineralized by simulated body fluid (SBF). Physical properties of hydrogels were comprehensively characterized. In vitro studies demonstrated that the incorporation of PRP and biomineralization promoted the biocompatibility of hydrogel. Strikingly, the osteogenic bioactivities, including ALP activity, mineralized nodule formation, and expression of osteogenic markers were found substantially enhanced by this biomineralized PRP-hydrogel. Finally, a rabbit model of bone defect was employed to assess in vivo bone regeneration, micro-CT analysis showed that the biomineralized PRP-hydrogels could significantly accelerate bone generation. We believed that this novel biomineralized PRP-incorporated IPN hydrogel could be promising scaffolds for bone tissue regeneration.

Systematic evaluation of the associations between mental disorders and dementia: An umbrella review of systematic reviews and meta-analyses.

BACKGROUND: Increasing evidence support the correlation between mental disorders and the likelihood of developing dementia. We aim to conduct an umbrella review to assess the risk of dementia in patients with eight mental disorders. METHODS: We searched PubMed, Embase, Web of science, CNKI, VIP, and Wanfang databases from inception to October 29, 2021. For each included meta-analysis, the effect size with a 95% confidence interval was estimated using either a random effect model or a fixed effect model, and between-study heterogeneity was expressed by I2 and Cochran's Q test. The ROBIS tool was used to assess the risk of bias. RESULTS: A total of ten systematic reviews were included. Among these studies, we identified seven risk factors, including anxiety disorder, bipolar disorder, depression, late-life depression, post-traumatic stress disorder, schizophrenia, and sleep disorder. Light to moderate alcohol drinking was identified as a protective factor. The evaluation results of the ROBIS tool showed that nine systematic reviews had high risk of bias and one had low risk of bias. The strength of evidence supporting the associations between late-life depression and all-cause dementia, Alzheimer's disease, and vascular dementia was high; the strength of evidence supporting the association between depression and all-cause dementia was moderate. LIMITATIONS: Most associations had low strength of evidence and high risk of bias. CONCLUSIONS: This umbrella review shows that high and moderate evidence supports the associations between some mental disorders and dementia. More cohort studies are needed to support the associations between mental disorders and dementia.

The sulfoquinovosyl glycerol binding protein SmoF binds and accommodates plant sulfolipids.

Sulfoquinovose (SQ) is the anionic headgroup of the ubiquitous plant sulfolipid, sulfoquinovosyl diacylglycerol (SQDG). SQDG can undergo delipidation to give sulfoquinovosyl glycerol (SQGro) and further glycoside cleavage to give SQ, which can be metabolized through microbial sulfoglycolytic pathways. Exogenous SQDG metabolites are imported into bacteria through membrane spanning transporter proteins. The recently discovered sulfoglycolytic sulfoquinovose monooxygenase (sulfo-SMO) pathway in Agrobacterium tumefaciens features a periplasmic sulfoquinovosyl glycerol binding protein, SmoF, and an ATP-binding cassette (ABC) transporter. Here, we use X-ray crystallography, differential scanning fluorimetry and isothermal titration calorimetry to study SQ glycoside recognition by SmoF. This work reveals that in addition to SQGro, SmoF can also bind SQ, a simple methyl glycoside and even a short-chain SQDG analogue. Molecular recognition of these substrates is achieved through conserved interactions with the SQ-headgroup together with more plastic interactions with the aglycones. This suggests that the solute binding protein of A. tumefaciens, and related SQ-binding proteins from other sulfoglycolytic pathways, can provide their host organisms direct access to most of the SQ metabolites known to be produced by phototrophs.

Prediction of suicidal ideation among Chinese college students based on radial basis function neural network.

Background: Suicide is one of the leading causes of death for college students. The predictors of suicidal ideation among college students are inconsistent and few studies have systematically investigated psychological symptoms of college students to predict suicide. Therefore, this study aims to develop a suicidal ideation prediction model and explore important predictors of suicidal ideation among college students in China. Methods: We recruited 1,500 college students of Sichuan University and followed up for 4 years. Demographic information, behavioral and psychological information of the participants were collected using computer-based questionnaires. The Radial Basis Function Neural Network (RBFNN) method was used to develop three suicidal ideation risk prediction models and to identify important predictive factors for suicidal ideation among college students. Results: The incidence of suicidal ideation among college students in the last 12 months ranged from 3.00 to 4.07%. The prediction accuracies of all the three models were over 91.7%. The area under curve scores were up to 0.96. Previous suicidal ideation and poor subjective sleep quality were the most robust predictors. Poor self-rated mental health has also been identified to be an important predictor. Paranoid symptom, internet addiction, poor self-rated physical health, poor self-rated overall health, emotional abuse, low average annual household income per person and heavy study pressure were potential predictors for suicidal ideation. Conclusions: The study suggested that the RBFNN method was accurate in predicting suicidal ideation. And students who have ever had previous suicidal ideation and poor sleep quality should be paid consistent attention to.

Structural snapshots of human pre-60S ribosomal particles before and after nuclear export.

Ribosome biogenesis is an elaborate and energetically expensive program that involve two hundred protein factors in eukaryotes. Nuclear export of pre-ribosomal particles is one central step which also serves as an internal structural checkpoint to ensure the proper completion of nuclear assembly events. Here we present four structures of human pre-60S particles isolated through a nuclear export factor NMD3, representing assembly stages immediately before and after nuclear export. These structures reveal locations of a dozen of human factors, including an uncharacterized factor TMA16 localized between the 5S RNA and the P0 stalk. Comparison of these structures shows a progressive maturation for the functional regions, such as peptidyl transferase centre and peptide exit tunnel, and illustrate a sequence of factor-assisted rRNA maturation events. These data facilitate our understanding of the global conservation of ribosome assembly in eukaryotes and species-specific features of human assembly factors.

Ly6C(low) and not Ly6C(high) macrophages accumulate first in the heart in a model of murine pressure-overload.

Cardiac tissue remodeling in the course of chronic left ventricular hypertrophy requires phagocytes which degrade cellular debris, initiate and maintain tissue inflammation and reorganization. The dynamics of phagocytes in left ventricular hypertrophy have not been systematically studied. Here, we characterized the temporal accumulation of leukocytes in the cardiac immune response by flow cytometry and fluorescence microscopy at day 3, 6 and 21 following transverse aortic constriction (TAC). Cardiac hypertrophy due to chronic pressure overload causes cardiac immune response and inflammation represented by an increase of immune cells at all three time points among which neutrophils reached their maximum at day 3 and macrophages at day 6. The cardiac macrophage population consisted of both Ly6C(low) and Ly6C(high) macrophages. Ly6C(low) macrophages were more abundant peaking at day 6 in response to pressure overload. During the development of cardiac hypertrophy the expression pattern of adhesion molecules was investigated by qRT-PCR and flow cytometry. CD11b, CX3CR1 and ICAM-1 determined by qRT-PCR in whole cardiac tissue were up-regulated in response to pressure overload at day 3 and 6. CD11b and CX3CR1 were significantly increased by TAC on the surface of Ly6C(low) but not on Ly6C(high) macrophages. Furthermore, ICAM-1 was up-regulated on cardiac endothelial cells. In fluorescence microscopy Ly6C(low) macrophages could be observed attached to the intra- and extra-vascular vessel-wall. Taken together, TAC induced the expression of adhesion molecules, which may explain the accumulation of Ly6C(low) macrophages in the cardiac tissue, where these cells might contribute to cardiac inflammation and remodeling in response to pressure overload.

Determination of n-octanol/water partition coefficients of weak ionizable solutes by RP-HPLC with neutral model compounds.

The utilization of neutral compounds as model compounds is put forward for determination of the n-octanol/water partition coefficient (K(ow)) of highly hydrophobic, weak acidic compounds by reversed-phase high performance liquid chromatography (RP-HPLC). It is based on a linear relationship between the logarithm of apparent n-octanol/water partition coefficient (log K(ow)″), expressing hydrophobicity of acidic solutes more accurately, and the logarithm of RP-HPLC retention factor of the solutes corresponding to the neat aqueous fraction of mobile phase (log k(w)). The availability of neutral model compounds was theoretically tested for this novel protocol. Moreover, a high consistency of linear log K(ow)″-log k(w) correlations was demonstrated between a mixed training set of neutral and acidic model compounds, and a training set of neutral model compounds. It is proved in theory that for a certain set of compounds investigated, all derived linear relationships between log K(ow)″ and log k(w) have a unit slope and the same intercept, regardless of mobile phase pH. This model was applied to measure log K(ow) of lipophilic aristolochic acid I (AA I) and aristolochic acid II (AA II). Log K(ow) values for AA I and AA II are 4.45±0.07 and 3.99±0.06, respectively. To the best of our knowledge, this is the first report on experimental log K(ow) data for AAs. The proposed strategy solves the problem of lacking suitable acidic model compounds with reliable experimental K(ow) in determining K(ow) of lipophilic acidic solutes by RP-HPLC.

Determination of n-octanol/water partition coefficient for DDT-related compounds by RP-HPLC with a novel dual-point retention time correction.

n-Octanol/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C(18) column using methanol-water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (t(R)) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logk(w), the logarithm of the retention factor extrapolated to pure water, was investigated for a set of 12 benzene homologues and DDT-related compounds with reliable experimental P as model compounds. A linear regression logP=(1.10±0.04) logk(w) - (0.60±0.17) was established with correlation coefficient R(2) of 0.988, cross-validated correlation coefficient R(cv)(2) of 0.983 and standard deviation (SD) of 0.156. This model was further validated using four verification compounds, naphthalene, biphenyl, 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene (p,p'-DDE) with similar structure to DDT. The RP-HPLC-determined P values showed good consistency with shake-flask (SFM) or slow-stirring (SSM) results, especially for highly hydrophobic compounds with logP in the range of 4-7. Then, the P values for five DDT-related compounds, 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (o,p'-DDT), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane (o,p'-DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene (o,p'-DDE), and 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol) and its main degradation product 4,4'-dichlorobenzophenone (p,p'-DBP) were evaluated by the improved RP-HPLC method for the first time. The excellent precision with SD less than 0.03 proved that the novel DP-RTC protocol can significantly increases the determination accuracy and reliability of P by RP-HPLC.