Application of the partial least square regression method in determining the natural background of soil heavy metals: A case study in the Songhua River basin, China.

The "background" is an essential index for identifying anthropogenic inputs and potential ecological risks of soil heavy metals. However, the lithology of bedrock can cause significant spatial variation in the natural background of soil elements, posing considerable difficulties in estimating background values. In this study, an attempt was made to calculate the natural background through regression analysis of soil chemical composition, and reasonably evaluate the impact of lithology. A total of 1771 surface soil samples were collected from the Songhua River Basin, China, for chemical composition analysis, and the partial least square regression (PLSR) method was employed to establish the relationship between heavy metals (As, Hg, Cr, Cd, Pb, Cu, Zn, and Ni) and soil chemical composition/environmental parameters (SiO2, Al2O3, TFe2O3, MgO, CaO, K2O, Na2O, La, Y, Zr, V, Sc, Sr, Li and pH). The result shows that As, Cr, Pb, Cu, Zn, and Ni have significant linear relationships with soil chemical composition. Each of these six heavy metals obtained 1771 regression background values; some were higher than the uniform background value obtained from the boxplot, while others were lower. The regression background values recognized not only subtle anthropogenic inputs and potential ecological risks in low-background regions but also spurious contamination in high-background areas. All these indicate that the PLSR method can effectively improve the determination accuracy of the natural background of soil heavy metals. More attention should be paid to the serious anthropogenic inputs appearing in some places of the study area.

Cyclo[2]pyridine[8]pyrrole: An Expanded Porphyrinoid with Three Closed-Shell Oxidation States.

We report here an expanded porphyrinoid, cyclo[2]pyridine[8]pyrrole, 1, that can exist at three closed-shell oxidation levels. Macrocycle 1 was synthesized via the oxidative coupling of two open chain precursors and fully characterized by means of NMR and UV-vis spectroscopies, MS, and X-ray crystallography. Reduction of the fully oxidized form (1, blue) with NaBH4 produced either the half-oxidized (2, teal) or fully reduced forms (3, pale yellow), depending on the amount of reducing agent used and the presence or absence of air. Reduced products 2 or 3 can be oxidized to 1 by various oxidants (quinones, FeCl3, and AgPF6). Macrocycle 1 also undergoes proton-coupled reductions with I-, Br-, Cl-, SO32-, or S2O32- in the presence of an acid. Certain thiol-containing compounds likewise reduce 1 to 2 or 3. This conversion is accompanied by a readily discernible color change, making cyclo[2]pyridine[8]pyrrole 1 able to differentiate biothiols, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH).

Unraveling the allosteric mechanisms of prolyl endopeptidases for celiac disease therapy: Insights from molecular dynamics simulations.

Prolyl endopeptidases (PEP) from Sphingomonas capsulata (sc) and Myxococcus xanthus (mx) selectively degrade gluten peptides in vitro, offering a potential therapeutic strategy for celiac disease. However, the mechanisms governing the interaction of these enzymes with their substrates remain unclear. In this study, conventional molecular dynamics simulations with a microsecond timescale and targeted molecular dynamics simulations were performed to investigate the native states of mxPEP and scPEP enzymes, as well as their allosteric binding with a representative substrate, namely, Z-Ala-Pro-p-nitroanilide (pNA). The simulations reveal that the native scPEP is in an open state, while the native mxPEP is in a closed state. When pNA approaches a closed mxPEP, it binds to an allosteric pocket located at the first and second ß-sheet of the ß-propeller domain, inducing the opening of this enzyme. Neither enzyme is active in the open or partly-open states. Enzymatic activity is enabled only when the catalytic pocket in the closed state fully accommodates the substrates. The internal capacity of the catalytic pocket of PEP in the closed state determines the maximum size of the gluten peptides that the enzymes can catalyze. The present work provides essential molecular dynamics information for the redesign or engineering of PEP enzymes.

LncRNA CYP4A22-AS1 promotes the progression of lung adenocarcinoma through the miR-205-5p/EREG and miR-34c-5p/BCL-2 axes.

OBJECTIVES: Lung adenocarcinoma (LUAD) exhibits a higher fatality rate among all cancer types worldwide, yet the precise mechanisms underlying its initiation and progression remain unknown. Mounting evidence suggests that long non-coding RNAs (lncRNAs) exert significant regulatory roles in cancer development and progression. Nevertheless, the precise involvement of lncRNA CYP4A22-AS1 in LUAD remains incompletely comprehended. METHODS: Bioinformatics analyses evaluated the expression level of CYP4A22-AS1 in lung adenocarcinoma and paracancer. The LUAD cell line with a high expression of CYP4A22-AS1 was constructed to evaluate the role of CYP4A22-AS1 in the proliferation and metastasis of LUAD by CCK8, scratch healing, transwell assays, and animal experiments. We applied transcriptome and microRNA sequencing to examine the mechanism of CYP4A22-AS1 enhancing the proliferation and metastasis of LUAD. Luciferase reporter gene analyses, west-blotting, and qRT-PCR were carried out to reveal the interaction between CYP4A22-AS1, miR-205-5p/EREG, and miR-34c-5p/BCL-2 axes. RESULTS: CYP4A22-AS1 expression was significantly higher in LUAD tissues than in the adjacent tissues. Furthermore, we constructed a LUAD cell line with a high expression of CYP4A22-AS1 and noted that the high expression of CYP4A22-AS1 significantly enhanced the proliferation and metastasis of LUAD. We applied transcriptome and microRNA sequencing to examine the mechanism of CYP4A22-AS1 enhancing the proliferation and metastasis of LUAD. CYP4A22-AS1 increased the expression of EREG and BCL-2 by reducing the expression of miR-205-5p and miR-34-5p and activating the downstream signaling pathway of EGFR and the anti-apoptotic signaling pathway of BCL-2, thereby triggering the proliferation and metastasis of LUAD. The transfection of miR-205-5p and miR-34-5p mimics inhibited the role of CYP4A22-AS1 in enhancing tumor progression. CONCLUSION: This study elucidates the molecular mechanism whereby CYP4A22-AS1 overexpression promotes LUAD progression through the miR-205-5p/EREG and miR-34c-5p/BCL-2 axes.

Role of the EM clustering method in determining the geochemical background of As and Cr in soils: a case study in the north of Changchun, China.

Determining the geochemical background for heavy metals is vital in soil management activities. Although many statistical methods for geochemical background determination have been proposed, the multi-population problem of geochemical data, primarily regional ones, derived mainly from mixing multiple populations belonging to various geological sources or processes, needs to be better addressed. In this study, the Expectation-Maximization (EM) algorithm was employed to separate multiple populations in a 1:250,000 scale regional geochemical data set of soils in a lithologically complex region in the north of Changchun, China. The data set included 3746 surface soil samples analyzed for SiO2, K2O, Al2O3, CaO, La, Rb, Y, Ti, Ce, V, Cr, and As. The potential high-risk areas of As and Cr were determined before and after the separation of multiple populations. The comparison results show that the EM clustering method can efficiently separate multiple populations and determine soil geochemical background more reasonably, thus eliminating false contamination that is easily misidentified and better revealing concealed contamination that is challenging to detect.

Environmental contamination and health risk assessment of potentially toxic trace metal elements in soils near gold mines - A global meta-analysis.

Gold mining is the most important anthropogenic source of heavy metal emissions into the environment. Researchers have been aware of the environmental impacts of gold mining activities and have conducted studies in recent years, but they have only selected one gold mining site and collected soil samples in its vicinity for analysis, which does not reflect the combined impact of all gold mining activities on the concentration of potentially toxic trace elements (PTES) in nearby soils at a global scale. In this study, 77 research papers from 24 countries were collected from 2001 to 2022, and a new dataset was developed to provide a comprehensive study of the distribution characteristics, contamination characteristics, and risk assessment of 10 PTEs (As, Cd, Cr, Co, Cu, Hg, Mn, Ni, Pb, and Zn) in soils near the deposits. The results show that the average levels of all 10 elements are higher than the global background values and are at different levels of contamination, with As, Cd, and Hg at strong contamination levels and serious ecological risks. As and Hg contribute to a greater non-carcinogenic risk to both children and adults in the vicinity of the gold mine, and the carcinogenic risks of As, Cd, and Cu are beyond the acceptable range. Gold mining on a global scale has already caused serious impacts on nearby soils and should be given adequate attention. Timely heavy metal treatment and landscape restoration of extracted gold mines and environmentally friendly approaches such as bio-mining of unexplored gold mines where adequate protection is available are of great significance.

Isopimaric acid, an ion channel regulator, regulates calcium and oxidative phosphorylation pathways to inhibit breast cancer proliferation and metastasis.

Breast cancer is the globally most common malignant tumor and the biggest threat to women. Even though the diagnosis and treatment of breast cancer are progressing continually, a large number of breast cancer patients eventually develop a metastatic tumor, especially triple-negative breast cancer (TNBC). Recently, metal ion homeostasis and ion signaling pathway have become important targets for cancer therapy. In this study, We analyzed the effects and mechanisms of isopimaric acid (IPA), an ion channel regulator, on the proliferation and metastasis of breast cancer cells (4 T1, MDA-MB-231and MCF-7) by cell functional assay, flow cytometry, western blot, proteomics and other techniques in vitro and in vivo. Results found that IPA significantly inhibited the proliferation and metastasis of breast cancer cells (especially 4 T1). Further studies on the anti-tumor mechanism of IPA suggested that IPA might affect EMT and Wnt signaling pathways by targeting mitochondria oxidative phosphorylation and Ca2+ signaling pathways, and then inducing breast cancer cell cycle arrest and apoptosis. Our research reveals the therapeutic value of IPA in breast cancer and provides a theoretical basis for the new treatment of breast cancer.

Pyridazine-bridged expanded rosarin and semi-rosarinogen.

The synthesis of the pyridazine-bridged expanded rosarin 1 and a reduced precursor, semi-rosarinogen 2, is reported. A single crystal X-ray diffraction analysis of 1 and theoretical calculations show that both 1 and 2 have distorted structures. Expanded rosarin 1 and its precursor 2 can differentiate various thiols in organic solvents by means of species-specific colour changes and reaction times.

Effects of dietary stachyose levels on caecal skatole concentration, hepatic cytochrome P450 mRNA expressions and enzymatic activities in broilers.

Effects of dietary supplemental stachyose on caecal skatole concentration, hepatic cytochrome P450 (CYP450, CYP) mRNA expressions and enzymatic activities in broilers were evaluated. Arbor Acre commercial mixed male and female chicks were assigned randomly into six treatments. The positive control (PC) diet was based on maize-soyabean meal, and the negative control (NC) diet was based on maize-non-soyabean meal. The NC diet was then supplemented with 4, 5, 6 and 7 g/kg stachyose to create experimental diets, named S-4, S-5, S-6 and S-7, respectively. Each diet was fed to six replicates of ten birds from days 1 to 49. On day 49, the caecal skatole concentrations in the PC, S-4, S-5, S-6 and S-7 groups were lower than those in the NC group by 42·28, 23·68, 46·09, 15·31 and 45·14 % (P < 0·01), respectively. The lowest pH value was observed in the S-5 group (P < 0·05). The stachyose-fed groups of broilers had higher caecal acetate and propionate levels compared with control groups, and propionate levels in the S-6 and S-7 groups were higher than those in the S-4 and S-5 groups (P < 0·001). The highest CYP3A4 expression was found in the S-7 group (P < 0·05), but this was not different from PC, S-4, S-5 and S-6 treatments. There was no significant difference in CYP450 (1A2, 2D6 and 3A4) enzymatic activities among the groups (P > 0·05). In conclusion, caecal skatole levels can be influenced by dietary stachyose levels, and 5 g/kg of stachyose in the diet was suggested.

Primary pulmonary extranodal NK/T-cell lymphoma: a case report and literature review.

Extranodal natural killer/T-cell lymphoma (ENKTL) is rare lymphoma subtype with a very poor prognosis. ENKTL in the lung is strongly associated with Epstein-Barr virus (EBV) and is extremely rare; only a few cases have been reported. In the present study, we report a case that a 40-year-old male who presented with cough, sputum and intermittent fever for one month. Chest radiograph revealed progressive multiple nodules in both lungs with ground-glass opacities and bilateral pleural effusion. Based on clinical characteristics and computed tomography (CT) findings, he was initially treated with empirical antibiotics. As there was no significant improvement, bone marrow puncture, left axillary mass biopsy and CT- guided percutaneous lung biopsy were conducted. Therefore, a diagnosis of primary pulmonary ENKTL was confirmed by pathology as cells are positive for CD2, cytoplasmic CD3e, CD56. In situ hybridization for EBV-encoded ribonucleic acid (EBER) was positive. Next generation sequencing (NGS) was used to determine potential therapeutic targets, and the missense mutation of signal transducer and activator of transcription 3 (STAT3) was found. However, the patient demonstrated rapid deterioration and refused chemotherapy. He died shortly following diagnosis. In conclusion: A diagnosis of ENKTL should be considered when patients present with fever and expansive consolidation of the lung, which do not respond to antibiotics. To our knowledge, our patient was the first to undergo NGS for primary pulmonary ENKTL.

Correlation between the pKa and nuclear shielding of α-hydrogen of ketones.

The α-H acidity is an important chemical property of ketones that has attracted much research interest. Theoretical prediction of pKa for ketone α-H is significant. In this work, we theoretically studied the nuclear shielding of various α-Hs in a set of ketones and that of the corresponding enolic hydroxyl Hs in tautomeric enol forms. It has been demonstrated through linear regression analyses that the pKa values of these ketones correlate with both sets of the calculated nuclear shielding values. The correlation coefficient R2 of the linear correlation relationship is 0.90. The present work has provided a new approach to computationally evaluating the acidity of α-Hs in ketones, enabling us to semi-empirically predict the ketone α-H acidity from the calculated nuclear shielding values. Graphical AbstractExperimental pKa values in DMSO vs predicted pKa values calculated from 1H nuclear shielding for the hydroxyl hydrogens in the enol forms and for the α-Hs in the keto forms. The surrounding solvent effects were modelled by keto/enol-DMSO clusters and SMD solvent models.

Alda­1, an aldehyde dehydrogenase­2 agonist, improves long­term survival in rats with chronic heart failure following myocardial infarction.

Alda­1, an aldehyde dehydrogenase 2 (ALDH2) agonist, has been demonstrated to reduce injury caused by acute myocardial infarction (MI) and ischemia/reperfusion. The present study aimed to investigate whether oral administration of Alda­1 improved long­term survival of rats with chronic heart failure (CHF) post­MI. MI model rats treated daily with Alda­1 exhibited an increase in 20­week survival rate compared with untreated MI rats. Alda­1 treatment decreased the heart weight/body weight ratio, collagen volume, left ventricular (LV) internal diameter at the end of diastole and LV internal diameter at the end of systole, while increasing LV ejection fraction with evident LV fractional shortening. Myocardial cell apoptosis index, the activity of caspase­3 and the expression of cleaved­caspase­3 were also reduced by Alda­1 treatment. The protective effects of Alda­1 were associated with reduced 4­hydroxynonenal accumulation. The results of the present study revealed that the long­term treatment with Alda­1 prevented the progression of ventricular remodeling and improved the long­term survival of rats with CHF post­MI.

Correlations between the 1H NMR chemical shieldings and the pKa values of organic acids and amines.

The acid dissociation constants and 1H NMR chemical shieldings of organic compounds are important properties that have attracted much research interest. However, few studies have explored the relationship between these two properties. In this work, we theoretically studied the NMR chemical shifts of a series of carboxylic acids and amines in the gas phase and in aqueous solution. It was found that the negative logarithms of the experimental acid dissociation constants (i.e., the pKa values) of the organic acids and amines in aqueous solution correlate almost linearly with the corresponding calculated NMR chemical shieldings. Key factors that affect the theoretically predicted pKa values are discussed in this paper. The present work provides a new way to predict the pKa values of organic/biochemical compounds. Graphical abstract The chemical shielding values of organic acids and amines correlate near linearly with their corresponding pKa values.

Fasudil inhibits neutrophil-endothelial cell interactions by regulating the expressions of GRP78 and BMPR2.

Regulation of leukocyte-endothelial cell interactions and of vascular permeability plays a critical role in the maintenance of functional pulmonary microvascular barriers. Little is yet known about the effect of the Rho-associated protein kinase (ROCK) inhibitor fasudil on leukocyte-endothelial cell interactions or the underlying mechanism. In the present study, as evaluated using co-culture systems of neutrophils and human pulmonary microvascular endothelial cells (HPMECs), fasudil dose-dependently suppressed neutrophil chemotaxis by decreasing the production of chemotactic factors in lipopolysaccharide (LPS)-treated HPMECs. The inhibitory role of fasudil in neutrophil chemotaxis was mediated by down-regulation of the chaperone glucose-regulated protein 78 (GRP78), since the inhibition was abolished by 4-phenyl butyric acid (a chemical chaperone mimicking GRP78). In addition, fasudil inhibited LPS-induced neutrophil-endothelial adhesion by reducing the expression of intercellular adhesion molecule (ICAM)-1. By use of lentiviral transfection in HPMECs, bone morphogenic protein receptor 2 (BMPR2) overexpression suppressed the LPS-induced increase of both ICAM-1 expression and neutrophil-endothelial adhesion, whereas knocking down BMPR2 abolished the inhibitory role of fasudil in both ICAM-1 expression and neutrophil-endothelial adhesion. Moreover, fasudil alleviated LPS-induced hyperpermeability of HPMEC monolayers by leading to the recovery of intercellular junctions, thereafter reduced neutrophil transendothelial cell migration. Therefore, fasudil inhibited leukocyte-endothelial cell interactions and vascular hyperpermeability through modulation of GRP78 and BMPR2 expression, suggesting a potential role for ROCK as a switch for inhibiting leukocyte-endothelial cell interactions.

Multiple halide anion doped layered bismuth terephthalate with excellent photocatalysis for pollutant removal.

In order to improve the photocatalytic activities of layered MOF bismuth terephthalate, five multiple halide anion doped bismuth terephthalate composites were prepared by doping three or four halide anions each with a molar ratio of X-/Bi3+ (X = F-, Cl-, Br-, I-) at 0.25. The F-, Cl-, Br- codoped and F-, Cl-, Br-, I- codoped bismuth terephthalate composites exhibit 41 and 35 times higher photocatalytic degradation activities for RhB, 7 and 6 times higher for salicylic acid than that of bismuth terephthalate. Excellent photocatalytic activities could be ascribed to the microstructure of multiple halide anion doped composites, large specific BET surface area and effective separation of photogenerated electron-hole pairs. Incorporating multiple negatively charged F-, Cl-, Br-, I- into layered bismuth terephthalate can improve the photocatalytic and electrochemical activities of bismuth terephthalate. The composites presented in this study can be potentially applied in photocatalysis and electrochemical fields as multifunctional materials.

Risk Assessment and Source Identification of 17 Metals and Metalloids on Soils from the Half-Century Old Tungsten Mining Areas in Lianhuashan, Southern China.

Background: Mining activities always emit metal(loid)s into the surrounding environment, where their accumulation in the soil may pose risks and hazards to humans and ecosystems. Objective: This paper aims to determine of the type, source, chemical form, fate and transport, and accurate risk assessment of 17 metal(loid) contaminants including As, Cd, Cu, Ni, Pb, Zn, Cr, Ag, B, Bi, Co, Mo, Sb, Ti, V, W and Sn in the soils collected from an abandoned tungsten mining area, and to guide the implementing of appropriate remediation strategies. Methods: Contamination factors (CFs) and integrated pollution indexes (IPIs) and enrichment factors (EFs) were used to assess their ecological risk and the sources were identified by using multivariate statistics analysis, spatial distribution investigation and correlation matrix. Results: The IPI and EF values indicated the soils in the mine site and the closest downstream one were extremely disturbed by metal(loid)s such as As, Bi, W, B, Cu, Pb and Sn, which were emitted from the mining wastes and acid drainages and delivered by the runoff and human activities. Arsenic contamination was detected in nine sites with the highest CF values at 24.70 next to the mining site. The Cd contamination scattered in the paddy soils around the resident areas with higher fraction of bioavailable forms, primarily associated with intense application of phosphorus fertilizer. The lithogenic elements V, Ti, Ag, Ni, Sb, Mo exhibit low contamination in all sampling points and their distribution were depended on the soil texture and pedogenesis process. Conclusions: The long term historical mining activities have caused severe As contamination and higher enrichment of the other elements of orebody in the local soils. The appropriate remediation treatment approach should be proposed to reduce the bioavailability of Cd in the paddy soils and to immobilize As to reclaim the soils around the mining site. Furthermore, alternative fertilizing way and irrigating water sources are urgencies to reduce the input of Cd and As into the local soils effectively.

A Practical System for High-Throughput Screening of Mutants of Bacillus fastidiosus Uricase.

For high-throughput screening (HTS) of Bacillus fastidiosus uricase mutants, a practical system was proposed. By error-prone PCR with final 1.5 mM MnCl2, two focused libraries of mutants for A1-V158 and V150-D212 were generated separately. After induced expression of individual clones in 48-well microplates, Escherichia coli cells (BL21) were lyzed by 1.0 M Tris-HCl at pH 9.0 in 96-well microplates at 25 °C for 7.5 ~ 10.5 h; uricase reaction was continuously monitored with 0.15 mM uric acid in 96-well plates by absorbance at 298 nm to estimate V m/K m by kinetic analysis of reaction curve for comparison. V m/K m was resistant to initial uric acid levels with an upper limit 3-fold over that of initial rates. By receiver-operator-characteristic analysis of the recognition of the one of higher activity in uricase pair whose specific activity ratio was 1.8 or 3.3, the area-under-the-curve was comparable to that with cell lysates prepared by sonication treatment. A cutoff for the maximum Youden index was thus developed to recognize positive mutants of 1-fold higher activity. Indeed, mutant L171I/Y182F/Y187F/A193S of higher activity but lower thermostability at pH 7.4 and mutant V144A of higher activity and consistent thermostability were discovered. Therefore, the proposed system was practical for HTS of uricase mutants.

Pulmonary Fungal Diseases in Immunocompetent Hosts: A Single-Center Retrospective Analysis of 35 Subjects.

BACKGROUND: Pulmonary fungal disease is an emerging issue in immunocompetent patients, for whom the characteristics are only partially understood. METHODS: We conducted a single-center retrospective study of histologically verified pulmonary fungal disease in Eastern China from 2006 to 2014 to understand the demographics, clinical manifestations, therapeutic approaches, and factors associated with prognosis in this population. All cases were diagnosed according to the 2008 European Organization for the Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infection Diseases Mycoses Study Group definition criteria. RESULTS: A total of 112 cases of pulmonary fungal diseases were enrolled (35 proven, 16 probable, 61 possible), and we analyzed the 35 patients with histologically proven pulmonary fungal diseases in this study. The main fungal species identified were Aspergillus (51.4 %), Cryptococcus (22.9 %), and Mucor (2.4 %). Treatment consisted of antifungal therapeutic agents (54.3 %), surgery and postsurgical agents (25.7 %), or surgery alone (14.3 %). The overall crude mortality rate was 14.3 %, and the mortality due to pulmonary fungal infections was 2.9 %. Significant predictors of mortality by univariate analysis were hypoalbuminemia (P = 0.005), cancer (P = 0.008), and positive culture (P = 0.044). Additionally, hypoalbuminemia was the only risk factor for mortality by multivariate analysis (RR = 7.56, 95 % CI 1.38-41.46). CONCLUSION: Pulmonary fungal disease in immunocompetent patients, with Aspergillus as the most common identified species, had a prognosis that was influenced by the level of serum albumin.

[Analysis of pathogenic spectrum and risk factors in 165 non-transplant patients with invasive fungal disease].

OBJECTIVE: To describe the clinical characteristics of and risk factors for invasive fungal disease, and therefore to improve the early diagnosis and treatment of fungal infections. METHODS: The clinical data of invasive fungal disease in 165 patients without transplantation from 2006 to 2012 in the First Affiliated Hospital of Nanjing Medical University were retrospectively analyzed. The diagnosis was based on the following guidelines: diagnosis and treatment guidelines of critically ill patients with invasive fungal infection (2007), diagnostic criteria and treatment principle of invasive fungal infection in patients with hematopathy/malignant tumors (fourth edition, 2013), diagnostic criteria and treatment principle of invasive pulmonary fungal infection (draft, 2006). RESULTS: Invasive fungal disease was mostly diagnosed in the respiratory department (31.5%). The major pathogens were cryptococcus (48.3%), aspergillus (31.7%) and followed by mucor (5.9%). The most common symptoms included cough, haemoptysis, and fever. Radiological Findings were non-specific, nodules or opacities being more common as compared to classical aspergilloma, halo sign, and crescent sign. The most common underlying diseases were diabetes (15.8%), chronic obstructive pulmonary disease (13.3%), and malignant hematological disease (10.3%). Moreover, 66.1% cases of invasive fungal disease were accompanied by one or more risk factors (eg. administration of antibiotics more than 7 days, invasive operations, and therapy with long-term glucocorticoids or immunosuppressant drugs). The mortality of invasive fungal disease with more than 2 risk factors was 10.6%. CONCLUSIONS: The most common pathogens of invasive fungal disease in non-transplant patients were cryptococcus, aspergillus and mucor. The lung and the brain were the mostly involved organs. Compared to cryptococcus, invasive fungal disease caused by other fungal pathogens mainly occurred in patients with serious underlying diseases and risk factors.

Cocaine esterase-cocaine binding process and the free energy profiles by molecular dynamics and potential of mean force simulations.

The combined molecular dynamics (MD) and potential of mean force (PMF) simulations have been performed to determine the free energy profiles for the binding process of (-)-cocaine interacting with wild-type cocaine esterase (CocE) and its mutants (T172R/G173Q and L119A/L169K/G173Q). According to the MD simulations, the general protein-(-)-cocaine binding mode is not affected by the mutations; e.g.. the benzoyl group of (-)-cocaine is always bound in a subsite composed of aromatic residues W151, W166, F261, and F408 and hydrophobic residue L407, while the carbonyl oxygen on the benzoyl group of (-)-cocaine is hydrogen-bonded with the oxyanion-hole residues Y44 and Y118. According to the PMF-calculated free energy profiles for the binding process, the binding free energies for (-)-cocaine with the wild-type, T172R/G173Q, and L119A/L169K/G173Q CocEs are predicted to be -6.4, -6.2, and -5.0 kcal/mol, respectively. The computational predictions are supported by experimental kinetic data, as the calculated binding free energies are in good agreement with the experimentally derived binding free energies, i.e., -7.2, -6.7, and -4.8 kcal/mol for the wild-type, T172R/G173Q, and L119A/L169K/G173Q, respectively. The reasonable agreement between the computational and experimental data suggests that the PMF simulations may be used as a valuable tool in new CocE mutant design that aims to decrease the Michaelis-Menten constant of the enzyme for (-)-cocaine.