Molecular mechanism of the metal-independent production of hydroxyl radicals by thiourea dioxide and H2O2

It is well-known that highly reactive hydroxyl radicals (HO•) can be produced by the classic Fenton system and our recently discovered haloquinone/H2O2 system, but rarely from thiol-derivatives. Here, we found, unexpectedly, that HO• can be generated from H2O2 and thiourea dioxide (TUO2), a widely used and environmentally friendly bleaching agent. A carbon-centered radical and sulfite were detected and identified as the transient intermediates, and urea and sulfate as the final products, with the complementary application of electron spin-trapping, oxygen-18 isotope labeling coupled with HPLC/MS analysis. Density functional theory calculations were conducted to further elucidate the detailed pathways for HO• production. Taken together, we proposed that the molecular mechanism for HO• generation by TUO2/H2O2: TUO2 tautomerizes from sulfinic acid into ketone isomer (TUO2-K) through proton transfer, then a nucleophilic addition of H2O2 on the S atom of TUO2-K, forming a S-hydroperoxide intermediate TUO2-OOH, which dissociates homolytically to produce HO•. Our findings represent the first experimental and computational study on an unprecedented new molecular mechanism of HO• production from simple thiol-derived sulfinic acids, which may have broad chemical, environmental, and biomedical significance for future research on the application of the well-known bleaching agent and its analogs.

Performance evaluation of core genome multilocus sequence typing for genotyping of Mycobacterium tuberculosis strains in China: based on multicenter, population-based collection

PURPOSE

To evaluate the performance of core genome multilocus sequence typing (cgMLST) for genotyping Mycobacterium tuberculosis (M.tuberculosis) Strains in regions where the lineage 2 strains predominate.

METHODS

We compared clustering by whole-genome SNP typing with cgMLST clustering in the analysis of WGS data of 6240 strains from five regions of China. Using both the receiver operating characteristic (ROC) curve and epidemiological investigation to determine the optimal threshold for defining genomic clustering by cgMLST. The performance of cgMLST was evaluated by quantifying the sensitivity, specificity and concordance of clustering between two methods. Logistic regression was used to gauge the impact of strain genetic diversity and lineage on cgMLST clustering.

RESULTS

The optimal threshold for cgMLST to define genomic clustering was determined to be ≤ 10 allelic differences between strains. The overall sensitivity and specificity of cgMLST averaged 99.6% and 96.3%, respectively; the concordance of clustering between two methods averaged 97.1%. Concordance was significantly correlated with strain genetic diversity and was 3.99 times (95% CI, 2.94-5.42) higher in regions with high genetic diversity (π > 1.55 × 10-4) compared to regions with low genetic diversity. The difference missed statistical significance, while concordance for lineage 2 strains (96.8%) was less than that for lineage 4 strains (98.3%). CONCLUSION : cgMLST showed a discriminatory power comparable to whole-genome SNP typing and could be used to genotype clinical M.tuberculosis strains in different regions of China. The discriminative power of cgMLST was significantly correlated with strain genetic diversity and was slightly lower with strains from regions with low genetic diversity.

Study of the PI3K/Akt/mTOR signaling pathway in vitro and molecular docking analysis of periplocin inhibits cell cycle progression and induces apoptosis in MDA-MB-231

Breast cancer mainly affects women and is the second leading cause of cancer-related deaths worldwide. Breast cancer affects women aged 15-59. The current study explored periplocin's anticancer activities against breast cancer MDA-MB-231 cells by down-regulating the PI3K/Akt/mTOR pathway. The MTT assay assessed control-treated and periplocin (2.5-50 μM) treated MDA-MB-231 cell viability. ROS accumulation and apoptosis levels in periplocin-treated cells were examined using DAPI, dual staining, and Annexin V-FITC/PI assays. Caspase enzymes were studied using assay kits. Flow cytometry was used to measure cell cycle distributions. Periplocin-treated cells were analyzed using RT-PCR assays and insilico analyses for the expression of PI3K/Akt/mTOR molecules. The periplocin treatment remarkably reduced the viability of the MDA-MB-231 cells, with an IC50 concentration of 7.5 μM. The fluorescent staining assays revealed a substantial increase in ROS levels and apoptotic events in the periplocin-treated cells. The flow cytometry analysis revealed that periplocin triggered apoptosis and arrested the cell cycle in G0/G1 phases. Periplocin increased the caspase-3, -8, and -9 enzyme activities. In MDA-MB-231 cells, Periplocin decreased PI3K/Akt/mTOR activity, and in silico analysis, Periplocin was inhibited by CDK8-Cyclin C interactions. Periplocin has anticancer properties against breast cancer and may be an effective therapeutic agent for treating breast cancer.

Chemical Mechanism of Fireworm Bioluminescence - A Theoretical Proposition

Odontosyllis undecimdonta is a marine worm, commonly known as a fireworm, that exhibits bluish-green bioluminescence (BL). The luciferin (L) and oxyluciferin (OL) during fireworm BL have been experimentally identified in vitro. The L and OL are the respective starting point and ending point of a series of complicated chemical reactions in the BL. However, the chemical mechanism of the fireworm BL remains largely unknown. Before the experiments provided strong evidence for the mechanism, based on our previously successful studies on several bioluminescent systems, we theoretically proposed the chemical mechanism of the fireworm BL in this article. By means of the spin-flip and time-dependent density functional calculations, we clearly described the complete process from L to OL: under the catalysis of luciferase, L undergoes deprotonation and reacts with 3O2 to form a dioxetanone anion via the single-electron transfer mechanism; the dioxetanone anion decomposes into the OL at the first singlet excited state (S1) by the gradually reversible charge-transfer-induced luminescence mechanism; and the S1-OL emits light and deexcites to OL in the ground state.

The landscape of N6-methyladenosine modification patterns and altered transcript profiles in the cardiac-specific deletion of natriuretic peptide receptor A

The atrial natriuretic peptide (ANP) and the brain natriuretic peptide (BNP) are critical biological makers and regulators of cardiac functions. Our previous results show that NPRA (natriuretic peptide receptor A)-deficient mice have distinct metabolic patterns and expression profiles compared with the control. Still, the molecular mechanism that could account for this observation remains to be elucidated. Here, methylation alterations were detected by mazF-digestion, and differentially expressed genes of transcriptomes were detected by a Genome Oligo Microarray using the myocardium from NPRA-deficient (NPRA^-/-) mice and wild-type (NPRA^+/+) mice as the control. Comprehensive analysis of m6A methylation data gave an altered landscape of m6A modification patterns and altered transcript profiles in cardiac-specific NPRA-deficient mice. The m6A "reader" igf2bp3 showed a clear trend of increase, suggesting a function in altered methylation and expression in cardiac-specific NPRA-deficient mice. Intriguingly, differentially m6A-methylated genes were enriched in the metabolic process and insulin resistance pathway, suggesting a regulatory role in cardiac metabolism of m6A modification regulated by NPRA. Notably, it was confirmed that the pyruvate dehydrogenase kinase 4 (Pdk4) gene upregulated the gene expression and the hypermethylation level simultaneously, which may be the key factor for the cardiac metabolic imbalance and insulin resistance caused by natriuretic peptide signal resistance. Taken together, cardiac metabolism might be regulated by natriuretic peptide signaling, with decreased m6A methylation and a decrease of Pdk4.

Mechanistic Investigation of H2 O2 -dependent Chemiluminescence from Tetrabromo-1,4-Benzoquinone

As a H₂ O₂ -dependent bioluminescent substrate, tetrabromo-1,4-benzoquinone (TBBQ) was first isolated from acorn worm. The mechanism of chemiluminescence (CL) corresponding to the bioluminescence (BL) of acorn worm is largely unknown, let alone the mechanism of BL. In this article, we firstly studied the chemical and physical processes, and mechanism of H₂ O₂ -dependent CL from TBBQ by theoretical and experimental methods. The research results indicate: the CL process is initiated by a nucleophilic substitution reaction, which leads to the formation of an anionic dioxetane through five consecutive reactions; the anionic dioxetane decomposes to the first singlet excited state (S₁ ) via a conical interaction of the potential energy surfaces (PESs) between the ground (S₀ ) and S₁ state; the anionic S₁ -state changes to its neutral form by a proton transfer from the solvent and this neutral product is assigned as the actual luminophore. Moreover, the experimental detection of CL, ^. OH and the identifications of 2,3-dibromo maleic acid and 2-bromo malonic acid as the major final products provide direct evidence of the theoretically suggested mechanism. Finally, this study proves that the activity of the H₂ O₂ -dependent CL from TBBQ is significantly lower than the one from tetrachloro-1,4-benzoquinone (TCBQ), which is caused by the weaker electron withdrawing effect and the stronger heavy atomic effect of bromine.

The acquisition of Mycobacterium tuberculosis infection in village doctors in China: a prospective study

BACKGROUND: Occupational exposure-related risk of Mycobacterium tuberculosis infection has been reported for village doctors in China. This prospective study aims to estimate the infection acquisition in this key population.METHODS: At baseline, all village doctors registered in Zhongmu County were tested by QuantiFERON^®-TB Gold In-Tube (QFT) and QuantiFERON^®-TB Gold Plus (QFT-Plus) in parallel. Those negatives for either of the tests were retested to identify conversions at the 2-year follow-up investigation.RESULTS: A total of 367 eligible participants completed the 2-year follow-up survey with frequency of conversion of 5.0% (18/361) for QFT and 6.1% (21/343) for QFT-Plus. The agreement of follow-up results between the tests was 93.2% with a κ coefficient of 0.43 (95%CI 0.20-0.65). Among QFT-Plus convertors, the difference between TB1 and TB2 tubes (TB2-TB1) was significantly increased as compared with baseline results (P = 0.039). Participants from the villages with occurrence of microbiologically confirmed pulmonary TB showed higher frequency of QFT conversions (11.0% vs. 3.2%, P = 0.011) and QFT-Plus conversions (12.3% vs. 4.4%, P = 0.027) than those from the villages without occurrence.CONCLUSION: Our results consistently suggest that capability on occupational protection and M. tuberculosis infection control should be improved in village doctors in China.

Structural evolution and mechanical behaviour of Pt nanoparticle superlattices at high pressure

High pressure is an effective means for tuning the interparticle distances of nanoparticle (NP) superlattices and thus for modifying their physical properties and functionalities. In this work, we determined the evolution of inter-NP distances of a Pt NP superlattice with increasing pressure using an in situ synchrotron small-angle X-ray scattering (SAXS) technique in a diamond-anvil cell (DAC). Transmission electron microscopy (TEM) was used to characterize the microstructures of pre- and post-compression samples. Our results demonstrate that the evolution of Pt NP assemblies with increasing pressure consists of four stages: (1) ligand elastic response, (2) uniform compression, (3) ligand detachment from NP surfaces, and (4) deviatoric compression of ligands between neighboring NPs. By controlling the magnitudes of applied pressure and deviatoric stress, one can sinter NPs into novel architectures such as nanowires and nanoceramics.

Yes-associated protein (YAP) expression is involved in epithelial-mesenchymal transition in hepatocellular carcinoma

PURPOSE

To investigate biological impact of the downregulation of yes-associated protein (YAP) through RNA interference in the process of epithelial-mesenchymal transition in MHCC97H and MHCC97L.

METHODS

MHCC97H and MHCC97L cells were transiently transfected by YAP-siRNA. Furthermore, protein expressions and mRNA levels of characteristic markers of epithelial-mesenchymal transition (E-cadherin, N-cadherin) were examined by Western blotting and real-time polymerase chain reaction, and transwell invasion assay was used to detect changes of invasiveness of MHCC97H and MHCC97L cells.

RESULTS

The transfected group with YAP-siRNA in MHCC97H after 72 h by Western blotting showed obviously higher expression of E-cadherin compared with the control group (P < 0.05), and lower expression of N-cadherin (P < 0.05). In MHCC97L cells, the expression of E-cadherin was also significantly increased (P < 0.05); however, N-cadherin expression did not significantly change (P > 0.05). Moreover, compared with the control group, Transwell invasion assay showed that the number of the transfected groups was significantly decreased in MHCC97H and MHCC97L cell lines (both P < 0.05). The result of real-time polymerase chain reaction indicated that mRNA levels of E-cadherin increased (P < 0.05), but the mRNA levels of N-cadherin did not significantly change (P > 0.05) in these two cell lines, indicating some effects of post-transcriptional regulation mechanism after silencing YAP.

CONCLUSIONS

YAP expression in human hepatocellular carcinoma cell lines MHCC97H and MHCC97L is closely related with the characteristic markers of epithelial-mesenchymal transition, N-cadherin and E-cadherin expression.

Atorvastatin suppresses Toll-like receptor 4 expression and NF-κB activation in rabbit atherosclerotic plaques

BACKGROUND

Toll-like receptor 4 (TLR4) plays an essential role in the pathogenesis and progression of atherosclerosis, which overexpresses in atherosclerotic lesions and mediates the production of inflammatory factors. The aim of this study was to investigate the effects of atorvastatin on TLR4 protein and mRNA expression and its downstream factor NF-κB activation in rabbit atherosclerotic plaques.

MATERIALS AND METHODS

Rabbits continuously fed with high-fat diet for 24 weeks were randomly divided into two groups, the drug-treated group orally administrated with atorvastatin (2 mg/kg/day) three weeks after high-fat diet feeding and the model group with no treatment. The expression of TLR4 protein and mRNA, the level of activated NF-κB (p65) were respectively detected by western blotting, quantitative RT-PCR, and ELISA.

RESULTS

The results showed that atorvastatin treatment reduced the expression of TLR4 protein and mRNA by 24.1% (p < 0.05) and 46.9% (p < 0.01), respectively, and also inhibited NF-κB activation by 76.0% (p < 0.001) in the atherosclerotic plaques.

CONCLUSIONS

Thus, it was suggested that atorvastatin could exert an anti-atherosclerotic activity besides inhibiting cholesterol biosynthesis.

Outcomes of Endovascular Coiling versus Surgical Clipping in the Treatment of Ruptured Intracranial Aneurysms

Objective:

The effects of treatment modality (endovascular coiling or surgical clipping) on incidence of cerebral vasospasm and infarction following aneurysmal subarachnoid haemorrhage (aSAH) remain controversial. This study compared outcomes between endovascular coiling versus surgical clipping to treat patients with acute (< 72 h) aSAH.

Methods:

Patients with aSAH were randomized to receive endovascular or surgical treatment. All patients underwent clinical assessments, angiography and brain computed tomography.

Results:

Data from 186 patients were analysed: 94 in the endovascular group and 92 in the surgical group. Demographics and severity of aSAH were comparable between the groups. Incidence of symptomatic vasospasm, cerebral infarction and complete occlusion were significantly lower in the endovascular coiling group than in the surgical clipping group. Good clinical recovery 12 months after aSAH was seen in 75.0% and 69.7% of surviving patients in the endovascular versus coiling group, respectively.

Conclusions:

In this study, coiling yielded less symptomatic vasospasm, cerebral infarction and complete occlusion than surgical clipping, with no between-group differences in clinical outcome.

Preoperative Lanreotide Treatment Improves Outcome in Patients with Acromegaly Resulting from Invasive Pituitary Macroadenoma

OBJECTIVE: To investigate whether 3 months' preoperative treatment with lanreotide improved outcome in newly diagnosed patients with acromegaly resulting from invasive pituitary macroadenoma. METHODS: After baseline evaluation, untreated patients were randomized to undergo direct trans-sphenoidal surgery or lanreotide treatment (30 mg via intramuscular injection every 2 weeks, increased to 30 mg/week at week 8 if growth hormone nadir > 2.5 μg/l), for 3 months prior to surgery. Tumour shrinkage following lanreotide treatment was analysed. Cure was evaluated at 3 months postsurgery by measuring growth hormone and insulinlike growth factor-1 (IGF-1) levels. RESULTS: Preoperative lanreotide treatment significantly reduced mean tumour size. Growth hormone and IGF-1 levels were lower in the pretreatment group than in the direct surgery group at 3 months postsurgery. According to combined growth hormone and IGF-1 levels, significantly more patients were cured by trans-sphenoidal surgery in the pretreatment group compared with the direct surgery group (11 of 24 and five of 25 patients, respectively). CONCLUSIONS: Lanreotide treatment for 3 months before trans-sphenoidal surgery effectively reduced tumour size, and improved surgical cure rate, in newly diagnosed patients with acromegaly resulting from invasive pituitary macroadenoma.

Study on performance of granular ANAMMOX process and characterization of the microbial community in sludge

Anaerobic Ammonium Oxidation (ANAMMOX) is a novel biological nitrogen removal process, which is regarded as the most economical process at present. In this paper, two lab-scale UASB reactors, one of which was inoculated with the mixture of anaerobic sludge and aerobic sludge, the other with river sediments, were started up, using the inorganic synthetic water containing ammonium and nitrite as influent. After 421 days' and 356 days operation respectively, the ammonium removal efficiencies in two reactors reached 94% and 86% respectively, the total nitrogen volumetric loading rates were 2.5 and 1.6 kgN/m3 x d. ANAMMOX granules were obtained in both reactors; the color of most granules was brown, but some of them were red. Based on the observation and studies on the microstructure of the granules, three kinds of ANAMMOX granular sludge formation mechanisms were proposed: adhering biofilm and disintegrated granular core mechanism, adhering biofilm and inorganic core mechanism and the self-coherence mechanism. For phylogenetic characterization of anaerobic ammonium oxidizers, 16S rDNA approach was performed using Planctomycetales-specific PCR amplification. The dominant anammox bacteria occupied more than 90% of Planctomycetales-specific bacteria, and 27% of all bacteria in reactors. The dominant anammox bacteria distantly related to all currently reported candidate anammox genera. Functional gene of amoA was analyzed to investigate the 'aerobic' ammonium-oxidizing bacteria in beta-Proteobacteria. The 'aerobic' ammonium-oxidizing bacteria were more diverse than anammox bacteria, but most of them clustered in anoxic ammonium-oxidizing Nitrosomonas eutropha/europaea groups. The composition of 'aerobic' ammonium-oxidizing bacteria is only 2% of all of bacteria in reactors.

Composite Au/TiO(2) Nanoparticles: Synthesis, Characterization, and Assembly by Using Potentiostatic Technique

Composite Au/TiO(2) nanoparticles were synthesized using TiO(2) nanoparticles as nuclei. The particles were characterized by UV-vis spectroscopy, zeta potential, EDS, and TEM. The mean diameter of the particles is about 23.6 nm, and the position of the surface plasma absorption band peak is at 533 nm, with a red shift of 15 nm compared with that of Au sol. The zeta potential is +31.3 mV. Monolayers of composite Au/TiO(2) nanoparticles were obtained using the potentiostatic technique. Copyright 2000 Academic Press.

[The accessory diagnosis of rectal carcinoma by ICM and oncogene expressions]

OBJECTIVE

To enhance the diagnostic accurate rate of preoperative biopsy on rectal carcinoma.

METHODS

The paraffin embedded biopsy tissues of 17 cases of preoperatively unconfirmed rectal carcinoma and 15 cases of normal rectal mucosa (control group) were examined by routine pathology, image cytometry (ICM), and the expressions of protein products of oncogene p53 and ras.

RESULTS

In the experimental group, 53% specimens were classified as non-diploid by ICM, and the positive rates of p53 and ras expressions were 71% and 47% respectively. The positive rates were higher than those of routine pathology and the differences were significant. In the control group, the results of ICM and oncogene expressions were negative. In the experimental group, there were 11 cases of atypical hyperplasia and 5 cases of chronic inflammation only. Non-diploid, and positive expressions of p53 and ras were found in 8, 11 and 7 cases of atypical hyperplasia respectively; however, they were all negative in chronic inflammation. The differences between atypical hyperplasia and chronic inflammation were significant. ICM was correlated well with expressions of p53 and ras oncogene.

CONCLUSIONS

The techniques of ICM and detecting the expressions of protein products of oncogene p53 and ras can be a supplementary tool for routine pathology to improve the diagnostic rate of rectal carcinoma.

[Effect of recombinant human growth hormone with total parenteral nutrition on albumin synthesis in patients with peritoneal sepsis]

OBJECTIVE

To investigate the effect of recombinant human growth hormone (rhGH) in combination with total parenteral nutrition (TPN) on albumin synthesis in patients with peritoneal sepsis.

METHOD

17 patients with peritoneal sepsis were divided randomly into two groups. The control group received TPN only for 7 days, and the GH group received both rhGH (12 U/d) and TPN for 7 days. The TPN scheme and other treatment were the same in the two groups.

RESULT

Serum albumin, prealbumin, and transferrin concentration were increased in patients in the GH group (P < 0.01), but no apparent effect was observed in the control group (P > 0.05).

CONCLUSION

In condition of serious peritoneal sepsis, TPN can not increase albumin, prealbumin, and transferrin synthesis alone, whereas rhGH in combination with TPN significantly increase the synthesis of visceral proteins.

Prospective studies on the relationship between the 50 g glucose challenge test and pregnant outcome

The 50 g oral glucose challenge test (50gGCT) was performed on 622 pregnant women, and 75 g oral glucose tolerance test (75gGTT) was further done on subjects with screening tests value of > or = 7.78 mmol/L. The results showed that there were 16.56% (103/622) women with screening value of > or = 7.78 mmol/L, among whom, 32 were identified as having gestational impaired glucose tolerance (GIGT) and 12, gestational diabetes mellitus (GDM) by confirmatory test of 75gGTT. The sensitivity of 50gGCT was 42.72%(44/103). The incidences of edema-proteinuria-hypertension syndrome (EPH-syndrome), premature rupture of membranes, fetal macrosomia, operative deliveries and perinatal morbidity were higher in women with GIGT/GDM than in women without GIGT/GDM. It suggests that 50gGCT is an ideal method of screening for GDM and should be performed on all pregnant women.

Role of cytochrome P-450IIE1 in N-nitroso-N-methylaniline induced hepatocyte cytotoxicity

1. The cytotoxicity of N-nitrosomethylaniline (NMA) towards hepatocytes isolated from rats was prevented by acetone or ethanol (inhibitors for cytochrome P-450IIE1) but not by metyrapone or SKF525A (inhibitors for cytochrome P-450IIB1/2). Various alcohols, secondary ketones and isothiocyanates that induced cytochrome P-450IIE1 were also found to be protective. Various aromatic and chlorinated hydrocarbon solvents that are substrates or inducers of cytochrome P-450IIE1 also prevented NMA cytotoxicity. Nitrogen-containing heterocycles that induced cytochrome P-450IIE1 were less effective. Further evidence that cytochrome P-450IIE1 was responsible for the activation of NMA was the marked increase in hepatocyte susceptibility if hepatocytes from pyrazole-induced rats were used. 2. NMA was more cytotoxic to hepatocytes isolated from phenobarbital-pretreated rats than uninduced rats. However, metyrapone now prevented and SKF525A delayed the cytotoxicity whereas ethanol, acetone, allyl isocyanate, isoniazid or trichloroethylene had no effect on the susceptibility of phenobarbital-induced hepatocytes. Furthermore, microsomes isolated from phenobarbital-pretreated rats had higher NMA-N-demethylase activity which was more inhibited by metyrapone and SKF525A than that of uninduced microsomal activity. By contrast the N-demethylase activity of phenobarbital induced microsomes was more resistant to acetone, ethanol, hexanal, trichloroethylene and toluene than uninduced microsome. 3. The above results suggest that cytochrome P-450IIE1 catalyses the cytotoxic activation of NMA in normal or pyrazole-induced hepatocytes whereas cytochrome P-450IIB1/2 is responsible for cytotoxicity in phenobarbital-induced hepatocytes.