Structural Characterization of the Metalized Radical Cations of Adenosine ([Ade+Li-H]•+ and [Ade+Na-H]•+) by Infrared Multiphoton Dissociation Spectroscopy and Theoretical Studies.

Nucleoside radicals are key intermediates in the process of DNA damage, and alkali metal ions are a common group of ions in living organisms. However, so far, there has been a significant lack of research on the structural effects of alkali metal ions on nucleoside free radicals. In this study, we report a new method for generating metalized nucleoside radical cations in the gas phase. The radical cations [Ade+M-H]•+ (M = Li, Na) are generated by the 280 nm ultraviolet photodissociation (UVPD) of the precursor ions of lithiated and sodiated ions of 2-iodoadenine in a Fourier transform ion cyclotron resonance (FT ICR) cell. Further infrared multiphoton dissociation (IRMPD) spectra of both radical cations were recorded in the region of 2750-3750 cm-1. By combining these results with theoretical calculations, the most stable isomers of both radicals can be identified, which share the common characteristics of triple coordination patterns of the metal ions. For both radical species, the lowest-energy isomers undergo hydrogen transfer. Although the sugar ring in the most stable isomer of [Ade+Li-H]•+ is in a (South, syn) conformation similar to that of [Ado+Na]+, [Ade+Na-H]•+ is distinguished by the unexpected opening of the sugar ring. Their theoretical spectra are in good agreement with experimental spectra. However, due to the flexibility of the structures and the complexity of their potential energy surfaces, the hydrogen transfer pathways still need to be further studied. Considering that the free radicals formed directly after C-I cleavage have some similar spectral characteristics, the existence of these corresponding isomers cannot be ruled out. The findings imply that the structures of nucleoside radicals may be significantly influenced by the attached alkali metal ions. More detailed experiments and theoretical calculations are still crucial.

Capture of small clusters by ligand-solvent interaction.

Clusters are considered to become increasingly significant for elaborating the nanocrystal's formation mechanism. However, capturing the clusters with high chemical potential is challenging because of the lack of effective strategies. In this work, the key role of ligand-solvent interaction has been revealed for the stabilization of clusters in silver telluride synthesis. The Flory interaction coefficient that comprehensively regards the temperature and dispersion, polarity, and hydrogen bonding of the solvent has been used to evaluate the ligand-solvent interaction and thus assist in the design of synthetic systems. Small silver telluride clusters have been successfully captured, and the composition of the smallest cluster is determined as Ag7Te8(SCy)2 (SCy represents the ligand). This work provides new insights into the design of cluster/nanocrystal synthesis systems and paves the way to revealing the mechanism of precursor-cluster-nanocrystal conversion.

Proteomics-based evaluation of the mechanism underlying vascular injury via DNA interstrand crosslinks, glutathione perturbation, mitogen-activated protein kinase, and Wnt and ErbB signaling pathways induced by crotonaldehyde.

Crotonaldehyde (CRA)-one of the major environmental pollutants from tobacco smoke and industrial pollution-is associated with vascular injury (VI). We used proteomics to systematically characterize the presently unclear molecular mechanism of VI and to identify new related targets or signaling pathways after exposure to CRA. Cell survival assays were used to assess DNA damage, whereas oxidative stress was determined using colorimetric assays and by quantitative fluorescence study; additionally, cyclooxygenase-2, mitogen-activated protein kinase pathways, Wnt3a, ß-catenin, phospho-ErbB2, and phospho-ErbB4 were assessed using ELISA. Proteins were quantitated via tandem mass tag-based liquid chromatography-mass spectrometry and bioinformatics analyses, and 34 differentially expressed proteins were confirmed using parallel reaction monitoring, which were defined as new indicators related to the mechanism underlying DNA damage; glutathione perturbation; mitogen-activated protein kinase; and the Wnt and ErbB signaling pathways in VI based on Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses. Parallel reaction monitoring confirmed significant (p < 0.05) upregulation (> 1.5-fold change) of 23 proteins and downregulation (< 0.667-fold change) of 11. The mechanisms of DNA interstrand crosslinks; glutathione perturbation; mitogen-activated protein kinase; cyclooxygenase-2; and the Wnt and ErbB signaling pathways may contribute to VI through their roles in DNA damage, oxidative stress, inflammation, vascular dysfunction, endothelial dysfunction, vascular remodeling, coagulation cascade, and the newly determined signaling pathways. Moreover, the Wnt and ErbB signaling pathways were identified as new disease pathways involved in VI. Taken together, the elucidated underlying mechanisms may help broaden existing understanding of the molecular mechanisms of VI induced by CRA.

A novel method for photon unfolding spectroscopy of protein ions in the gas phase.

In this study, a new experimental method for photon unfolding spectroscopy of protein ions based on a Fourier transform ion cyclotron resonance (FT ICR) mass spectrometer was developed. The method of short-time Fourier transform has been applied here to obtain decay curves of target ions trapped in the cell of the FT ICR mass spectrometer. Based on the decay constants, the collision cross sections (CCSs) of target ions were calculated using the energetic hard-sphere model. By combining a tunable laser to the FT ICR mass spectrometer, the changes of CCSs of the target ions were recorded as a function of the wavelengths; thus, the photon isomerization spectrum was obtained. As one example, the photon isomerization spectrum of [Cyt c + 13H]13+ was recorded as the decay constants relative to the applied wavelengths of the laser in the 410-480 nm range. The spectrum shows a maximum at 426 nm, where an unfolded structure induced by a 4 s irradiation can be deduced. The strong peak at 426 nm was also observed for another ion of [Cyt c + 15H]15+, although some difference at 410 nm between the two spectra was found at the same time. This novel method can be expanded to ultraviolet or infrared region, making the experimental study of wavelength-dependent photon-induced structural variation of a variety of organic or biological molecules possible.

Geometrical Structures and Dissociation Channels of CuP2n + (n = 2-11): Studied by Mass Spectrometry and Theoretical Calculations.

Transition metal phosphorus cluster cations CuP2n + (2 ≤ n ≤ 11) were studied by laser ablation mass spectrometry and collision-induced dissociation (CID). The magic-numbered cluster ion of CuP8 + was identified experimentally, and cluster ions of CuP14 + and CuP18 + were also found to be generated with high abundance. CID results show that the dissociation channels of CuP2n + (n = 4 and 6-10) are all characterized by the loss of the P4 unit. Theoretical calculations combining global minima searching with the basin-hopping method and density functional theory (DFT) optimizations were performed for these clusters. Among them, the magic-numbered cluster CuP8 + was characterized by a D2d symmetry, with the Cu atom bridging two P4 units. The most stable isomer of CuP14 + was found to be characterized by a C2v symmetry. Calculations also reflect that the dissociation channels of the loss of the P4 unit are more energetically favorable than those of the loss of the P2 unit for CuP2n + (n = 4 and 6-10), which are in good consistent with the experimental results.

Differentiation of disaccharide isomers via a combination of IR and UV photodissociation mass spectrometry.

RATIONALE: The challenge of glycan identification due to their structural complexity and diversity has profited enormously from recent developments in mass spectrometry (MS)-related methods. For photodissociation MS, infrared (IR) and ultraviolet (UV) lasers can generate complementary fragment ions, so an effective combination of the two methods may provide rich and valuable fragmentation patterns for glycan analysis. METHODS: A 7.0 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer equipped with a double-beam laser system was applied for the experiments. 3,5-Diiodo-L-tyrosine was selected as the assistant molecule to form complex ions with ten isomeric disaccharides through electrospray ionization. The complex ions were further isolated and irradiated by IR and UV lasers separately or continuously in the FTICR cell. RESULTS: By combining the two complementary fragment spectra generated from the IR and UV lasers, a clear identification of all the ten isomers was achieved using their binary codes based on their fragmentation patterns. The double-beam method simplifies the experiment by introducing the two lasers sequentially in one experiment, providing richer fragmentation patterns and making the full discrimination easier. CONCLUSIONS: This study demonstrates the capabilities of the combination of IR and UV photodissociation MS in the identification of diverse glycan isomers. The double-beam photodissociation method described here distinguished compositional, configurational and connectivity disaccharide isomers successfully. Compared with the data accumulation method based on separate IR and UV experiments, this method is simpler, faster, more flexible and also characterized by richer fragmentation patterns.

Glyoxal damages human aortic endothelial cells by perturbing the glutathione, mitochondrial membrane potential, and mitogen-activated protein kinase pathways.

BACKGROUND: Exposure to glyoxal, the smallest dialdehyde, is associated with several diseases; humans are routinely exposed to glyoxal because of its ubiquitous presence in foods and the environment. The aim of this study was to examine the damage caused by glyoxal in human aortic endothelial cells. METHODS: Cell survival assays and quantitative fluorescence assays were performed to measure DNA damage; oxidative stress was detected by colorimetric assays and quantitative fluorescence, and the mitogen-activated protein kinase pathways were assessed using western blotting. RESULTS: Exposure to glyoxal was found to be linked to abnormal glutathione activity, the collapse of mitochondrial membrane potential, and the activation of mitogen-activated protein kinase pathways. However, DNA damage and thioredoxin oxidation were not induced by dialdehydes. CONCLUSIONS: Intracellular glutathione, members of the mitogen-activated protein kinase pathways, and the mitochondrial membrane potential are all critical targets of glyoxal. These findings provide novel insights into the molecular mechanisms perturbed by glyoxal, and may facilitate the development of new therapeutics and diagnostic markers for cardiovascular diseases.

Palladium-catalyzed intermolecular [4 + 2] formal cycloaddition with (Z)-3-iodo allylic nucleophiles and allenamides.

A highly chemo- and regioselective [4 + 2] formal cycloaddition of (Z)-3-iodo allylic nucleophiles and allenamides catalyzed by palladium is reported. The methodology proceeds under mild reaction conditions and is tolerant of alkyl and aryl functional groups. The SN2' substitution at the proximal C[double bond, length as m-dash]C bond performed against the Heck or SN2 pathway delivered a variety of 2-amino-dihydropyrans and 2-amino-tetrahydropiperidines in moderate to satisfactory yields. The [4 + 2] formal cycloaddition derivatives are convertible to interesting scaffolds 2,6,7,7a-tetrahydropyrano[2,3-b]pyrrole and 2,6,7,7a-tetrahydro-1H-pyrrolo[2,3-b]pyridine derivatives via ring-closing metathesis (RCM) with Grubbs catalyst II.

Palladium-catalyzed heck-type cascade cyclization of (Z)-1-iodo-1,6-dienes with N-tosyl hydrazones.

A palladium-catalyzed heck-type cascade cyclization of (Z)-1-iodo-1,6-dienes with N-tosyl hydrazones is reported. The alkylpalladium intermediate coupled with the diazo compound, generating the second alkylpalladium species bearing two ß-H, which generated a terminal alkene as the major products in the anti-Zaitsev way via the highly regioselective ß-H elimination. It provided a new way to synthesize tetrahydropyridine derivatives bearing a terminal alkene.

miRNA-221 promotes proliferation, migration and invasion by targeting TIMP2 in renal cell carcinoma.

INTRODUCTION: MicroRNAs (miRNAs) play important roles in tumorigenesis. In this study, we investigated the role of miR-221 in the development and progression of clear cell renal cell carcinoma (ccRCC). METHODS: Quantitative real-time PCR (qRT-PCR) was used to measure the expression level of miR-221 in ccRCC tissues and cell lines. Then, we investigated the role of miR-221 to determine its potential roles on renal cancer cell proliferation, migration and invasion in vitro. A luciferase reporter assay was conducted to confirm the target gene of miR-221 and the results were validated in renal cancer cells. RESULTS: In the present study, we found that miR-221 was significantly increased in ccRCC tissues and cell lines. Knocked-down expression of miR-221 remarkably inhibited cell proliferation, migration and invasion of renal cancer cells. Moreover, at the molecular level, our results suggested that TIMP2 as a direct target of miR-221 through which miR-221 promoted tumor cell proliferation, migration and invasion. CONCLUSIONS: These findings suggested that miR-221 play an oncogenic role in the renal cancer cell proliferation, migration and invasion by directly inhibiting the tumor suppressor TIMP2, indicating miR-221 act as a potential new therapeutic target for the treatment of ccRCC.

Predictive value of vascular endothelial growth factor polymorphisms on the risk of renal cell carcinomas: a case-control study.

We conducted this case-control study to assess the role of vascular endothelial growth factor (VEGF) -2578C/A, +460T/C, +1612G/A, +936C/T, and -634G/C polymorphisms in the development of renal cell carcinoma (RCC), and analyzed the association of gene polymorphisms with demographic and clinical characteristics of RCC. This study included 412 consecutive primary RCC patients and 824 controls. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to detect VEGF -2578C/A, +460T/C, +1612G/A, +936C/T, and -634G/C polymorphisms. Compared with the control subjects, the RCC cancer cases were more likely to have a habit of cigarette smoking, and suffered from hypertension and diabetes. Conditional logistic regression analysis showed that individuals carrying the AA genotype of -2578C/A were more likely to greatly increase risk of RCC, and the CC genotype of +460T/C revealed a significant association with increased risk of RCC. The CA + AA genotype of -2578C/A had a significantly increased risk of RCC in ever cigarette smokers, and individuals who suffered from hypertension and diabetes. TC + CC genotype of +460T/C was significantly associated with the elevated risk of RCC in those suffered from hypertension and diabetes. Our study suggests that -2578C/A and +460T/C polymorphisms of VEGF modulate the risk of developing RCC in Chinese population.

An infectious molecular clone in early infection with HIV-1 subtype CRF01_AE strains: construction and biological properties.

Our aim was to construct infectious molecular clones of the CRF01_AE subtype in the primary infection phase of an acute HIV-1 infections in people screened from MSM populations, as well as continue preliminary research on this virus and its biological properties pertaining to deriving viruses. Walking sequencing was performed on a half-molecular clone with target fragment inserted. Western Blot was used to detect protein expression in HIV-1 infected 293T cells. Sequence analysis of HIV-1 genomic clones showed full-length HIV-1 genomic clones without frame shift mutation or termination codon. HIV-1 p24 antigens generated from 08-IMC were slightly greater than those from infectious molecular clones pNL4-3 3 and 93JP-NH1, but without statistical difference (all P > 0.05). The relative light units of 08-ISO was higher than those of 08-IMC, but no significant difference was observed (all P > 0.05). 08-IMC-driven virus was linked to lower replication kinetics. The replication levels of pNL4-3 and 08-ISO were significantly higher than the 08-IMC replication level but close to NH1 replication level (all P < 0.05). 08-IMC could infect the cells expressing CCR5 and be replicated in the CCR5-expressing cells with a positive percentage of 24.3 %, 08-ISO may use CCR5-using macrophage-tropic isolates as coreceptor, while pNL4-3 viruses with T cell tropisms utilize the CXCR4 co-receptor. Our study showed that the infectious molecular clones of viruses in the primary infection phase have a close relationship with the major prevalent CRF01_AE strains and have high homology with the viral RNA in plasma.

Effect of traditional Chinese medicine (Xiaochaihu Tang) on the expression of MMP-2 and MMP-9 in rats with endometriosis.

The aim of this study was to explore the effect of a traditional Chinese medicine (Xiaochaihu Tang, XCHT) on the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 in rats with endometriosis (EMs). A total of 48 specific-pathogen-free (SPF) female Sprague-Dawley (SD) rats were randomly divided into control (n=8) and EMs (n=40) groups. The EMs model was established using a surgical procedure. At 21 days, the rats with EMs were screened and divided into four subgroups (n=8): the model control, low-dose (7.5 g/kg) XCHT-treated, high-dose (15 g/kg) XCHT-treated and gestrinone-treated (0.5 mg/kg) groups. Following 21 days of treatment, the rats were sacrificed. Reverse transcription-polymerase chain reaction (RT-PCR) and western blotting were used to examine the mRNA and protein levels of MMP-2 and MMP-9 in the endometrium. The expression levels of MMP-2 and MMP-9 were significantly increased in the rats with EMs compared with those in normal rats. Moreover, XCHT was able to significantly inhibit the expression of MMP-2 and MMP-9 compared with that in the model control group. In conclusion, XCHT was able to decrease the expression of MMP-2 and MMP-9 in the ectopic endometrium. The present results may provide a potential theoretical basis for the therapy of EMs.

[Clinical study of dynamic change of inflammatory factors in serum of acute paraquat rats].

OBJECTIVE: To investigate the change of inflammatory factor in lung tissue of acute paraquat (PQ) poisoned rats. METHODS: hundred SD rats were randomly divided into two groups: the normal control group (NC group, n = 10) and the PQ group (n = 80). The 1 ml saline was administered once in normal control group. The PQ group was administered with 25 mg/kg 1% PQ by intraperitoneal injection to establish the model of PQ induced renal injury. At six hours, at the first, the third and the seventh day the PQ group were sacrificed, while at the first day the normal control group was sacrificed. The level of normal tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), IL-6 in serum of rats were detected. Meanwhile, pathological changes of the renal were examined under optical microscope. RESULTS: Histopathological findings of an earlier, a large number of patients edema clearly inflammatory cell infiltration. Compared with the control group, PQ exposure of serum TNF-α, IL-2, IL-6, the level at each time point were elevated. PQ treated group 6 h and 1, 3, 7 d when the IL-2 levels were (2.16 ± 0.65), (2.95 ± 1.02), (3.05 ± 1.12), (2.21 ± 0.62) µg/L, IL-6 were (62.5 ± 8.6), (85.6 ± 13.5), (90.3 ± 15.6), (65.3 ± 9.1) ng/ml, TNF-α were (1.95 ± 0.53), (2.86 ± 0.92), (3.15 ± 1.02), (2.06 ± 0.71) µg/L, compared with the control group, are significantly higher, the differences were statistically significant (P < 0.01). CONCLUSION: acute PQ poisoning serum TNF-α, IL-2, IL-6 levels were significantly increased both early and late inflammatory factors involved in PQ poisoning the pathogenesis of renal injury.

[Urinary neutrophil gelatinase-associated lipocalin (uNGAL) and early diagnosis of paraquat poisoning patients with acute kidney injury].

OBJECTIVE: To explore the use of the urinary neutrophil gelatinase associated lipocalin (uNGAL) in the early diagnosis of paraquat poisoning patients with acute kidney injury (AKI). METHODS: Eighty five patients were from the emergency department in our hospital. Five ml blood and urine were collected from each patient at 15 min, 2, 4, 6, 8, 10, 12, 18, 24, 36, 48 and 72 h, 5 and 7d after admission. The uNGAL levels of urine were detected with ELISA test and the SCr levels were measured with creatine oxidase assay. RESULTS: Sixty two cases of paraquat intoxication suffered from AKI, the incidence was 72.94% (62/85). The SCr levels of 62 cases with AKI at 18, 24, 36, 48, 72 h and 5, 7 d after admission increased significantly, as compared with the baseline value and control group (P < 0.01). At 24, 36, 48, 72 h and 5, 7 d after admission, there was significant difference of the SCr levels between AKI group and non-AKI group (P < 0.01). At 2 h after admission, the uNGAL level of urine in paraquat intoxication AKI group was (96.21 +/- 45.32) microg/L which was significantly higher than the baseline value. At 10, 12, 18, 24, 36, 48, 72 h and 5, 7 d after admission, the uNGAL levels of urine in AKI group and non-AKI group obviously enhanced, as compared with the baseline value and control group (P < 0.01 or P < 0.05). At all time points, there was significant difference of the uNGAL level between AKI group and non-AKI group (P < 0.01). CONCLUSION: The uNGAL level of urine in paraquat intoxication patients at 2 h after admission significantly enhanced, which is earlier than enhanced SCr. So the uNGAL level of urine may serve as early diagnostic biomarker for AKI induced by paraquat intoxication.