[Analysis of the Effect of Temperature on the Microbial Flora Structure During the Nitrite Oxidation Process Using 16S rRNA High-throughput Sequencing]

In order to further understand the influence of high temperature shock on the microbial community structure of activated sludge during the process of nitrite oxidation, the enriched nitrifying activated sludge under different NO₂^--N concentration was taken as the research object in this study. 16S rRNA high-throughput sequencing technology was used to analyze the changes in the microbial community abundance and structural characteristics of activated sludge by changing the environmental temperature. The results of high-throughput sequencing showed that microorganisms were more likely to grow at 25℃, and the diversity of the microbial community in the activated sludge was the most abundant. With increased temperature, the richness, evenness, and diversity of the flora in the system decreased. In addition, it was found that the main nitrifying bacterium in the system was Nitrospira of Nitrospirae, whereby 35℃ was more suitable for its growth. Meanwhile, a higher temperature also caused differences in the structure of non-nitrifying functional microorganisms (e.g., Bacteroidetes, Chlorofulexi, Halomonas, and Pseudomonas) in the activated sludge. The results of this study provide some theoretical reference for the investigation of the distribution characteristics of microbial flora during the process of nitrite oxidation under high temperature shock, and can also be used as reference for relevant high temperature shock tests.

miR-361-5p suppresses lung cancer cell lines progression by targeting FOXM1

Lung cancer is the most common type of cancer and the leading cause of death in worldwide. MicroRNAs are known to be key players in a variety of biological processes, including tumorigenesis. In present study, we investigated the effect of miR-361-5p on lung cancer progression. We found that miR-361-5p was down-regulated in lung cancer. Overexpression of miR-361-5p suppressed lung cancer proliferation and invasion. Mechanistically, FOXM1 was identified as a direct target of miR-361-5p. Furthermore, miR-361-5p inhibits EMT-like phenotype through down-regulation of FOXM1 expression in lung cancer cells. In conclusion, our results indicated that miR-361-5p acts as a tumor suppressor in lung cancer.

[Determination of titanium dioxide in the air of workplace by inductivehy coupled plasma optical emission spectrometry]

Objective: To establish the method for determination of titanium dioxide in the air of workplace by inductivehy coupled plasma optical emission spectrometry (ICP-OES) . Methods: The titanium dioxide was collected by filter membrane and then digested by microwave digestion apparatus in the mixed solvents (HNO(3)∶HF∶H(2)O=4∶1∶1) , dilutedto 25 ml and detected by ICP-OES. Results: The sampling efficiency was higher than 95%; the linearity of ICP-OES was good at the range of 10-500 μg/ml, the minimum quantitation concentration was 0.72 mg/m(3) (as collecting 150 L air sample) , the maximum quantitation concentration was 21.7 mg/m(3) (as collecting 960 L air sample) , the recovery was ranged from 99.0%-102.0%, the RSD of intra- and inter-batch precision were 0.5%-3.2% and 1.7%-3.5%, respectively. Conclusion: The sampling method and determination method meet the requirements of guide for establishing occupational health standards-part 4: determinatin methods of air chemicals in workplace (GBZ/T 210.4-2008) , and areapplys to the collection and determination of TiO(2) in the air of workplace.

Expression of stem cell factor in gastrointestinal stromal tumors: Implications for proliferation and imatinib resistance

KIT autophosphorylation caused by mutation of KIT is considered to be a critical mechanism for the oncogenesis of gastrointestinal stromal tumors (GISTs). However, little is known regarding whether stem cell factor (SCF), the KIT ligand, is able to induce the proliferation of GIST cells by activating the wild-type KIT receptor in GISTs. Imatinib, a tyrosine kinase inhibitor, has been demonstrated to be effective as treatment for the majority of GISTs. However, primary resistance to imatinib in GISTs with wild-type KIT and acquired resistance in GISTs with mutant KIT are becoming increasingly significant problems. The aims of this study were to detect the expression and function of SCF in 68 GIST samples, and to explore the relationship between SCF activity and imatinib resistance using immunohistochemical staining and western blot analysis. Results showed abundant expression of SCF in GISTs and demonstrated that SCF is capable of enhancing GIST cell proliferation. Similar to its ineffectiveness in wild-type GISTs, imatinib also failed to inhibit SCF-induced KIT activation in GISTs with mutant KIT. We also found increased SCF expression in GIST cells treated with imatinib. Overall, our results indicated that SCF-induced KIT activation is a novel essential pathway for the proliferation of GISTs. Imatinib was not able to inhibit the activity of SCF, while it promoted the expression of SCF, which may have contributed to acquired imatinib resistance.

Stem cell factor-mediated wild-type KIT receptor activation is critical for gastrointestinal stromal tumor cell growth

AIM: To clarify the biological role of stem cell factor (SCF)-mediated wild-type KIT receptor activation in gastrointestinal stromal tumor (GIST) growth.

METHODS: The co-expression of wild-type KIT receptor and SCF was evaluated in 51 GIST samples using mutation analysis and immunohistochemistry, and the results were correlated with clinicopathological parameters, including the mitotic count, proliferative index (Ki-67 immunohistochemical staining), mitotic index (phospho-histone H3 immunohistochemical staining) and apoptotic index (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling). Using primary cultured GIST cells, the effect of SCF-mediated wild-type KIT receptor activation was determined by western blotting, methyl thiazolyl tetrazolium (MTT), and apoptosis assays.

RESULTS: We found that wild-type KIT receptor and SCF protein were expressed in 100% and 76.5% of the 51 GIST samples, respectively, and the co-expression of wild-type KIT receptor and SCF was associated with known indicators of poor prognosis, including larger tumor size (P = 0.0118), higher mitotic count (P = 0.0058), higher proliferative index (P = 0.0012), higher mitotic index (P = 0.0282), lower apoptosis index (P = 0.0484), and increased National Institutes of Health risk level (P = 0.0012). We also found that the introduction of exogenous SCF potently increased KIT kinase activity, stimulated cell proliferation (P < 0.01) and inhibited apoptosis (P < 0.01) induced by serum starvation, while a KIT immunoblocking antibody suppressed proliferation (P = 0.01) and promoted apoptosis (P < 0.01) in cultured GIST cells.

CONCLUSION: SCF-mediated wild-type KIT receptor activation plays an important role in GIST cell growth. The inhibition of SCF-mediated wild-type KIT receptor activation may prove to be particularly important for GIST therapy.

G501C polymorphism of the oxidized LDL receptor gene is associated with albuminuria in Chinese essential hypertension patients

Albuminuria is an independent predictor of renal and cardiovascular complications in hypertensive subjects. We previously showed that lectin-like oxidized low density lipoprotein receptor 1 (OLR-1) polymorphisms at G501C are associated with susceptibility to essential hypertension and serum C-reactive protein levels. We have now investigated a possible association between OLR-1 polymorphisms at G501C, genotyped by PCR-RFLP, and severity of albuminuria in 307 hypertensive Chinese subjects and 225 age- and sex-matched controls. Urine albumin concentration /urine creatinine concentrations (ACR) were measured to evaluate the severity of albuminuria. Hypertensive subjects had a significantly higher frequency of the CC genotype and the C allele of the OLR-1 polymorphism than controls; this was also true for . hypertensive subjects with macroalbuinuria and microalbuminuria compared to those with normoalbuminuria. The mean ACR levels and mean serum C-reactive protein levels in CC carriers were significantly higher than in GG and GC carriers. There was a significant, positive correlation between serum hs-C-reactive protein levels and ACR levels. We conclude that OLR-1 polymorphisms at G501C affect the severity of albuminuria in essential hypertension patients.

[Transforming effect of PDGFRA gene mutant on the cell function in gastrointestinal stromal tumor]

OBJECTIVE

To explore the effect of malignant transformation of the L839P, a new mutation site of the PDGFRA gene, on the pathogenesis of gastrointestinal stromal tumors.

METHODS

All recombinant plasmids were stably transfected into CHO cells by liposomes. Western blotting was used to detect the expression of PDGFRA protein. The cell growth curve was plotted by cell counting. Flow cytometry was used to detect the cell cycle and apoptosis of CHO cell, respectively. The stably transformed cells were inoculated subcutaneously into the back of nude mice and the mice were used to observe the tumorigenesis. Transient transfection of the mutant-type plasmids of PDGFRA gene and the wild-type plasmids of kit gene into the CHO cells was performed. Western blot was used to detect the expression of kit protein and its phosphorylated forms.

RESULTS

PDGFRA protein expressed in the negative control, experimental group and positive control, except the empty vector. The growth curve showed that it was accelerated in the experimental group and positive control. The ratios of cells in proliferative phase were 28.4% (blank), 24.5% (negative control), 43.8% (experimental group) and 40.9% (positive control). Their apoptotic indexes were 1.8%, 1.9%, 1.5% and 1.6%, respectively. After three weeks, tumors were observed in the nude mice of experimental group and positive control, inoculated with the stably transformed cells. Moreover, the expression of phosphorylated protein of kit was enhanced after cotransfection of the mutant-type plasmids of PDGFRA and the wild-type plasmid of kit.

CONCLUSION

The PDGFRA mutant L839P is a gain-of-function mutation and has obviously malignant transforming effect on normal cells, and may activate kit protein accelerating the tumorigenesis. Gastrointestinal stromal tumors;

Crystal structure of Natratoxin, a novel snake secreted phospholipaseA2 neurotoxin from Naja atra venom inhibiting A-type K+ currents

Snake secreted phospholipasesA2 (sPLA2s) are widely used as pharmacological tools to investigate their role in diverse pathophysiological processes. Some members of snake venom sPLA2s have been found to block voltage-activated K(+) channels (K(v) channels). However, most studies involved in their effects on ion channels were indirectly performed on motor nerve terminals while few studies were directly done on native neurons. Here, a novel snake sPLA2 peptide neurotoxin, Natratoxin, composed of 119 amino acid residues and purified from Naja atra venom was reported. It was characterized using whole-cell patch-clamp in acutely dissociated rat dorsal root ganglion (DRG) neurons. It was found to effectively inhibit A-type K(+) currents and cause alterations of channel gating characters, such as the shifts of steady-state activation and inactivation curves to hyperpolarization direction and changes of V(1/2) and slope factor. Therefore, Natratoxin was suggested to be a gating modifier of K(v) channel. In addition, this inhibitory effect was found to be independent of its enzymatic activity. These results suggested that the toxin enacted its inhibitory effect by binding to K(v) channel. To further elucidate the structural basis for this electrophysiological phenomenon, we determined the crystal structure of Natratoxin at 2.2 A resolution by molecular replacement method and refined to an R-factor of 0.190. The observed overall fold has a different structural organization from other K(+) channel inhibitors in animal toxins. Compared with other K(v) channel inhibitors, a similar putative functional surface in its C-terminal was revealed to contribute to protein-protein interaction in such a blocking effect. Our results demonstrated that the spatial distribution of key amino acid residues matters most in the recognition of this toxin towards its channel target rather than its type of fold.

Algebraic Description of Anharmonic Stretching Vibrations

A U(2) algebraic model is presented to describe stretching vibrations of XYn (n = 2, 3, and 4) systems, where anharmonic interactions between the bond modes are considered. This model in a limit corresponds to an anharmonically coupled local-mode model. As an example, the model for a molecule XY4 is applied to recently observed spectra of methane in both gas and liquid phases, and the results obtained are in good agreement with the experiments. Copyright 1999 Academic Press.