Efficient Electrochemical Water Oxidation Mediated by Pyridylpyrrole-Carboxylate Ruthenium Complexes.

Spurred by the rapid growth of Ru-based complexes as molecular water oxidation catalysts (WOCs), we propose novel ruthenium(II) complexes bearing pyridylpyrrole-carboxylate (H2ppc) ligands as members of the WOC family. The structure of these complexes has 4-picoline (pic)/dimethyl sulfoxide (DMSO) in [Ru(ppc)(pic)2(dmso)] and pic/pic in [Ru(ppc)(pic)3] as axial ligands. Another ppc2- ligand and one pic ligand are located at the equatorial positions. [Ru(ppc)(pic)2(dmso)] behaves as a WOC as determined by electrochemical measurement and has an ultrahigh electrocatalytic current density of 8.17 mA cm-2 at 1.55 V (vs NHE) with a low onset potential of 0.352 V (vs NHE), a turnover number of 241, a turnover frequency of 203.39 s-1, and kcat of 16.34 s-1 under neutral conditions. The H2O/pic exchange of the complexes accompanied by oxidation of a ruthenium center is the initial step in the catalytic cycle. The cyclic voltametric measurements of [Ru(ppc)(pic)2(dmso)] at various scan rates, Pourbaix diagrams (plots of E vs pH), and kinetic studies suggested a water nucleophilic attack mechanism. HPO42- in a phosphate buffer solution is invoked in water oxidation as the proton acceptor.

Neutral Cyclometalated Ir(III) Complexes with Pyridylpyrrole Ligand for Photocatalytic Hydrogen Generation from Water.

To explore structure-activity relationships with respect to light-harvesting behavior, a family of neutral iridium complexes [Ir(ppy)2(LR)] 1-4 (where ppy = 2-phenylpyridine, and N̂N = 2-(1H-pyrrol-2-yl)pyridine and its functionalized derivatives) were designed and synthesized. The structural modifications in metal complexes are accomplished through the attributions of electron-donating CH3 in 2, OCH3 in 3, and electron-withdrawing CF3 in 4. The structural analysis displays that the pyridylpyrrole acts as one-negative charged bidentated ligand to chelate the iridium center. The electrochemical and photophysical properties of these complexes were systematically studied. The neutral 1-4 as well as the ionic structurally analogous [Ir(ppy)2(bpy)](PF6) (5) were utilized as PSs in photocatalytic hydrogen generation from water with [Co(bpy)3](PF6)2 as catalyst and triethanolamine (TEOA) as electron sacrificial agent in the presence of salt LiCl. Complex 1 maintains activity for more than 144 h under irradiation, and the total turnover number is up to 1768. The electrochemical properties and the quenching reaction indicate the H2 generation by neutral complexes 1-4 is involved exclusively in the oxidative quenching process.

A Ru diphosphonato complex with a metal-metal bond for water oxidation.

Unlike [Ru2(µ-O2CCH3)4], the structurally analogous water-soluble RuII,III2 diphosphonato complex K3[Ru2(hedp)2(H2O)2] (K3·1) is only involved in stoichiometric water oxidation with a maximum 67% O2 yield under CAN/HNO3 solution (pH 1.0) for 2.5 h. The water oxidation mechanism and intermediate products were ascertained by UV-vis, ESI-MS and DFT calculation.

Zinc complexes supported by pyridine-N-oxide ligands: synthesis, structures and catalytic Michael addition reactions.

New dipyridylpyrrole N-oxide ligands HL1 and HL2 are designed and synthesized via oxidation of 2-(5-(pyridin-2-yl)-1H-pyrrol-2-yl)pyridine (Hdpp) by using 3-chloroperbenzoic acid (m-CPBA) in CH2Cl2. The treatment of ZnEt2 with two equiv. of HL1 and HL2 affords [Zn(L1)2] and [Zn(L2)2] in medium yield, respectively. These ligands and zinc complexes are fully characterized by NMR, IR, UV-vis and ESI-MS spectroscopy and X-ray diffraction analysis. The structure of HL1 and HL2 shows a planar geometry. The intramolecular hydrogen-bond interactions between the imino hydrogen and N-oxide oxygen atom are observed. In [Zn(L1)2] and [Zn(L2)2], two ligands chelate to the zinc metal with a cross perpendicular geometry. The zinc complexes were employed as a highly efficient catalyst for the thiol-Michael addition of thiols to α,ß-unsaturated ketones in EtOH at room temperature. The loading of the catalyst is lowered to 0.01 mol%. The catalytic mechanism was proposed based on NMR and ESI-MS experiments.

Long-term culture and cryopreservation of interstitial cells of Cajal.

OBJECTIVE: Interstitial cells of Cajal (ICCs) in the gastrointestinal tract generate and propagate slow waves and mediate neuromuscular neurotransmission. Damage to ICCs has been described in several gastrointestinal motor disorders, and although many studies have examined ICCs in culture, they have been largely limited to freshly dissociated cells or short-term cultures. An efficient and reliable method to establish a source of ICCs is much needed. The aim of this study was to investigate methods for culturing, subculturing, cryopreservation, and recovery of ICCs. METHODS: ICCs were derived from intestinal segments of domestic rabbits, and immunohistochemistry for c-Kit was used to identify ICCs in culture and after recovery. Recovered ICCs were also examined for motilin receptor expression. RESULTS: Optimal conditions for ICC culture and cryopreservation were based on cell growth curves and MTT assay. On the basis of these findings, recovered cells were cultured for 7 days and then sorted via flow cytometry based on c-Kit immunoreactivity. The percent of c-Kit positive cells was 64.3%, and the number of ICCs sorted was 6.7 × 10(5). Reverse-transcription polymerase chain reaction and western blotting verified motilin receptor expression in c-Kit-positive ICCs. CONCLUSIONS: This is the first study to describe the culture, passage, and recovery of ICCs and to show motilin receptor expression. Our results suggest that ICCs play an important role, at least in some species, in initiating the migrating myoelectric complex induced by motilin.

[Immunophenotypes in 207 pediatric patients with ALL and theirs correlation with cytogenetics and clinical features].

The objective of this study was to investigate the immunophenotypic subtype profiles of 207 pediatric patients with acute lymphoblastic leukemia (ALL) and its correlation with cytogenetics and clinical features. 207 children with ALL were immunophenotyped by four color flow cytometry using a panel of monoclonal antibodies. 207 patients were enrolled in this study, out of which 146 cases were subjected to karyotype analysis by R-banding technology. The results showed that 11.6% out of 207 children with ALL were identified as T-ALL, 88.4% as B-ALL. Myeloid antigen (MyAg) expression was documented in 42.5% out of 207 cases analyzed and CD13 was the most commonly expressed MyAg (31.4%). No difference was observed in the expression of MyAg between the groups of patients with T-ALL (41.7%) and B-ALL (42.6%). Abnormal karyotypes were detected in 84 out of 146 (57.5%) children. The clinical and biological characteristics of ALL patients between MyAg(+) and MyAg(-) groups showed that higher percentage of patients with high WBC count (> 50 × 10(9)/L) and higher CD34 positivity were found to be correlated with MyAg(+) ALL. It is concluded that immunophenotype analysis is useful for ALL diagnosis and classification, and the immunophenotypes are in relevance to the abnormal cytogenetic changes as well as clinical features in childhood ALL.

[Motilin receptor expression in the interstitial cells of Cajal].

OBJECTIVE: To look for the evidences of motilin receptor expression on interstitial cells of Cajal (ICC) of the rabbit. METHOD: Smooth muscle segments with ICC were isolated from the small intestine of 10-day old rabbits. The tissue segments equilibrated in Ca(2+)-free Hanks' solution were dispersed with an enzyme solution containing collagenase type II and then Ficoll density centrifugation was used to dissociate ICC. The cells were suspended and cultured in the M199 medium. The c-kit antibody was applied to distinguish the cultured ICC. The motilin receptor was identified by immunocytochemical assay with GPR38 antibody, c-kit antibody and hoechst 33342 combined to label ICC. Cells cultured for a few days were sorted for ICC with c-kit stained green fluorescent through flow cytometry. The total RNA and proteins extracted from the sorted ICC were respectively used to verify motilin receptor on the ICC by reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blotting. RESULT: We had successfully dissociated and cultured ICC of rabbit small intestine in vitro. Fluorescent staining with c-kit antibody confirmed that the culture ICC was successful. Triple-labeled immunofluorescent staining had detected the motilin receptor on membrane of ICC. Flow cytometry analysis showed that the ratio of c-kit positive cell in the cultured cells was 64.3%. The number of sorted ICC was 6.7 × 10(5) and 5.6 × 10(6). The results of RT-PCR and Western blot confirmed that the ICC had motilin receptor expression. CONCLUSION: Our study demonstrated presence of motilin receptor on ICC of the rabbit. The present results may suggest that ICC play an important role in gastrointestinal movement induced by motilin.

[Role of caspase-8 in TRAIL-induced apoptosis of neuroblastoma cell lines].

OBJECTIVE: The aim of this study was to investigate whether the induction of caspase-8 by γ-interferon (IFNγ) renders neuroblastoma (NB) cells sensitive to tumor necrosis factor related apoptosis inducing ligand(TRAIL). METHODS: Caspase-8 mRNA expression was determined by RT-PCR. The effects of IFNγ, TRAIL, IFNγ +TRAIL and caspase-8 inhibitor+ TRAIL on the growth and apoptosis of NB cells were detected with the methods of reduction rate of Alamar Blue assay and flow cytometry. The relative caspase-8 activity was measured with colorimetric assay. RESULTS: Caspase-8 expression was detectable in CHP212 cells which were sensitive to TRAIL, with an increased expression after treatment with IFNγ. Caspase-8 was undetectable in SH-SY5Y(SY5Y) cells which were resistant to TRAIL, but an increased expression of caspase-8 mRNA was found after treatment with IFNγ. Moreover, TRAIL combined with IFNγ induced apoptosis in SY5Y cells. The relative caspase-8 activity of CHP212 cells increased with the prolonged TRAIL action time. The relative caspase-8 activity of SY5Y cells in the IFNγ+TRAIL group was significantly higher than those of the control, IFNγ, TRAIL and inhibitor groups. CONCLUSIONS: NB cells expressing caspase-8 are sensitive to TRAIL. TRAIL induces apoptosis in NB cells with an increase of relative caspase-8 activity.

[Immunophenotypes, cytogenetics and clinical features of 192 patients with acute myeloid leukemia].

The objective of this study was to investigate the immunophenotypic subtype profiles of 192 patients with acute myeloid leukemia (AML) and its association to cytogenetics and clinical features. Immunophenotyping of 192 patients was performed by flow cytometry using a panel of monoclonal antibodies. The karyotypes in 125 out of 192 cases were analyzed by G-banding technology. The results showed that CD33, CD13, myeloperoxidase (MPO) and CD117 were the most commonly expressed antigens in AML. CD117 expressed in 84.6% of AML-M3 cases. A combination of intensive autofluorescence, both CD34- and HLA-DR-, and high expression of CD13, CD33 and MPO had significant value for AML-M3 diagnosis. CD14 expressed only in AML-M4 and AML-M5, and both intensive positivity of CD64 and CD15 with high expression of HLA-DR may suggest great possibility for diagnosis of AML-M5. Lymphoid marker expression was documented in 47.9% of the 192 AML cases. CD56 (26.0%) and CD7 (20.8%) were the most commonly expressed lymphoid markers in AML patients, followed by CD19 (9.9%) and CD2 (7.3%). Abnormal karyotypes were detected in 76 out of 125 cases (60.8%). Correlation test showed that t(8;21) was found only in 17 cases of AML-M2 and strongly associated with the individual or combinational expressions of CD15/CD19/CD56. And 28 cases of t(15;17) were found in AML-M3; 2 cases of inv(16) were found in AML-M4EO. Higher CD34 positivity was found in LymAg+ group (77.2%) than that in LymAg- group (48.0%). It is concluded that immunophenotype analysis is useful for AML diagnosis and classification, and the immunophenotype has close relevance to the abnormal cytogenetic changes and clinical features in AML. The results suggested that a new prognostic scoring system that integrated the morphology, cytogenetic abnormalities and immunophenotype parameters would benefit the diagnosis, classification, and estimation of prognosis in AML patients.

[MICM characteristics and typing diagnosis in acute myelogenous leukemia patients (AML-M2) with complex karyotype t (2;21;8)(p12;q22;q22)].

This study was purposed to investigate the acute myeloid leukemia with complex karyotype t(2;21;8)(p12;q22;q22) (AML-M(2)) by using morphologic, immunologic, cytogenetic and molecular biologic classification technique (MICM) and to analyze the MICM characteristics of AML-M(2) and their diagnostic significance. The FAB typing of bone marrow cells (BMCs) was performed by Wright-Giemsa staining and histochemical staining of BM smears; the immunophenotype of leukemic cells was detected by flow cytometry; the karyotypes of chromosome samples prepared by short-term (48 hours) conventional culture of fresh BMCs were analyzed by RHG banding technique; the FISH signaling in mitotic metaphase was determined by dual color and dual fusion AML/ETO probe and chromosome painting probe, and was compared with results of conventional cytogenetic assay; the AML/ETO fusion transcripts were detected by nested RT-PCR. The results indicated that the bone marrow smears of case 1 showed extremely hyperplasia with myeloblasts in which a ratio of eosinophilic granulocytes and monocytes increased. Case 2 accorded with AML-M(2b) in which abnormal increase of myelocytes mainly appeared. The complex karyotype t(2;21;8)(p12;q22;q22) was detected by cytogenetic analysis combined with FISH in both two cases and AML1/ETO fusion transcripts were found by RT-PCR as well. The immunophenotype assay showed high co-expression of CD34 and HLA-DR accompanied with CD19 and CD56 expressions. It is concluded that application of MICM has an important significance for correct diagnostic typing of AML-M2 with complex karyotype variant of t(8; 21)(p12;q22;q22).

Enhanced effect of IFNgamma on the induced apoptosis of neuroblastoma cells by cytotoxic drugs.

The objective of this study was to explore the antitumor effects of cytotoxic drugs combined with IFNgamma on neuroblastoma cell line SH-SY5Y cells. The expression of caspase 8 mRNA and protein was detected with RT-PCR and Western blot analysis. The effects of cytotoxic drugs and IFNgamma combined with cytotoxic drugs on the growth and apoptosis of SH-SY5Y cells were detected with the methods of MTT and flow cytometry. Caspase 8 activity was measured by colorimetric assay. Caspase 8 was undetectable in SH-SY5Y cells with an increased expression of caspase 8 after the treatment of IFNgamma. SH-SY5Y cells were sensitive to Adriamycin relatively but resistant to TNFalpha and TRAIL, while IFNgamma-pretreated SH-SY5Y cells were more sensitive to the cytotoxic drugs with an increase of caspase 8 activity. The authors conclude that IFNgamma can sensitize SH-SY5Y cells to Adriamycin-, TNFalpha-, and TRAIL-induced apoptosis and this may be realized by the upregulation of caspase 8.

[Blocking TrkB-BDNF signal pathway decreases the livability of neuroblastoma cells].

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) and its specific tryrosin kinase receptor-B (TrkB) are highly correlated to the chemoresistance of neuroblastoma (NB) cells and poor prognosis. This study observed the changes of the sensibility of NB cells to chemotherapy drug cisplatin (CDDP) before and after blockage of TrkB-BDNF signal pathway by specific tyrosin kinase inhibitor K252a. METHODS: Human NB cell line SH-SY5Y (SY5Y) was routinely cultured. Expression of TrkB was induced with nM all trans-retinoid acid (ATRA). Then BDNF, CDDP or K252a were added to the cultured SY5Y cells. Cell livability was assessed by methyl thiazolyl tetrazolium (MTT) assay. TrkB autophosphorylation was determined by Western blot analysis. Cell apoptosis rate was detected by flow cytometry (FCM). The conformation of apoptosis cells was observed by transmission electron microscopy (TEM). RESULTS: The livability and apoptosis rate in SY5Y cells treated with ATRA, BDNF and CDDP were not different from the blank control group. However, after K252a together with ATRA, BDNF and CDDP treatment, the sensibility of SY5Y cells to chemotherapy drug CDDP increased, the livability decreased and the apoptosis rate increased in SY5Y cells when compared with the blank control group (P <0.01). K252a treatment resulted in blockage of TrkB autophosphorylation. CONCLUSIONS: The blockage of TrkB-BDNF signal pathway by K252a use can increase sensibility of NB cells to chemotherapy and thus decrease the livability of NB cells.

Combination of gamma-interferon with TRAIL and cisplatin or etoposide induces apoptosis in human neuroblastoma cell line SH-SY5Y.

OBJECTIVE: To study the effect of gamma-interferon (IFNgamma), tumor necrosis factor related apoptosis inducing ligand (TRAIL), and cisplatin or etoposide induced apoptosis in human neuroblastoma cell line SH-SY5Y and its possible molecular mechanisms. METHODS: The expressions of Caspase 8 mRNA and protein were detected with RT-PCR and Western blot analysis. The effects of IFN-gamma, TRAIL, IFNgamma + TRAIL, IFN-gamma + Caspase 8 inhibitor + TRAIL, IFNgamma + cisplatin + TRAIL, and IFNgamma + etoposide + TRAIL on the growth and apoptosis of SH-SY5Y cells were detected with the methods of MTT and flow cytometry. The relative Caspase 8 activity was measured with colorimetric assay. RESULTS: Caspase 8 was undetectable in SH-SY5Y cells but an increased expression of Caspase 8 mRNA and protein was found after treatment with IFNgamma. SH-SY5Y cells themselves were not sensitive to TRAIL, but those expressing Caspase 8 after treatment with IFNgamma were. The killing effect of TRAIL on SH-SY5Y cells expressing Caspase 8 was depressed by Caspase 8 inhibitor. Cisplatin and etoposide could enhance the sensitivity of TRAIL on SH-SY5Y cells. The relative Caspase 8 activity of SH-SY5Y cells in IFN-gamma + TRAIL group was significantly higher than those of control group, IFN-gamma group, TRAIL group, and inhibitor group (P < 0.01). There was no significant difference among IFN-gamma + TRAIL group, IFNgamma + cisplatin + TRAIL group, and IFNgamma + etoposide + TRAIL group. CONCLUSIONS: IFNgamma could sensitize SH-SY5Y cells to TRAIL-induced apoptosis and this may be realized by the up-regulation of Caspase 8. Cisplatin and etoposide could enhance the killing effect of TRAIL on SH-SY5Y cells.

[Role of caspase-8 and DR5 in TRAIL-induced apoptosis of neuroblastoma cells].

OBJECTIVE: Tumor necrosis factor related apoptosis inducing ligand (TRAIL) induces cell death in a variety of tumors but not in normal cells. TRAILdouble ended arrow-resistance of most neuroblastoma (NB) cell lines is related to the loss of caspase-8 expression and the expression and distribution of membrane TRAIL-receptors. This study investigated the role of caspase-8 and DR5 in TRAIL-induced apoptosis of NB cell line SKNDZ. METHODS: The expression of caspase-8 mRNA was detected by RT-PCR. The expression of DR5 protein was detected by Western Blot analysis. The effects of TRAIL, IFNgamma +TRAIL, chemotherapeutic agent (adriamycin or etoposide) + TRAIL, and chemotherapeutic agent +TRAIL+ IFNgamma on the growth and apoptosis of SKNDZ cells were detected by MTT assay and flow cytometry. RESULTS: caspase-8 was not expressed in SKNDZ cells but IFNgamma treatment resulted in an increase of caspase-8 expression. Expression of DR5 protein was not detected in SKNDZ cells but an increased DR5 protein expression was found after treatment with adriamycin or etoposide. The SKNDZ cells expressing caspase-8 were not sensitive to TRAIL but those SKNDZ cells expressing both caspase-8 and DR5 were sensitive. The early apoptosis rates of the adriamycin /etoposide + IFNgamma+TRAIL groups [(17.9 +/- 3.6)%, (14.8 +/- 3.3)%] were higher than that of the IFNgamma+TRAIL group [(3.9 +/- 1.2)% ](F=26.233, P < 0.01). CONCLUSIONS: SKNDZ cells expressing both caspase-8 and DR5 restored the TRAIL sensitivity. Caspase-8 and DR5 play a key role in TRAIL-induced apoptosis of NB cells.