Palladium-Catalyzed Ligand-Controlled Switchable Hetero-(5 + 3)/Enantioselective [2σ+2σ] Cycloadditions of Bicyclobutanes with Vinyl Oxiranes

For nearly 60 years, significant research efforts have been focused on developing strategies for the cycloaddition of bicyclobutanes (BCBs). However, higher-order cycloaddition and catalytic asymmetric cycloaddition of BCBs have been long-standing formidable challenges. Here, we report Pd-catalyzed ligand-controlled, tunable cycloadditions for the divergent synthesis of bridged bicyclic frameworks. The dppb ligand facilitates the formal (5+3) cycloaddition of BCBs and vinyl oxiranes, yielding valuable eight-membered ethers with bridged bicyclic scaffolds in 100% regioselectivity. The Cy-DPEphos ligand promotes selective hetero-[2σ+2σ] cycloadditions to access pharmacologically important 2-oxabicyclo[3.1.1]heptane (O-BCHeps). Furthermore, the corresponding catalytic asymmetric synthesis of O-BCHeps with 94-99% ee has been achieved using chiral (S)-DTBM-Segphos, representing the first catalytic asymmetric cross-dimerization of two strained rings. The obtained O-BCHeps are promising bioisosteres for ortho-substituted benzenes.

Switching between the [2π+2σ] and Hetero-[4π+2σ] Cycloaddition Reactivity of Bicyclobutanes with Lewis Acid Catalysts Enables the Synthesis of Spirocycles and Bridged Heterocycles

The exploration of the complex chemical diversity of bicyclo[n.1.1]alkanes and their use as benzene bioisosteres has garnered significant attention over the past two decades. Regiodivergent syntheses of thiabicyclo[4.1.1]octanes (S-BCOs) and highly substituted bicyclo[2.1.1]hexanes (BCHs) using a Lewis acid-catalyzed formal cycloaddition of bicyclobutanes (BCBs) and 3-benzylideneindoline-2-thione derivatives have been established. The first hetero-(4+3) cycloaddition of BCBs, catalyzed by Zn(OTf)2, was achieved with a broad substrate scope under mild conditions. In contrast, the less electrophilic BCB ester undergoes a Sc(OTf)3-catalyzed [2π+2σ] reaction with 1,1,2-trisubstituted alkenes, yielding BCHs with a spirocyclic quaternary carbon center. Control experiments and preliminary theoretical calculations suggest that the diastereoselective [2π+2σ] product formation may involve a concerted cycloaddition between a zwitterionic intermediate and E-1,1,2-trisubstituted alkenes. Additionally, the hetero-(4+3) cycloaddition may involve a concerted nucleophilic ring-opening mechanism.

Photochemical α-selective radical ring-opening reactions of 1,3-disubstituted acyl bicyclobutanes with alkyl halides: modular access to functionalized cyclobutenes

Although ring-opening reactions of bicyclobutanes bearing electron-withdrawing groups, typically with β-selectivity, have evolved as a powerful platform for synthesis of cyclobutanes, their application in the synthesis of cyclobutenes remains underdeveloped. Here, a novel visible light induced α-selective radical ring-opening reaction of 1,3-disubstituted acyl bicyclobutanes with alkyl radical precursors for the synthesis of functionalized cyclobutenes is described. In particular, primary, secondary, and tertiary alkyl halides are all suitable substrates for this photocatalytic transformation, providing ready access to cyclobutenes with a single all-carbon quaternary center, or with two contiguous centers under mild reaction conditions.

Chloroquine enhances the efficacy of chemotherapy drugs against acute myeloid leukemia by inactivating the autophagy pathway

Current therapy for acute myeloid leukemia (AML) is largely hindered by the development of drug resistance of commonly used chemotherapy drugs, including cytarabine, daunorubicin, and idarubicin. In this study, we investigated the molecular mechanisms underlying the chemotherapy drug resistance and potential strategy to improve the efficacy of these drugs against AML. By analyzing data from ex vivo drug-response and multi-omics profiling public data for AML, we identified autophagy activation as a potential target in chemotherapy-resistant patients. In THP-1 and MV-4-11 cell lines, knockdown of autophagy-regulated genes ATG5 or MAP1LC3B significantly enhanced AML cell sensitivity to the chemotherapy drugs cytarabine, daunorubicin, and idarubicin. In silico screening, we found that chloroquine phosphate mimicked autophagy inactivation. We showed that chloroquine phosphate dose-dependently down-regulated the autophagy pathway in MV-4-11 cells. Furthermore, chloroquine phosphate exerted a synergistic antitumor effect with the chemotherapy drugs in vitro and in vivo. These results highlight autophagy activation as a drug resistance mechanism and the combination therapy of chloroquine phosphate and chemotherapy drugs can enhance anti-AML efficacy.

C(sp2)-H cyclobutylation of hydroxyarenes enabled by silver-π-acid catalysis: diastereocontrolled synthesis of 1,3-difunctionalized cyclobutanes

Ring-opening of bicyclo[1.1.0]butanes (BCBs) is emerging as a powerful strategy for 1,3-difunctionalized cyclobutane synthesis. However, reported radical strain-release reactions are typically plagued with diastereoselectivity issues. Herein, an atom-economic protocol for the highly chemo- and diastereoselective polar strain-release ring-opening of BCBs with hydroxyarenes catalyzed by a π-acid catalyst AgBF4 has been developed. The use of readily available starting materials, low catalyst loading, high selectivity (up to >98 : 2 d.r.), a broad substrate scope, ease of scale-up, and versatile functionalizations of the cyclobutane products make this approach very attractive for the synthesis of 1,1,3-trisubstituted cyclobutanes. Moreover, control experiments and theoretical calculations were performed to illustrate the reaction mechanism and selectivity.

Highly stereoselective synthesis of spirocyclopropylthiooxindoles and biological evaluation

We present a novel highly stereoselective Rh-catalyzed cyclopropanation of diazothiooxindoles with a broad range of α-functionalized styrenes, enabling facile access of chiral spirocyclopropylthiooxindoles in high to excellent enantiomeric excess.

Me2(CH2CH)SiCN: a bifunctional ethylene equivalent for Diels–Alder reaction based controllable tandem synthesis

A bifunctional silyl reagent Me₂(CH₂CH)SiCN has been developed as a novel ethylene equivalent for the Diels–Alder (DA) reaction. The use of this reagent enables the controllable synthesis of value-added cyclohexenyl ketones or 2-acyl cyclohexancarbonitrile derivatives through a five- or six-step tandem sequence based on a Wittig/cyanosilylation/DA reaction/retro-cyanosilylation/isomerization sequence that involves a temporary silicon-tethered intramolecular DA reaction.

We report an unprecedented tandem Wittig/cyanosilylation/DA reaction/retro-cyanosilylation/isomerization sequence by using our designed bifunctional ethylene equivalent Me₂(CH₂CH)SiCN.

Activation of unfolded protein response overcomes Ibrutinib resistance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most widespread type of non-Hodgkin lymphoma (NHL). As the most aggressive form of the DLBCL, the activated B-cell-like (ABC) subtype is often resistant to standard chemotherapies. Bruton's tyrosine kinase (BTK) inhibitor ibrutinib provides a potential therapeutic approach for the DLBCL but fails to improve the outcome in the phase III trial. In the current study, we investigated the molecular mechanisms underlying ibrutinib resistance and explored new combination therapy with ibrutinib. We generated an ibrutinib-resistant ABC-DLBCL cell line (OCI-ly10-IR) through continuous exposure to ibrutinib. Transcriptome analysis of the parental and ibrutinib-resistant cell lines revealed that the ibrutinib-resistant cells had significantly lower expression of the unfolded protein response (UPR) marker genes. Overexpression of one UPR branch-XBP1s greatly potentiated ibrutinib-induced apoptosis in both sensitive and resistant cells. The UPR inhibitor tauroursodeoxycholic acid (TUDCA) partially reduced the apoptotic rate induced by the ibrutinib in sensitive cells. The UPR activator 2-deoxy-D-glucose (2-DG) in combination with the ibrutinib triggered even greater cell growth inhibition, apoptosis, and stronger calcium (Ca2+) flux inhibition than either of the agents alone. A combination treatment of ibrutinib (15 mg·kg-1·d-1, po.) and 2-DG (500 mg/kg, po, b.i.d.) synergistically retarded tumor growth in NOD/SCID mice bearing OCI-ly10-IR xenograft. In addition, ibrutinib induced the UPR in the sensitive cell lines but not in the resistant cell lines of the DLBCL. There was also a combined synergistic effect in the primary resistant DLBCL cell lines. Overall, our results suggest that targeting the UPR could be a potential combination strategy to overcome ibrutinib resistance in the DLBCL.

[Correlation between spatial navigation disorder and white matter hyperintensity in patients with mild cognitive impairment]

Objective: To investigate the relationship between white matter lesions and spatial navigation ability in patients with mild cognitive impairment (MCI). Methods: A total of 32 MCI patients [age (66±11) years, 16 males and 16 females] who were treated in the Affiliated Drum Tower Hospital of Nanjing University Medical School from January 2015 to February 2018 were selected, and matched with age, gender and education level of 28 healthy controls (NC) [age (70±11) years, 19 males and 9 females] underwent spatial navigation ability test and neuropsychology scale evaluation. In the cross-sectional study, all subjects simultaneously underwent 3.0T magnetic resonance three-dimensional liquid inversion recovery sequence and high-resolution T(1) weighted imaging scan. The Wisconsin White Matter Hyperintensities Segmentation Toolbox (W2MHS) was used to automatically mark and extract the volume of the white matter hyperintensity. Results: The average error distances of egocentric virtual (P=0.002) and allocentric virtual (P=0.039) of MCI patients are greater than that of the control group, but the average error distance of mixed (allocentric-egocentric virtual) navigation had no statistic difference between two groups (P=0.070). The volume of the whole white matter hyperintensity, periventricular white matter hyperintensity, and deep white matter hyperintensity showed no significant differences between two groups (all P>0.05). Partial correlation analysis showed that after controlling for age, gender, education level and whole brain volume, the average error distance of mixed (allocentric-egocentric virtual) navigation in MCI patients was positively correlated to the volume of the whole white matter hyperintensity, deep white matter intensity, and periventricular white matter hyperintensity (r=0.469, 0.434, 0.512, all P<0.05). The average error distance of allocentric virtual navigation is positively correlated with the volume of periventricular white matter hyperintensity (r=0.403, P=0.033). There is no correlation between the average error distance of egocentric virtual navigation and the hyperintensity of white matter. Conclusions: The spatial navigation ability of patients with MCI is related to white matter lesions, which is of great significance for further research on the potential biological mechanisms affecting human spatial navigation ability.

Numerical investigation of cavitation generated by an ultrasonic dental scaler tip vibrating in a compressible liquid

Bacterial biofilm accumulation around dental implants is a significant problem leading to peri-implant diseases and implant failure. Cavitation occurring in the cooling water around ultrasonic scaler tips can be used as a novel solution to remove debris without any surface damage. However, current clinically available instruments provide insufficient cavitation around the activated tip surface. To solve this problem a critical understanding of the vibro-acoustic behaviour of the scaler tip and the associated cavitation dynamics is necessary. In this research, we carried out a numerical study for an ultrasound dental scaler with a curved shape tip vibrating in water, using ABAQUS based on the finite element method. We simulated the three-dimensional, nonlinear and transient interaction between the vibration and deformation of the scaler tip, the water flow around the scaler and the cavitation formation and dynamics. The numerical model was well validated with the experiments and there was excellent agreement for displacement at the free end of the scaler. A systematic parametric study has been carried out for the cavitation volume around the scaler tip in terms of the frequency, amplitude and power of the tip vibration. The numerical results indicate that the amount of cavitation around the scaler tip increases with the frequency and amplitude of the vibration. However, if the frequency is far from the natural frequency, the cavitation volume around the free end decreases due to reduced free end vibration amplitude.

Multi-messenger nanoprobes of hidden magnetism in a strained manganite

The ground-state properties of correlated electron systems can be extraordinarily sensitive to external stimuli, offering abundant platforms for functional materials. Using the multi-messenger combination of atomic force microscopy, cryogenic scanning near-field optical microscopy, magnetic force microscopy and ultrafast laser excitation, we demonstrate both 'writing' and 'erasing' of a metastable ferromagnetic metal phase in strained films of La_2/3Ca_1/3MnO₃ (LCMO) with nanometre-resolved finesse. By tracking both optical conductivity and magnetism at the nanoscale, we reveal how strain-coupling underlies the dynamic growth, spontaneous nanotexture and first-order melting transition of this hidden photoinduced metal. Our first-principles calculations reveal that epitaxially engineered Jahn-Teller distortion can stabilize nearly degenerate antiferromagnetic insulator and ferromagnetic metal phases. We propose a Ginzburg-Landau description to rationalize the co-active interplay of strain, lattice distortions and magnetism nano-resolved here in strained LCMO, thus guiding future functional engineering of epitaxial oxides into the regime of phase-programmable materials.

[Association of miRNA-196b-5p and miRNA-99a-5p with autophagy and apoptosis in multiple myeloma cells]

目的

探讨多发性骨髓瘤（MM）细胞miRNA-196b-5p和miRNA-99a-5p表达与自噬和凋亡的关系。

方法

以人MM细胞株U266细胞及45例MM患者瘤细胞为研究对象，以40例健康体检者为对照，采用实时定量PCR法测定细胞中miRNA-196b-5p和miRNA-99a-5p表达水平，采用Western blot法测定自噬相关蛋白（LC3-Ⅱ、LC3-Ⅰ、P62、Beclin-1）、凋亡相关分子（CL caspase3、CL caspase7、Bcl-2、Bax）和TGF-β/Smad通路相关蛋白（TGF-β1、Smad2/3、p-Smad3、Smad7）表达水平，采用流式细胞术测定细胞凋亡率，分析miRNA表达水平与MM患者临床特征的相关性。

结果

①与正常浆细胞比较，U266细胞、MM患者瘤细胞的miRNA-196b-5p表达显著增加（0.43±0.15对2.44±0.63、2.02±0.85，P值均<0.001），miRNA-99a-5p表达显著降低（1.87±0.61对0.62±0.15、0.80±0.33，P值均<0.001），LC3-Ⅱ/LC3-Ⅰ、Beclin-1、Bcl-2表达显著增加，P62、Bax、CL caspase3、CL caspase7表达显著降低，细胞凋亡率降低（P值均<0.05）。②正常CD138⁺浆细胞分别转染miRNA-196b-5p mimic或miRNA-99a-5p inhibitor 48 h后，与未转染对照组比较，LC3-Ⅱ/LC3-Ⅰ、Beclin-1、TGF-β1、p-Smad3表达显著增高，P62、Smad7表达显著降低，细胞凋亡率减少（P值均<0.05）；上述反应体系加入自噬抑制剂3-甲基腺嘌呤后，细胞凋亡率未见明显改变（P值均>0.05）。③miRNA-196b-5p和miRNA-99a-5p表达与MM患者DS分期（P值分别为0.004、0.012）、ISS分期显著相关（P值均为0.001）。

结论

miRNA-196b-5p和miRNA-99a-5p表达与MM患者临床特征密切相关，miRNA-196b-5p过表达和miRNA-99a-5p表达下调通过上调自噬水平抑制骨髓瘤细胞凋亡，其机制与活化TGF-β/Smad信号通路有关。

Coulomb Correlations Intertwined with Spin and Orbital Excitations in LaCoO_{3}

We carried out temperature-dependent (20-550 K) measurements of resonant inelastic x-ray scattering on LaCoO_{3} to investigate the evolution of its electronic structure across the spin-state crossover. In combination with charge-transfer multiplet calculations, we accurately quantified the renomalized crystal-field excitation energies and spin-state populations. We show that the screening of the effective on-site Coulomb interaction of 3d electrons is orbital selective and coupled to the spin-state crossover in LaCoO_{3}. The results establish that the gradual spin-state crossover is associated with a relative change of Coulomb energy versus bandwidth, leading to a Mott-type insulator-to-metal transition.

l-Phenylalanine Triflate as Organocatalyst for Divergent ­Approaches to Trisubstituted Hexahydroimidazo[1,2-a]pyridine and 1,4-Diazepane Derivatives

The convergent synthesis of two biologically significant classes of trisubstituted hexahydroimidazo[1,2-a]pyridine and 1,4-diazepane derivatives from readily available aromatic aldehydes, ketones, and ethane-1,2-diamine is reported. This protocol is promoted by the highly effective l-phenylalanine triflate catalyst through intermolecular annulation, and tolerates a variety of functional groups with excellent yields.

Jahn-Teller distortion driven magnetic polarons in magnetite

The first known magnetic mineral, magnetite, has unusual properties, which have fascinated mankind for centuries; it undergoes the Verwey transition around 120 K with an abrupt change in structure and electrical conductivity. The mechanism of the Verwey transition, however, remains contentious. Here we use resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe²⁺ and Fe³⁺ states. Comparison of the experimental results with crystal-field multiplet calculations shows that the spin–orbital dd excitons of the Fe²⁺ sites arise from a tetragonal Jahn-Teller active polaronic distortion of the Fe²⁺O₆ octahedra. These low-energy excitations, which get weakened for temperatures above 350 K but persist at least up to 550 K, are distinct from optical excitations and are best explained as magnetic polarons.

The Verwey transition of magnetite is complex due to the coexistence of strong correlations and electron-phonon coupling. Here, the authors use resonant inelastic X-ray scattering to show evidence for magnetic polarons in magnetite and provide insight into the nature of the transition.

[Change of white matter neuronal integrity associated with spatial navigation impairment in mild cognitive impairment]

Objective: To analyze the correlation between white matter integrity and spatial navigation impairment in patients with mild cognitive impairment (MCI). Methods: A total of 27 MCI subjects and 24 healthy controls were enrolled from the Affiliated Drum Tower Hospital of Nanjing University Medical School from May 2015 to February 2016, who underwent 3.0 T MRI scan and 2D-computer version spatial navigation test.DTI preprocessing and tract-based spatial statistics (TBSS) were performed by PANDA.Two sample t-test and partial correlation coefficients were performed to investigate the correlation of white matter impairments and spatial navigation decline. Results: Relative to controls, MCI showed worse egocentric navigation (t=-2.202, P<0.05). Decreased FA in superior longitudinal fasciculus (left t=2.95, right t=2.95, P<0.05), inferior longitudinal fasciculus and inferior fronto-occipital fasciculus (left t=2.66, right t=2.96, P<0.05), corpus callosum (t=2.09, P<0.05), cingulum (left t=2.76, right t=2.41, P<0.05), fornix (t=4.83, P<0.05), and corticospinal tract (left t=2.33, right t=2.26, P<0.05), were found in the MCI subjects.The decreased FA value of superior longitudinal fasciculus (left r=-0.354, right r=-0.347, P<0.05), inferior longitudinal fasciculus (left r=-0.338, right r=-0.336, P<0.05), cingulum (left r=-0.395, right r=-0.370, P<0.05), right corticospinal tract (r=-0.362, P<0.05) and fornix (r=-0.369, P<0.05) were correlated with increased ego average total error.Allo average total error were negative correlated with FA value of superior longitudinal fasciculus (left r=-0.329, right r=-0.350, P<0.05), inferior longitudinal fasciculus (left r=-0.349, right r=-0.378, P<0.05), splenium of corpus callosum (r=-0.364, P<0.05) and cingulum (left r=-0.340, right r=-0.406, P<0.05). Conclusion: This study implicated the potential white matter structural basis of spatial navigation impairment and will have an impact on the further study of the neurobiological mechanisms of human spatial navigation ability.

[Application of frailty index for comprehensive geriatric assessment in the elderly in China]

OBJECTIVE

To discuss the suitability of frailty index for comprehensive geriatric assessment(FI-CGA)in the elderly in China, and evaluate the application of FI-CGA in China.

METHODS

A comprehensive geriatric assessment was conducted among 118 old adults receiving health examination, and frailty index was calculated. Clinical frailty scale(CFS)was also used to evaluate the frail status of the old adults. The correlation between FI-CGA value and CFS level of the old adults was analyzed.

RESULTS

The mean value of FI-CGA was 0.19 ± 0.07, and the average level of CFS was 3.11 ± 1.46. Women had higher mean value of FI-CGA and higher CFS level than men(FI-CGA= 0.20 ± 0.02 for women, 0.19 ± 0.07 for men; CFS =3.40 ± 0.55 for women, 3.10 ± 1.48 for men), but the differences had no significance(t=0.270, 0.452, P=0.788, 0.652). The FI-CGA value and CFS level increased with age(F=10.437, 5.651, P=0.000, 0.001); and there was a positive correlation between FI-CGA value and CFS level(r=0.615, P=0.000).

CONCLUSION

FI-CGA is an effective model for the quantitative evaluation of the frail status of the elderly, and can be used in the clinical practice of geriatric medicine.

[Study on the difference of blood coagulation function in patients with traumatic brain injury in plain and plateau area]

Objective: In this study, we tested platelet count (PC), prothrombin time (PT), activated partial thromboplastin time (APTT), and other indicators of coagulation function, and revealed their difference in patients with traumatic brain injury (TBI) between plain and plateau area. Base on the results, we may provide research basis for the therapy of TBI associated coagulopathy in different areas. Methods: 151 TBI patients from Tianjin Medical University General Hospital, and 74 from People's Hospital of Tibet Autonomous Region in the period from Dec 2013 to Dec 2015 were enrolled.Coagulation function, including PC, platelet distribution width (PDW), mean platelet volume (MPV), platelet - large cell ratio (P- LCR), PT, APTT, fibrinogen (FIB), and D- Dimer were tested within 8 h. The difference in patients with TBI between plain and plateau areas were compared and analyzed. Results: Compared with plain area, the PC of patients with TBI in plateau area is lower [(168±49)×10⁹/L vs (196±72)×10⁹/L, P<0.05], while PT and APTT were extended [(13.5±1.3) s vs (12.0±4.0) s, (38±4) s vs(27±6) s, P<0.01]. On the other hand, FIB increases [(3.1±1.2) g/L vs (2.6±1.0) g/L, P<0.01] and D-Dimer decreases [(3.1±3.3) μg/L vs (4.7±3.6) μg/L, P<0.01] in plateau area compared with plain area. Conclusion: Due to the people of plateau area living in hypoxia state, the coagulation function is activated for a long time.Once TBI happens, the platelets and coagulation factors may be excessive consumption, resulting in hypocoagulable state and high risk of rebleeding, while the fibrinolysis system in patients with TBI of plateau area is not activated obviously.Therefore, it should give full consideration to these differences in the treatment of patients with TBI in plateau area, instead of directly copying the standard therapy of the people in plain area.The treatment recommendations should primarily supplement coagulation materials, and antifibrinolytics may unlikely have the therapy effect.

Orbital Engineering in Nickelate Heterostructures Driven by Anisotropic Oxygen Hybridization rather than Orbital Energy Levels

Resonant inelastic x-ray scattering is used to investigate the electronic origin of orbital polarization in nickelate heterostructures taking LaTiO_{3}-LaNiO_{3}-3×(LaAlO_{3}), a system with exceptionally large polarization, as a model system. We find that heterostructuring generates only minor changes in the Ni 3d orbital energy levels, contradicting the often-invoked picture in which changes in orbital energy levels generate orbital polarization. Instead, O K-edge x-ray absorption spectroscopy demonstrates that orbital polarization is caused by an anisotropic reconstruction of the oxygen ligand hole states. This provides an explanation for the limited success of theoretical predictions based on tuning orbital energy levels and implies that future theories should focus on anisotropic hybridization as the most effective means to drive large changes in electronic structure and realize novel emergent phenomena.

Raman and fluorescence characteristics of resonant inelastic X-ray scattering from doped superconducting cuprates

Measurements of spin excitations are essential for an understanding of spin-mediated pairing for superconductivity; and resonant inelastic X-ray scattering (RIXS) provides a considerable opportunity to probe high-energy spin excitations. However, whether RIXS correctly measures the collective spin excitations of doped superconducting cuprates remains under debate. Here we demonstrate distinct Raman- and fluorescence-like RIXS excitations of Bi_1.5Pb_0.6Sr_1.54CaCu₂O_8+δ. Combining photon-energy and momentum dependent RIXS measurements with theoretical calculations using exact diagonalization provides conclusive evidence that the Raman-like RIXS excitations correspond to collective spin excitations, which are magnons in the undoped Mott insulators and evolve into paramagnons in doped superconducting compounds. In contrast, the fluorescence-like shifts are due primarily to the continuum of particle-hole excitations in the charge channel. Our results show that under the proper experimental conditions RIXS indeed can be used to probe paramagnons in doped high-T_c cuprate superconductors.

The first catalytic asymmetric thioacetalization by chiral phosphoric acid catalysis

We report here the first catalytic asymmetric thioacetalization of salicylaldehyde and dithiol. Chiral phosphoric acid STRIP C5 is identified as a powerful catalyst for this reaction to afford various chiral dithioacetals in high to excellent yields and enantioselectivities under mild conditions.

Meta-analysis of the association between the rs7903146 polymorphism at the TCF7L2 locus and type 2 diabetes mellitus susceptibility

Type 2 diabetes mellitus (T2DM) is a chronic disease caused by genetic and environmental factors. T2DM has been associated with specific polymorphisms in the TCF7L2 gene. This study evaluates the relationship between the rs7903146 locus polymorphism of the TCF7L2 gene and T2DM susceptibility through meta-analysis; the overall aim is to provide a basis for evidence-based medicinal treatment of T2DM. Cohort and case-control studies from Medline, PubMed, EMBASE, CBM, CNKI, and academic conferences/dissertations that examined the correlation between T2DM and rs7903146 polymorphisms were evaluated. We determined whether the TCF7L2 rs7903146 locus was associated with T2DM susceptibility by comparing alleles and genotypes. The Stata 11.0 software was applied for meta-analysis, and a random-effects model was adopted for heterogeneity testing and odds ratio (OR) calculation. A fixed-effect model was used for quantitative analysis of the heterogeneity between different studies, and for calculating the percentage of variability I(2). A total of 10 studies related to the rs7903146 loci and T2DM susceptibility were enrolled; this included 3404 cases of T2DM patients and 6473 control cases. Meta-analysis showed that the T allele of rs7903146 was significantly correlated with the risk of T2DM, with both a dominant fixed-effect model (OR = 1.653, 95%CI = 1.416-1.653) and a co-dominant-fixed effect model (OR = 1.525, 95%CI = 1.350-1.723). Meta-analysis revealed that the T allele of rs7903146 was also correlated with T2DM susceptibility.

Agonist of farnesoid X receptor protects against bile acid induced damage and oxidative stress in mouse placenta--a study on maternal cholestasis model

INTRODUCTION

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific disorder, which is characterized by raised serum bile acid level and potential adverse fetal outcome. Farnesoid X receptor (FXR), also known as a bile acid receptor, was found to be expressed in placenta with low level. Whether activation of FXR by specific agonists could regulate the pathogenesis of ICP is still unclear.

METHODS

A model of maternal cholestasis was induced by administration of 17α-ethynylestradiol (E2) in pregnant mice for 6 days. We explored the regulatory effect of WAY-362450 (W450), a highly selective and potent FXR agonist on placenta.

RESULTS

In this study, we demonstrated that administration of E2 increased bile acid levels in mouse serum, liver and amniotic fluid. Bile acid levels were significantly decreased after W450 treatment. W450 protected against the impairment of placentas induced by E2, including severe intracellular edema and apoptosis of trophoblasts. Moreover, W450 significantly induced the expressions of FXR target bile acid transport gene ATP-binding cassette, sub-family B (MDR/TAP), member 11 (Abcb11;Bsep) in placenta. W450 could also attenuate placental oxidative stress and increase the expressions of antioxidant enzymes Prdx1 and Prdx3.

DISCUSSION AND CONCLUSION

In conclusion, our data demonstrated that FXR agonist W450 modulated bile acid balance and protected against placental oxidative stress. Thus, our results support that potent FXR agonists might represent promising drugs for the treatment of ICP.

Highly efficient beamline and spectrometer for inelastic soft X-ray scattering at high resolution

The design, construction and commissioning of a beamline and spectrometer for inelastic soft X-ray scattering at high resolution in a highly efficient system are presented. Based on the energy-compensation principle of grating dispersion, the design of the monochromator-spectrometer system greatly enhances the efficiency of measurement of inelastic soft X-rays scattering. Comprising two bendable gratings, the set-up effectively diminishes the defocus and coma aberrations. At commissioning, this system showed results of spin-flip, d-d and charge-transfer excitations of NiO. These results are consistent with published results but exhibit improved spectral resolution and increased efficiency of measurement. The best energy resolution of the set-up in terms of full width at half-maximum is 108 meV at an incident photon energy tuned about the Ni L3-edge.

Recycling of organic materials and solder from waste printed circuit boards by vacuum pyrolysis-centrifugation coupling technology

Here, we focused on the recycling of waste printed circuit boards (WPCBs) using vacuum pyrolysis-centrifugation coupling technology (VPCT) aiming to obtain valuable feedstock and resolve environmental pollution. The two types of WPCBs were pyrolysed at 600°C for 30 min under vacuum condition. During the pyrolysis process, the solder of WPCBs was separated and recovered when the temperature range was 400-600°C, and the rotating drum was rotated at 1000 rpm for 10 min. The type-A of WPCBs pyrolysed to form an average of 67.91 wt.% residue, 27.84 wt.% oil, and 4.25 wt.% gas; and pyrolysis of the type-B of WPCBs led to an average mass balance of 72.22 wt.% residue, 21.57 wt.% oil, and 6.21 wt.% gas. The GC-MS and FT-IR analyses showed that the two pyrolysis oils consisted mainly of phenols and substituted phenols. The pyrolysis oil can be used for fuel or chemical feedstock for further processing. The recovered solder can be recycled directly and it can also be a good resource of lead and tin for refining. The pyrolysis residues contained various metals, glass fibers and other inorganic materials, which could be recovered after further treatment. The pyrolysis gases consisted mainly of CO, CO(2), CH(4), and H(2), which could be collected and recycled.

A snake venom metalloproteinase, kistomin, cleaves platelet glycoprotein VI and impairs platelet functions

BACKGROUND AND OBJECTIVES

Injuries to the vessel wall and subsequent exposure of the matrix of the subendothelial layer resulted in thrombus formation. Platelet glycoprotein (GP) Ib and VI play a crucial role in matrix-induced activation and aggregation of platelets.

METHODS AND RESULTS

In the present study, we reported that the GPIb-cleaving snake venom metalloproteinase (SVMP), kistomin, inhibited collagen-induced platelet aggregation. Moreover, kistomin inhibited platelet aggregation induced by convulxin (CVX, a GPVI agonist) and a GPVI-specific antibody in a concentration and time-dependent manner. Kistomin treatment decreased platelet GPVI but not integrin alpha2beta1 and alphaIIbbeta3, accompanied with the formation of GPVI cleavage fragments, as determined by flow cytometric and Western blot analyses. In addition, intact platelet GPVI and recombinant GPVI were digested by kistomin to release 25- and 35-kDa fragments, suggesting that kistomin cleaved GPVI near the mucin-like region. We designed four synthetic peptides ranging from Leu180 to Asn249 as the substrates for kistomin and found that kistomin cleaved these synthetic peptides at FSE205/A206TA and NKV218/F219TT, as analyzed by MALDI-TOF-MS. In addition, GPVI-specific antibody-induced tyrosine kinase phosphorylation in platelets was reduced after kistomin pretreatment, and platelet adhesion to collagen but not to fibrinogen was attenuated by kistomin.

CONCLUSIONS

We provided here the first evidence that a P-I snake venom metalloproteinase, kistomin, inhibits the interaction between collagen and platelet GPVI through its proteolytic activity on GPVI, thus providing an alternative strategy for developing new anti-thrombotic agents.

Magnetic ground state and transition of a quantum multiferroic LiCu2O2

Based on resonant soft x-ray magnetic scattering, we report that LiCu2O2 exhibits a large interchain coupling which suppresses quantum fluctuations along spin chains, and a quasi-2D short-range magnetic order prevails at temperatures above the magnetic transition. These observations unravel the fact that the ground state of LiCu2O2 possesses long-range 2D-like incommensurate magnetic order rather than being a gapped spin liquid as expected from the nature of quantum spin-1/2 chains. In addition, the spin coupling along the c axis is found to be essential for inducing electric polarization.

Determination of carotenoids and their esters in fruits of Lycium barbarum Linnaeus by HPLC-DAD-APCI-MS

The fruit of Lycium barbarum Linnaeus, a traditional Chinese herb containing functional components such as carotenoids, flavonoids and polysaccharides, has been widely used in the health food industry because of its possible role in the prevention of chronic disease like age-related macular degeneration. The objectives of this study were to develop a high performance liquid chromatography-photo diode array detection-mass spectrometry (HPLC-DAD-MS) method with atmospheric pressure chemical ionization (APCI) mode for qualitative and quantitative analyses of carotenoids in fruits of L. barbarum. Dried samples of L. barbarum were subjected to extraction without saponification or extraction followed by saponification. A C30 column with a gradient mobile phase of methylene chloride (100%) and methanol-acetonitrile-water (81:14:5, v/v/v) was used to separate carotenoids, with a total of 11 free carotenoids and 7 carotenoid esters being resolved from unsaponified and saponified L. barbarum extracts within 51 and 41 min, respectively. The fatty acid composition of carotenoid esters was confirmed by gas chromatography. Zeaxanthin dipalmitate (1143.7 microg/g) was present in the largest amount, followed by beta-cryptoxanthin monopalmitate and its two isomers (32.9-68.5 microg/g), zeaxanthin monopalmitate and its two isomers (11.3-62.8 microg/g), all-trans-beta-carotene (23.7 microg/g) and all-trans-zeaxanthin (1.4 microg/g).

Anti-inflammatory effects of isoflavone powder produced from soybean cake

Soybean cake, a byproduct obtained during the processing of soybean oil, has been shown to be a rich source of isoflavones. The objectives of this study were to use soybean cake as raw material for processing into powder and to evaluate the anti-inflammatory activity. Eleven treatments, including powders of malonylglucoside, glucoside, acetylglucoside, aglycone, ISO-1, and ISO-2, as well as genistein standard, gamma-PGA, control, normal, and PDTC, were used for evaluation. A total of 77 mice were each provided daily with tube feeding for 4 weeks at a dose of 0.3 mL of aqueous solution from each treatment, and inflammation was induced with intraperitoneal injection of 1 mg/kg of body weight lipopolysaccharide (LPS). Results showed that all of the isoflavone powders and genistein standard were effective in inhibiting LPS-induced inflammation, lowering leukocyte number in mice blood and reducing production of IL-1beta, IL-6, NO, and PGE2 in both peritoneal exudate cell supernatant and peritoneal exudate fluid. All of the isoflavone treatments failed to retard T cell proliferation; however, both ISO-1 and ISO-2 could inhibit B cell proliferation. The difference in anti-inflammatory activity was minor between any of the isoflavone treatments.

Selection of a phage-displayed peptide recognized by monoclonal antibody directed blocking the site of hepatitis C virus E2 for human CD81

The human CD81 (hCD81) molecule has been identified as a putative receptor for hepatitis C virus (HCV). HCV envelope glycoprotein 2 (E2) most likely plays a pivotal role in binding to host cells by interacting with the hCD81 molecule. In this study, a phage-displayed peptide library was used to select small peptides with anti-hCD81 monoclonal antibody JS-81. The output/input ratio of phages increased about 91 fold after the third round of selection. Eight of the 30 phage clones selected from the phage library showed specific binding to the anti-hCD81 by enzyme linked immunosorbent assay (ELISA). Competitive inhibition test further demonstrated that HCV E2 could significantly inhibit the binding of a positive phage clone to anti-hCD81 JS-81. Exogenous small peptide ATWVCGPCT contained by the positive phage clones showed aligned with the hCD81 sequence from 153-161 by sequence analyses. These results suggest that the selected ATWVCGPCT is a novel hCD81-like small peptide, which can block the binding site of HCV E2 for hCD81. It may be of further application on development of antiviral agents targeting the stage of HCV entry.

Charge-orbital ordering and Verwey transition in magnetite measured by resonant soft X-ray scattering

We report experimental evidence for the charge-orbital ordering in magnetite below the Verwey transition temperature T(V). Measurements of O K-edge resonant x-ray scattering on magnetite reveal that the O 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering along the c axis with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. Such a charge-orbital ordering vanishes abruptly above T(V) and exhibits a thermal hysteresis, correlating closely with the Verwey transition in magnetite.

Orbital symmetry and electron correlation in NaxCoO2

Measurements of polarization-dependent soft x-ray absorption reveal that the electronic states determining the low-energy excitations of NaxCoO2 have predominantly a(1g) symmetry with significant O 2p character. In contrast to the prediction of band theory, doping-dependent O 1s x-ray absorption shows a large transfer of spectral weight, providing spectral evidence for strong electron correlations of the layered cobaltates. We also found that NaxCoO2 exhibits a charge-transfer electronic character rather than a Mott-Hubbard character.

Spin and orbital magnetic moments of Fe3O4

We present measurements of the spin and orbital magnetic moments of Fe3O4 by using SQUID and magnetic circular dichroism in soft x-ray absorption. The measurements show that Fe3O4 has a noninteger spin moment, in contrast to its predicted half-metallic feature. Fe3O4 also exhibits a large unquenched orbital moment. Calculations using the local density approximation including the Hubbard U method and the configuration interaction cluster-model suggest that strong correlations and spin-orbit interaction of the 3d electrons result in the noninteger spin and large orbital moments of Fe3O4.

Orbital ordering in La0.5Sr1.5MnO4 studied by soft X-ray linear dichroism

We found that the conventional model of orbital-ordering of 3x(2)-r(2)/3y(2)-r(2) type in the e(g) states of La0.5Sr1.5MnO4 is incompatible with measurements of linear dichroism in the Mn 2p-edge x-ray absorption, whereas these e(g) states exhibit predominantly cross-type orbital ordering of x(2)-z(2)/y(2)-z(2). LDA+U band-structure calculations reveal that such a cross-type orbital-ordering results from a combined effect of antiferromagnetic structure, Jahn-Teller distortion, and on-site Coulomb interactions.

Crotalin, a vWF and GP Ib cleaving metalloproteinase from venom of Crotalus atrox

Binding of von Willebrand factor (vWF) to a variety of extracellular matrix (ECM) components and to platelet glycoprotein (GP) Ib-IX-V complex is important in mediating platelet adhesion and aggregation in the early stage of hemostasis. We previously purified a potent antithrombotic protein, named crotalin, functionally acting as a GP lb antagonist (1). In this study, we further characterized crotalin as a P-I metalloproteinase with a molecular mass of 25 kDa as determined by gel filtration and two-dimensional SDS-PAGE. Crotalin is a vWF binding and cleaving metalloproteinase. In addition, crotalin cleaved platelet GP lb as judged by flow cytometry and Western blotting. The multiple effects of crotalin on vWF and platelet GP lb antagonized ristocetin-, but not collagen and thrombin-induced platelet aggregation, suggesting that its effect is specific. We also found that crotalin autoproteolytically degraded to approximately 14 and approximately 10 kDa fragments in the presence of SDS. Interestingly, both degradation fragments, intact and reduced crotalin were able to bind vWF, suggesting the binding of crotalin to vWF is conformation-independent. In conclusion, the results presented further explain the potent antithrombotic effect of crotalin in vivo. In addition, the multiple effects of crotalin may be used as a tool to determine the binding motifs that are responsible for the vWF-ECMs or vWF-GP lb interaction.

Purification, molecular cloning and mechanism of action of graminelysin I, a snake-venom-derived metalloproteinase that induces apoptosis of human endothelial cells

Apoptosis, a programmed, physiological mode of cell death, is important in tissue homoeostasis. Here we report that a new metalloproteinase, graminelysin I, purified from Trimeresurus gramineus venom, induced apoptosis of human endothelial cells as examined by electrophoresis and flow cytometry. Graminelysin I contains only a metalloproteinase domain. It is a single-chain proteinase with a molecular mass of 27020 Da. cDNA sequence analysis revealed that the disintegrin-like and cysteine-rich domains of the putative precursor protein of graminelysin I are likely to be processed post-translationally, producing the proteinase domain (graminelysin I). Graminelysin I cleaved the alpha chain of fibrinogen preferentially and cleaved the beta chain either on longer incubation or at higher concentration. Graminelysin I inhibited the adhesion of human umbilical-vein endothelial cells (HUVECs) to immobilized fibrinogen and induced HUVECs detachment in a dose-dependent manner. These effects on HUVECs were abolished when graminelysin I was pretreated with EDTA. However, graminelysin I did not inhibit the adhesion of HUVECs to immobilized collagen. HUVECs were susceptible to death after treatment with graminelysin I when they were cultured on immobilized fibrinogen. In contrast, HUVECs were rather resistant to treatment with graminelysin I if they were cultured on immobilized collagen. Furthermore, graminelysin I induced apoptosis of HUVECs in a dose-dependent manner. Similarly, its apoptosis-inducing activity was blocked if it was treated with EDTA. These results suggest that the catalytic activity of graminelysin I on matrix proteins contributes to its apoptosis-inducing activity.

Viper venom components affecting angiogenesis

Angiogenesis is a complex process consisting of the proliferation, migration and differentiation of endothelial cells, and it is essential for the progression of malignant solid tumors. In this report, we examine the effects of disintegrins (e.g. rhodostomin and accutin) and glycoprotein-lb-binding proteins (e.g. agkistin) on each step in angiogenesis using in vitro and in vivo models. Rhodostomin (but not agkistin) inhibited the viability of human umbilical vein endothelial cells (HUVECs) and capillary tube formation of HUVECs. Rhodostomin also inhibited HUVEC migration and invasion evoked by basic fibroblast growth factor (bFGF). In in vivo studies, rhodostomin inhibited bFGF-, but not vascular-endothelial-growth-factor (VEGF)- associated angiogenesis in chick chorioallantoic membrane model, blocked both bFGF and B16F10 melanoma cell-induced neovascularization, and suppressed the growth of subcutaneously inoculated B16F10 solid tumor, leading to a prolonged survival of the C57BL/6 mice treated with rhodostomin. The antiangiogenic effects of rhodostomin on bFGF-treated HUVECs may be mainly related to the blockade of the interaction of endothelial alpha(v)beta(3) and extracellular matrix.

P2Y(2) receptor-stimulated phosphoinositide hydrolysis and Ca(2+) mobilization in tracheal epithelial cells

Extracellular nucleotides have been implicated in the regulation of secretory function through the activation of P2 receptors in the epithelial tissues, including tracheal epithelial cells (TECs). In this study, experiments were conducted to characterize the P2 receptor subtype on canine TECs responsible for stimulating inositol phosphate (InsP(x)) accumulation and Ca(2+) mobilization using a range of nucleotides. The nucleotides ATP and UTP caused a concentration-dependent increase in [(3)H]InsP(x) accumulation and Ca(2+) mobilization with comparable kinetics and similar potency. The selective agonists for P1, P2X, and P2Y(1) receptors, N(6)-cyclopentyladenosine and AMP, alpha,beta-methylene-ATP and beta, gamma-methylene-ATP, and 2-methylthio-ATP, respectively, had little effect on these responses. Stimulation of TECs with maximally effective concentrations of ATP and UTP showed no additive effect on [(3)H]InsP(x) accumulation. The response of a maximally effective concentration of either ATP or UTP was additive to the response evoked by bradykinin. Furthermore, ATP and UTP induced a cross-desensitization in [(3)H]InsP(x) accumulation and Ca(2+) mobilization. These results suggest that ATP and UTP directly stimulate phospholipase C-mediated [(3)H]InsP(x) accumulation and Ca(2+) mobilization in canine TECs. P2Y(2) receptors may be predominantly mediating [(3)H]InsP(x) accumulation, and, subsequently, inositol 1,4,5-trisphosphate-induced Ca(2+) mobilization may function as the transducing mechanism for ATP-modulated secretory function of tracheal epithelium.

Exact distribution of edge-preserving MAP estimators for linear signal models with Gaussian measurement noise

We derive the exact statistical distribution of maximum a posteriori (MAP) estimators having edge-preserving nonGaussian priors. Such estimators have been widely advocated for image restoration and reconstruction problems. Previous investigations of these image recovery methods have been primarily empirical; the distribution we derive enables theoretical analysis. The signal model is linear with Gaussian measurement noise. We assume that the energy function of the prior distribution is chosen to ensure a unimodal posterior distribution (for which convexity of the energy function is sufficient), and that the energy function satisfies a uniform Lipschitz regularity condition. The regularity conditions are sufficiently general to encompass popular priors such as the generalized Gaussian Markov random field prior and the Huber prior, even though those priors are not everywhere twice continuously differentiable.

Pharmacological and functional characterization of bradykinin receptors in rat cultured vascular smooth muscle cells

The pharmacological properties of bradykinin receptors were characterized in rat cultured vascular smooth muscle cells (VSMCs) using [3H]-bradykinin as a ligand. Analysis of binding isotherms gave an apparent equilibrium dissociation constant (K(D)) of 1.2 +/- 0.2 nM and a maximum receptor density (Bmax) of 47.3 +/- 4.4 fmol/mg protein. The specific binding of [3H]-bradykinin to VSMCs was inhibited by the B2 receptor-selective agonists (bradykinin and kallidin) and antagonists ([D-Arg0, Hyp3, Thi5, D-Tic7, Oic8]-bradykinin (Hoe 140) and [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin) with an order of potency as kallidin = bradykinin = Hoe 140 > [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin, but not by a B1 receptor-selective agonist (des-Arg9-bradykinin) and antagonist ([Leu8, des-Arg9]-bradykinin). Stimulation of VSMCs by bradykinin produced a concentration-dependent inositol phosphate (IP) accumulation, and initial transient peak of [Ca2+]i with half-maximal responses (pEC50) were 7.53 and 7.69, respectively. B2 receptor-selective antagonists (Hoe 140 and [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin) significantly antagonized the bradykinin-induced responses with pK(B) values of 8.3-8.7 and 7.2-7.9, respectively. Pretreatment of VSMCs with pertussis toxin (100 ng/ml, 24 h) did not alter the bradykinin-induced inositol phosphate accumulation and [Ca2+]i changes in VSMCs. Removal of external Ca2+ led to a significant attenuation of responses induced by bradykinin. Influx of external Ca2+ was required for the bradykinin-induced responses, since Ca2+-channel blockers, nifedipine, verapamil, and Ni2+, partially inhibited the bradykinin-induced IP accumulation and Ca2+ mobilization. These results demonstrate that bradykinin stimulates phosphoinositide hydrolysis and Ca2+ mobilization via a pertussis toxin-insensitive G-protein in rat VSMCs. Bradykinin B2 receptors may be predominantly mediating IP accumulation and subsequently induction of Ca2+ mobilization may function as the transducing mechanism for bradykinin-stimulated contraction of vascular smooth muscle.

Inhibition of bradykinin-induced phosphoinositide hydrolysis and Ca2+ mobilisation by phorbol ester in rat cultured vascular smooth muscle cells

Regulation of the increase in inositol phosphate (IP) production and intracellular Ca2+ concentration ([Ca2+]i by protein kinase C (PKC) was investigated in cultured rat vascular smooth muscle cells (VSMCs). Pretreatment of VSMCs with phorbol 12-myristate 14-acetate (PMA, 1 microM) for 30 min almost abolished the BK-induced IP formation and Ca2+ mobilisation. This inhibition was reduced after incubating the cells with PMA for 4 h, and within 24 h the BK-induced responses were greater than those of control cells. The concentrations of PMA giving a half-maximal (pEC50) and maximal inhibition of BK induced an increase in [Ca2+]i, were 7.8 +/- 0.3 M and 1 microM, n = 8, respectively. Prior treatment of VSMCs with staurosporine (1 microM), a PKC inhibitor, inhibited the ability of PMA to attenuate BK-induced responses, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. Paralleling the effect of PMA on the BK-induced IP formation and Ca2+ mobilisation, the translocation and downregulation of PKC isozymes were determined by Western blotting with antibodies against different PKC isozymes. The results revealed that treatment of the cells with PMA for various times, translocation of PKC-alpha, betaI, betaII, delta, epsilon, and zeta isozymes from the cytosol to the membrane were seen after 5 min, 30 min, 2 h, and 4 h of treatment. However, 24-h treatment caused a partial downregulation of these PKC isozymes in both fractions. Treatment of VSMCs with 1 microM PMA for either 1 or 24 h did not significantly change the K(D) and Bmax of the BK receptor for binding (control: K(D) = 1.7 +/- 0.2 nM; Bmax = 47.3 +/- 4.4 fmol/mg protein), indicating that BK receptors are not a site for the inhibitory effect of PMA on BK-induced responses. In conclusion, these results demonstrate that translocation of PKC-alpha, betaI, betaII, delta, epsilon, and zeta induced by PMA caused an attenuation of BK-induced IPs accumulation and Ca2+ mobilisation in VSMCs.

Uncoupling of bradykinin-induced phosphoinositide hydrolysis and Ca2+ mobilization by phorbol ester in canine cultured tracheal epithelial cells

1. Regulation of the increase in inositol phosphates (IPs) production and intracellular Ca2+ concentration ([Ca2+]i by protein kinase C (PKC) was investigated in canine cultured tracheal epithelial cells (TECs). Stimulation of TECs by bradykinin (BK) led to IPs formation and caused an initial transient [Ca2+]i peak in a concentration-dependent manner. 2. Pretreatment of TECs with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min attenuated the BK-induced IPs formation and Ca2+ mobilization. The maximal inhibition occurred after incubating the cells with PMA for 2 h. 3. The concentrations of PMA that gave half-maximal (pEC50) inhibition of BK-induced IPs accumulation and an increase in [Ca2+]i were 7.07 M and 7.11 M, respectively. Inactive phorbol ester, 4alpha-phorbol 12,13-didecanoate at 1 microM, did not inhibit these responses. Prior treatment of TECs with staurosporine (1 microM), a PKC inhibitor, inhibited the ability of PMA to attenuate BK-induced responses, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. 4. In parallel with the effect of PMA on the BK-induced IPs formation and Ca2+ mobilization, the translocation and down-regulation of PKC isozymes were determined. Analysis of cell extracts by Western blotting with antibodies against different PKC isozymes revealed that TECs expressed PKC-alpha, betaI, betaII, gamma, delta, epsilon, theta and zeta. With PMA treatment of the cells for various times, translocation of PKC-alpha, betaI, betaII, gamma, delta, epsilon and theta from cytosol to the membrane was seen after 5 min, 30 min, 2 h, and 4 h treatment. However, 6 h treatment caused a partial down-regulation of these PKC isozymes. PKC-zeta was not significantly translocated and down-regulated at any of the times tested. 5. Treatment of TECs with 1 microM PMA for either 30 min or 6 h did not significantly change the KD, and Bmax receptor for BK binding (control: KD=1.7+/-0.3 nM; Bmax=50.5+/-4.9 fmol/mg protein), indicating that BK receptors are not a site for the inhibitory effect of PMA on BK-induced responses. 6. In conclusion, these results suggest that activation of PKC may inhibit the phosphoinositide hydrolysis and consequently attenuate the [Ca2+]i increase or inhibit independently both responses to BK. The translocation of pKC-alpha, betaI, betaII, delta, epsilon, gamma, and theta induced by PMA caused an attenuation of BK-induced IPs accumulation and Ca2+ mobilization in TECs.

Biodegradation of benzene, toluene, and other aromatic compounds by Pseudmonas sp. D8

Pseudomonas sp. D8 strain, which has the potential to utilize toluene as a sole carbon source, was isolated. At a concentration of 100 mg/l, this strain was found to efficiently degrade toluene and benzene (both individually and in mixture) in culture medium at 30 degrees C and pH7. Following a two-hour lag phase, complete biodegradation of 100 mg/l toluene or benzene occurred within 6 to 8 hours. The addition of nitrate, phosphate, or sulfate at various concentrations were found to have significant influence on both toluene and benzene degradation. In addition, results show that the D8 strain has the ability to degrade monochlorophenols, nitrophenols, and phenol, but not aliphatic compounds. Inoculation of groundwater samples containing 100 mg/l toluene or benzene with Pseudmonas sp. D8 resulted in rapid degradation within 24-33 hours.

Purinoceptor-stimulated phosphoinositide hydrolysis in Madin-Darby canine kidney (MDCK) cells

Extracellular nucleotides, acting through P2-purinoceptors, have been implicated in the regulation of ion transport in epithelia, including Madin-Darby canine kidney (MDCK) cells. In this study, experiments were conducted to characterize the P2-purinoceptor subtype on MDCK cells responsible for stimulating inositol phosphate (IP) accumulation using a range of nucleotide analogues. In Ca2+- and Mg2+-free Krebs-Henseleit solution (KHS), ATP, UTP, and ATPgammaS caused an increase in IP accumulation as a function of concentration with comparable kinetics. The order of potency for the nucleotide analogues was UTP = ATPgammaS > ATP = 2-chloro ATP (Cl-ATP) >> alpha,beta-methylene ATP (alpha,beta-MeATP) = 2-methylthio ATP (2MeSATP). Selective agonists for P1-, P2X- and P2Y-purinoceptors, such as N6-cyclopentyl adenosine, AMP, alpha,beta-MeATP, and 2MeSATP, had little effect. Stimulation of MDCK cells with maximally effective concentrations of ATP and UTP showed no additive effect and furthermore, ATP, UTP, and ATPgammaS induced cross-desensitization of the IP response, suggesting that ATP and UTP act upon a common nucleotide receptor, i.e. a P2U-purinoceptor. In Ca2+- and Mg2+-containing KHS, the concentration-response curves of ATP, UTP, and ATPgammaS were shifted to the right of those obtained in Ca2+- and Mg2+-free buffer, and asymptotic maxima were not reached, indicating that ATP4- and not MgATP2- or CaATP2- was the active agonist. Pretreatment of MDCK cells with pertussis toxin (PTX) inhibited ATP- and UTP-induced IP accumulation in a concentration-dependent fashion but did not completely abolish the IP accumulation, indicating that a PTX-sensitive G protein was partially involved in the IP response. In conclusion, ATP- and UTP-stimulated IP accumulation in MDCK cells appears to be mediated through the activation of P2U-purinoceptors coupled to a G protein that is partially sensitive to PTX. A form of nucleotide uncomplexed with divalent ions such as ATP4- seems to be the preferential agonist form for the purinoceptors on MDCK cells.