Enantioselective palladium-catalyzed C(sp2)-C(sp2) σ bond activation of cyclopropenones by merging desymmetrization and (3 + 2) spiroannulation with cyclic 1,3-diketones.

Catalytic asymmetric variants for functional group transformations based on carbon-carbon bond activation still remain elusive. Herein we present an unprecedented palladium-catalyzed (3 + 2) spiro-annulation merging C(sp2)-C(sp2) σ bond activation and click desymmetrization to form synthetically versatile and value-added oxaspiro products. The operationally straightforward and enantioselective palladium-catalyzed atom-economic annulation process exploits a TADDOL-derived bulky P-ligand bearing a large cavity to control enantioselective spiro-annulation that converts cyclopropenones and cyclic 1,3-diketones into chiral oxaspiro cyclopentenone-lactone scaffolds with good diastereo- and enantio-selectivity. The click-like reaction is a successful methodology with a facile construction of two vicinal carbon quaternary stereocenters and can be used to deliver additional stereocenters during late-state functionalization for the synthesis of highly functionalized or more complex molecules.

Field metabolic rates of giant pandas reveal energetic adaptations.

Knowledge of energy expenditure informs conservation managers for long term plans for endangered species health and habitat suitability. We measured field metabolic rate (FMR) of free-roaming giant pandas in large enclosures in a nature reserve using the doubly labeled water method. Giant pandas in zoo like enclosures had a similar FMR (14,182 kJ/day) to giant pandas in larger field enclosures (13,280 kJ/day). In winter, giant pandas raised their metabolic rates when living at - 2.4 °C (36,108 kJ/day) indicating that they were below their thermal neutral zone. The lower critical temperature for thermoregulation was about 8.0 °C and the upper critical temperature was about 28 °C. Giant panda FMRs were somewhat lower than active metabolic rates of sloth bears, lower than FMRs of grizzly bears and polar bears and 69 and 81% of predicted values based on a regression of FMR versus body mass of mammals. That is probably due to their lower levels of activity since other bears actively forage for food over a larger home range and pandas often sit in a patch of bamboo and eat bamboo for hours at a time. The low metabolic rates of giant pandas in summer, their inability to acquire fat stores to hibernate in winter, and their ability to raise their metabolic rate to thermoregulate in winter are energetic adaptations related to eating a diet composed almost exclusively of bamboo. Differences in FMR of giant pandas between our study and previous studies (one similar and one lower) appear to be due to differences in activity of the giant pandas in those studies.

Non-Interpenetrated Single-Crystal Covalent Organic Frameworks.

Growth of covalent organic frameworks (COFs) as single crystals is extremely challenging. Inaccessibility of open-structured single-crystal COFs prevents the exploration of structure-oriented applications. Herein we report for the first time a non-interpenetrated single-crystal COF, LZU-306, which possesses the open structure constructed exclusively via covalent assembly. With a high void volume of 80 %, LZU-306 was applied to investigate the intrinsic dynamics of reticulated tetraphenylethylene (TPE) as the individual aggregation-induced-emission moiety. Solid-state 2 H NMR investigation has determined that the rotation of benzene rings in TPE, being the freest among the reported cases, is as fast as 1.0×104  Hz at 203 K to 1.5×107  Hz at 293 K. This research not only explores a new paradigm for single-crystal growth of open frameworks, but also provides a unique matrix-isolation platform to reticulate functional moieties into a well-defined and isolated state.

Stereospecific Si-C coupling and remote control of axial chirality by enantioselective palladium-catalyzed hydrosilylation of maleimides.

Hydrosilylation of unsaturated carbon-carbon bonds with hydrosilanes is a very important process to access organosilicon compounds and ranks as one of the most fundamental reactions in organic chemistry. However, catalytic asymmetric hydrosilylation of activated alkenes and internal alkenes has proven elusive, due to competing reduction of carbon-carbon double bond or isomerization processes. Herein, we report a highly enantioselective Si-C coupling by hydrosilylation of carbonyl-activated alkenes using a palladium catalyst with a chiral TADDOL-derived phosphoramidite ligand, which inhibits O-hydrosilylation/olefin reduction. The stereospecific Si-C coupling/hydrosilylation of maleimides affords a series of silyl succinimides with up to 99% yield, >99:1 diastereoselectivity and >99:1 enantioselectivity. The high degree of stereoselectivity exerts remote control of axial chirality, leading to functionalized, axially chiral succinimides which are versatile building blocks. The product utility is highlighted by the enantioselective construction of N-heterocycles bearing up to three stereocenters.

Catalytic Asymmetric trans-Selective Hydrosilylation of Bisalkynes to Access AIE and CPL-Active Silicon-Stereogenic Benzosiloles.

Chirality widely exists in a diverse array of biologically active molecules and life forms, and the catalytic constructions of chiral molecules have triggered a heightened interest in the fields of chemistry and materials and pharmaceutical sciences. However, the synthesis of silicon-stereogenic organosilicon compounds is generally recognized as a much more difficult task than that of carbon-stereogenic centers because of no abundant organosilicon-based chiral sources in nature. Herein, we reported a highly enantioselective rhodium-catalyzed trans-selective hydrosilylation of silicon-tethered bisalkynes to access chiral benzosiloles bearing a silicon-stereogenic center. This protocol featured with chiral Ar-BINMOL-Phos bearing hydrogen-bond donors as a privileged P-ligand for catalytic asymmetric hydrosilylation that is operationally simple and has 100% atom-economy with good functional group tolerability as well as high enantioselectivity (up to >99:1 er). Benefiting from the trans-selective hydrosilylation with the aid of Rh/Ar-BINMOL-Phos-based asymmetric catalysis, the Si-stereogenic benzosiloles exhibited pronounced aggregation-induced emission (AIE) and circularly polarized luminescence (CPL) activity.

Controllable Si-C Bond Activation Enables Stereocontrol in the Palladium-Catalyzed [4+2] Annulation of Cyclopropenes with Benzosilacyclobutanes.

A novel and unusual palladium-catalyzed [4+2] annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si-C(sp2 ) bond activation in synergy with ring expansion/insertion of cyclopropenes to form new C(sp2 )-C(sp3 ) and Si-C(sp3 ) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo[4.1.0]heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles.

Catalytic asymmetric cycloaddition of unsymmetrical EWG-activated alkenes to fully substituted pyrrolidines bearing three different carbonyl groups.

A unique 1,3-dipolar [3+2] cycloaddition of alkyl 4-oxo-4-arylbut-2-enoates bearing two different electron-withdrawing groups was completed by using the silver/(R)-DTBM-Segphos catalyst system, which gives the corresponding fully substituted pyrrolidines with four stereogenic centers in good yields and with excellent enantioselectivities (up to 98% ee).

No association between MTHFR C677T and serum uric acid levels among Japanese with ABCG2 126QQ and SLC22A12 258WW.

Several genome-wide association studies (GWAS) have revealed that single nucleotide polymorphisms (SNPs) of ABCG2 and SLC22A12 were strongly associated with serum uric acid (SUA), but those of methylene tetrahydrofolate reductase (MTHFR) were not. However, there were several studies indicating the association with MTHFR C677T polymorphism. This study examined the association with the polymorphism, taking into account the genotypes of ABCG2 Q126X and SLC22A12 W258X. Subjects were 5,028 health checkup examinees of Seirei Preventive Health Care Center (3,416 males and 1,612 females) aged 35 to 69 years, who participated in the Japan Multi-Institutional Collaborative Cohort Study (J-MICC Study). Hyperuricemia was defined as SUA equal to 7 mg/dL or over. The genotype frequency was 35.9% for CC, 48.1% for CT, and 16.0% for TT, being in Hardy-Weinberg equilibrium (p=0.90). Among 4,425 participants with ABCG2 126QQ and SLC22A12 258WW who were not under medication for hyperuricemia, the mean SUA was 5.6 mg/dL, 5.6 mg/dL, and 5.7 mg/dL, respectively. When 114 participants with ABCG2 126QQ and SLC22A12 258WW under medication for hyperuricemia were included in hyperuricemia cases, the sex-age adjusted odds ratio (OR) of hyperuricemia was not significant; OR=1.00 (95% confidence interval, 0.89-1.24) for CT genotype and OR=0.98 (0.84-1.32) for TT genotype, relative to CC genotype. The present study indicated no association between SUA and MTHFR C677T genotype, after the influences of ABCG2 Q126X and SLC22A12 W258X were removed.

Chronic hepatitis B virus infection and risk of pancreatic cancer: a meta-analysis.

OBJECTIVES: A number of studies have shown that chronic hepatitis B virus infection is implicated in susceptibility to pancreatic cancer. However, the results are still controversial. This meta-analysis aimed to quantitatively assess the relationship between chronic hepatitis B virus infection and incidence of pancreatic cancer of cohort and case-control studies. METHODS: A literature search was performed for entries from 1990 to 2012 using PUBMED and EMBASE. Studies were included if they reported odds ratios (ORs) and corresponding 95% CIs of pancreatic cancer with respect to the infection of hepatitis B virus. RESULTS: Eight studies met the inclusion criteria, which included five case-control studies and three cohort studies. Compared with individuals who have not infection of hepatitis B virus, the pooled OR of pancreatic cancer was 1.403 (95%CI: 1.139-1.729, P=0.001) for patients with hepatitis B virus infection. Sub-group analysis by study design showed that the summary OR was 1.43 (95%CI: 1.06-1.94, P=0.021) when pooling case-control studies and 1.31 (95%CI: 1.00- 1.72, P=0.05) when pooling cohort studies. CONCLUSION: Findings from this meta-analysis suggest that chronic hepatitis B virus infection may increase the risk of pancreatic cancer. This relationship needs to be confirmed by further follow-up studies.

1.5T conventional MR-guided iodine-125 interstitial implants for hepatocellular carcinoma: feasibility and preliminary clinical experience.

PURPOSE: To evaluate the feasibility and therapeutic efficacy of 1.5 T conventional MR-guided percutaneous interstitial implantation of I-125 radioactive seeds in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: The institutional ethics committee approved this study. After imformed consent was obtained, twenty-three patients suffering from a total of 65 HCC lesions were treated with I-125 seed permanent interstitial implantation under the guidance of a 1.5T conventional magnetic resonance imaging (MRI) system. The FSE T2WI, T1 FSPGR, FIESTA 2D, 3D Dyn T1WI sequences were used to guide an 18 G MR-compatible needle inserted into the lesions to introduce the I-125 seeds. The response evaluation criteria in solid tumors (RECIST) were used to evaluate the curative effect. RESULTS: The needle and I-125 seed were seen clearly on MRI images. The final dose delivered to total decay was 173.46 ± 32.44 Gy (range, 110-270 Gy) as calculated by postoperative TPS. The complete response (CR) was seen in 22 lesions (33.8%), partial response (PR) in 24 lesions (36.9%), stable disease (SD) in 9 lesions (13.8%), and progressive disease (PD) in 10 lesions (15.4%). The post-operative alpha-fetoprotein (AFP) was decreased (t = 3.117, P = 0.005<0.05). Two patients were observed a small area of subcapsular bleeding that did not lead to any symptoms or clinical sequelae. CONCLUSION: MR-guided I-125 implantation for HCC is technically feasible and effective.

[Effect of comprehensive control and management of schistosomiasis at plateaus regions in Yunnan Province].

OBJECTIVE: To evaluate the effect of comprehensive control and management of schistosomiasis at plateaus regions in Yunnan Province. METHODS: Xiaolian and Kangfu villages at plateaus regions where schistosomiasis was endemic were selected as study areas from 2006 to 2011, the schistosomiasis comprehensive control measures were conducted, and these measures included the health education, chemotherapy, stool and water management, grazing forbidden, Oncomelania snail control, etc. combined with the infrastructure of farmland water conservancy, agricultural comprehensive development, adjustment of industry structure, returning farmland to forest, ditch hardening, and aquaculture. RESULTS: At Xiaolian Village, no schistosomiasis patient and livestock were found from 2008; and at Kangfu Village, no schistosomiasis patient was detected from 2006 and no schistosomiasis domestic animal was found from 2008. In 2011, the snail area, percent of frames with living snails, the number of snails, average concentration of living snails, and the highest concentration of living snails descended by 69.99%, 81.86%, 88.86%, 89.71%, 57.95% at Xiaolian Village, and descended by 27.65%, 1.11%, 94.71%, 92.16%, 88.00% at Kangfu Village, respectively, compared with those in 2006. The ratios of infected snail area to snail area were 68.91% in 2006 and 69.13% in 2007 at Xiaolian Village, and 61.73% in 2006 and 43.24% in 2007 at Kangfu Village. There were no infected snails from 2008 in the two villages. CONCLUSION: The comprehensive control and management measures can effectively control the schistosomiasis prevalence at plateaus regions.

Source and distribution of lead in the surface sediments from the South China Sea as derived from Pb isotopes.

Rapid economic development in East Asian countries has inevitably resulted in environmental degradation in the surrounding seas, and concern for the environment and its protection against pollutants is increasing. Identification of sources of contaminants and evaluation of current environmental status are essential to environmental pollution management, but relatively little has been done in the South China Sea (SCS). In order to investigate the abundance, distribution, and sources of Pb within the SCS, stable Pb isotopes and their ratios were employed to assess the contamination status and to differentiate between natural and anthropogenic origins of Pb in the surface sediments. The total Pb concentrations in sediments varied from 4.18 to 58.7 mg kg(-1), with an average concentration of 23.6 ± 8.9 mg kg(-1). The observed Pb isotope ratios varied from 18.039 to 19.211 for (206)Pb/(204)Pb, 15.228 to 16.080 for (207)Pb/(204)Pb, 37.786 to 39.951 for (208)Pb/(204)Pb, 1.176 to 1.235 for (206)Pb/(207)Pb, and 2.468 to 2.521 for (208)Pb/(207)Pb. The majority of these ratios are similar to those reported for natural detrital materials. Combined with Pb enrichment factor values, our results show that Pb found within most of the SCS sediments was mainly derived from natural sources, and that there was not significant Pb pollution from anthropogenic sources before 1998. Further studies are needed to reconstruct deposition history and for trend analysis.

Artificial pneumothorax with position adjustment for computed tomography-guided percutaneous core biopsy of mediastinum lesions.

PURPOSE: This study was designed to assess the use of artificial pneumothorax with position adjustment to gain a pleural space approach in computed tomographic-guided core biopsy of mediastinal masses. DESCRIPTION: Eleven patients with mediastinal lesions who were undergoing percutaneous core biopsies received an artificial pneumothorax with a 22-gauge lumbar puncture needle. Each patient's position was adjusted to place the lesion as high as possible in the thoracic cavity. Air was injected until the lung was displaced from the path of the biopsy needle. After completion of the biopsy, a comparable volume of air was aspirated. EVALUATION: In all patients, satisfactory displacement of the lung from the biopsy site was achieved with the artificial pneuomothorax procedure enabling the target lesion to be reached. No postoperative air leaks requiring tube drainage were encountered. CONCLUSIONS: Artificial pneumothorax with position adjustment is a safe and effective method that provides access for computed tomographic-guided biopsy of mediastinal lesions without the risks of traversing aerated lung tissue and with a relatively low volume of injected air.